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Chen, Yvonne Y., and Jeremy B. Caplan. "Rhythmic Activity and Individual Variability in Recognition Memory: Theta Oscillations Correlate with Performance whereas Alpha Oscillations Correlate with ERPs." Journal of Cognitive Neuroscience 29, no. 1 (January 2017): 183–202. http://dx.doi.org/10.1162/jocn_a_01033.
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During study trials of a recognition memory task, alpha (∼10 Hz) oscillations decrease, and concurrently, theta (4–8 Hz) oscillations increase when later memory is successful versus unsuccessful (subsequent memory effect). Likewise, at test, reduced alpha and increased theta activity are associated with successful memory (retrieval success effect). Here we take an individual-differences approach to test three hypotheses about theta and alpha oscillations in verbal, old/new recognition, measuring the difference in oscillations between hit trials and miss trials. First, we test the hypothesis that theta and alpha oscillations have a moderately mutually exclusive relationship; but no support for this hypothesis was found. Second, we test the hypothesis that theta oscillations explain not only memory effects within participants, but also individual differences. Supporting this prediction, durations of theta (but not alpha) oscillations at study and at test correlated significantly with d′ across participants. Third, we test the hypothesis that theta and alpha oscillations reflect familiarity and recollection processes by comparing oscillation measures to ERPs that are implicated in familiarity and recollection. The alpha-oscillation effects correlated with some ERP measures, but inversely, suggesting that the actions of alpha oscillations on memory processes are distinct from the roles of familiarity- and recollection-linked ERP signals. The theta-oscillation measures, despite differentiating hits from misses, did not correlate with any ERP measure; thus, theta oscillations may reflect elaborative processes not tapped by recollection-related ERPs. Our findings are consistent with alpha oscillations reflecting visual inattention, which can modulate memory, and with theta oscillations supporting recognition memory in ways that complement the most commonly studied ERPs.
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Young, M. P., K. Tanaka, and S. Yamane. "On oscillating neuronal responses in the visual cortex of the monkey." Journal of Neurophysiology 67, no. 6 (June 1, 1992): 1464–74. http://dx.doi.org/10.1152/jn.1992.67.6.1464.
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1. Recent studies of visual processing in the cat have shown stimulus-related oscillations in the 30- to 70-Hz range. We sought to replicate these findings in the monkey. 2. We recorded multiunit activity (MUA) and local field potentials (LFP) in areas V1 and middle-temporal area (MT), and MUA from the inferotemporal cortex (IT) of monkeys (Macaca fuscata). Recordings in all areas were made under conditions of anesthesia as close as possible to those in previous studies of oscillating responses in the cat. In addition, we recorded MUA in the IT of behaving monkeys while the monkeys performed a face discrimination task. 3. In areas V1 and MT, LFP power spectra showed broadband increases (1-100 Hz) in amplitude on stimulation by swept optimally oriented light bars, and not a shift in power from low to midfrequency, as has been reported in the cat. 4. MUA autocorrelograms (ACGs) classified by fitting Gabor functions, showed oscillations at approximately 10% of recording sites in V1 and MT, but these oscillations were in the alpha range (12-13 Hz). 5. MUA ACGs from IT in the anesthetized monkey showed no oscillations. 6. For MUA ACGs from IT in the behaving monkey, only two recording sites (out of 50) showed an oscillating response, with frequencies of 44 and 48 Hz. One oscillating response was associated with stimulation, and the other was associated with the absence of stimulation. 7. The very low incidence in the monkey of oscillating responses in the 30- to 70-Hz range (2 in 424 recordings made at 142 recording sites) and the absence of stimulus dependence suggest that such oscillations are unlikely to serve a function in the monkey, and that there may be a species difference between monkey and cat in the dynamics of neural activity in the visual cortex. 8. We found that methods of classifying responses as oscillating used in some of the studies of the cat may have led to overestimation of both the number of sites showing oscillation and the number of pairs of sites showing phase coherence. These problems arise from the failure to take account of badness of fit between Gabor functions and their corresponding ACGs, and from Gabor functions "ringing" in response to short phasic phenomena that could be consistent with nonoscillatory activity.
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Yan, Qin, and Qingfang Zhang. "Theta Band (4–8 Hz) Oscillations Reflect Online Processing of Rhythm in Speech Production." Brain Sciences 12, no. 12 (November 22, 2022): 1593. http://dx.doi.org/10.3390/brainsci12121593.
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How speech prosody is processed in the brain during language production remains an unsolved issue. The present work used the phrase-recall paradigm to analyze brain oscillation underpinning rhythmic processing in speech production. Participants were told to recall target speeches aloud consisting of verb–noun pairings with a common (e.g., [2+2], the numbers in brackets represent the number of syllables) or uncommon (e.g., [1+3]) rhythmic pattern. Target speeches were preceded by rhythmic musical patterns, either congruent or incongruent, created by using pure tones at various temporal intervals. Electroencephalogram signals were recorded throughout the experiment. Behavioral results in 2+2 target speeches showed a rhythmic priming effect when comparing congruent and incongruent conditions. Cerebral-acoustic coherence analysis showed that neural activities synchronized with the rhythmic patterns of primes. Furthermore, target phrases that had congruent rhythmic patterns with a prime rhythm were associated with increased theta-band (4–8 Hz) activity in the time window of 400–800 ms in both the 2+2 and 1+3 target conditions. These findings suggest that rhythmic patterns can be processed online. Neural activities synchronize with the rhythmic input and speakers create an abstract rhythmic pattern before and during articulation in speech production.
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Goldreich, D., R. J. Krauzlis, and S. G. Lisberger. "Effect of changing feedback delay on spontaneous oscillations in smooth pursuit eye movements of monkeys." Journal of Neurophysiology 67, no. 3 (March 1, 1992): 625–38. http://dx.doi.org/10.1152/jn.1992.67.3.625.
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1. Our goal was to discriminate between two classes of models for pursuit eye movements. The monkey's pursuit system and both classes of model exhibit oscillations around target velocity during tracking of ramp target motion. However, the mechanisms that determine the frequency of oscillations differ in the two classes of model. In "internal feedback" models, oscillations are controlled by internal feedback loops, and the frequency of oscillation does not depend strongly on the delay in visual feedback. In "image motion" models, oscillations are controlled by visual feedback, and the frequency of oscillation does depend on the delay in visual feedback. 2. We measured the frequency of oscillation during pursuit of ramp target motion as a function of the total delay for visual feedback. For the shortest feedback delays of approximately 70 ms, the frequency of oscillation was between 6 and 7 Hz. Increases in feedback delay caused decreases in the frequency of oscillation. The effect of increasing feedback delay was similar, whether the increases were produced naturally by dimming and decreasing the size of the tracking target or artificially with the computer. We conclude that the oscillations in eye velocity during pursuit of ramp target motion are controlled by visual inputs, as suggested by the image motion class of models. 3. Previous experiments had suggested that the visuomotor pathways for pursuit are unable to respond well to frequencies as high as the 6-7 Hz at which eye velocity oscillates in monkeys. We therefore tested the response to target vibration at an amplitude of +/- 8 degrees/s and frequencies as high as 15 Hz. For target vibration at 6 Hz, the gain of pursuit, defined as the amplitude of eye velocity divided by the amplitude of target velocity, was as high as 0.65. We conclude that the visuomotor pathways for pursuit are capable of processing image motion at high temporal frequencies. 4. The gain of pursuit was much larger when the target vibrated around a constant speed of 15 degrees/s than when it vibrated around a stationary position. This suggests that the pursuit pathways contain a switch that must be closed to allow the visuomotor pathways for pursuit to operate at their full gain. The switch apparently remains open for target vibration around a stationary position. 5. The responses to target vibration revealed a frequency at which eye velocity lagged target velocity by 180 degrees and at which one monkey showed a local peak in the gain of pursuit.(ABSTRACT TRUNCATED AT 400 WORDS)
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Flint, A. C., and B. W. Connors. "Two types of network oscillations in neocortex mediated by distinct glutamate receptor subtypes and neuronal populations." Journal of Neurophysiology 75, no. 2 (February 1, 1996): 951–57. http://dx.doi.org/10.1152/jn.1996.75.2.951.
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1. Two distinct forms of spontaneous synchronous oscillations were investigated with field potential recordings in slices of rat somatosensory cortex in vitro. 2. The first type of synchronous oscillation was activated by low extracellular [Mg2+] and had dominant frequencies of 8-12 Hz. It was abolished reversibly by the N-methyl-D-aspartate (NMDA) receptor antagonists D-2-amino-5-phosphonovaleric acid and was relatively unaffected by the non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX). The duration of oscillatory events was increased by blocking gamma-aminobuturic acid-A receptors with bicuculline or by activating metabotropic glutamate receptors with trans-1-aminocyclopentane-1,3-dicarboxylic acid. 3. A second form of synchronous oscillation was activated by acute application of kainic acid (10 microM), had dominant frequencies of 1-5 Hz, and was abolished reversibly by DNQX. Low concentrations of domoic acid mimicked the effects of kainate, but alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid or quisqualic acid did not, suggesting a role for the GluR5-7 and KA1-2 glutamate receptor subunits. 4. Surgical isolation of cortical layers showed that spontaneous NMDA receptor-dependent oscillations originated within layer 5 exclusively, but kainate receptor-dependent oscillations were uniquely generated by neurons in layers 2/3. 5. Our results suggest that neocortical neurons in layers 2/3 and layer 5 can independently generate two distinct forms of rhythmic population activity, each dependent upon activation of a different subtype of glutamate receptor.
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Leonard, Bridget L., Roger G. Evans, Michael A. Navakatikyan, and Simon C. Malpas. "Differential neural control of intrarenal blood flow." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 279, no. 3 (September 1, 2000): R907—R916. http://dx.doi.org/10.1152/ajpregu.2000.279.3.r907.
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To test whether renal sympathetic nerve activity (RSNA) can differentially regulate blood flow in the renal medulla (MBF) and cortex (CBF) of pentobarbital sodium-anesthetized rabbits, we electrically stimulated the renal nerves while recording total renal blood flow (RBF), CBF, and MBF. Three stimulation sequences were applied 1) varying amplitude (0.5–8 V), 2) varying frequency (0.5–8 Hz), and 3) a modulated sinusoidal pattern of varying frequency (0.04–0.72 Hz). Increasing amplitude or frequency of stimulation progressively decreased all flow variables. RBF and CBF responded similarly, but MBF responded less. For example, 0.5-V stimulation decreased CBF by 20 ± 9%, but MBF fell by only 4 ± 6%. The amplitude of oscillations in all flow variables was progressively reduced as the frequency of sinusoidal stimulation was increased. An increased amplitude of oscillation was observed at 0.12 and 0.32 Hz in MBF and to a lesser extent RBF, but not CBF. MBF therefore appears to be less sensitive than CBF to the magnitude of RSNA, but it is more able to respond to these higher frequencies of neural stimulation.
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Akeju, Oluwaseun, Kara J. Pavone, M. Brandon Westover, Rafael Vazquez, Michael J. Prerau, Priscilla G. Harrell, Katharine E. Hartnack, et al. "A Comparison of Propofol- and Dexmedetomidine-induced Electroencephalogram Dynamics Using Spectral and Coherence Analysis." Anesthesiology 121, no. 5 (November 1, 2014): 978–89. http://dx.doi.org/10.1097/aln.0000000000000419.
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Abstract Background Electroencephalogram patterns observed during sedation with dexmedetomidine appear similar to those observed during general anesthesia with propofol. This is evident with the occurrence of slow (0.1 to 1 Hz), delta (1 to 4 Hz), propofol-induced alpha (8 to 12 Hz), and dexmedetomidine-induced spindle (12 to 16 Hz) oscillations. However, these drugs have different molecular mechanisms and behavioral properties and are likely accompanied by distinguishing neural circuit dynamics. Methods The authors measured 64-channel electroencephalogram under dexmedetomidine (n = 9) and propofol (n = 8) in healthy volunteers, 18 to 36 yr of age. The authors administered dexmedetomidine with a 1-µg/kg loading bolus over 10 min, followed by a 0.7 µg kg−1 h−1 infusion. For propofol, the authors used a computer-controlled infusion to target the effect-site concentration gradually from 0 to 5 μg/ml. Volunteers listened to auditory stimuli and responded by button press to determine unconsciousness. The authors analyzed the electroencephalogram using multitaper spectral and coherence analysis. Results Dexmedetomidine was characterized by spindles with maximum power and coherence at approximately 13 Hz (mean ± SD; power, −10.8 ± 3.6 dB; coherence, 0.8 ± 0.08), whereas propofol was characterized with frontal alpha oscillations with peak frequency at approximately 11 Hz (power, 1.1 ± 4.5 dB; coherence, 0.9 ± 0.05). Notably, slow oscillation power during a general anesthetic state under propofol (power, 13.2 ± 2.4 dB) was much larger than during sedative states under both propofol (power, −2.5 ± 3.5 dB) and dexmedetomidine (power, −0.4 ± 3.1 dB). Conclusion The results indicate that dexmedetomidine and propofol place patients into different brain states and suggest that propofol enables a deeper state of unconsciousness by inducing large-amplitude slow oscillations that produce prolonged states of neuronal silence.
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Feld, Gordon B., Til O. Bergmann, Marjan Alizadeh-Asfestani, Viola Stuke, Jan-Philipp Wriede, Surjo Soekadar, and Jan Born. "Specific changes in sleep oscillations after blocking human metabotropic glutamate receptor 5 in the absence of altered memory function." Journal of Psychopharmacology 35, no. 6 (April 25, 2021): 652–67. http://dx.doi.org/10.1177/02698811211005627.
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Background: Sleep consolidates declarative memory by repeated replay linked to the cardinal oscillations of non-rapid eye movement (NonREM) sleep. However, there is so far little evidence of classical glutamatergic plasticity induced by this replay. Rather, we have previously reported that blocking N-methyl-D-aspartate (NMDA) or α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors does not affect sleep-dependent consolidation of declarative memory. Aims: The aim of this study was to investigate the role of metabotropic glutamate receptor 5 (mGluR5) in memory processing during sleep. Methods: In two placebo-controlled within-subject crossover experiments with 20 healthy humans each, we used fenobam to block mGluR5 during sleep. In Experiment I, participants learned word-pairs (declarative task) and a finger sequence (procedural task) in the evening, then received the drug and recall was tested the next morning. To cover possible effects on synaptic renormalization processes during sleep, in Experiment II participants learned new word-pairs in the morning after sleep. Results/outcomes: Surprisingly, fenobam neither reduced retention of memory across sleep nor new learning after sleep, although it severely altered sleep architecture and memory-relevant EEG oscillations. In NonREM sleep, fenobam suppressed 12–15 Hz spindles but augmented 2–4 Hz delta waves, whereas in rapid eye movement (REM) sleep it suppressed 4–8 Hz theta and 16–22 Hz beta waves. Notably, under fenobam NonREM spindles became more consistently phase-coupled to the slow oscillation. Conclusions/interpretations: Our findings indicate that mGluR5-related plasticity is not essential for memory processing during sleep, even though mGlurR5 are strongly implicated in the regulation of the cardinal sleep oscillations.
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Destexhe, A., T. Bal, D. A. McCormick, and T. J. Sejnowski. "Ionic mechanisms underlying synchronized oscillations and propagating waves in a model of ferret thalamic slices." Journal of Neurophysiology 76, no. 3 (September 1, 1996): 2049–70. http://dx.doi.org/10.1152/jn.1996.76.3.2049.
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1. A network model of thalamocortical (TC) and thalamic reticular (RE) neurons was developed based on electrophysiological measurements in ferret thalamic slices. Single-compartment TC and RE cells included voltage- and calcium-sensitive currents described by Hodgkin-Huxley type of kinetics. Synaptic currents were modeled by kinetic models of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), gamma-aminobutyric acid-A (GABAA) and GABAB receptors. 2. The model reproduced successfully the characteristics of spindle and slow bicuculline-induced oscillations observed in vitro. The characteristics of these two types of oscillations depended on both the intrinsic properties of TC and RE cells and their pattern of interconnectivity. 3. The oscillations were organized by the reciprocal recruitment between TC and RE cells, due to their manual connectivity and bursting properties. TC cells elicited AMPA-mediated excitatory postsynaptic potentials (EPSPs) in RE cells, whereas RE cells elicited a mixture of GABAA and GABAB inhibitory postsynaptic potentials (IPSPs) in TC cells. Because of the presence of a T current, sufficiently strong EPSPs could elicit a burst in RE cells, and TC cells could generate a rebound burst following GABAergic IPSPs. Under these conditions, interaction between the TC and RE cells produced sustained oscillations. 4. In the absence of spontaneous oscillation in any cell, the TC-RE network remained quiescent. Spindle oscillations with a frequency of 9-11 Hz could be initiated by stimulation of either TC or RE neurons. A few spontaneously oscillating TC neurons recruited the entire network model into a "waxing-and waning" oscillation. These "initiator" cells could be an extremely small proportion of TC cells. 5. In intracellular recordings, TC cells display a reduced ability for burst firing after a sequence of bursts. The "waning" phase of spindles was reproduced in the network model by assuming an activity-dependent upregulation of Ih operating via a calcium-binding protein in TC cells, as shown previously in a two-cell model. 6. Following the global suppression of GABAA inhibition, the disinhibited RE cells produced prolonged burst discharges that elicited strong GABAB-mediated currents in TC cells. The enhancement of slow IPSPs in TC cells was also due to cooperativity in the activation of GABAB-mediated current. These slow IPSPs recruited TC and RE cells into slower waxing-and-waning oscillations (3-4 HZ) that were even more highly synchronized. 7. Local axonal arborization of the TC to RE and RE to TC projections allowed oscillations to propagate through the network. An oscillation starting at a single focus induced a propagating wavefront as more cells were recruited progressively. The waning of the oscillation also propagated due to upregulation of Ih in TC cells, leading to waves of spindle activity as observed in experiments. 8. The spatiotemporal properties of propagating waves in the model were highly dependent on the intrinsic properties of TC cells. The spatial pattern of spiking activity was markedly different for spindles compared with bicuculline-induced oscillations and depended on the rebound burst behavior of TC cells. The upregulation of Ih produced a refractory period so that colliding spindle waves merged into a single oscillation and extinguished. Finally, reducing the Ih conductance led to sustained oscillations. 9. Two key properties of cells in the thalamic network may account for the initiation, propagation, and termination of spindle oscillations, the activity-dependent upregulation of Ih in TC cells, and the localized axonal projections between TC and RE cells. In addition, the model predicts that a nonlinear stimulus dependency of GABAB responses accounts for the genesis of prolonged synchronized discharges following block of GABAA receptors.
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Yungher, Don A., Tiffany R. Morris, Valentina Dilda, James M. Shine, Sharon L. Naismith, Simon J. G. Lewis, and Steven T. Moore. "Temporal Characteristics of High-Frequency Lower-Limb Oscillation during Freezing of Gait in Parkinson’s Disease." Parkinson's Disease 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/606427.
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A cardinal feature of freezing of gait (FOG) is high frequency (3–8 Hz) oscillation of the legs, and this study aimed to quantify the temporal pattern of lower-body motion prior to and during FOG. Acceleration data was obtained from sensors attached to the back, thighs, shanks, and feet in 14 Parkinson’s disease patients performing timed-up-and-go tasks, and clinical assessment of FOG was performed by two experienced raters from video. A total of 23 isolated FOG events, defined as occurring at least 5 s after gait initiation and with no preceding FOG, were identified from the clinical ratings. The corresponding accelerometer records were analyzed within a 4 s window centered at the clinical onset of freezing. FOG-related high-frequency oscillation (an increase in power in the 3–8 Hz band >3 SD from baseline) followed a distal to proximal onset pattern, appearing at the feet, shanks, thighs, and then back over a period of 250 ms. Peak power tended to decrease as the focus of oscillation moved from feet to back. There was a consistent delay (mean 872 ms) between the onset of high frequency oscillation at the feet and clinical onset of FOG. We infer that FOG is characterized by high frequency oscillation at the feet, which progresses proximally and is mechanically damped at the torso.
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Boynton, B. R., G. Glass, I. D. Frantz, and J. J. Fredberg. "Rib cage vs. abdominal displacement in dogs during forced oscillation to 32 Hz." Journal of Applied Physiology 67, no. 4 (October 1, 1989): 1472–78. http://dx.doi.org/10.1152/jappl.1989.67.4.1472.
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Allen et al. (J. Clin. Invest. 76: 620–629, 1985) reported that during oscillatory forcing the base of isolated canine lungs distends preferentially relative to the apex as frequency and tidal volume increase. The tendency toward such nonuniform phasic lung distension might influence phasic displacement of the rib cage (RC) relative to the abdomen (ABD). To test this hypothesis we measured RC and ABD displacement in four anesthetized dogs during forced oscillation. Sinusoidal volume changes were delivered through a tracheostomy at 1–32 Hz and measured by body plethysmography. RC and ABD displacements were measured by inductive plethysmography. During oscillation with air at fixed tidal volumes (10–80 ml) RC, normalized to unity at 1 Hz, increased to 2.06–2.22 at 8 Hz (P less than 0.001) and then decreased to 1.06–1.35 (P less than 0.0025) at 32 Hz. ABD, normalized to unity at 1 Hz, was 1.12–1.16 at 4 Hz (P less than 0.001) and decreased to 0.12–0.14 at 32 Hz (P less than 0.001). Displacement of ABD relative to RC did not increase systematically with increasing tidal volume during sinusoidal forcing at any frequency. Thus we found no discernible influence of nonuniform phasic lung distension on chest wall behavior. We infer that in the dog the nonuniform mechanical behavior of the chest wall dominates the nonuniform (but opposing) mechanical tendency of the lung.
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Steriade, M., F. Amzica, and A. Nunez. "Cholinergic and noradrenergic modulation of the slow (approximately 0.3 Hz) oscillation in neocortical cells." Journal of Neurophysiology 70, no. 4 (October 1, 1993): 1385–400. http://dx.doi.org/10.1152/jn.1993.70.4.1385.
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1. The pedunculopontine tegmental (PPT) cholinergic nucleus and the locus coeruleus (LC) noradrenergic nucleus were electrically stimulated to investigate their effects on the recently described slow oscillation (approximately 0.3 Hz) of neocortical neurons. Intracellular recordings of slowly oscillating, regular-spiking and intrinsically bursting neurons from cortical association areas 5 and 7 (n = 140) were performed in anesthetized cats. 2. Pulse trains to the PPT nucleus produced the blockage of rhythmic (approximately 0.3 Hz) depolarizing-hyperpolarizing sequences in 79% of tested cortical neurons and transformed this slow cellular rhythm into tonic firing. The latency of the cortical cellular response to PPT stimulation was 1.2 +/- 0.5 (SE) s and its duration was 15.9 +/- 1.9 s. The PPT-elicited suppression of the slow cellular oscillation was accompanied by an activation of the electroencephalogram (EEG) having a similar time course. Fast Fourier transform analyses of EEG activities before and after PPT stimulation showed that the PPT-evoked changes consisted of decreased power of slow rhythms (0-8 Hz) and increased power of fast rhythms (24-33 Hz); these changes were statistically significant. 3. The blockage of the slow cellular oscillation was mainly achieved through the diminution or suppression of the long-lasting hyperpolarizations separating the rhythmic depolarizing envelopes. This effect was observed even when PPT pulse trains disrupted the oscillation without inducing overt depolarization and increased firing rate. The durations of the prolonged hyperpolarizations were measured during a 40-s window (20 s before and 20 s after the PPT pulse train) and were found to decrease from 1.5 +/- 0.2 to 0.7 +/- 0.1 s. The values of the product resulting from the duration (in seconds), the amplitude (in millivolts), and number of such hyperpolarizing events within 20-s periods were 51.5 +/- 5 and 5.1 +/- 1.9 before and after PPT stimulation, respectively. 4. The PPT effect was suppressed by systemic administration of a muscarinic antagonist, scopolamine, but not by mecamylamine, a nicotinic antagonist. 5. The PPT effect on cellular and EEG cortical slow oscillation survived, although its duration was reduced, in animals with kainate-induced lesions of thalamic nuclei projecting to areas 5 and 7 (n = 3) as well as in animals with similar excitotoxic lesions leading to extensive neuronal loss in nucleus basalis (n = 2). These data indicate that the PPT effect is transmitted to neocortex through either thalamic or basal forebrain relays.(ABSTRACT TRUNCATED AT 400 WORDS)
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Liu, Peng, Hongkui Shen, and Shumei Ji. "Functional Connectivity Pattern Analysis Underlying Neural Oscillation Synchronization during Deception." Neural Plasticity 2019 (February 13, 2019): 1–10. http://dx.doi.org/10.1155/2019/2684821.
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To characterize system cognitive processes during deception, event-related coherence was computed to investigate the functional connectivity among brain regions underlying neural oscillation synchronization. In this study, 15 participants were randomly assigned to honesty or deception groups and were instructed to tell the truth or lie when facing certain stimuli. Meanwhile, event-related potential signals were recorded using a 64-channel electroencephalography cap. Event-related coherence was computed separately in four frequency bands (delta (1-3.5 Hz), theta (4-7 Hz), alpha (8-13 Hz), and beta (14-30 HZ)) for the long-range intrahemispheric electrode pairs (F3P3, F4P4, F3T7, F4T8, F3O1, and F4O2). The results indicated that deceptive responses elicited greater connectivities in the frontoparietal and frontotemporal networks than in the frontooccipital network. Furthermore, the deception group displayed lower values of coherence in the frontoparietal electrode pairs in the alpha and beta bands than the honesty group. In particular, increased coherence in the delta and theta bands on specific left frontoparietal electrode pairs was observed. Additionally, the deception group exhibited higher values of coherence in the delta band and lower values of coherence in the beta band on the frontotemporal electrode pairs than did the honesty group. These data indicated that the active cognitive processes during deception include changes in ensemble activities between the frontal and parietal/temporal regions.
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Yussof, HW, SS Bahri, AN Phan, and AP Harvey. "Effect of oscillation amplitude on the residence time distribution for the mesoscale oscillatory baffled reactor." Chemical Engineering Research Bulletin 19 (September 10, 2017): 111. http://dx.doi.org/10.3329/cerb.v19i0.33804.
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<p>A recent development in oscillatory baffled reactor technology is down-scaling the reactor, so that it can be used for the applications such as small-scale continuous production of bioethanol. A mesoscale oscillatory baffled reactor (MOBR) with central baffle system was developed and fabricated at mesoscales (typically 5 mm diameter). This present work aims to analyse the mixing conditions inside the MOBR by evaluating the residence time distribution (RTD) against the dynamic parameters of net flow Reynolds number (<em>Re</em><em><sub>n</sub></em>) at 4.2, 8.4 and 12.6 corresponding to flow rates of 1.0, 2.0 and 3.0 ml/min respectively, oscillatory Reynolds number (<em>Re</em><em><sub>o</sub></em>) between 62 to 622, and Strouhal number (<em>Str</em>) between 0.1 to 1.59. The effect of oscillation frequency and amplitude on RTD performance were studied at frequency, amplitude, and velocity ratio ranging from 4 to 8 Hz, 1 to 4 mm and 1 to 118, respectively. Effect of oscillation frequency has resulted in the variance of the RTD increased as the oscillation frequency increased from 5 Hz to 8 Hz and peak at 6 Hz of 0.264. A further increase in the frequency above 5 Hz caused the RTD to slightly broaden and positively skewed. At frequency of 5 Hz, the RTD profiles were close to Gaussian form for all tested amplitude values from 1 mm to 4 mm. At low amplitudes, i.e. xo = 1 mm, the variance exhibited its minimum around 0.842 at <em>Re</em><em><sub>o</sub></em><em> </em>=156. An increase in <em>Re</em><em><sub>o</sub></em><em> </em>above 300 resulted in increased in the variance rapidly to 1.28, and later eliminated the plug flow behaviour and the reactor behaved similar to a single continuous stirred tank reactor.</p><p>Chemical Engineering Research Bulletin 19(2017) 111-117</p>
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Robinson, F. R., M. O. Fraser, J. R. Hollerman, and D. L. Tomko. "Yaw direction neurons in the cat inferior olive." Journal of Neurophysiology 60, no. 5 (November 1, 1988): 1739–52. http://dx.doi.org/10.1152/jn.1988.60.5.1739.
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1. Single units that responded to yaw rotation were recorded extracellularly in the caudal inferior olive (IO) of barbiturate-anesthetized cats. Of 276 neurons, 55 responded reliably to yaw, and extensive quantitative data were recorded from 25. 2. No yaw-sensitive IO neuron responded to somatosensory or auditory stimuli but two responded, though unreliably, to flash. 3. Yaw-sensitive IO cells fired at low (1-4 spikes/s), irregular rates during one direction of rotation. Though cells responded reliably during yaw, firing rates varied considerably from cycle to cycle. Rotation speed and acceleration were not represented in any cell's firing rate. 4. Eighty five percent (47/55) of yaw-sensitive cells fired during contralateral rotation, 9% (5/55) during ipsilateral rotation, and 6% (3/55) fired from late in the ipsilateral phase of a sinusoidal oscillation to the middle of the contralateral phase. 5. Responses were tested to 0.1-Hz sinusoidal yaw oscillations with a range of peak angular velocities (1-200 degrees/s). Thresholds were not sharp because of the cycle to cycle variability in response rates but were estimated using averaged responses. The peak rate of the most sensitive cell was driven to criterion (2 SD above spontaneous rate) by an oscillation with a peak velocity of 1 degrees/s. Other cells reached criterion between 5 and 50 degrees/s. 6. Sinusoidal oscillation at all frequencies tested (0.01-0.5 Hz) elicited approximately the same firing rates. Even at 0.01 Hz cells responded well. Responses lagged acceleration by approximately 25 degrees at 0.01 Hz and shifted to later parts of the cycle as frequency increased so that firing lagged acceleration by approximately 200 degrees at 0.5 Hz. 7. Histological reconstruction showed that yaw-sensitive neurons were recorded in olivary subnucleus beta (N beta), the dorsal cap of Kooy (DC), the posterior medial region of the medial accessory division of the inferior olive (MAO), and in the medial-lateral center of the caudal MAO. 8. Yaw-sensitive neurons in the inferior olive provide a signal to the cerebellum that indicates the direction of passive rotation over a wide range of velocity and acceleration. The signal from individual neurons does not reliably encode either rotation velocity or acceleration. Yaw-sensitive IO neurons are therefore unlike other central vestibular neurons but are similar to somatosensory IO cells which signal the presence, but not the intensity of a stimulus.
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Timofeev, I., and M. Steriade. "Low-frequency rhythms in the thalamus of intact-cortex and decorticated cats." Journal of Neurophysiology 76, no. 6 (December 1, 1996): 4152–68. http://dx.doi.org/10.1152/jn.1996.76.6.4152.
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1. The patterns and synchronization of low-frequency, sleeplike rhythms (slow, spindle and delta oscillations) were compared in the intact-cortex and decorticated hemispheres of cats under ketamine-xylazine anesthesia. Intracellular recordings were performed in intact and decorticated hemispheres from 58 rostrolateral thalamic reticular (RE) neurons and from 164 thalamocortical (TC) neurons in the ventrolateral (VL) nucleus. In the decorticated hemisphere, dual intracellular recordings were performed from five RE-VL cell couples and from 12 TC cell couples within the VL nucleus. In addition, field potentials were simultaneously recorded from the neocortex (electroencephalogram) and ipsilateral thalamus [electrothalamogram (EThG)] of the intact (right) hemisphere, while EThG was recorded from the VL nucleus of the decorticated (left) hemisphere. 2. The slow oscillation (< 1 Hz) was absent in all 72 VL cells and in 23 of 25 RE cells from the decorticated hemisphere, as well as in the EThG recorded from the VL nucleus in the decorticated hemisphere, whereas it was simultaneously present in the cortex and thalamus of the intact hemisphere. The remaining two RE neurons (8%) in the decorticated hemisphere oscillated in close time relation with the slow oscillation in the cortex and thalamus of the opposite hemisphere; averaged activities showed that the onset of depolarization in RE cell followed 12 ms after the sharp depth-negative (depolarizing) component in the contralateral cortex. We view this result as the electrophysiological correlate of a disynaptic excitatory pathway consisting of crossed cortical projections, first relayed in contralateral dorsal thalamic nuclei. 3. The patterns of thalamic spindles (7–14 Hz) differed between the two hemispheres. Whereas the decorticated hemisphere displayed prolonged, waxing and waning spindles, the spindles in the intact-cortex hemisphere were short and exclusively waning and followed the depth-negative component of cortical slow oscillation. This result indicates that the synchronized corticothalamic drive associated with the slow oscillation fully entrains thalamic circuits from the onset of spindles, thus preventing further waxing. Similar differences between waxing and waning and waning spindles were obtained by stimulating with different intensities the thalamus in the decorticated hemisphere. 4. Simultaneous intracellular recordings from two VL cells or from RE and VL cells showed nearly simultaneous spindle sequences in the decorticated hemisphere. 5. The hyperpolarization-activated intrinsic delta oscillation (1–4 Hz) of TC cells was asynchronous in the decorticated hemisphere. 6. These results strengthen the idea that the slow oscillation is cortical in origin; demonstrate a full, short-range, intrathalamic synchrony of spindles in the absence of cortex; and indicate that the pattern of spindles, a sleep rhythm that is conventionally regarded as purely thalamic, is shaped by the corticothalamic feedback.
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Bergman, H., T. Wichmann, B. Karmon, and M. R. DeLong. "The primate subthalamic nucleus. II. Neuronal activity in the MPTP model of parkinsonism." Journal of Neurophysiology 72, no. 2 (August 1, 1994): 507–20. http://dx.doi.org/10.1152/jn.1994.72.2.507.
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1. The neuronal mechanisms underlying the major motor signs of Parkinson's disease were studied in the basal ganglia of parkinsonian monkeys. Three African green monkeys were systemically treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) until parkinsonian signs, including akinesia, rigidity, and a prominent 4- to 8-Hz tremor, appeared. The activity of neurons in the subthalamic nucleus (STN) and in the internal segment of the globus pallidus (GPi) was recorded before (STN, n = 220 cells; GPi, n = 175 cells) and after MPTP treatment (STN, n = 326 cells; GPi, n = 154 cells). 2. In STN the spontaneous firing rate was significantly increased from 19 +/- 10 (SD) spikes/s before to 26 +/- 15 spikes/s after MPTP treatment. Division of STN neurons recorded after MPTP treatment into cells with rhythmic bursts of discharge occurring at 4–8 Hz (as defined by autocorrelation analysis) and neurons without 4- to 8-Hz periodic activity revealed an even more prominent increase in the firing rate of the 4- to 8-Hz oscillatory neurons. 3. In GPi overall changes in the average firing rate of cells were inconsistent between different animals and behavioral states. However, the average firing rate of the subpopulation of neurons with 4- to 8-Hz periodic oscillatory activity after treatment with MPTP was significantly increased over that of all neurons before MPTP treatment (from 53 to 76 spikes/s, averaged across monkeys). 4. In the normal state the percentage of neurons with burst discharges (as defined by autocorrelation analysis) was 69% and 78% in STN and GPi, respectively. After MPTP treatment the percentage of cells that discharged in bursts was increased to 79% and 89%, respectively. At the same time the average burst duration decreased (from 121 +/- 98 to 81 +/- 99 ms in STN and from 213 +/- 120 to 146 +/- 134 ms in GPi) with no significant change in the average number of spikes per burst. 5. Periodic oscillatory neuronal activity at low frequency, highly correlated with tremor, was detected in a large number of cells in STN and GPi after MPTP treatment (average oscillation frequency 6.0 and 5.1 Hz, respectively). The autocorrelograms of spike trains of these neurons confirm that the periodic oscillatory activity was very stable. The percentage of cells with 4- to 8-Hz periodic activity significantly increased from 2% to 16% in STN and from 0.6% to 25% in GPi with the MPTP treatment.(ABSTRACT TRUNCATED AT 400 WORDS)
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Tan, Xiao-Ming, Hui-fang Liu, Zhi-Gang Yang, Jie Zhang, Zhong-gang Wang, and Yu-wei Wu. "Characteristics and Mechanism Analysis of Aerodynamic Noise Sources for High-Speed Train in Tunnel." Complexity 2018 (December 9, 2018): 1–19. http://dx.doi.org/10.1155/2018/5858415.
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We aim to study the characteristics and mechanism of the aerodynamic noise sources for a high-speed train in a tunnel at the speeds of 50 m/s, 70 m/s, 83 m/s, and 97 m/s by means of the numerical wind tunnel model and the nonreflective boundary condition. First, the large eddy simulation model was used to simulate the fluctuating flow field around a 1/8 scale model of a high-speed train that consists of three connected vehicles with bogies in the tunnel. Next, the spectral characteristics of the aerodynamic noise source for the high-speed train were obtained by performing a Fourier transform on the fluctuating pressure. Finally, the mechanism of the aerodynamic noise was studied using the sound theory of cavity flow and the flow field structure. The results show that the spectrum pattern of the sound source energy presented broadband and multipeak characteristics for the high-speed train. The dominant distribution frequency range is from 100 Hz to 4 kHz for the high-speed train, accounting for approximately 95.1% of the total sound source energy. The peak frequencies are 400 Hz and 800 Hz. The sound source energy at 400 Hz and 800 Hz is primarily from the bogie cavities. The spectrum pattern of the sound source energy has frequency similarity for the bottom structure of the streamlined part of the head vehicle. The induced mode of the sound source energy is probably the dynamic oscillation mode of the cavity and the resonant oscillation mode of the cavity for the under-car structure at 400 Hz and 800 Hz, respectively. The numerical computation model was checked by the wind tunnel test results.
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Hantos, Z., A. Adamicza, E. Govaerts, and B. Daroczy. "Mechanical impedances of lungs and chest wall in the cat." Journal of Applied Physiology 73, no. 2 (August 1, 1992): 427–33. http://dx.doi.org/10.1152/jappl.1992.73.2.427.
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In nine anesthetized and paralyzed cats, the mechanical impedances of the total respiratory system (Zrs) and the lungs (ZL) were measured with small-volume pseudorandom forced oscillations between 0.2 and 20 Hz. ZL was measured after thoracotomy, and chest wall impedance (Zw) was calculated as Zw = Zrs-ZL. All impedances were determined by using input airflow [input impedance (Zi)] and output flow measured with a body box [transfer impedance (Zt)]. The differences between Zi and Zt were small for Zrs and negligible for ZL. At 0.2 Hz, the real and imaginary parts of ZL amounted to 33 +/- 4 and 35 +/- 3% (SD), respectively, of Zrs. Up to 8 Hz, all impedances were consistent with a model containing a frequency-independent resistance and inertance and a constant-phase tissue part (G-jH)/omega alpha, where G and H are coefficients for damping and elastance, respectively, omega is angular frequency, and alpha determines the frequency dependence of the real and imaginary parts. G/H was higher for Zw than for ZL (0.29 +/- 0.05 vs. 0.22 +/- 0.04, P less than 0.01). In four cats, the amplitude dependence of impedances was studied: between oscillation volumes of 0.8 and 3 ml, GL, HL, Gw, and Hw decreased on average by 3, 9, 26, and 29%, respectively, whereas the change in G/H was small for both ZL (7%) and Zw (-4%). The values of H were two to three times higher than the quasistatic elastances estimated with greater volume changes (greater than 20 ml).
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Butcher, Scott J., Michal P. Pasiorowski, and Richard L. Jones. "Effects of Changes in Lung Volume on Oscillatory Flow Rate During High-Frequency Chest Wall Oscillation." Canadian Respiratory Journal 14, no. 3 (2007): 153–58. http://dx.doi.org/10.1155/2007/514573.
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BACKGROUND: The effectiveness of high-frequency chest wall oscillation (HFCWO) in mucolysis and mucous clearance is thought to be dependant on oscillatory flow rate (Fosc). Therefore, increasing Fosc during HFCWO may have a clinical benefit.OBJECTIVES: To examine effects of continuous positive airway pressure (CPAP) on Fosc at two oscillation frequencies in healthy subjects and patients with airway obstruction.METHODS: Five healthy subjects and six patients with airway obstruction underwent 12 randomized trials of HFCWO (CPAP levels of 0 cm H2O, 2 cm H2O, 4 cm H2O, 6 cm H2O, 8 cm H2O and 10 cm H2O at frequencies of 10 Hz and 15 Hz) within a body plethysmograph, allowing measurements of changes in lung volume. Fosc was measured by reverse plethysmography using a 20 L isothermic chamber near the mouth. At the end of each randomized trial, an inspiratory capacity manoeuvre was used to determine end-expiratory lung volume (EELV).RESULTS: EELV increased significantly (P<0.05) with each level of CPAP regardless of oscillation frequency. Fosc also significantly increased with CPAP (P<0.05) and it was correlated with EELV (r=0.7935, P<0.05) in obstructed patients but not in healthy subjects (r=0.125, P=0.343). There were no significant differences in perceived comfort across the levels of CPAP.CONCLUSIONS: Significant increases in Fosc with CPAP-induced increases in lung volume were observed, suggesting that CPAP may be useful as a therapeutic adjunct in patients who have obstructive airway disease and who require HFCWO.
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Langner, G., and C. E. Schreiner. "Periodicity coding in the inferior colliculus of the cat. I. Neuronal mechanisms." Journal of Neurophysiology 60, no. 6 (December 1, 1988): 1799–822. http://dx.doi.org/10.1152/jn.1988.60.6.1799.
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1. Temporal properties of single- and multiple-unit responses were investigated in the inferior colliculus (IC) of the barbiturate-anesthetized cat. Approximately 95% of recording sites were located in the central nucleus of the inferior colliculus (ICC). Responses to contralateral stimulation with tone bursts and amplitude-modulated tones (100% sinusoidal modulation) were recorded. Five response parameters were determined for neurons at each location: 1) characteristic frequency (CF); 2) onset latency of responses to CF-tones 60 dB above threshold; 3) Q10 dB (CF divided by bandwidth of tuning curve 10 dB above threshold); 4) best modulation frequency for firing rate (rBMF or BMF; amplitude modulation frequency that elicited the highest firing rate); and 5) best modulation frequency for synchronization (sBMF; amplitude modulation frequency that elicited the highest degree of phase-locking to the modulation frequency). 2. Response characteristics for single units and multiple units corresponded closely. A BMF was obtained at almost all recording sites. For units with a similar CF, a range of BMFs was observed. The upper limit of BMF increased approximately proportional to CF/4 up to BMFs as high as 1 kHz. The lower limit of encountered BMFs for a given CF also increased slightly with CF. BMF ranges for single-unit and multiple-unit responses were similar. Twenty-three percent of the responses revealed rBMFs between 10 and 30 Hz, 51% between 30 and 100 Hz, 18% between 100 and 300 Hz, and 8% between 300 and 1000 Hz. 3. For single units with modulation transfer functions of bandpass characteristics, BMFs determined for firing rate and synchronization were similar (r2 = 0.95). 4. Onset latencies for responses to CF tones 60 dB above threshold varied between 4 and 120 ms. Ninety percent of the onset latencies were between 5 and 18 ms. A range of onset latencies was recorded for different neurons with any given CF. The onset response latency of a given unit or unit cluster was significantly correlated with the period of the BMF and the period of the CF (P less than 0.05). 5."Intrinsic oscillations" of short duration, i.e., regularly timed discharges of units in response to stimuli without a corresponding temporal structure, were frequently observed in the ICC. Oscillation intervals were commonly found to be integer multiples of 0.4 ms. Changes of stimulus frequency or intensity had only minor influences on these intrinsic oscillations.(ABSTRACT TRUNCATED AT 400 WORDS)
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Gruart, Agnès, Bernard G. Schreurs, Eduardo Domínguez del Toro, and JoséMaría Delgado-García. "Kinetic and Frequency-Domain Properties of Reflex and Conditioned Eyelid Responses in the Rabbit." Journal of Neurophysiology 83, no. 2 (February 1, 2000): 836–52. http://dx.doi.org/10.1152/jn.2000.83.2.836.
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Eyelid position and the electromyographic activity of the orbicularis oculi muscle were recorded unilaterally in rabbits during reflex and conditioned blinks. Air-puff–evoked blinks consisted of a fast downward phase followed sometimes by successive downward sags. The reopening phase had a much longer duration and slower peak velocity. Onset latency, maximum amplitude, peak velocity, and rise time of reflex blinks depended on the intensity and duration of the air puff–evoking stimulus. A flashlight focused on the eye also evoked reflex blinks, but not flashes of light, or tones. Both delayed and trace classical conditioning paradigms were used. For delayed conditioning, animals were presented with a 350-ms, 90-dB, 600-Hz tone, as conditioned stimulus (CS). For trace conditioning, animals were presented with a 10-ms, 1-k/cm2 air puff, as CS. The unconditioned stimulus (US) consisted of a 100-ms, 3-k/cm2 air puff. The stimulus interval between CS and US onsets was 250 ms. Conditioned responses (CRs) to tones were composed of downward sags that increased in number through the successive conditioning sessions. The onset latency of the CR decreased across conditioning at the same time as its maximum amplitude and its peak velocity increased, but the time-to-peak of the CR remained unaltered. The topography of CRs evoked by short, weak air puffs as the CS showed three different components: the alpha response to the CS, the CR, and the reflex response to the US. Through conditioning, CRs showed a decrease in onset latency, and an increase in maximum amplitude and peak velocity. The time-to-peak of the CR remained unchanged. A power spectrum analysis of reflex and conditioned blink acceleration profiles showed a significant ≈8-Hz oscillation within a broadband of frequencies between 4 and 15 Hz. Nose and mandible movements presented power spectrum profiles different from those characterizing reflex and conditioned blinks. It is concluded that eyelid reflex responses in the rabbit present significant differences from CRs in their profiles and metric properties, suggesting different neural origins, but that a common ≈8-Hz neural oscillator underlies lid motor performance. According to available data, the frequency of this putative oscillator seems to be related to the species size.
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Tsai, Sheng-Tzung, Todd M. Herrington, Shaun Patel, Kristen Kanoff, Alik S. Widge, Darin D. Dougherty, and Emad N. Eskandar. "149 Human Subthalamic Nucleus Neurons Exhibit Increased Theta-band Phase-locking During High-conflict Decision Making." Neurosurgery 64, CN_suppl_1 (August 24, 2017): 236. http://dx.doi.org/10.1093/neuros/nyx417.149.
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Abstract INTRODUCTION The subthalamic nucleus (STN) is thought to be preferentially engaged during high-conflict decision making in humans. The population neuronal spike rate in the STN has been reported to increase during decision conflict. Conflict and feedback-related activity is also reflected in theta-band (4-8 Hz) oscillations in the STN. It remains unknown how single-neuron activity and theta-band local field potentials (LFP) oscillations interact to support decision making. METHODS We simultaneously recorded single-neuron spike activity and LFP from the STN of eight Parkinson's disease (PD) patients while they performed a novel Aversion-Reward conflict (ARC) task. Subjects decide whether to accept an offer of a monetary reward paired with a variable risk of an aversive air puff to the eye. By varying the reward and risk, we are able to study approach-avoidance decision making across a range of conflict. Using this task, we examined the mechanism of how theta-frequency oscillation and entrained single neurons involve humans' integration of cost and benefit and decision at various conflict statuses. RESULTS >The ARC task reveals diverse risk-reward tradeoff strategies of patients. Consistent across patients, there is a positive correlation between the degree of decision conflict and reaction time (e.g., higher conflict offers require longer for subjects to decide). During high-conflict decisions, LFP in STN had increased activity of sub-theta oscillation, while increased activity of theta was found during low-conflict decisions. Single-trial STN theta-band power was correlated with degree of decision conflict. Interestingly, the decision to take or forgo the reward is predicted by theta-frequency phase-locked of STN neurons. CONCLUSION Our findings support the hypothesis that theta-band oscillations in single-neurons reflect the engagement of STN during conflict decision making. Furthermore, STN neurons with theta-band entrainment correlate with willingness to approach risk to pursue reward.
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Coe, C. I., and N. B. Pride. "Effects of correcting arterial hypoxaemia on respiratory resistance in patients with chronic obstructive pulmonary disease." Clinical Science 84, no. 3 (March 1, 1993): 325–29. http://dx.doi.org/10.1042/cs0840325.
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1. We have re-examined the effects of breathing 100% O2 on airflow resistance in hypoxaemic patients with chronic obstructive pulmonary disease. We measured arterial O2 saturation with an ear oximeter and total respiratory resistance by imposing forced oscillations at the mouth over the range 6–26 Hz during tidal breathing. Six normal subjects (mean age, 27.3 years; forced expiratory volume in 1 s, 3.82 litres) and 18 patients with severe chronic obstructive pulmonary disease and hypoxaemia (mean age, 66.6 years; forced expiratory volume in 1 s, 0.61 litres; O2 saturation breathing air, 88.4%) were examined in the sitting position breathing air and 100% O2. Eleven of the patients with chronic obstructive pulmonary disease were also studied before and after treatment with nebulized salbutamol (2.5 mg). 2. In normal subjects total respiratory resistance at 8 Hz breathing air was 2.35(0.16) cmH2Ol−1 s [mean (SEM)]; after salbutamol there was a small decrease in total respiratory resistance to 1.99(0.12) cmH2Ol−1 s. Breathing 100% O2 had no effect on total respiratory resistance either before or after salbutamol treatment. 3. In the patients with chronic obstructive pulmonary disease, values of total respiratory resistance fell with increasing frequency of oscillation; at 8 Hz, total respiratory resistance was 4.53(0.35) cmH2Ol−1 s breathing air and 3.73(0.28) cmH2Ol−1 s breathing 100% O2 (paired t-test, P = 0.001). The reduction in total respiratory resistance with O2 breathing varied between patients but was not related to the severity of hypoxaemia breathing air. Inhaled salbutamol had no significant effect on total respiratory resistance breathing air or 100% O2. 4. These studies show that arterial hypoxaemia contributes to increased airflow resistance in patients with chronic obstructive pulmonary disease. Our results show that the airway response to correcting hypoxaemia is independent of the response to β-adrenoceptor agonists. Further studies are required to investigate the site and mechanism of the airway effects of hypoxaemia.
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Ngo, Chuong, Sarah Spagnesi, Carlos Munoz, Sylvia Lehmann, Thomas Vollmer, Berno Misgeld, and Steffen Leonhardt. "Assessing regional lung mechanics by combining electrical impedance tomography and forced oscillation technique." Biomedical Engineering / Biomedizinische Technik 63, no. 6 (November 27, 2018): 673–81. http://dx.doi.org/10.1515/bmt-2016-0196.
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Abstract There is a lack of noninvasive pulmonary function tests which can assess regional information of the lungs. Electrical impedance tomography (EIT) is a radiation-free, non-invasive real-time imaging that provides regional information of ventilation volume regarding the measurement of electrical impedance distribution. Forced oscillation technique (FOT) is a pulmonary function test which is based on the measurement of respiratory mechanical impedance over a frequency range. In this article, we introduce a new measurement approach by combining FOT and EIT, named the oscillatory electrical impedance tomography (oEIT). Our oEIT measurement system consists of a valve-based FOT device, an EIT device, pressure and flow sensors, and a computer fusing the data streams. Measurements were performed on five healthy volunteers at the frequencies 3, 4, 5, 6, 7, 8, 10, 15, and 20 Hz. The measurements suggest that the combination of FOT and EIT is a promising approach. High frequency responses are visible in the derivative of the global impedance index $\Delta {Z_{{\text{eit}}}}(t,{f_{{\text{os}}}}).$ The oEIT signals consist of three main components: forced oscillation, spontaneous breathing, and heart activity. The amplitude of the oscillation component decreases with increasing frequency. The band-pass filtered oEIT signal might be a new tool in regional lung function diagnostics, since local responses to high frequency perturbation could be distinguished between different lung regions.
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Kunovac Hodžić, Vedad, Amaury H. M. J. Triaud, Heather M. Cegla, William J. Chaplin, and Guy R. Davies. "Orbital misalignment of the super-Earth π Men c with the spin of its star." Monthly Notices of the Royal Astronomical Society 502, no. 2 (January 29, 2021): 2893–911. http://dx.doi.org/10.1093/mnras/stab237.
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ABSTRACT Planet–planet scattering events can leave an observable trace of a planet’s migration history in the form of orbital misalignment with respect to the stellar spin axis, which is measurable from spectroscopic time-series taken during transit. We present high-resolution spectroscopic transits observed with ESPRESSO of the close-in super-Earth π Men c. The system also contains an outer giant planet on a wide, eccentric orbit, recently found to be inclined with respect to the inner planetary orbit. These characteristics are reminiscent of past dynamical interactions. We successfully retrieve the planet-occulted light during transit, and find evidence that the orbit of π Men c is moderately misaligned with the stellar spin axis with λ = − 24${_{.}^{\circ}}$0 ± 4${_{.}^{\circ}}$1 ($\psi = {26{_{.}^{\circ}} 9}^{+5{_{.}^{\circ}}8 }_{-4{_{.}^{\circ}}7 }$). This is consistent with the super-Earth π Men c having followed a high-eccentricity migration followed by tidal circularization, and hints that super-Earths can form at large distances from their star. We also detect clear signatures of solar-like oscillations within our ESPRESSO radial velocity time series, where we reach a radial velocity precision of ∼20 cm s−1. We model the oscillations using Gaussian processes (GPs) and retrieve a frequency of maximum oscillation, $\nu _\mathrm{max}{} = 2771^{+65}_{-60}\, \mu \mathrm{Hz}$. These oscillations make it challenging to detect the Rossiter–McLaughlin effect using traditional methods. We are, however, successful using the reloaded Rossiter–McLaughlin approach. Finally, in the appendix, we also present physical parameters and ephemerides for π Men c from a GP transit analysis of the full Transiting Exoplanet Survey Satellite Cycle 1 data.
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Salathe, M., and R. J. Bookman. "Coupling of [Ca2+]i and ciliary beating in cultured tracheal epithelial cells." Journal of Cell Science 108, no. 2 (February 1, 1995): 431–40. http://dx.doi.org/10.1242/jcs.108.2.431.
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The molecular mechanisms responsible for the regulation of ciliary beating frequency (CBF) are only partially characterized. To determine whether elevation of intracellular Ca2+ ([Ca2+]i) can cause an increase in CBF, we measured CBF and Ca2+ in single cells. Ovine tracheal epithelial cells, obtained by dissociation with protease, were grown in primary culture for 1 to 28 days in a mucus-free system. CBF of a single cilium was measured by digital video phase-contrast microscopy and on-line Fourier-transform analysis. Changes in [Ca2+]i from single cells were determined with fura-2, using ratio imaging video microscopy. Activation of a muscarinic pathway with 10 microM ACh (acetylcholine) increased [Ca2+]i from 53 +/- 9 nM (mean +/- s.e.m.) to 146 +/- 12 nM or to 264 +/- 51% above initial baseline. In the same cells, ACh increased CBF from a baseline of 7 +/- 0.5 Hz to 9 +/- 0.2 Hz or to 31 +/- 2.8% above baseline (n = 14). The elevations of both [Ca2+]i and CBF were transient and relaxed back to an elevated plateau (10/14 cells) as long as ACh was present. To elevate [Ca2+]i by mechanisms independent of a G-protein-coupled receptor, we measured [Ca2+]i and CBF of the same cells in extracellular solutions with either 0 Ca2+ (+ 1 mM EGTA) or 10 mM Ca2+. Both signals rose and fell with similar kinetics in response to changing [Ca2+]0, suggesting that changes in [Ca2+]i alone can modulate CBF. In a second independent manipulation, cells were treated with 1 microM thapsigargin, an irreversible inhibitor of the endoplasmic reticulum Ca(2+)-ATPase. Upon thapsigargin addition, 37 of 42 cells showed a transient [Ca2+]i increase and, as measured in different experiments, 8 of 9 cells showed a transient increase in CBF. Interestingly, application of ACh after cells were treated with thapsigargin produced decreases in both [Ca2+]i and CBF in 8/8 cells. Lastly, after 1–3 days in culture, addition of 10 microM ACh often produced [Ca2+]i oscillations rather than transients in [Ca2+]i. Measurements of CBF in these cells showed frequency modulation of CBF with the same peak-to-peak time interval as the Ca2+ oscillation. These results show that: (1) CBF can be measured from a single cilium and monitored on-line to track changes; (2) CBF and [Ca2+]i can be measured in the same single cell; (3) transient changes in [Ca2+]i (induced by 4 different manipulations) are associated with kinetically similar changes in CBF; and (4) [Ca2+]i oscillations are coupled to frequency modulation of ciliary beating.(ABSTRACT TRUNCATED AT 400 WORDS)
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King, M., A. Zidulka, DM Phillips, D. Wight, D. Gross, and HK Chang. "Tracheal mucus clearance in high-frequency oscillation: effect of peak flow rate bias." European Respiratory Journal 3, no. 1 (January 1, 1990): 6–13. http://dx.doi.org/10.1183/09031936.93.03010006.
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We have reported previously that high-frequency oscillation of the chest wall (HFO/CW) enhances the tracheal mucus clearance rate (TMCR) in dogs. This enhancement of TMCR may be due in part to the expiratory bias in peak flow rate (VE/VI greater than 1) that occurs during HFO/CW. We examined this factor in 8 anaesthetized, spontaneously breathing dogs by comparing TMCR during the following manoeuvers: 1) HFO/CW, applied by means of a thoracic cuff; 2) symmetric high-frequency oscillation via the airway opening (HFO/AO), applied by means of a piston pump driven by sinusoidal signal; 3) HFO/AO with an expiratory bias in peak flow, and 4) HFO/AO with an inspiratory bias in peak flow. All manoeuvers were of 5 min duration and were performed at 13 Hz and an oscillatory tidal volume of 1.5 ml.kg-1. In the latter two manoeuvers, the piston pump was driven by a nonsinusoidal signal such that peak VE/VI was greater than and less than unity, respectively. A high-impedance, cross-current flow of warmed, humidified air was provided at the tracheal tube. The order of manoeuvers 2, 3 and 4 was randomized, while manoeuver 1 was repeated at the end. TMCR was determined by direct bronchoscopic visualization of charcoal particle transport. Each HFO manoeuver was bracketed by a control period of spontaneous breathing. We found that TMCR during HFO/CW was 2.4 x control (p less than 0.001), in line with previous results.(ABSTRACT TRUNCATED AT 250 WORDS)
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Peslin, R., and C. Duvivier. "Partitioning of airway and respiratory tissue mechanical impedances by body plethysmography." Journal of Applied Physiology 84, no. 2 (February 1, 1998): 553–61. http://dx.doi.org/10.1152/jappl.1998.84.2.553.
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Peslin, R., and C. Duvivier. Partitioning of airway and respiratory tissue mechanical impedances by body plethysmography. J. Appl. Physiol. 84(2): 553–561, 1998.—We have tested the feasibility of separating the airway (Zaw) and tissue (Zti) components of total respiratory input impedance (Zrs,in) in healthy subjects by measuring alveolar gas compression by body plethysmography (Vpl) during pressure oscillations at the airway opening. The forced oscillation setup was placed inside a body plethysmograph, and the subjects rebreathedbtps gas. Zrs,in and the relationship between Vpl and airway flow (Hpl) were measured from 4 to 29 Hz. Zaw and Zti were computed from Zrs,in and Hpl by using the monoalveolar T-network model and alveolar gas compliance derived from thoracic gas volume. The data were in good agreement with previous observations: airway and tissue resistance exhibited some positive and negative frequency dependences, respectively; airway reactance was consistent with an inertance of 0.015 ± 0.003 hPa ⋅ s2 ⋅ l−1and tissue reactance with an elastance of 36 ± 8 hPa/l. The changes seen with varying lung volume, during elastic loading of the chest and during bronchoconstriction, were mostly in agreement with the expected effects. The data, as well as computer simulation, suggest that the partitioning is unaffected by mechanical inhomogeneity and only moderately affected by airway wall shunting.
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Thomas, Simon H. L., Jackie A. Langford, Robert J. D. George, and Duncan M. Geddes. "Aerosol deposition in the human lung: Effect of high-frequency oscillation on the deposition characteristics of an inhaled nebulized aerosol." Clinical Science 75, no. 5 (November 1, 1988): 535–42. http://dx.doi.org/10.1042/cs0750535.
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1. Oral high-frequency oscillation (OHFO) may have important effects on aerosol deposition in the lungs. In order to investigate these, a technique was devised to measure regional deposition rates of a nebulized radio-labelled aerosol in the lungs during normal tidal breathing. 2. The effect of three frequencies of OHFO on pulmonary aerosol deposition rate (PADR) in four normal subjects and five patients with chronic airways obstruction (CAO) were assessed using the technique. 3. In separate experiments employing three normal subjects, the effect of OHFO was studied on the deposition rate of aerosol on the oropharynx and delivery apparatus, and on the amount and characteristics of aerosol inhaled by the subjects. 4. Total PADR was significantly reduced by OHFO at 8 Hz and 16 Hz in the normal subjects, and by all three frequencies of OHFO in the CAO patients. In the normal subjects, the regional distribution of aerosol deposition was unchanged, but in the CAO patients a larger proportion of total aerosol deposition occurred in peripheral lung. 5. OHFO reduced the oropharyngeal aerosol deposition rate, increased the loss of aerosol to the atmosphere before inhalation, and increased the deposition of aerosol on the delivery apparatus. The end result was a reduction in the amount of aerosol inhaled, and in the particle sizes measured at the mouthpiece. 6. We conclude that OHFO reduces the amount of aerosol inhaled, but may improve peripheral deposition of inhaled aerosol in patients with CAO. This effect may be of value in the clinical administration of nebulized drugs.
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Nigbur, Roland, Michael X. Cohen, K. Richard Ridderinkhof, and Birgit Stürmer. "Theta Dynamics Reveal Domain-specific Control over Stimulus and Response Conflict." Journal of Cognitive Neuroscience 24, no. 5 (May 2012): 1264–74. http://dx.doi.org/10.1162/jocn_a_00128.
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Cognitive control allows us to adjust to environmental changes. The medial frontal cortex (MFC) is thought to detect conflicts and recruit additional resources from other brain areas including the lateral prefrontal cortices. Here we investigated how the MFC acts in concert with visual, motor, and lateral prefrontal cortices to support adaptations of goal-directed behavior. Physiologically, these interactions may occur through local and long-range synchronized oscillation dynamics, particularly in the theta range (4–8 Hz). A speeded flanker task allowed us to investigate conflict-type-specific control networks for perceptual and response conflicts. Theta power over MFC was sensitive to both perceptual and response conflict. Interareal theta phase synchrony, however, indicated a selective enhancement specific for response conflicts between MFC and left frontal cortex as well as between MFC and the presumed motor cortex contralateral to the response hand. These findings suggest that MFC theta-band activity is both generally involved in conflict processing and specifically involved in linking a neural network controlling response conflict.
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Moscoso, Andres, Jaime Reinoso, Jorge Samaniego, Daniel Argudo, Juan Alvarado, and Diego Galarza. "Cryopreservation of Fighting rooster spermatozoa: effect of different concentrations of glycerol." SPERMOVA 12, no. 1 (July 31, 2022): 21–26. http://dx.doi.org/10.18548/aspe/0010.04.
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Glycerol (Gly) is the cryoprotective agent (CPA) most widely used to cryopreserve rooster semen. However, its cryoprotection, toxicity, and efficacy may vary in different breeds of roosters (e.g.,fighting rooster). In this sense, this investigation evaluated the effect of different concentrations of Gly added to the Lake-Ravie extender on the kinetic variables and plasma membrane integrity (PMI, equivalent to viability) of rooster spermatozoa. A total of 42 semen ejaculates from 6 Spanish fighting roosters (collected in 7 weekly sessions) by dorsal massage technique were used to conform 7-pools. Each pool was divided into 6-aliquots and then 6 treatments were formed according to Gly concentrations: 0 (control), 2% (Gly-2), 4% (Gly-4), 6% (Gly-6), 8% (Gly-8), and 10% (Gly10). The samples were frozen in static liquid nitrogen vapors, and their post-thaw sperm quality was analyzed using the CASA system (SCA-2018®) and Fluorescence (PI). Results after thawing showed that total (MT, %) and progressive (MP, %) motilities were higher (P<0.01) with the Gly-8 treatment compared to the control group and the Gly-4 and Gly-6 treatments. Regarding the postthaw kinetics, the oscillation (WOB, %) and the beat-cross frequency (BCF, Hz) were higher (P < 0.05) in the Gly-6, Gly-8, and Gly-10 treatments compared to their control. Finally, the PMI (%) was greater with the Gly-8 treatment compared to the Gly-2 treatment (P<0.05) and the control group (P<0.01). In conclusion, the addition of 8% glycerol to the freezing medium produced better sperm cryosurvival based on higher kinetics and integrity of the plasma membrane of fighting rooster spermatozoa.
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An, Yong Woo, Yangmi Kang, Hyung-Pil Jun, and Eunwook Chang. "Anterior Cruciate Ligament Reconstructed Patients Who Recovered Normal Postural Control Have Dissimilar Brain Activation Patterns Compared to Healthy Controls." Biology 11, no. 1 (January 12, 2022): 119. http://dx.doi.org/10.3390/biology11010119.
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Postural control, which is a fundamental functional skill, reflects integration and coordination of sensory information. Damaged anterior cruciate ligament (ACL) may alter neural activation patterns in the brain, despite patients’ surgical reconstruction (ACLR). However, it is unknown whether ACLR patients with normal postural control have persistent neural adaptation in the brain. Therefore, we explored theta (4–8 Hz) and alpha-2 (10–12 Hz) oscillation bands at the prefrontal, premotor/supplementary motor, primary motor, somatosensory, and primary visual cortices, in which electrocortical activation is highly associated with goal-directed decision-making, preparation of movement, motor output, sensory input, and visual processing, respectively, during first 3 s of a single-leg stance at two different task complexities (stable/unstable) between ACLR patients and healthy controls. We observed that ACLR patients showed similar postural control ability to healthy controls, but dissimilar neural activation patterns in the brain. To conclude, we demonstrated that ACLR patients may rely on more neural sources on movement preparation in conjunction with sensory feedback during the early single-leg stance period relative to healthy controls to maintain postural control. This may be a compensatory protective mechanism to accommodate for the altered sensory inputs from the reconstructed knee and task complexity. Our study elucidates the strategically different brain activity utilized by ACLR patients to sustain postural control.
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Wouters, E. F. "Impedance measurement during air and He-O2 breathing before and after salbutamol in normal subjects." Journal of Applied Physiology 69, no. 5 (November 1, 1990): 1665–69. http://dx.doi.org/10.1152/jappl.1990.69.5.1665.
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Total respiratory resistance and reactance from 4 to 52 Hz were determined by the method of forced pseudorandom noise oscillation in 20 normal male subjects before and after inhalation of 0.200 mg salbutamol (albuterol) and before and after the subjects were equilibrated with 80% He-20% O2. During air breathing, there was a statistically significant decrease of resistance values at lower frequencies after inhalation of salbutamol. When the subject was equilibrated with 80% He-20% O2, total respiratory resistance markedly decreased at all frequencies, and a negative frequency dependence of resistance was observed between 8 and 20 Hz. Resistance values further decreased during He-O2 breathing after inhalation of salbutamol. After inhalation of salbutamol, reactance values increased during air and He-O2 breathing. The density-dependent decrease of the real part of impedance can be explained by a decrease of turbulence in the larger airways. The bronchodilating effect of salbutamol was not influenced by a change in the physical properties of the inhaled gas. During He-O2 breathing, reactance values significantly decreased, resulting in an increase of resonant frequency due to a decrease of inductive reactance. It is concluded that an increase in the capacitance of the respiratory system must be supposed to explain the increase in reactance values after inhalation of the beta-adrenergic agonist salbutamol.
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Mitru, Andrei, Augustin Semenescu, George Simion, Elena Scutelnicu, and Ionelia Voiculescu. "Study on the Weldability of Copper—304L Stainless Steel Dissimilar Joint Performed by Robotic Gas Tungsten Arc Welding." Materials 15, no. 16 (August 11, 2022): 5535. http://dx.doi.org/10.3390/ma15165535.
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The welding process of dissimilar metals, with distinct chemical, physical, thermal, and structural properties, needs to be studied and treated with special attention. The main objectives of this research were to investigate the weldability of the dissimilar joint made between the 99.95% Cu pipe and the 304L stainless steel plate by robotic Gas Tungsten Arc Welding (GTAW), without filler metal and without preheating of materials, and to find the optimum welding regime. Based on repeated adjustments of the main process parameters—welding speed, oscillation frequency, pulse frequency, main welding current, pulse current, and decrease time of welding current at the process end—it was determined the optimum process and, further, it was possible to carry out joints free of cracks and porosity, with full penetration, proper compactness, and sealing properties, that ensure safety in operating conditions. The microstructure analysis revealed the fusion zone as a multi-element alloy with preponderant participation of Cu that has resulted from mixing the non-ferrous elements and iron. Globular Cu- or Fe-rich compounds were developed during welding, being detected by Scanning Electron Microscope (SEM). Moreover, the Energy Dispersive X-ray Analysis (EDAX) recorded the existence of a narrow double mixing zone formed at the interface between the fusion zone and the 304L stainless steel that contains about 66 wt.% Fe, 18 wt.% Cr, 8 wt.% Cu, and 4 wt.% Ni. Due to the formation of Fe-, Cr-, and Ni-rich compounds, a hardness increase up to 127 HV0.2 was noticed in the fusion zone, in comparison with the copper material, where the average measured microhardness was 82 HV0.2. The optimization of the robotic welding regime was carried out sequentially, by adjusting the parameters values, and, further, by analyzing the effects of welding on the geometry and on the appearance of the weld bead. Finally, employing the optimum welding regime—14 cm/min welding speed, 125 A main current, 100 A pulse current, 2.84 Hz oscillation frequency, and 5 Hz pulse frequency—appropriate dissimilar joints, without imperfections, were achieved.
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Tabak, S., J. B. Smeets, and H. Collewijn. "Modulation of the human vestibuloocular reflex during saccades: probing by high-frequency oscillation and torque pulses of the head." Journal of Neurophysiology 76, no. 5 (November 1, 1996): 3249–63. http://dx.doi.org/10.1152/jn.1996.76.5.3249.
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1. We probed the gain and phase of the vestibuloocular reflex (VOR) during the execution of voluntary gaze saccades, with continuous oscillation or acceleration pulses, applied through a torque helmet. 2. Small-amplitude (< 1 degree), high-frequency (10-14 Hz) head oscillations in the horizontal or vertical plane were superimposed on ongoing horizontal gaze saccades (40-100 degrees). Torque pulses to the head (“with” or “against” gaze) were superimposed on 40 degrees horizontal saccades. Eye and head movements were precisely measured with sensor coils in magnetic fields. 3. Techniques were developed to separate the oscillatory (horizontal or vertical) component from the gaze shift and obtain VOR gain and phase with Fourier techniques from the relation between eye-in-head and head oscillations. These involved either subtraction of exactly matching saccades with and without oscillation (drawback: low yield) or time shifting of successive trials to synchronize the oscillations (drawback: slight time blurring of saccades). 4. The results of these matching and synchronization methods were essentially identical and consistent. Presaccadic gain values of the horizontal VOR (typically about unity) were reduced by, on average, approximately 20 and 50% during horizontal saccades of 40 and 100 degrees, respectively. These percentages may be truncated because of methodological limitations, but even after taking these into account (on the basis of simulation experiments with 2 different, theoretical profiles of suppression) our results do not support a complete saccadic VOR suppression for any substantial fraction of saccadic duration. Qualitatively similar changes were found when the vertical VOR was probed during 100 degrees horizontal saccades. 5. Concomitantly with the reductions in gain, VOR phase was advanced by approximately 20 degrees during the saccade. 6. In the wake of gaze saccades, VOR gain was consistently elevated (to approximately 1.0) above the presaccadic level (approximately 0.9). We submit that this mechanism ensures stable fixation of the newly acquired target at a time when the head is still moving substantially. 7. Although the responses to head torque pulses showed idiosyncratic asymmetries, analysis of the differences in eye and head movements for pulses with and against consistently showed a sharp fall of VOR gain at saccadic onset, following an approximately exponential course with a time constant of approximately 50 ms. This decay may be assumed to reflect VOR gain for a period of approximately 50 ms, after which secondary gaze control mechanisms become dominant. 8. The time course of the gain decay and phase shift of the VOR suggest that suppression of the “integrative (position) loop” of the VOR circuit was more complete than suppression of the direct, “velocity” pathway.
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Lorx, András, Dorottya Czövek, Zoltán Gingl, Gergely Makan, Bence Radics, Dóra Bartusek, Szabolcs Szigeti, et al. "Airway dynamics in COPD patients by within-breath impedance tracking: effects of continuous positive airway pressure." European Respiratory Journal 49, no. 2 (February 2017): 1601270. http://dx.doi.org/10.1183/13993003.01270-2016.
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Tracking of the within-breath changes of respiratory mechanics using the forced oscillation technique may provide outcomes that characterise the dynamic behaviour of the airways during normal breathing.We measured respiratory resistance (Rrs) and reactance (Xrs) at 8 Hz in 55 chronic obstructive pulmonary disease (COPD) patients and 20 healthy controls, and evaluated Rrs and Xrs as functions of gas flow (V′) and volume (V) during normal breathing cycles. In 12 COPD patients, additional measurements were made at continuous positive airway pressure (CPAP) levels of 4, 8, 14 and 20 hPa.The Rrs and Xrsversus V′ and V relationships displayed a variety of loop patterns, allowing characterisation of physiological and pathological processes. The main outcomes emerging from the within-breath analysis were the Xrsversus V loop area (AXV) quantifying expiratory flow limitation, and the tidal change in Xrs during inspiration (ΔXI) reflecting alteration in lung inhomogeneity in COPD. With increasing CPAP, AXV and ΔXI approached the normal ranges, although with a large variability between individuals, whereas mean Rrs remained unchanged.Within-breath tracking of Rrs and Xrs allows an improved assessment of expiratory flow limitation and functional inhomogeneity in COPD; thereby it may help identify the physiological phenotypes of COPD and determine the optimal level of respiratory support.
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Gilmour, K. M., and C. P. Ellington. "POWER OUTPUT OF GLYCERINATED BUMBLEBEE FLIGHT MUSCLE." Journal of Experimental Biology 183, no. 1 (October 1, 1993): 77–100. http://dx.doi.org/10.1242/jeb.183.1.77.
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The properties of asynchronous insect flight muscle have been examined using a glycerol- extracted single-fibre preparation of dorsal longitudinal muscle from the bumblebees Bombus lucorum and B. terrestris. Chemical, mechanical and thermal conditions were controlled with the objective of maximizing power output. The problems arising from diffusion limitation were avoided through a combination of fibre paring and the use of an ATP backup system. Work and power output tended to increase with increasing oscillatory strain in the range 1–5 %. Workloop shape, and hence work and power, varied with fibre extension; optimum extensions ranged from 4 to 12 %. The mechanical performance of glycerinated bumblebee muscle fibres was strongly temperature-dependent, and rate processes (frequency, power) displayed higher thermal sensitivities than processes associated with tension development (work). The experimental conditions that maximized the power output were identified as: oscillatory strain epsilon=4-5 %, extension epsilono=8-10 %, oscillation frequency f=50 Hz and temperature T=40°C. The maximum power output observed under these ‘optimal’ conditions was about 110 W kg-1 (muscle), demonstrating for the first time that glycerinated fibres are capable of producing the power predicted from free-flight studies to be required for flight: 100 W kg-1.
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Kamimura, S., and R. Kamiya. "High-frequency vibration in flagellar axonemes with amplitudes reflecting the size of tubulin." Journal of Cell Biology 116, no. 6 (March 15, 1992): 1443–54. http://dx.doi.org/10.1083/jcb.116.6.1443.
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Flagellar axonemes of sea urchin sperm display high-frequency (approximately 300 Hz) vibration with nanometer-scale amplitudes in the presence of ATP (Kamimura, S., and R. Kamiya. 1989. Nature (Lond.). 340:476-478). The vibration appears to represent normal mechanochemical interaction between dynein and microtubules because the dependence of the frequency on MgATP concentration is similar to that of the axonemal motility, and because it is inhibited by micromolar concentrations of vanadate. In this study a two-dimensional photo-sensor was used to characterize this phenomenon in detail. Several new features were revealed. First, the vibration was found to be due to a back-and-forth movement of the doublet microtubules along the axonemal length. Two beads attached to different parts of the same axoneme vibrated in unison, i.e., synchronized exactly in phase. This suggested that the outer doublet can be regarded as a stiff rod in vibrating axonemes. Second, evidence was obtained that the amplitude of the vibration reflected the number of active dynein arms. Third, under certain conditions, the vibration amplitude took stepwise values of 8 x N + 4 nm (N = 0, 1, 2, 3, or 4), indicating that the amplitude of microtubule sliding was limited by the size of tubulin dimer (8 nm) or monomer (4 nm). To explain this phenomenon, a model is presented based on an assumption that the force production by dynein is turned off when dynein is subjected to tensile force; i.e., dynein is assumed to be equipped with a feedback mechanism necessary for oscillation.
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Sedeek, Khaled A., Muneyuki Takeuchi, Klaudiusz Suchodolski, Sara O. Vargas, Motomu Shimaoka, Jay J. Schnitzer, and Robert M. Kacmarek. "Open-lung Protective Ventilation with Pressure Control Ventilation, High-frequency Oscillation, and Intratracheal Pulmonary Ventilation Results in Similar Gas Exchange, Hemodynamics, and Lung Mechanics." Anesthesiology 99, no. 5 (November 1, 2003): 1102–11. http://dx.doi.org/10.1097/00000542-200311000-00016.
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Background Pressure control ventilation (PCV), high-frequency oscillation (HFO), and intratracheal pulmonary ventilation (ITPV) may all be used to provide lung protective ventilation in acute respiratory distress syndrome, but the specific approach that is optimal remains controversial. Methods Saline lavage was used to produce acute respiratory distress syndrome in 21 sheep randomly assigned to receive PCV, HFO, or ITPV as follows: positive end-expiratory pressure (PCV and ITPV) and mean airway pressure (HFO) were set in a pressure-decreasing manner after lung recruitment that achieved a ratio of Pao2/Fio2 > 400 mmHg. Respiratory rates were 30 breaths/min, 120 breaths/min, and 8 Hz, respectively, for PCV, ITPV, and HFO. Eucapnia was targeted with peak carinal pressure of no more than 35 cm H2O. Animals were then ventilated for 4 h. Results There were no differences among groups in gas exchange, lung mechanics, or hemodynamics. Tidal volume (PCV, 8.9 +/- 2.1 ml/kg; ITPV, 2.7 +/- 0.8 ml/kg; HFO, approximately 2.0 ml/kg) and peak carinal pressure (PCV, 30.6 +/- 2.6 cm H2O; ITPV, 22.3 +/- 4.8 cm H2O; HFO, approximately 24.3 cm H2O) were higher in PCV. Pilot histologic data showed greater interstitial hemorrhage and alveolar septal expansion in PCV than in HFO or ITPV. Conclusion These data indicate that HFO, ITPV, and PCV when applied with an open-lung protective ventilatory strategy results in the same gas exchange, lung mechanics, and hemodynamic response, but pilot data indicate that lung injury may be greater with PCV.
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Nuding, Ulrich, Seiji Ono, Michael J. Mustari, Ulrich Büttner, and Stefan Glasauer. "A Theory of the Dual Pathways for Smooth Pursuit Based on Dynamic Gain Control." Journal of Neurophysiology 99, no. 6 (June 2008): 2798–808. http://dx.doi.org/10.1152/jn.90237.2008.
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The smooth pursuit eye movement (SPEM) system is much more sensitive to target motion perturbations during pursuit than during fixation. This sensitivity is commonly attributed to a dynamic gain control mechanism. Neither the neural substrate nor the functional architecture for this gain control has been fully revealed. There are at least two cortical areas that crucially contribute to smooth pursuit and are therefore eligible sites for dynamic gain control: the medial superior temporal area (MST) and the pursuit area of the frontal eye fields (FEFs), which both project to brain stem premotor structures via parallel pathways. The aim of this study was to develop a model of smooth pursuit based on behavioral, anatomical, and neurophysiological results to account for nonlinear dynamic gain control. Using a behavioral paradigm in humans consisting of a sinusoidal oscillation (4 Hz, ±8°/s) superimposed on a constant velocity target motion (0–24°/s), we were able to identify relevant gain control parameters in the model. A salient feature of our model is the emergence of two parallel pathways from higher visual cortical to lower motor areas in the brain stem that correspond to the MST and FEF pathways. Detailed analysis of the model revealed that one pathway mainly carries eye velocity related signals, whereas the other is associated mostly with eye acceleration. From comparison with known neurophysiological results we conclude that the dynamic gain control can be attributed to the FEF pathway, whereas the MST pathway serves as the basic circuit for maintaining an ongoing SPEM.
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Chandler, S. H., and L. J. Goldberg. "Effects of pontomedullary reticular formation stimulation on the neuronal networks responsible for rhythmical jaw movements in the guinea pig." Journal of Neurophysiology 59, no. 3 (March 1, 1988): 819–32. http://dx.doi.org/10.1152/jn.1988.59.3.819.
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1. In the ketamine-anesthetized guinea pig, electromyographic (EMG) responses of the digastric muscle and vertical and horizontal movements of the mandible were studied when loci within the caudal pontine and rostral medullary reticular formation were stimulated during rhythmic jaw movements (RJMs) evoked by stimulation of the masticatory area of the cortex. 2. Within these regions electrical brain stem stimulation of the pontis nucleus caudalis and nucleus gigantocellularis (PnC-Gi) of the reticular formation completely blocked RJMs at stimulus intensities as low as 10 microA while suppressing the short-latency digastric EMG response that was time locked to each cortical stimulus in the train. PnC-Gi stimulation did not, however, reduce the excitability of the short-latency corticotrigeminal excitatory pathway to digastric motoneurons when tested by short pulse train stimulation at 2 Hz (3 pulses, 500 Hz, 0.3 ms) in the absence of RJMs. 3. Short trains (80 ms) of PnC-Gi stimuli delivered at various phases of the RJM cycle produced a permanent phase shift of the RJM rhythm. If the stimulus train was delivered at an early phase of the cycle (8-40%) the next cycle onset was advanced; if the train was delivered later in the cycle (60-80%) the next cycle onset was delayed. Long trains of PnC-Gi stimuli (100, 200, 300, and 400 ms) increased the time of onset of the next cycle by an amount directly proportional to the duration of the stimulus train. 4. Digastric EMG activity occurring during cortically evoked RJMs occupied nearly 50% of the cycle. If a short train of PnC-Gi stimuli was delivered between approximately 5 and 125 ms after the onset of the burst, the duration of the burst was significantly shortened. 5. These results demonstrate that the suppression of cortically evoked RJMs resulting from PnC-Gi stimulation is due to direct effects on central circuits responsible for the production of the RJM behavior and not on the motoneurons themselves. The evidence presented is consistent with our previously presented hypothesis that the neurons involved in mediating the short-latency corticotrigeminal pathway to digastric motoneurons are separate and distinct from those neurons comprising the central networks responsible for the production of the fundamental jaw oscillation during RJMs.
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Cowan, R. L., and C. J. Wilson. "Spontaneous firing patterns and axonal projections of single corticostriatal neurons in the rat medial agranular cortex." Journal of Neurophysiology 71, no. 1 (January 1, 1994): 17–32. http://dx.doi.org/10.1152/jn.1994.71.1.17.
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1. Spontaneous fluctuations of membrane potential, patterns of spontaneous firing, dendritic branching patterns, and intracortical and striatal axonal arborizations were compared for two types of corticostriatal neurons in the medial agranular cortex of urethan-anesthetized rats: 1) pyramidal tract (PT) cells identified by antidromic activation from the medullary pyramid and 2) crossed corticostriatal (CST) neurons identified by antidromic activation from the contralateral neostriatum. The ipsilateral corticostriatal projections of intracellularly stained PT neurons as well as contralateral corticostriatal neurons were confirmed after labeling by intracellular injection of biocytin. 2. All well-stained PT neurons had intracortical and intrastriatal collaterals. The more common type (6 of 8) was a large, deep layer V neuron that had an extensive intracortical axon arborization but a limited axon arborization in the neostriatum. The less common type of PT neuron (2 of 8) was a medium-sized, superficial layer V neuron that had a limited intracortical axon arborization but a larger and more dense intrastriatal axonal arborization. Both subclasses of PT neurons had anatomic and physiological properties associated with slow PT cells in cats and monkeys and conduction velocities < 10 m/s. All of the PT cells but one were regular spiking cells. The exception cell fired intrinsic bursts. 3. Intracellularly stained CST neurons were located in the superficial half of layer V and the deep part of layer III. Their layer I apical dendrites were few and sparsely branched. Their axons gave rise to an extensive arbor of local axon collaterals that distributed in the region of the parent neuron, frequently extending throughout the more superficial layers, including layer I. Axon collaterals were also traced to the corpus callosum, as expected from their contralateral projections, and they contributed axon collaterals to the ipsilateral neostriatum. In the neostriatum, these axons formed extended arborizations sparsely occupying a large volume of striatal tissue. All CST neurons were regular spiking cells. 4. Both types of cells displayed spontaneous membrane fluctuations consisting of a polarized state (-60 to -90 mV) that was interrupted by 0.1- to 3.0-s periods of depolarization (-55 to -45 mV) accompanied by action potentials. The membrane potential was relatively constant in each state, and transitions between the depolarized and hyperpolarized states were sometimes periodic with a frequency of 0.3–1.5 Hz. A much faster (30-45 Hz) subthreshold oscillation of the membrane potential was observed only in the depolarized state and triggered action potentials that locked to the depolarizing peaks of this rhythm.(ABSTRACT TRUNCATED AT 400 WORDS)
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Zimmermann, Sabine C., Jacqueline Huvanandana, Chinh D. Nguyen, Amy Bertolin, Joanna C. Watts, Alessandro Gobbi, Claude S. Farah, et al. "Day-to-day variability of forced oscillatory mechanics for early detection of acute exacerbations in COPD." European Respiratory Journal 56, no. 3 (May 19, 2020): 1901739. http://dx.doi.org/10.1183/13993003.01739-2019.
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BackgroundTelemonitoring trials for early detection of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) have provided mixed results. Day-to-day variations in lung function measured by the forced oscillation technique (FOT) may yield greater insight. We evaluated the clinical utility of home telemonitoring of variability in FOT measures in terms of 1) the relationship with symptoms and quality of life (QoL); and 2) the timing of variability of FOT measures and symptom changes prior to AECOPD.MethodsDaily FOT parameters at 5 Hz (resistance (R) and reactance (X); Resmon Pro Diary, Restech Srl, Milan, Italy), daily symptoms (COPD Assessment Test (CAT)) and 4-weekly QoL data (St George's Respiratory Questionnaire (SGRQ)) were recorded over 8–9 months from chronic obstructive pulmonary disease (COPD) patients. Variability of R and X was calculated as the standard deviation (sd) over 7-day running windows and we also examined the effect of varying window size. The relationship of FOT versus CAT and SGRQ was assessed using linear mixed modelling, daily changes in FOT variability and CAT prior to AECOPD using one-way repeated measures ANOVA.ResultsFifteen participants with a mean±sd age of 69±10 years and a % predicted forced expiratory volume in 1 s (FEV1) of 39±10% had a median (interquartile range (IQR)) adherence of 95.4% (79.0–98.8%). Variability of the inspiratory component of X (indicated by the standard deviation of inspiratory reactance (SDXinsp)) related to CAT and weakly to SGRQ (fixed effect estimates 1.57, 95% CI 0.65–2.49 (p=0.001) and 4.41, 95% CI −0.06 to 8.89 (p=0.05), respectively). SDXinsp changed significantly on the same day as CAT (1 day before AECOPD, both p=0.02) and earlier when using shorter running windows (3 days before AECOPD, p=0.01; accuracy=0.72 for 5-day windows).ConclusionsSDXinsp from FOT telemonitoring reflects COPD symptoms and may be a sensitive biomarker for early detection of AECOPD.
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JIANG, Yuchen, Xiao CAI, and Qingfang ZHANG. "Theta band (4~8 Hz) oscillations reflect syllables processing in Chinese spoken word production." Acta Psychologica Sinica 52, no. 10 (2020): 1199. http://dx.doi.org/10.3724/sp.j.1041.2020.01199.
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Rutecki, Paul A., and Yili Yang. "Ictal Epileptiform Activity in the CA3 Region of Hippocampal Slices Produced by Pilocarpine." Journal of Neurophysiology 79, no. 6 (June 1, 1998): 3019–29. http://dx.doi.org/10.1152/jn.1998.79.6.3019.
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Rutecki, Paul A. and Yili Yang. Ictal epileptiform activity in the CA3 region of hippocampal slices produced by pilocarpine. J. Neurophysiol. 79: 3019–3029, 1998. Pilocarpine, a muscarinic agonist, produces status epilepticus that is associated with the later development of chronic recurrent seizures. When applied to rat hippocampal slices, pilocarpine (10 μM) produced brief (<200 ms) epileptiform discharges that resembled interictal activity that occurs between seizures, as well as more prolonged synchronous neuronal activation that lasted seconds (3–20 s), and was comparable to ictal or seizures-like discharges. We assessed the factors that favored ictal patterns of activity and determined the biophysical properties of the ictal discharge. The probability of observing ictal discharges was increased when extracellular potassium ([K+]o) was increased from 5 to 7.5 mM. Raising [K+]o to 10 mM resulted in loss of ictal patterns and, in 20 of 34 slices, desynchronization of epileptiform activity. Making the artificial cerebrospinal fluid (ACSF) hyposmotic favored ictal discharges at 5 mM [K+]o, but shifted 7.5 mM [K+]o ACSF patterns to interictal discharges or desynchronized activity. Conversely, increasing osmolality suppressed ictal patterns. The pilocarpine-induced ictal discharges were blocked by atropine (1 μM, n = 5), a muscarinic antagonist, and pirenzepine (1 μM, n = 6), a selective M1 receptor antagonist. Kainate/α-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid receptor blockade stopped all epileptiform activity ( n = 8). The N-methyl-d-aspartate antagonist d,l-2-amino-5-phosphonovaleric acid (100 μM, n = 34) did not change the pattern of epileptiform activity but significantly increased the rate of interictal discharges and prolonged the duration of ictal discharges. The ictal discharge was characterized intracellularly by a depolarization that was associated with action potential generation and persisted as a membrane oscillation of 4–10 Hz. The ictal oscillations reversed in polarity at −22.7 ± 2.2 mV ( n = 11) with current-clamp recordings and −20.9 ± 3.1 mV ( n = 7) with voltage-clamp recordings. The reversal potential of the ictal discharge in the presence of the γ-aminobutyric acid-A blocker bicuculline (10 μM, n = 6) was −2.2 ± 2.6 mV and was significantly different from that measured without bicuculline. Bicuculline added to 7.5 mM [K+]o and 10 μM pilocarpine did not cause epileptiform activity to change pattern but significantly increased the rate of interictal discharges and prolonged the ictal discharge duration. Both synaptic and nonsynaptic mechanisms are important for the generation of ictal patterns of epileptiform activity. Although the synchronous epileptiform activity produced by pilocarpine required fast glutamate-mediated synaptic transmission, the transition from an interictal to ictal pattern of activity depended on [K+]o and could be influenced by extracellular space.
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Gervais, R., D. Kleinfeld, K. R. Delaney, and A. Gelperin. "Central and reflex neuronal responses elicited by odor in a terrestrial mollusk." Journal of Neurophysiology 76, no. 2 (August 1, 1996): 1327–39. http://dx.doi.org/10.1152/jn.1996.76.2.1327.
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1. We studied the responses to odor of a central olfactory processing organ and subsequent central outputs in the terrestrial mollusk Limax maximus. We used extracellular recording techniques and optical recording from preparations stained with a voltage-sensitive dye to characterize network responses in the central organ and whole nerve recording to characterize central odor-elicited outputs. 2. The central olfactory organ, the procerebral (PC) lobe, is a highly interconnected network of local olfactory interneurons that receives input from primary olfactory receptors. In the absence of odor the PC network is known to exhibit periodic waves of excitation and inhibition at a frequency of approximately 0.7 Hz. Here we study how different odor inputs affect the intrinsic oscillatory dynamics. 3. Odor stimulation causes the propagation of electrical activity along the lobe to transiently switch from the state with propagating waves, with typical phase shifts of one half cycle along the lobe, to a state with few or no phase differences along the lobe. The collapse of the phase gradient typically occurs without spatially localized changes in the amplitude of the oscillation, at least on the scale of our optical resolution, approximately 0.1 times the length of the lobe. In some trials, however, we resolved spatial nonuniformities in the magnitude of excitation across the lobe. 4. The collapse of the phase gradient along the lobe in response to odor stimulation is robust on a trial-by-trial basis. Further, the change in phase gradient can occur with little or no change in the frequency of oscillation, as occasionally observed in response to weak odor stimulation. 5. Typically odor stimulation causes changes in the frequency of the oscillation. Two odors, one attractive (potato) and one repellent (amyl acetate), produced different patterns of change; potato induced a transient increase in frequency, whereas amyl acetate produced an initial decrease in frequency followed by a transient increase in frequency. We do not yet know whether these frequency change patterns are unique to these specific odors or to their behavioral meaning. 6. Previous work demonstrated direct connections from the PC lobe to the buccal and pedal ganglia, centers controlling feeding and locomotion, respectively. To establish a correlation between odor-induced changes in the PC lobe and activation of such centers and subsequently effector organs, we recorded from selected central connectives and peripheral nerve roots. The dependence of odor-elicited activity recorded in connectives and nerve roots on PC integrity was assessed by measurements of odor-elicited activity before and after PC ablation. 7. Odor stimulation caused activation of multiple units in the cerebrobuccal connective. One output of the buccal ganglion, the salivary nerve, also showed odor-elicited activation of an identified unit, the slow burster. The necessity of the PC lobe for activation of the slow burster was established by measurements of odor-elicited activity before and after PC ablation. 8. Odor stimulation also caused activation of multiple units in the buccal mass retractor nerve. Activation of a fraction of these units (3 of 10) was dependent on an intact PC lobe, like the slow burster neuron in the salivary nerve. 9. Our results clearly show how stimuli may lead to changes in the spatial-temporal pattern of activity in a central circuit without changing the overall average level of activity in that circuit.
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Papageorgiou, Christos, Efstathios Manios, Eleftheria Tsaltas, Eleni Koroboki, Maria Alevizaki, Elias Angelopoulos, Meletios-Athanasios Dimopoulos, Charalabos Papageorgiou, and Nikolaos Zakopoulos. "Brain Oscillations Elicited by the Cold Pressor Test: A Putative Index of Untreated Essential Hypertension." International Journal of Hypertension 2017 (2017): 1–17. http://dx.doi.org/10.1155/2017/7247514.
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Objective. Essential hypertension is associated with reduced pain sensitivity of unclear aetiology. This study explores this issue using the Cold Pressor Test (CPT), a reliable pain/stress model, comparing CPT-related EEG activity in first episode hypertensives and controls. Method. 22 untreated hypertensives and 18 matched normotensives underwent 24-hour ambulatory blood pressure monitoring (ABPM). EEG recordings were taken before, during, and after CPT exposure. Results. Significant group differences in CPT-induced EEG oscillations were covaried with the most robust cardiovascular differentiators by means of a Canonical Analysis. Positive correlations were noted between ABPM variables and Delta (1–4 Hz) oscillations during the tolerance phase; in high-alpha (10–12 Hz) oscillations during the stress unit and posttest phase; and in low-alpha (8–10 Hz) oscillations during CPT phases overall. Negative correlations were found between ABPM variables and Beta2 oscillations (16.5–20 Hz) during the posttest phase and Gamma (28.5–45 Hz) oscillations during the CPT phases overall. These relationships were localised at several sites across the cerebral hemispheres with predominance in the right hemisphere and left frontal lobe. Conclusions. These findings provide a starting point for increasing our understanding of the complex relationships between cerebral activation and cardiovascular functioning involved in regulating blood pressure changes.
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VerMaas, Jacy R., Brandon J. Lew, Michael P. Trevarrow, Tony W. Wilson, and Max J. Kurz. "Children with Cerebral Palsy Have Altered Occipital Cortical Oscillations during a Visuospatial Attention Task." Cerebral Cortex 31, no. 7 (February 22, 2021): 3353–62. http://dx.doi.org/10.1093/cercor/bhab016.
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Abstract Dynamically allocating neural resources to salient features or objects within our visual space is fundamental to making rapid and accurate decisions. Impairments in such visuospatial abilities have been consistently documented in the clinical literature on individuals with cerebral palsy (CP), although the underlying neural mechanisms are poorly understood. In this study, we used magnetoencephalography (MEG) and oscillatory analysis methods to examine visuospatial processing in children with CP and demographically matched typically developing (TD) children. Our results indicated robust oscillations in the theta (4–8 Hz), alpha (8–14 Hz), and gamma (64–80 Hz) frequency bands in the occipital cortex of both groups during visuospatial processing. Importantly, the group with CP exhibited weaker cortical oscillations in the theta and gamma frequency bands, as well as slower response times and worse accuracy during task performance compared to the TD children. Furthermore, we found that weaker theta and gamma oscillations were related to greater visuospatial performance deficits across both groups. We propose that the weaker occipital oscillations seen in children with CP may reflect poor bottom-up processing of incoming visual information, which subsequently affects the higher-order visual computations essential for accurate visual perception and integration for decision-making.
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Lee, Johanna M., Oluwaseun Akeju, Kristina Terzakis, Kara J. Pavone, Hao Deng, Timothy T. Houle, Paul G. Firth, Erik S. Shank, Emery N. Brown, and Patrick L. Purdon. "A Prospective Study of Age-dependent Changes in Propofol-induced Electroencephalogram Oscillations in Children." Anesthesiology 127, no. 2 (August 1, 2017): 293–306. http://dx.doi.org/10.1097/aln.0000000000001717.
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Abstract Background In adults, frontal electroencephalogram patterns observed during propofol-induced unconsciousness consist of slow oscillations (0.1 to 1 Hz) and coherent alpha oscillations (8 to 13 Hz). Given that the nervous system undergoes significant changes during development, anesthesia-induced electroencephalogram oscillations in children may differ from those observed in adults. Therefore, we investigated age-related changes in frontal electroencephalogram power spectra and coherence during propofol-induced unconsciousness. Methods We analyzed electroencephalogram data recorded during propofol-induced unconsciousness in patients between 0 and 21 yr of age (n = 97), using multitaper spectral and coherence methods. We characterized power and coherence as a function of age using multiple linear regression analysis and within four age groups: 4 months to 1 yr old (n = 4), greater than 1 to 7 yr old (n = 16), greater than 7 to 14 yr old (n = 30), and greater than 14 to 21 yr old (n = 47). Results Total electroencephalogram power (0.1 to 40 Hz) peaked at approximately 8 yr old and subsequently declined with increasing age. For patients greater than 1 yr old, the propofol-induced electroencephalogram structure was qualitatively similar regardless of age, featuring slow and coherent alpha oscillations. For patients under 1 yr of age, frontal alpha oscillations were not coherent. Conclusions Neurodevelopmental processes that occur throughout childhood, including thalamocortical development, may underlie age-dependent changes in electroencephalogram power and coherence during anesthesia. These age-dependent anesthesia-induced electroencephalogram oscillations suggest a more principled approach to monitoring brain states in pediatric patients.