Journal articles on the topic 'Evoked potentials (Electrophysiology)'
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Tomberg, C. "Electrophysiology correlates of selective attention: somatosensory evoked potentials." Electroencephalography and Clinical Neurophysiology 95, no. 5 (November 1995): P108. http://dx.doi.org/10.1016/0013-4694(95)92409-s.
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Picton, Terry. "Human Brain Electrophysiology. Evoked Potentials and Evoked Magnetic Fields in Science and Medicine." Journal of Clinical Neurophysiology 7, no. 3 (July 1990): 450–51. http://dx.doi.org/10.1097/00004691-199007000-00010.
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Jeffreys, Aled. "Human Brain Electrophysiology: Evoked Potentials and Evoked Magnetic Fields in Science and Medicine." Trends in Neurosciences 12, no. 10 (January 1989): 413–14. http://dx.doi.org/10.1016/0166-2236(89)90083-0.
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van Dijk, J. G. "Human brain electrophysiology: Evoked potentials and evoked magnetic fields in science and medicine." Journal of the Neurological Sciences 95, no. 1 (January 1990): 113. http://dx.doi.org/10.1016/0022-510x(90)90122-4.
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Hughes, John R. "Human brain electrophysiology. Evoked potentials and evoked magnetic fields in science and medicine." Electroencephalography and Clinical Neurophysiology 73, no. 1 (July 1989): 84. http://dx.doi.org/10.1016/0013-4694(89)90022-9.
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Galloway, N. R. "Human Brain Electrophysiology: Evoked Potentials and Evoked Magnetic Fields in Science and Medicine." British Journal of Ophthalmology 74, no. 4 (April 1, 1990): 255. http://dx.doi.org/10.1136/bjo.74.4.255-a.
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Bromm, B. "Human brain electrophysiology. Evoked potentials and evoked magnetic fields in science and medicine." Pain 39, no. 3 (December 1989): 371–72. http://dx.doi.org/10.1016/0304-3959(89)90058-4.
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Papathanasiou, Eleftherios S., Thomas Cronin, Barry Seemungal, and Jaswinder Sandhu. "Electrophysiological testing in concussion: A guide to clinical applications." Journal of Concussion 2 (January 2018): 205970021881263. http://dx.doi.org/10.1177/2059700218812634.
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The diagnosis of mild traumatic brain injury in concussion is difficult since it is often unwitnessed, the patient’s recall is unreliable and initial clinical examination is often unrevealing, correlating poorly with the extent of brain injury. At present, there are no objective biomarkers of mild traumatic brain injury in concussion. Thus, a sensitive gold standard test is required to enable the effective and safe triage of patients who present to the acute services. As well as triage, objective monitoring of patients’ recovery over time and separate from clinical features that patients may develop following the injury (e.g. depression and migraine) is also needed. In contrast to neuroimaging, which is widely used to investigate traumatic brain injury patients, electrophysiology is readily available, is cheap and there are internationally recognized standardised methodologies. Herein, we review the existing literature on electrophysiological testing in concussion and mild traumatic brain injury; specifically, electroencephalogram, polysomnography, brainstem auditory evoked potentials, electro- and videonystagmography, vestibular evoked myogenic potentials, visually evoked potentials, somatosensory evoked potentials and transcranial magnetic stimulation.
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Миронович, Артем, Artem Mironovich, Сергей Бояринов, and Sergey Boyarinov. "Visual evoked potentials in veterinary ophthalmology: literature review." Russian veterinary journal 2019, no. 5 (October 1, 2019): 23–29. http://dx.doi.org/10.32416/article_5d935e18017700.96578341.
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Diagnosis of causes of blindness in veterinary ophthalmology is an urgent issue. There are a large number of diseases of central and peripheral nervous system, which can lead to partial or complete loss of visual function in animals. Visual evoked potentials (VEP) of brain can be a reliable diagnostic research method to clarify the location of the disfunction and causes of blindness in dogs and cats. Together, the visual evoked potentials and electroretinography complement each other and give a greater idea of electrophysiology of visual process. In this article on the basis of large quantity of information we examine the ways of applying this method and the problems, connected with its use. It is important to understand that the VEP can reveal the functional disturbances of visual way, but does not give the information about the structural changes.
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Thomas, E., PS Sándor, A. Ambrosini, and J. Schoenen. "A Neural Network Model of Sensitization of Evoked Cortical Responses in Migraine." Cephalalgia 22, no. 1 (February 2002): 48–53. http://dx.doi.org/10.1046/j.1468-2982.2002.00309.x.
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Migraine patients show abnormalities of cerebral electrophysiology that manifest themselves mainly during the attack interval. Cortical-evoked potentials of migraineurs fail to habituate to repetitive presentations of visual stimuli, and the amplitude of components of their auditory cortical-evoked potentials have a higher dependence on the stimulus intensities than in healthy subjects. A computer model of a neural network has been developed that is able to reproduce both these neurophysiological dysfunctions. It predicts a positive correlation between the magnitudes of both these dysfunctions. The model also offers an explanation of why mutations in the same ion channel gene with opposite consequences on channel function, e.g. P/Q Ca2+ channels in migraine, may lead to similar electrophysiological abnormalities.
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Smith, Spencer. "Translational Applications of Machine Learning in Auditory Electrophysiology." Seminars in Hearing 43, no. 03 (August 2022): 240–50. http://dx.doi.org/10.1055/s-0042-1756166.
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AbstractMachine learning (ML) is transforming nearly every aspect of modern life including medicine and its subfields, such as hearing science. This article presents a brief conceptual overview of selected ML approaches and describes how these techniques are being applied to outstanding problems in hearing science, with a particular focus on auditory evoked potentials (AEPs). Two vignettes are presented in which ML is used to analyze subcortical AEP data. The first vignette demonstrates how ML can be used to determine if auditory learning has influenced auditory neurophysiologic function. The second vignette demonstrates how ML analysis of AEPs may be useful in determining whether hearing devices are optimized for discriminating speech sounds.
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Charng, Jason, Zheng He, Algis J. Vingrys, Rebecca L. Fish, Rachel Gurrell, Bang V. Bui, and Christine T. Nguyen. "Retinal Electrophysiology Is a Viable Preclinical Biomarker for Drug Penetrance into the Central Nervous System." Journal of Ophthalmology 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/5801826.
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Objective. To examine whether retinal electrophysiology is a useful surrogate marker of drug penetrance into the central nervous system (CNS).Materials and Methods. Brain and retinal electrophysiology were assessed with full-field visually evoked potentials and electroretinograms in conscious and anaesthetised rats following systemic or local administrations of centrally penetrant (muscimol) or nonpenetrant (isoguvacine) compounds.Results. Local injections into the eye/brain bypassed the blood neural barriers and produced changes in retinal/brain responses for both drugs. In conscious animals, systemic administration of muscimol resulted in retinal and brain biopotential changes, whereas systemic delivery of isoguvacine did not. General anaesthesia confounded these outcomes.Conclusions. Retinal electrophysiology, when recorded in conscious animals, shows promise as a viable biomarker of drug penetration into the CNS. In contrast, when conducted under anaesthetised conditions confounds can be induced in both cortical and retinal electrophysiological recordings.
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Hossmann, K. A., and B. Grosse Ophoff. "Recovery of Monkey Brain after Prolonged Ischemia. I. Electrophysiology and Brain Electrolytes." Journal of Cerebral Blood Flow & Metabolism 6, no. 1 (February 1986): 15–21. http://dx.doi.org/10.1038/jcbfm.1986.3.
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Adult normothermic monkeys were submitted to 1 h of total cerebral ischemia, followed by blood recirculation for 1.5–24 h. During ischemia EEG and evoked potentials were suppressed within 12 s and 3 min, respectively. Upon recirculation, high-voltage EEG bursts began to reappear after 82–125 min, followed by gradual return of continuous background activity and near normalization of EEG frequency pattern within 24 h. Somatically evoked potentials, in contrast, exhibited only partial recovery, and consciousness did not return during the observation period. At the end of the experiments, tissue contents of sodium, potassium, calcium, and magnesium were measured in the gray and white matter of parietal lobe by atomic absorption spectros-copy. Gray matter sodium content gradually increased by ∼50% from 41.0 to 59.8 μmol/g wet wt during 24 h of recirculation. The other electrolytes including calcium did not change during the observation period. Postisch-emic recovery reported in this and the accompanying article is attributed to careful control of postischemic general physiological state and prevention or treatment of postischemic complicating side effects such as postischemic brain edema, hypotension, acidosis, pulmonary distress, and anuria. No specific drug treatment such as application of calcium antagonists or metabolic inhibitors was necessary to achieve this effect.
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McBurney, R. N., and S. J. Kehl. "Electrophysiology of neurosecretory cells from the pituitary intermediate lobe." Journal of Experimental Biology 139, no. 1 (September 1, 1988): 317–28. http://dx.doi.org/10.1242/jeb.139.1.317.
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One of the goals in studying the electrical properties of neurosecretory cells is to relate their electrical activity to the process of secretion. A central question in these studies concerns the role of transmembrane calcium ion flux in the initiation of the secretory event. With regard to the secretory process in pituitary cells, several research groups have addressed this question in vitro using mixed primary anterior pituitary cell cultures or clonal cell lines derived from pituitary tumours. Other workers, including ourselves, have used homogeneous cell cultures derived from the pituitary intermediate lobes of rats to examine the characteristics of voltage-dependent conductances, the contribution of these conductances to action potentials and their role in stimulus-secretion coupling. Pars intermedia (PI) cells often fire spontaneous action potentials whose frequency can be modified by the injection of sustained currents through the recording electrode. In quiescent cells action potentials can also be evoked by the injection of depolarizing current stimuli. At around 20 degrees C these action potentials have a duration of about 5 ms. Although most of the inward current during action potentials is carried by sodium ions, a calcium ion component can be demonstrated under abnormal conditions. Voltage-clamp experiments have revealed that the membrane of these cells contains high-threshold, L-type, Ca2+ channels and low-threshold Ca2+ channels. Since hormone release from PI cells appears not to be dependent on action potential activity but does depend on external calcium ions, it is not clear what role these Ca2+ channels play in stimulus-secretion coupling in cells of the pituitary pars intermedia. One possibility is that the low-threshold Ca2+ channels are more important to the secretory process than the high-threshold channels.
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Härmä, Maiju, Leena Lauronen, Junnu Leikola, Jyri Hukki, and Anne Saarikko. "Somatosensory evoked potentials are abnormal with plagiocephaly." Archives of Craniofacial Surgery 23, no. 2 (April 20, 2022): 59–63. http://dx.doi.org/10.7181/acfs.2022.00157.
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Background: Deformational plagiocephaly is usually managed conservatively, as it tends to improve over time and with the use of conservative measures. However, before the year 2017 we operated on patients with severe plagiocephaly and neurological symptoms at the Helsinki Cleft Palate and Craniofacial Center.Methods: Of the 20 infants with severe deformational plagiocephaly and neurological symptoms referred to us between 2014 and 2016, 10 underwent cranioplasty open reshaping of the posterior cranial vault. The parents of the last 10 patients were given information on the natural history of the condition and the patients were followed up with an outpatient protocol. The aim of this study was to gain information on the brain electrophysiology and recovery of patients after total cranial vault reconstruction by measuring the electroencephalogram (EEG) somatosensory evoked potentials (SEP; median nerve).Results: Of the 10 participants in the operation arm, six had abnormal SEP at least on the affected cerebral hemisphere and all SEPs were recorded as normal when controlled postoperatively. In the follow-up arm, eight out of 10 participants had abnormal SEP at the age of approximately 24 months, and all had normalized SEPs at control visits.Conclusion: Our data suggest that cranioplasty open reshaping of the posterior cranial vault did not affect abnormal SEP-EEG recordings. We have abandoned the operations in deformational plagiocephaly patients due to findings suggesting that expanding cranioplasty is not beneficial for brain function in this patient group.
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Silva, Liliane Aparecida Fagundes, Maria Inês Vieira Couto, Carla Gentile Matas, and Ana Claudia Martinho de Carvalho. "Long latency auditory evoked potentials in children with cochlear implants: systematic review." CoDAS 25, no. 6 (November 25, 2013): 595–600. http://dx.doi.org/10.1590/s2317-17822013.05000009.
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The aim of this study was to analyze the findings on Cortical Auditory Evoked Potentials in children with cochlear implant through a systematic literature review. After formulation of research question and search of studies in four data bases with the following descriptors: electrophysiology (eletrofisiologia), cochlear implantation (implante coclear), child (criança), neuronal plasticity (plasticidade neuronal) and audiology (audiologia), were selected articles (original and complete) published between 2002 and 2013 in Brazilian Portuguese or English. A total of 208 studies were found; however, only 13 contemplated the established criteria and were further analyzed; was made data extraction for analysis of methodology and content of the studies. The results described suggest rapid changes in P1 component of Cortical Auditory Evoked Potentials in children with cochlear implants. Although there are few studies on the theme, cochlear implant has been shown to produce effective changes in central auditory path ways especially in children implanted before 3 years and 6 months of age.
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Michelson, Nicholas J., and Takashi D. Y. Kozai. "Isoflurane and ketamine differentially influence spontaneous and evoked laminar electrophysiology in mouse V1." Journal of Neurophysiology 120, no. 5 (November 1, 2018): 2232–45. http://dx.doi.org/10.1152/jn.00299.2018.
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General anesthesia is ubiquitous in research and medicine, yet although the molecular mechanisms of anesthetics are well characterized, their ultimate influence on cortical electrophysiology remains unclear. Moreover, the influence that different anesthetics have on sensory cortexes at neuronal and ensemble scales is mostly unknown and represents an important gap in knowledge that has widespread relevance for neural sciences. To address this knowledge gap, this work explored the effects of isoflurane and ketamine/xylazine, two widely used anesthetic paradigms, on electrophysiological behavior in mouse primary visual cortex. First, multiunit activity and local field potentials were examined to understand how each anesthetic influences spontaneous activity. Then, the interlaminar relationships between populations of neurons at different cortical depths were studied to assess whether anesthetics influenced resting-state functional connectivity. Lastly, the spatiotemporal dynamics of visually evoked multiunit and local field potentials were examined to determine how each anesthetic alters communication of visual information. We found that isoflurane enhanced the rhythmicity of spontaneous ensemble activity at 10–40 Hz, which coincided with large increases in coherence between layer IV with superficial and deep layers. Ketamine preferentially increased local field potential power from 2 to 4 Hz, and the largest increases in coherence were observed between superficial and deep layers. Visually evoked responses across layers were diminished under isoflurane, and enhanced under ketamine anesthesia. These findings demonstrate that isoflurane and ketamine anesthesia differentially impact sensory processing in V1. NEW & NOTEWORTHY We directly compared electrophysiological responses in awake and anesthetized (isoflurane or ketamine) mice. We also proposed a method for quantifying and visualizing highly variable, evoked multiunit activity. Lastly, we observed distinct oscillatory responses to stimulus onset and offset in awake and isoflurane-anesthetized mice.
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Watson, Ben C., Frances J. Freeman, Kenneth D. Pool, Terese Finitzo, Sandi B. Chapman, Dianne Mendelsohn, Michael D. Devous, Steven D. Schaefer, Lanny G. Close, and George V. Kondraske. "Laryngeal Reaction Time Profiles in Spasmodic Dysphonia." Journal of Speech, Language, and Hearing Research 34, no. 2 (April 1991): 269–78. http://dx.doi.org/10.1044/jshr.3402.269.
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This study combines measures of linguistic and vocal performance and long-latency auditory electrophysiology to investigate task-dependent variability in spasmodic dysphonia (SD). Linguistic performance was evaluated using several measures of relatively complex linguistic ability (i.e., discourse analysis). Vocal performance was evaluated by measuring acoustic laryngeal reaction time (LRT) for tasks that differ in complexity. Normal structure of the cortex and subcortex was confirmed by magnetic resonance imaging. Cortical function was measured using multichannel quantitative auditory evoked potentials (AEPs). As a group, SD subjects who demonstrated subtle linguistic deficits also demonstrated prolonged LRT for the complex task and repeated and persistent auditory electrophysiologic abnormalities over the anterior quadrant of the left hemisphere. As a group, linguistically normal SD subjects demonstrated no significant increase in LRT for the complex task and no recurrent electrophysiologic abnormalities over the left anterior cortex relative to normal controls. Results support a neurogenic origin of SD and suggest that some aspects of inter- and intrasubject variability may be related to differences in loci and magnitude of cortical abnormalities.
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Nambu, A., and R. Llinas. "Electrophysiology of globus pallidus neurons in vitro." Journal of Neurophysiology 72, no. 3 (September 1, 1994): 1127–39. http://dx.doi.org/10.1152/jn.1994.72.3.1127.
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1. We investigated the electrical properties of globus pallidus neurons intracellularly using brain slices from adult guinea pigs. Three types of neurons were identified according to their intrinsic electrophysiological properties. 2. Type I neurons (59%) were silent at the resting membrane level (-65 +/- 10 mV, mean +/- SD) and generated a burst of spikes, with strong accommodation, to depolarizing current injection. Calcium-dependent low-frequency (1-8 Hz) membrane oscillations were often elicited by membrane depolarization (-53 +/- 8 mV). A low-threshold calcium conductance and an A-current were also identified. The mean input resistance of this neuronal type was 70 +/- 22 M omega. 3. Type II neurons (37%) fired spontaneously at the resting membrane level (-59 +/- 9 mV). Their repetitive firing (< or = 200 Hz) was very sensitive to the amplitude of injected current and showed weak accommodation. Sodium-dependent high-frequency (20-100 Hz) subthreshold membrane oscillations were often elicited by membrane depolarization. This neuronal type demonstrated a low-threshold calcium spike and had the highest input resistance (134 +/- 62 M omega) of the three neuron types. 4. Type III neurons (4%) did not fire spontaneously at the resting membrane level (-73 +/- 5 mV). Their action potentials were characterized by a long duration (2.3 +/- 0.6 ms). Repetitive firing elicited by depolarizing current injection showed weak or no accommodation. This neuronal type had an A-current and showed the lowest input resistance (52 +/- 35 M omega) of the three neuron types. 5. Stimulation of the caudoputamen evoked inhibitory postsynaptic potentials (IPSPs) in Type I and II neurons. In Type II neurons the IPSPs were usually followed by rebound firing. Excitatory postsynaptic potentials and antidromic responses were also elicited in some Type I and II neurons. The estimated conduction velocity of the striopallidal projection was < 1 m/s (Type I neurons, 0.49 +/- 0.37 m/s; Type II neurons, 0.33 +/- 0.13 m/s).
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Musteata, Mihai, Irina Neculae, Mihaela Armasu, Christiana B. Balan, and Gheorghe Solcan. "Brainstem auditory evoked potentials in healthy cats recorded with surface electrodes." Acta Veterinaria Brno 82, no. 1 (2013): 97–101. http://dx.doi.org/10.2754/avb201382010097.
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The aim of this study was to evaluate the brainstem auditory evoked potentials of seven healthy cats, using surface electrodes. Latencies of waves I, III and V, and intervals I–III, I–V and III–V were recorded. Monaural and binaural stimulation of the cats were done with sounds ranging between 40 and 90 decibel Sound Pressure Level. All latencies were lower than those described in previous studies, where needle electrodes were used. In the case of binaural stimulation, latencies of waves III and V were greater compared to those obtained for monaural stimulation (P < 0.01), and relatively unchanged for wave I (P > 0.05). Regardless of the sound intensity, the interwave latency was constant (P > 0.05). Interestingly, no differences were noticed for latencies of waves III and V when sound intensity was higher than 80dB SPL. This study completes the knowledge in the field of electrophysiology and shows that the brainstem auditory evoked potentials in cats using surface electrodes is a viable method to record the transmission of auditory information. That can be faithfully used in clinical practice, when small changes of latency values may be an objective factor in health status evaluation.
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McQuiston, A. Rory, and Lawrence C. Katz. "Electrophysiology of Interneurons in the Glomerular Layer of the Rat Olfactory Bulb." Journal of Neurophysiology 86, no. 4 (October 1, 2001): 1899–907. http://dx.doi.org/10.1152/jn.2001.86.4.1899.
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In the mammalian olfactory bulb, glomeruli are surrounded by a heterogeneous population of interneurons called juxtaglomerular neurons. As they receive direct input from olfactory receptor neurons and connect with mitral cells, they are involved in the initial stages of olfactory information processing, but little is known about their detailed physiological properties. Using whole cell patch-clamp techniques, we recorded from juxtaglomerular neurons in rat olfactory bulb slices. Based on their response to depolarizing pulses, juxtaglomerular neurons could be divided into two physiological classes: bursting and standard firing. When depolarized, the standard firing neurons exhibited a range of responses: accommodating, nonaccommodating, irregular firing, and delayed to firing patterns of action potentials. Although the firing pattern was not rigorously predictive of a particular neuronal morphology, most short axon cells fired accommodating trains of action potentials, while most delayed to firing cells were external tufted cells. In contrast to the standard firing neurons, bursting neurons produced a calcium-channel-dependent low-threshold spike when depolarized either by current injection or by spontaneous or evoked postsynaptic potentials. Bursting neurons also could oscillate spontaneously. Most bursting cells were either periglomerular cells or external tufted cells. Based on their mode of firing and placement in the bulb circuit, these bursting cells are well situated to drive synchronous oscillations in the olfactory bulb.
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Flasbeck, Vera, Johannes Jungilligens, Isabell Lemke, Jule Beckers, Hilal Öztürk, Jörg Wellmer, Corinna Seliger, Georg Juckel, and Stoyan Popkirov. "Heartbeat evoked potentials and autonomic arousal during dissociative seizures: insights from electrophysiology and neuroimaging." BMJ Neurology Open 6, no. 1 (June 2024): e000665. http://dx.doi.org/10.1136/bmjno-2024-000665.
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IntroductionDissociative seizures often occur in the context of dysregulated affective arousal and entail dissociative symptoms such as a disintegration of bodily awareness. However, the interplay between affective arousal and changes in interoceptive processing at the onset of dissociative seizures is not well understood.MethodsUsing retrospective routine data obtained from video-electroencephalography telemetry in a university hospital epilepsy monitoring unit, we investigate ictal changes in cardiac indices of autonomic arousal and heartbeat evoked potentials (HEPs) in 24 patients with dissociative seizures.ResultsResults show autonomic arousal during seizures with increased heart rate and a shift towards sympathetic activity. Compared with baseline, ictal HEP amplitudes over central and right prefrontal electrodes (F8, Fz) were significantly less pronounced during seizures, suggesting diminished cortical representation of interoceptive information. Significant correlations between heart rate variability measures and HEPs were observed at baseline, with more sympathetic and less parasympathetic activity related to less pronounced HEPs. Interestingly, these relationships weakened during seizures, suggesting a disintegration of autonomic arousal and interoceptive processing during dissociative seizures. In a subgroup of 16 patients, MRI-based cortical thickness analysis found a correlation with HEP amplitudes in the left somatosensory association cortex.ConclusionsThese findings possibly represent an electrophysiological hint of how autonomic arousal could negatively impact bodily awareness in dissociative seizures, and how these processes might be related to underlying brain structure.
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Feng, Z. C., M. Rosenthal, and T. J. Sick. "Suppression of evoked potentials with continued ion transport during anoxia in turtle brain." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 255, no. 3 (September 1, 1988): R478—R484. http://dx.doi.org/10.1152/ajpregu.1988.255.3.r478.
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A key to turtle brain survival during anoxia is continued ion transport and avoidance of anoxic depolarization. Previous findings that ATP concentration remained constant during prolonged anoxia and calculations that ATP production decreased indicate that compensatory processes, other than consumption of energy stores or increased anaerobic glycolysis, must also contribute to ion homeostasis and brain survival. To determine whether preservation of ion transport is associated with changes in electrophysiology during loss of oxidative metabolism, the brains of pentobarbital sodium-anesthetized turtles were electrically stimulated 1) to provoke measurable increments in extracellular K+ activity (a degrees k) for determination of rates of K+ reaccumulation at the stimulus site and 2) to elicit polysynaptic extracellular field potentials (evoked potentials) recordable in the olfactory bulb. During anoxia, base-line a degrees k rose only a few millimolar, and rates of reaccumulation of K+, incremented by stimulation were slightly but not significantly slowed. In contrast, postsynaptic orthodromic responses of olfactory bulb granule cells were markedly depressed by anoxia. Monosynaptic responses of granule cells to antidromic stimulation of the lateral olfactory tract were less affected, and compound action potentials in the olfactory nerve were unchanged by anoxia. These data suggest that synaptic transmission in turtle brain, as in that of mammal, is highly dependent on oxidative metabolism and that the turtle brain may effectively conserve energy for ion transport during anoxia by depression of electrical activity.
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Van Lysebettens, Wouter, Kristl Vonck, Lars Emil Larsen, Mathieu Sprengers, Evelien Carrette, Charlotte Bouckaert, Jean Delbeke, Wytse Jan Wadman, Paul Boon, and Robrecht Raedt. "Hypothermia Masks Most of the Effects of Rapid Cycling VNS on Rat Hippocampal Electrophysiology." International Journal of Neural Systems 29, no. 09 (October 28, 2019): 1950008. http://dx.doi.org/10.1142/s0129065719500084.
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AIM. Vagus nerve stimulation (VNS) modulates hippocampal dentate gyrus (DG) electrophysiology and induces hypothermia in freely moving rats. This study evaluated whether hippocampal (CA1) electrophysiology is similarly modulated and to what extent this is associated with VNS-induced hypothermia. METHODS. Six freely moving rats received a first 4[Formula: see text]h session of rapid cycling VNS (7[Formula: see text]s on/18[Formula: see text]s off), while CA1 evoked potentials, EEG and core temperature were recorded. In a second 4[Formula: see text]h session, external heating was applied during the 3rd and 4th[Formula: see text]h of VNS counteracting VNS-induced hypothermia. RESULTS. VNS decreased the slope of the field excitatory postsynaptic potential (fEPSP), increased the population spike (PS) amplitude and latency, decreased theta (4–12[Formula: see text]Hz) and gamma (30–100[Formula: see text]Hz) band power and theta peak frequency. Normalizing body temperature during VNS through external heating abolished the effects completely for fEPSP slope, PS latency and gamma band power, partially for theta band power and theta peak frequency and inverted the effect on PS amplitude. CONCLUSIONS. Rapid cycle VNS modulates CA1 electrophysiology similarly to DG, suggesting a wide-spread VNS-induced effect on hippocampal electrophysiology. Normalizing core temperature elucidated that VNS-induced hypothermia directly influences several electrophysiological parameters but also masks a VNS-induced reduction in neuronal excitability.
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Niedermeyer, E. "Electrophysiology of the Frontal Lobe." Clinical Electroencephalography 34, no. 1 (January 2003): 5–12. http://dx.doi.org/10.1177/155005940303400105.
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The electrophysiology of the frontal lobe appears to be unimpressive when the view is limited to the routine EEG recording of a healthy waking adult. There is usually low voltage fast activity, which becomes more pronounced when recorded with depth leads. Three special EEG patterns of marginal to slightly abnormal character are discussed: a) rhythmical midfrontal 6–7/sec activity of juveniles, b) rhythmical midfrontal sharp 4–6/sec activity of infancy and early childhood with arousal from sleep, and c) frontal intermittent rhythmical delta activity (FIRDA) in waking adults with frontopolar maximum, possibly related to thought processes under abnormal conditions. With extension of the frequency range, ultraslow (DC-like) as well as fast beta (gamma, 40–80/sec) and ultrafast activity (80–1000/sec) are found particularly over the frontal lobes. Ultraslow baseline shifts are arousal-related and mixed with overlying ultrafast waves. Attention control and the “working memory” involve chiefly the dorsolateral prefrontal cortex, investigated with P300 responses and likely to show ultrafast spectra. Perception-related 40–80/sec gamma activity has been thought to be associated with the entrance into consciousness. Initiation and design of motor activity spreads from prefrontal to the frontomotor cortex, associated with powerful event-related potentials: contingent negative variation (CNV) and “Bereitschafts potential” (“readiness potential,” RP). Neuroscientific research of the highest frontal lobe functions has become a very active domain of neuroimaging. With the use of the extended frequency range, EEG and also evoked potential studies could add further information with acquisition in real time. Ultrafast frequency ranges presented in computerized frequency analysis and mapping might show impressive correlates of highest frontal lobe functions.
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Kareem, Ruaa M., Zaid Al-madfai, and Abdulmuttaleb A. Al-Sheikhly. "Somatosensory Evoked Potentials Study in Cervical Spondylotic Myelopathy Patients." Journal of the Faculty of Medicine Baghdad 56, no. 1 (April 1, 2014): 101–6. http://dx.doi.org/10.32007/jfacmedbagdad.561439.
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Background: Cervical spondylotic myelopathy (CSM) is considered the most serious consequence of cervical spondylosis and accounts for the majority of non_traumatic paraparesis and/or quadriparesis. The electrical property of the spinal cord and its susceptibility to injuries renders electrophysiology relevant to the management of CSM. Somatosensory evoked potentials study (SEPs) is an objective assessment of the functional integrity of the neural pathway.Objective: Utilizing both of the median and the posterior tibial SEPs in evaluating the functional integrity of the cervical spinal cord in patients with CSM and to correlate the SEPs findings with the clinical and MRI findings.Patients and methods: Twenty two patients with CSM (11 male and 11 female) ranging in age from 29 to 77 years with a mean age of (56 ±11) years and matched with 25 healthy subjects of the control group were enrolled in this study.Results: In this study, 86.36% of patients had abnormal SEPs study (either tibial or median or both tests abnormal), with 68.2% abnormal tibial and 63.6% abnormal median. There was no difference between right and left side study of neither median nor tibial SEPs studies (P>0.05). Loss of N13, loss or delayed N20 and loss or delayed N13-N20 were the most frequent abnormalities for median SEPs and loss or delayed P37 and LP-P37 were most frequent abnormalities in tibial SEPs. Results showed that normal SEPs findings mostly correlated with mild and early myelopathy (grade-1 and grade-2 Nurick). Abnormal SEPs findings are useful in prediction the progression of myelopathy in patients with mild clinical neurological deficits in the early stages of the disease.Conclusion: This study concluded that both median and tibial SEPs montages are useful important objective assessment of the spinal cord function to evaluate patients with CSM since MRI and SEPs may evaluate different aspects of the disease process.
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Thame, Ammar A., Najeeb H. Mohammed, and Akram M. Ibrahim. "Role of Visual Evoked Potentials in Multiple Sclerosis." Journal of the Faculty of Medicine Baghdad 56, no. 4 (December 31, 2014): 417–21. http://dx.doi.org/10.32007/jfacmedbagdad.564895.
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Background: Multiple sclerosis (MS) is a chronic, demyelinating disease of the central nervous system (CNS) affecting young adults and is considered as the leading cause of non traumatic neurological disability of young adults affecting nearly 2 million people worldwide. The pathogenesis of MS is at best incompletely understood. There are several proposed mechanisms that may be important in the production of MS plaques: autoimmunity, environment and heredity. Deviation of immune responses in a genetically susceptible patient plays a central role in its pathogenesis. Electrophysiological, spinal tap and Radiological tools are important laboratory investigations and have added so much to the clinical diagnosis and for the classification of MS. It was found that visual function and conduction has been changed in patients with multiple sclerosis.Objectives: The aims of the study is to estimate and evaluate the visual evoked potential (VEP) parameters in patients with MS and its relation to their disability degree (using the expanded disability status scale score "EDSS") and visual presentation of them in comparison with healthy individuals.Patients and Methods: 112 patients with multiple sclerosis and 50 subjects without any neurological or psychiatric diseases as control group were recruited in this study. The cases were collected from Baghdad teaching hospital, MS center, Baghdad, Iraq at the period from May 2012 to April 2013, and studied at the unit of electrophysiology in Al-Shaheed Ghazi Al-Hareri Hospital in the Medical city. All patients and control groups were tested for VEP.Results: The present study showed a significant increase in the P100 latency and inter-ocular (IO) latency difference and non statistical significant decrease in the IO amplitude difference in patients group than the control group. Also among patients group there was positive linear correlation between the severity of the disease measured by EDSS score and P100 latency while negative linear correlation with the amplitude. Conclusion: There was a higher percent of patients with defective VEP parameters and so their visual pathway even if it was asymptomatic, in addition to their relation with patients` disability than the control group, making it easy to quantify and predict MS disability objectively. Keywords: Multiple sclerosis, Expanded Disability Status Scale, VEP.
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Pescosolido, Nicola, Andrea Barbato, Alessio Stefanucci, and Giuseppe Buomprisco. "Role of Electrophysiology in the Early Diagnosis and Follow-Up of Diabetic Retinopathy." Journal of Diabetes Research 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/319692.
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Retinopathy is a severe and common complication of diabetes, representing a leading cause of blindness among working-age people in developed countries. It is estimated that the number of people with diabetic retinopathy (DR) will increase from 126.6 million in 2011 to 191 million by 2030. The pathology seems to be characterized not only by the involvement of retinal microvessels but also by a real neuropathy of central nervous system, similar to what happens to the peripheral nerves, particularly affected by diabetes. The neurophysiological techniques help to assess retinal and nervous (optic tract) function. Electroretinography (ERG) and visual evoked potentials (VEP) allow a more detailed study of the visual function and of the possible effects that diabetes can have on the visual function. These techniques have an important role both in the clinic and in research: the central nervous system, in fact, has received much less attention than the peripheral one in the study of the complications of diabetes. These techniques are safe, repeatable, quick, and objective. In addition, both the ERG (especially the oscillatory potentials and the flicker-ERG) and VEP have proved to be successful tools for the early diagnosis of the disease and, potentially, for the ophthalmologic follow-up of diabetic patients.
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FEBVRE-CHEVALIER, COLETTE, ANDRÉ BILBAUT, QUENTIN BONE, and JEAN FEBVRE. "Sodium-Calcium Action Potential Associated with Contraction in the Heliozoan Actinocoryne Contractilis." Journal of Experimental Biology 122, no. 1 (May 1, 1986): 177–92. http://dx.doi.org/10.1242/jeb.122.1.177.
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The electrophysiology of the contractile protozoan Actinocoryne contractilis was studied with conventional intracellular recording techniques. Resting membrane potential (−78 mV, s.d. = 8, N = 18) was dependent upon external K+. Rapid action potentials (overshoot up to 50 mV) were evoked either by mechanical stimulation or by current injection. Graded membrane depolarizations induced by graded mechanical stimuli correspond to receptor potentials. The receptor potential was mainly Na+-dependent; the action potential was also mainly Na+-dependent, but involved a minor Ca2+-dependence. The two components of the action potential could be separated in Ca2+-free solution containing EGTA (1 mmol l−1), in low-Na+ solutions or by the addition of Co2+. The repolarizing phase of the action potential was sensitive to TEA ions and to 4-aminopyridine (4-AP). Action potentials were followed in 10–20 ms by a rapid all-or-none contraction of the axopods and stalk. Contraction was blocked in Ca2+-free solution containing EGTA and by Co2+, which suggests a requirement of external Ca2+ for this event. Contraction was also abolished by 4-AP.
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NISHI, TAKAKO, TSUKASA GOTOW, and MAKOTO KOBAYASHI. "Changes in Electrical Connection During Cell Fusion in the Heliozoan, Echinosphaerium Akamae." Journal of Experimental Biology 135, no. 1 (March 1, 1988): 183–91. http://dx.doi.org/10.1242/jeb.135.1.183.
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The electrophysiology of cell fusion in the heliozoan, Echinosphaetium akamae, was studied by intracellular recording from two unicellular organisms undergoing fusion. Fusion was preceded by the electrical connection of axopodia of each cell to the cell body of the other. In the early stages of the fusion process, spikes evoked in one cell body failed to invade the other, but electrotonic potentials (subthreshold depolarizations) did pass to the other cell. When background depolarizing currents were injected into the organism into which the potentials had invaded, these potentials developed into spikes. In advanced stages of fusion, spikes were transmitted in both directions from one organism to the other, in the absence of polarizing current. At this time, application of appropriate hyperpolarizing currents to either of the two organisms prevented spikes produced in one from invading the other. These results suggest that in the early stage of fusion, relatively few axopodia were bridged by membrane fusion between paired cell bodies, and that the number of such bridged axopodia increased as fusion proceeded, allowing spikes to be transmitted between the two organisms.
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Yu, Pin Huan, and Yi-Tse Hsiao. "Delayed evoked potentials in zebra finch (Taeniopygia guttata) under midazolam-butorphanol-isoflurane anesthesia." PeerJ 7 (October 24, 2019): e7937. http://dx.doi.org/10.7717/peerj.7937.
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Avian animals are visually inclined, which has caused them to attract increasing attention for visual neurophysiology or electrophysiology studies, including the study of the visual evoked potential (VEP). VEP has developed into an investigative tool for understanding the physiology and the pathology of the visual pathway. Chemical restraint is a common method to minimize motion artifacts in animals when acquiring VEP data, but little is known about its influence on the signal in an avian animal. In addition, it is difficult to make comparisons between conscious state data when the animals are ultimately under anesthesia. Therefore, finding drugs and developing protocols that have an acceptable effect is valuable. We compared the local field potentials of physically and chemically restrained zebra finches (Taeniopygia guttata), a small avian species, to simulate a relatively challenging recording condition. Finches were sedated with midazolam-butorphanol, and anesthesia was maintained by isoflurane. Electrodes were implanted into the left nucleus rotundus, which is a visual nucleus in birds. The VEPs of the control group (N = 3) were recorded after they fully recovered and were restrained by towels. The other birds (N = 3) were recorded under anesthesia. The results show that without the visual stimuli, anesthesia generally suppressed the overall power of field potentials. However, by focusing on the spectra during VEPs, visual stimuli still triggered significant VEPs in frequencies below 30.8 Hz, which were even stronger than towel-restrained birds. The drugs also prolonged the latency of the VEP, increased the duration of the VEP when compared to towel-restrained birds. As regard to towel-restrained zebra finches, the field potentials were less synchronized and may need data preprocessing to have clear VEPs. In conclusion, the current study presents evidence of basic VEP for zebra finch under midazolam-butorphanol-isoflurane anesthesia with a protocol that is a safe and feasible anesthetic combination for chemical restraint, which is particularly useful for small animals when obtaining evoked potentials.
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Papakostopoulos, D., and S. Blackmore. "Reviews: Human Brain Electrophysiology: Evoked Potentials and Evoked Magnetic Fields in Science and Medicine, from Sentience to Symbols: Readings on Consciousness." Perception 22, no. 3 (March 1993): 375–77. http://dx.doi.org/10.1068/p220375.
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Al Abed, Amr, Yuan Wei, Reem M. Almasri, Xinyue Lei, Han Wang, Josiah Firth, Yingge Chen, et al. "Liquid crystal electro-optical transducers for electrophysiology sensing applications." Journal of Neural Engineering 19, no. 5 (October 1, 2022): 056031. http://dx.doi.org/10.1088/1741-2552/ac8ed6.
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Abstract Objective. Biomedical instrumentation and clinical systems for electrophysiology rely on electrodes and wires for sensing and transmission of bioelectric signals. However, this electronic approach constrains bandwidth, signal conditioning circuit designs, and the number of channels in invasive or miniature devices. This paper demonstrates an alternative approach using light to sense and transmit the electrophysiological signals. Approach. We develop a sensing, passive, fluorophore-free optrode based on the birefringence property of liquid crystals (LCs) operating at the microscale. Main results. We show that these optrodes can have the appropriate linearity (µ ± s.d.: 99.4 ± 0.5%, n = 11 devices), relative responsivity (µ ± s.d.: 57 ± 12%V−1, n = 5 devices), and bandwidth (µ ± s.d.: 11.1 ± 0.7 kHz, n = 7 devices) for transducing electrophysiology signals into the optical domain. We report capture of rabbit cardiac sinoatrial electrograms and stimulus-evoked compound action potentials from the rabbit sciatic nerve. We also demonstrate miniaturisation potential by fabricating multi-optrode arrays, by developing a process that automatically matches each transducer element area with that of its corresponding biological interface. Significance. Our method of employing LCs to convert bioelectric signals into the optical domain will pave the way for the deployment of high-bandwidth optical telecommunications techniques in ultra-miniature clinical diagnostic and research laboratory neural and cardiac interfaces.
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Atlı, Sibel Kocaaslan, Gonca Inanc, Adile Oniz, and Murat Ozgoren. "Dynamic Sleep Architecture Revealed: Sleep Auditory Evoked Potentials from N100 to P900." Neurological Sciences and Neurophysiology 41, no. 1 (2024): 41–47. http://dx.doi.org/10.4103/nsn.nsn_60_23.
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Background: The research landscape in sleep is currently shifting toward minute changes in brain functioning during different stages. This fine approach necessitates a dynamic assessment as in the case of electrophysiology. The present study aimed to investigate brain responsiveness during different stages and times of nocturnal sleep using auditory evoked potentials (AEPs). Materials and Methods: Sleep recordings of 18 volunteer subjects were analyzed. During sleep recordings, auditory stimuli were presented in the ear channels. Sleep stages were scored according to the American Academy of Sleep Medicine system. AEPs were analyzed in nonrapid eye movement sleep stages. Alterations of N100, P200, N300, P450, N550, and P900 waveforms were investigated in the first and second halves of sleep duration. Results: N100 amplitude was higher in light sleep, both in the first and the second halves of the night (sleep duration). The amplitude of P900 was higher in the deep sleep stage in both halves. Significant amplitude reductions were found in N100, P200, P450, and P900 in the second half of the sleep. Conclusions: The changes found suggest that they are related to the dynamics of sensory processing to maintain functional sleep. The findings of the present study emphasize that in the course of sleep, both the proportions of sleep stages and the microarchitecture within the stages alter between the first and second halves of sleep.
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STARR, ARNOLD. "Challenges for the Use of Evoked Potentials and Electrophysiology for Monitoring Patients in the Operating Theater." Central Nervous System Trauma 2, no. 2 (January 1985): 121–22. http://dx.doi.org/10.1089/cns.1985.2.121.
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Edwards, D. H. "Mechanisms of depolarizing inhibition at the crayfish giant motor synapse. I. Electrophysiology." Journal of Neurophysiology 64, no. 2 (August 1, 1990): 532–40. http://dx.doi.org/10.1152/jn.1990.64.2.532.
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1. Mechanisms of depolarizing synaptic inhibition were investigated at the crayfish giant motor synapse with the use of two-electrode current- and voltage-clamp techniques. Depolarizing inhibitory postsynaptic potentials (d-IPSPs) of between 5 and 15 mV in amplitude are produced there in the motor giant motoneuron (MoG) by motor giant inhibitor (MoGI) interneurons. 2. Three mechanisms of inhibition are activated by the d-IPSP: inactivation of a voltage-sensitive inward current (probably sodium), activation of the delayed rectifier, and reverse bias of the electrically rectifying giant motor synapse (GMS). These mechanisms supplement the inhibition produced by a gamma-aminobutyric acid (GABA)-mediated increase in postsynaptic conductance. 3. The d-IPSP is produced by a fast-rising increase in postsynaptic membrane conductance that peaks at 10 microS and lasts nearly 100 ms. 4. An 8-ms, 10-mV depolarizing prepulse inactivated 90% of the inward current evoked by a subsequent step to 33 mV above rest potential, which was -70 mV. d-IPSPs having similar amplitudes should have similar effects on the inward current evoked by an excitatory postsynaptic potential (EPSP). 5. The input resistance of MoG decreased by greater than 60% when the cell was depolarized to 11 mV above rest. This resistance change corresponds to delayed rectification, which should also contribute to the increase in input conductance during a d-IPSP. 6. Depolarization of MoG by 10 mV reduced the excitatory postsynaptic current through the GMS by up to 30%. The reduction in synaptic current occurs because postsynaptic depolarization reduces the transynaptic driving force and increases the reverse bias of the electrically rectifying synapse.(ABSTRACT TRUNCATED AT 250 WORDS)
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Bazley, Faith A., Charles Hu, Anil Maybhate, Amir Pourmorteza, Nikta Pashai, Nitish V. Thakor, Candace L. Kerr, and Angelo H. All. "Electrophysiological evaluation of sensory and motor pathways after incomplete unilateral spinal cord contusion." Journal of Neurosurgery: Spine 16, no. 4 (April 2012): 414–23. http://dx.doi.org/10.3171/2012.1.spine11684.
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Object Unilateral contusions represent an increasingly popular model for studying the pathways and recovery mechanisms of spinal cord injury (SCI). Current studies rely heavily on motor behavior scoring and histological evidence to make assessments. Electrophysiology represents one way to reliably quantify the functionality of motor pathways. The authors sought to quantify the functional integrity of the bilateral motor and sensory pathways following unilateral SCI by using measurements of motor and somatosensory evoked potentials (MEPs and SSEPs, respectively). Methods Eighteen rats were randomly divided into 3 groups receiving a mild unilateral contusion, a mild midline contusion, or a laminectomy only (control). Contusions were induced at T-8 using a MASCIS impactor. Electrophysiological analysis, motor behavior scoring, and histological quantifications were then performed to identify relationships among pathway conductivity, motor function, and tissue preservation. Results Hindlimb MEPs ipsilateral to the injury showed recovery by Day 28 after injury and corresponded to approximately 61% of spared corticospinal tract (CST) tissue. In contrast, MEPs of the midline-injured group did not recover, and correspondingly > 90% of the CST tissue was damaged. Somatosensory evoked potentials showed only a moderate reduction in amplitude, with no difference in latency for the pathways ipsilateral to injury. Furthermore, these SSEPs were significantly better than those of the midline-injured rats for the same amount of white matter damage. Conclusions Motor evoked potential recovery corresponded to the amount of spared CST in unilateral and midline injuries, but motor behavior consistently recovered independent of MEPs. These data support the idea that spared contralateral pathways aid in reducing the functional deficits of injured ipsilateral pathways and further support the idea of CNS plasticity.
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Krasińska-Płachta, Aleksandra, Agata Brązert, Joanna Mamczur-Załęcka, Marcin Gabriel, Michał Suchodolski, Beata Begier – Krasińska, and Jarosław Kocięcki. "Visual outcomes in carotid stenosis patients treated using endarterectomy." Polish Journal of Surgery 95, no. 4 (January 26, 2023): 1–5. http://dx.doi.org/10.5604/01.3001.0016.2123.
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Introduction Carotid arthrosclerosis can be a cause of visual impairment. It has been observed that carotid endarterectomy has a positive effect on ophthalmic parameters. The aim of this study was to evaluate the impact of endarterectomy on the optic nerve function. Materials and methods 54 asymptomatic patients (19 women and 35 men - 108 eyes) with unilateral carotid stenosis >70% of internal carotid artery, were recruited to the study. All of them were qualified for the endarterectomy procedure. The whole study group underwent Doppler ultrasonography of internal carotid arteries and ophthalmic examination before the surgery, with 22 of them (11 women and 11 men) were examined after the endarterectomy. The ophthalmic examination included; distant best-corrected visual acuity, measurement of the intraocular pressure, electrophysiology (pattern visual evoked potentials), perimetry, and optical coherent tomography (the retinal nerve fiber layer thickness). Discussion Carotid arteries supply brain and face with blood. Extensive research has observed a concomitant improvement in eyesight after enduring carotid endarterectomy in patients with artery stenosis. This effect was associated with a better blood flow in the ophthalmic artery and its branches, the central retinal artery and the ciliary artery; the major blood supply of the eye. Results The present study proved that carotid endarterectomy has a positive impact on the function of the optic nerve. The visual field parameters and amplitude of pattern visual evoked potentials significantly improved. Preoperative and postoperative values of intraocular pressure and the retinal nerve fiber layer thickness remained stable.
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Chun, Ingyu, Curtis J. Billings, Christi W. Miller, and Kelly L. Tremblay. "Aided Electrophysiology Using Direct Audio Input: Effects of Amplification and Absolute Signal Level." American Journal of Audiology 25, no. 1 (March 2016): 14–24. http://dx.doi.org/10.1044/2015_aja-15-0029.
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Purpose This study investigated (a) the effect of amplification on cortical auditory evoked potentials (CAEPs) at different signal levels when signal-to-noise ratios (SNRs) were equated between unaided and aided conditions, and (b) the effect of absolute signal level on aided CAEPs when SNR was held constant. Method CAEPs were recorded from 13 young adults with normal hearing. A 1000-Hz pure tone was presented in unaided and aided conditions with a linear analog hearing aid. Direct audio input was used, allowing recorded hearing aid noise floor to be added to unaided conditions to equate SNRs between conditions. An additional stimulus was created through scaling the noise floor to study the effect of signal level. Results Amplification resulted in delayed N1 and P2 peak latencies relative to the unaided condition. An effect of absolute signal level (when SNR was constant) was present for aided CAEP area measures, such that larger area measures were found at higher levels. Conclusion Results of this study further demonstrate that factors in addition to SNR must also be considered before CAEPs can be used to clinically to measure aided thresholds.
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Liu, Peng, Xiao Zhang, Xiaolan He, Zhenhua Jiang, Qun Wang, and Yan Lu. "Spinal GABAergic neurons are under feed-forward inhibitory control driven by Aδ and C fibers in Gad2 td-Tomato mice." Molecular Pain 17 (January 2021): 174480692199262. http://dx.doi.org/10.1177/1744806921992620.
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Background Spinal GABAergic neurons act as a critical modulator in sensory transmission like pain or itch. The monosynaptic or polysynaptic primary afferent inputs onto GABAergic neurons, along with other interneurons or projection neurons make up the direct and feed-forward inhibitory neural circuits. Previous research indicates that spinal GABAergic neurons mainly receive excitatory inputs from Aδ and C fibers. However, whether they are controlled by other inhibitory sending signals is not well understood. Methods We applied a transgenic mouse line in which neurons co-expressed the GABA-synthesizing enzyme Gad65 and the enhanced red fluorescence (td-Tomato) to characterize the features of morphology and electrophysiology of GABAergic neurons. Patch-clamp whole cell recordings were used to record the evoked postsynaptic potentials of fluorescent neurons in spinal slices in response to dorsal root stimulation. Results We demonstrated that GABAergic neurons not only received excitatory drive from peripheral Aβ, Aδ and C fibers, but also received inhibitory inputs driven by Aδ and C fibers. The evoked inhibitory postsynaptic potentials (eIPSPs) mediated by C fibers were mainly Glycinergic (66.7%) as well as GABAergic mixed with Glycinergic (33.3%), whereas the inhibition mediated by Aδ fibers was predominately both GABA and Glycine-dominant (57.1%), and the rest of which was purely Glycine-dominant (42.9%). Conclusion These results indicated that spinal GABAergic inhibitory neurons are under feedforward inhibitory control driven by primary C and Aδ fibers, suggesting that this feed-forward inhibitory pathway may play an important role in balancing the excitability of GABAergic neurons in spinal dorsal horn.
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Tedó, Carmen Muñoz, Pilar Herreros De Tejada, and Daniel G. Green. "Behavioral estimates of absolute threshold in rat." Visual Neuroscience 11, no. 6 (November 1994): 1077–82. http://dx.doi.org/10.1017/s0952523800006891.
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AbstractDark-adapted thresholds of albino and pigmented rats were estimated using behavioral methods. Albino and pigmented rats who had been water deprived learned to bar press for water reinforcement when a light stimulus was presented. Absolute threshold was defined to be the light intensity at which bar pressing behavior was significantly modified by the presence of the light stimulus. Albino rats had an average threshold of −5.23 log cd/m2 and the pigmented rats had a threshold of −5.0 log cd/m2. These values are close to −5.3 log cd/m2, the psychophysical threshold of human observers in the same apparatus. Consistent with our earlier electrophysiology, these behavioral experiments provide no evidence for an albino/pigmented sensitivity difference. Comparisons are made between behavioral and electrophysiological determinations of absolute threshold in albino and pigmented rats. Thresholds determined behaviorally agree remarkably well with those derived from visual evoked potentials.
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Handley, Siân E., Maja Šuštar, and Manca Tekavčič Pompe. "What can visual electrophysiology tell about possible visual-field defects in paediatric patients." Eye 35, no. 9 (July 16, 2021): 2354–73. http://dx.doi.org/10.1038/s41433-021-01680-1.
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AbstractRecognising a potential visual-field (VF) defect in paediatric patients might be challenging, especially in children before the age of 5 years and those with developmental delay or intellectual disability. Visual electrophysiological testing is an objective and non-invasive technique for evaluation of visual function in paediatric patients, which can characterise the location of dysfunction and differentiate between disorders of the retina, optic nerve and visual pathway. The recording of electroretinography (ERG) and visual-evoked potentials (VEP) is possible from early days of life and requires no subjective input from the patient. As the origins of ERG and VEP tests are known, the pattern of electrophysiological changes can provide information about the VF of a child unable to perform accurate perimetry. This review summarises previously published electrophysiological findings in several common types of VF defects that can be found in paediatric patients (generalised VF defect, peripheral VF loss, central scotoma, bi-temporal hemianopia, altitudinal VF defect, quadrantanopia and homonymous hemianopia). It also shares experience on using electrophysiological testing as additional functional evidence to other tests in the clinical challenge of diagnosing or excluding VF defects in complex paediatric patients. Each type of VF defect is illustrated with one or two clinical cases.
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Nunez, A., F. Amzica, and M. Steriade. "Electrophysiology of cat association cortical cells in vivo: intrinsic properties and synaptic responses." Journal of Neurophysiology 70, no. 1 (July 1, 1993): 418–30. http://dx.doi.org/10.1152/jn.1993.70.1.418.
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1. The intrinsic properties and synaptic responses of association cortical neurons (n = 179) recorded from cat's areas 5 and 7 were studied in vivo. Intracellular recordings were performed under urethane anesthesia. Resting membrane potential (Vm) was -71.7 +/- 1.2 (SE) mV, amplitude of action potential was 83.7 +/- 2.3 mV, and input resistance was 18.4 +/- 1.8 M omega. Cells were identified ortho- and antidromically from lateroposterior and centrolateral thalamic nuclei and from homotopic foci in the contralateral cortex. Physiologically identified neurons were intracellularly stained with Lucifer yellow (LY) and found to be pyramidal-shaped elements (n = 21). 2. We classified the neurons as regular-spiking and intrinsically bursting cells. Regular-spiking cells were further classified as slow- and fast-adapting according to the adaptation of spike frequency during long-lasting depolarizing current pulses. 3. Regular-spiking, slow-adapting neurons had a monophasic afterhyperpolarization (AHP) or a biphasic AHP with fast and medium components (FAHP, mAHP). Slow-adapting behavior was observed in 84% (n = 119) of the regular-spiking cells. 4. Regular-spiking, fast-adapting cells only fired a train of spikes at the beginning of the pulse. Thereafter, the Vm remained as a depolarizing plateau, occasionally triggering some spikes. These neurons had a monophasic AHP and represented 16% (n = 23) of the regular-spiking neurons. 5. Intrinsically bursting neurons (n = 37) were observed in 20% of neocortical cells at depolarized Vm. Their action potential was followed by a marked depolarizing afterpotential (DAP). Rhythmic (4-10 Hz) bursts occurred during long-lasting depolarizing current pulses. 6. Small (3-10 mV), fast (1.5-4 ms), all-or-none depolarizing potentials were triggered by depolarizing current pulses. They are tentatively regarded as dendritic spikes recorded from the soma because their rate of occurrence changed as a function of the Vm and they were eventually blocked by hyperpolarization. 7. Synaptic stimulation of either thalamic or homotopic contralateral cortical areas elicited a sequence of excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs). Two components of the EPSP were revealed. At a hyperpolarized Vm, the initial component of the EPSP increased in amplitude, whereas the secondary component was blocked. Repetitive (10 Hz) stimulation of the thalamus or contralateral cortex elicited incremental responses. The augmentation phenomenon was due to an increase in the secondary component of the EPSP. The cortically elicited augmenting responses survived extensive thalamic lesions. A short IPSP and a long-lasting IPSP were evoked by thalamic or cortical stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Muralimanohar, Ramesh Kumar, Lauren Charney, Marcin Wróblewski, Michelle R. Molis, and Curtis J. Billings. "Cortical encoding and cognition in reverberant speech perception in older adults." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A93. http://dx.doi.org/10.1121/10.0010764.
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Older listeners are more susceptible than younger listeners to noise and reverberation when communicating in everyday environments. This study investigated the effects of hearing loss and cognitive processing ability on older individuals’ ability to perceive reverberant speech. The effects of reverberation were examined using three types of measures (1) electrophysiology: cortical auditory evoked potentials (CAEPs), (2) cognition: working memory and inhibitory control aspect of executive function, and (3) speech perception: syllable discrimination and sentence intelligibility. These assessments were carried out in two age- and sex-matched groups of ten olderadults (>50 years) with either normal hearing (thresholds ≤ 25 dB HL ≤ 4 kHz) or with mild-to-moderate hearing loss. First, the effect of reverberation on the cortical encoding in each group was determined; then, the effects of hearing loss and cognitive function on syllable and sentence perception were examined. Preliminary analyses showed that increasing reverberation negatively impacts speech perception and alters the amplitude and timing of peaks in evoked responses. Differential effects of reverberation across group will also be discussed. The outcomes of this study will help design clinically applicable models to assess individual susceptibility to environmental interference. [Work supported by an Early Clinical Investigator Grant from Medical Research Foundation of Oregon to R.K.M.]
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Yuan, Q., and T. Knöpfel. "Olfactory Nerve Stimulation-Induced Calcium Signaling in the Mitral Cell Distal Dendritic Tuft." Journal of Neurophysiology 95, no. 4 (April 2006): 2417–26. http://dx.doi.org/10.1152/jn.00964.2005.
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Olfactory receptor neuron axons form the olfactory nerve (ON) and project to the glomerular layer of the olfactory bulb, where they form excitatory synapses with terminal arborizations of the mitral cell (MC) tufted primary dendrite. Clusters of MC dendritic tufts define olfactory glomeruli, where they involve in complex synaptic interactions. The computational function of these cellular interactions is not clear. We used patch-clamp electrophysiology combined with whole field or two-photon Ca2+ imaging to study ON stimulation-induced Ca2+ signaling at the level of individual terminal branches of the MC primary dendrite in mice. ON-evoked subthreshold excitatory postsnaptic potentials induced Ca2+ transients in the MC tuft dendrites that were spatially inhomogeneous, exhibiting discrete “hot spots.” In contrast, Ca2+ transients induced by backpropagating action potentials occurred throughout the dendritic tuft, being larger in the thin terminal dendrites than in the base of the tuft. Single ON stimulation-induced Ca2+ transients were depressed by the NMDA receptor antagonist d-aminophosphonovaleric acid (d-APV), increased with increasing stimulation intensity, and typically showed a prolonged rising phase. The synaptically induced Ca2+ signals reflect, at least in part, dendrodendritic interactions that support intraglomerular coupling of MCs and generation of an output that is common to all MCs associated with one glomerulus.
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Quinlan, E. M., K. Gregory, and A. D. Murphy. "An identified glutamatergic interneuron patterns feeding motor activity via both excitation and inhibition." Journal of Neurophysiology 73, no. 3 (March 1, 1995): 945–56. http://dx.doi.org/10.1152/jn.1995.73.3.945.
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1. Previously we demonstrated that glutamate is an important neurotransmitter in the CNS of Helisoma. Exogenous glutamate applied to the buccal ganglia mimicked both the excitatory and inhibitory effects of subunit 2 (S2) of the tripartite central pattern generator (CPG) on S2 postsynaptic motor neurons. Here we identify buccal interneuron B2 as an S2 interneuron by utilizing a combination of electrophysiology, pharmacology, and intracellular staining. In addition, neurons that were electrophysiologically and morphologically characterized as neuron B2 demonstrated antiglutamate immunoreactivity, suggesting that neuron B2 is a source of endogenous glutamate in the buccal ganglia. 2. Depolarization of neuron B2 evoked excitatory postsynaptic potentials in motor neurons excited by S2. The excitatory effects of B2 depolarization and S2 activation were reversibly antagonized by the ionotropic glutamate receptor antagonist 6-cyano-7-nitro-quinoxaline-2,3-dione, similar to the antagonism shown previously for application of exogenous glutamate. Depolarization of neuron B2 also evoked inhibitory postsynaptic potentials in motor neurons inhibited by S2. When such motor neurons were maintained in isolated cell culture, application of exogenous glutamate produced a direct hyperpolarization of the membrane potential. 3. The activity of neuron B2 is necessary for the production of the standard pattern of buccal motor neuron activity, which underlies functional feeding movements. The subunits of the tripartite buccal CPG must be active in the temporal sequence S1-S2-S3 to produce the standard feeding pattern. Rhythmic inhibition from neuron B2 terminated activity in S1 postsynaptic motor neurons and entrained the frequency of activity in S3 postsynaptic motor neurons. Hyperpolarization of neuron B2 disrupted the production of the standard motor pattern by eliminating S2 postsynaptic potentials in identified buccal motor neurons, thereby prolonging S1 activity and disrupting S3 bursting. 4. These data support the hypothesis that S2 neuron B2 is glutamatergic and demonstrate that glutamatergic transmission, and especially inhibition, is fundamental to the production of behaviorally critical motor neuron activity patterns in Helisoma.
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Shi, Zhaoyue, Ruiqi Wu, Pai-Feng Yang, Feng Wang, Tung-Lin Wu, Arabinda Mishra, Li Min Chen, and John C. Gore. "High spatial correspondence at a columnar level between activation and resting state fMRI signals and local field potentials." Proceedings of the National Academy of Sciences 114, no. 20 (May 1, 2017): 5253–58. http://dx.doi.org/10.1073/pnas.1620520114.
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Although blood oxygenation level-dependent (BOLD) fMRI has been widely used to map brain responses to external stimuli and to delineate functional circuits at rest, the extent to which BOLD signals correlate spatially with underlying neuronal activity, the spatial relationships between stimulus-evoked BOLD activations and local correlations of BOLD signals in a resting state, and whether these spatial relationships vary across functionally distinct cortical areas are not known. To address these critical questions, we directly compared the spatial extents of stimulated activations and the local profiles of intervoxel resting state correlations for both high-resolution BOLD at 9.4 T and local field potentials (LFPs), using 98-channel microelectrode arrays, in functionally distinct primary somatosensory areas 3b and 1 in nonhuman primates. Anatomic images of LFP and BOLD were coregistered within 0.10 mm accuracy. We found that the point spread functions (PSFs) of BOLD and LFP responses were comparable in the stimulus condition, and both estimates of activations were slightly more spatially constrained than local correlations at rest. The magnitudes of stimulus responses in area 3b were stronger than those in area 1 and extended in a medial to lateral direction. In addition, the reproducibility and stability of stimulus-evoked activation locations within and across both modalities were robust. Our work suggests that the intrinsic resolution of BOLD is not a limiting feature in practice and approaches the intrinsic precision achievable by multielectrode electrophysiology.
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Bear, C. E., and E. F. Reyes. "cAMP-activated chloride conductance in the colonic cell line, Caco-2." American Journal of Physiology-Cell Physiology 262, no. 1 (January 1, 1992): C251—C256. http://dx.doi.org/10.1152/ajpcell.1992.262.1.c251.
Full textAbstract:
In this study we investigated the properties of adenosine 3',5'-cyclic monophosphate (cAMP)-stimulated Cl- efflux in Caco-2 monolayers by measuring 125I efflux rates from preloaded cells and using patch-clamp electrophysiology. The addition of a cocktail containing 100 microM dibutyryl cAMP (DBcAMP), 10 microM forskolin, and 1 mM 3-isobutyl-1-methylxanthine caused a significant (P less than 0.05) increase in the rate of 125I efflux. Dissipation of cell potential by adding valinomycin (4.5 microM) with 135 mM extracellular KCl reduced the cAMP-evoked 125I efflux. These results suggest that cAMP-stimulated anion efflux occurs through a conductive pore or channel. Whole cell currents evoked with DBcAMP or forskolin were anion selective, PCl greater than PI greater than Pgluconate, and exhibited a linear current-voltage (I-V) relationship. Currents evoked with depolarizing or hyperpolarizing voltage steps showed no evidence of time-dependent activation or inactivation. Single Cl- channels were stimulated in cell-attached patches after treatment with cAMP. Onset of channel activity occurred after 20-30s of cAMP treatment, and the response was long lasting. The I-V relationship for the channel activated in cell-attached patches by cAMP was best fit using two linear regressions. The slope conductance of the channel was 3.2 +/- 0.6 and 7.4 +/- 0.3 pS at hyperpolarizing and depolarizing potentials, respectively. Substitution of 140 mM NaCl with 70 mM NaCl in the patch pipette resulted in a positive shift in reversal potential, indicating that the channel is anion selective.(ABSTRACT TRUNCATED AT 250 WORDS)
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Kumaravelu, Karthik, Chintan S. Oza, Christina E. Behrend, and Warren M. Grill. "Model-based deconstruction of cortical evoked potentials generated by subthalamic nucleus deep brain stimulation." Journal of Neurophysiology 120, no. 2 (August 1, 2018): 662–80. http://dx.doi.org/10.1152/jn.00862.2017.
Full textAbstract:
Parkinson’s disease is associated with altered neural activity in the motor cortex. Chronic high-frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN) is effective in suppressing parkinsonian motor symptoms and modulates cortical activity. However, the anatomical pathways responsible for STN DBS-mediated cortical modulation remain unclear. Cortical evoked potentials (cEP) generated by STN DBS reflect the response of cortex to subcortical stimulation, and the goal of this study was to determine the neural origin of STN DBS-generated cEP using a two-step approach. First, we recorded cEP over ipsilateral primary motor cortex during different frequencies of STN DBS in awake healthy and unilateral 6-OHDA-lesioned parkinsonian rats. Second, we used a detailed, biophysically based model of the thalamocortical network to deconstruct the neural origin of the recorded cEP. The in vivo cEP included short (R1)-, intermediate (R2)-, and long-latency (R3) responses. Model-based cortical responses to simulated STN DBS matched remarkably well the in vivo responses. The short-latency response was generated by antidromic activation of layer 5 pyramidal neurons, whereas recurrent activation of layer 5 pyramidal neurons via excitatory axon collaterals reproduced the intermediate-latency response. The long-latency response was generated by polysynaptic activation of layer 2/3 pyramidal neurons via the cortico-thalamic-cortical pathway. Antidromic activation of the hyperdirect pathway and subsequent intracortical and cortico-thalamo-cortical synaptic interactions were sufficient to generate cortical potential evoked by STN DBS, and orthodromic activation through basal ganglia-thalamus-cortex pathways was not required. These results demonstrate the utility of cEP to determine the neural elements activated by STN DBS that might modulate cortical activity and contribute to the suppression of parkinsonian symptoms. NEW & NOTEWORTHY Subthalamic nucleus (STN) deep brain stimulation (DBS) is increasingly used to treat Parkinson’s disease (PD). Cortical potentials evoked by STN DBS in patients with PD exhibit consistent short-latency (1–3 ms), intermediate-latency (5–15 ms), and long-latency (18–25 ms) responses. The short-latency response occurs as a result of antidromic activation of the hyperdirect pathway comprising corticosubthalamic axons. However, the neural origins of intermediate- and long-latency responses remain elusive, and the dominant view is that these are produced through the orthodromic pathway (basal ganglia-thalamus-cortex). By combining in vivo electrophysiology with computational modeling, we demonstrate that antidromic activation of the cortico-thalamic-cortical pathway is sufficient to generate the intermediate- and long-latency cortical responses to STN DBS.
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Cholanian, Marina, Sally J. Krajewski-Hall, Richard B. Levine, Nathaniel T. McMullen, and Naomi E. Rance. "Electrophysiology of Arcuate Neurokinin B Neurons in Female Tac2-EGFP Transgenic Mice." Endocrinology 155, no. 7 (July 1, 2014): 2555–65. http://dx.doi.org/10.1210/en.2014-1065.
Full textAbstract:
Neurons in the arcuate nucleus that coexpress kisspeptin, neurokinin B (NKB), and dynorphin (KNDy neurons) play an important role in the modulation of reproduction by estrogens. Here, we study the anatomical and electrophysiological properties of arcuate NKB neurons in heterozygous female transgenic mice with enhanced green fluorescent protein (EGFP) under the control of the Tac2 (NKB) promoter (Tac2-EGFP mice). The onset of puberty, estrous cyclicity, and serum LH were comparable between Tac2-EGFP and wild-type mice. The location of EGFP-immunoreactive neurons was consistent with previous descriptions of Tac2 mRNA-expressing neurons in the rodent. In the arcuate nucleus, nearly 80% of EGFP neurons expressed pro-NKB-immunoreactivity. Moreover, EGFP fluorescent intensity in arcuate neurons was increased by ovariectomy and reduced by 17β-estradiol (E2) treatment. Electrophysiology of single cells in tissue slices was used to examine the effects of chronic E2 treatment on Tac2-EGFP neurons in the arcuate nucleus of ovariectomized mice. Whole-cell recordings revealed arcuate NKB neurons to be either spontaneously active or silent in both groups. E2 had no significant effect on the basic electrophysiological properties or spontaneous firing frequencies. Arcuate NKB neurons exhibited either tonic or phasic firing patterns in response to a series of square-pulse current injections. Notably, E2 reduced the number of action potentials evoked by depolarizing current injections. This study demonstrates the utility of the Tac2-EGFP mouse for electrophysiological and morphological studies of KNDy neurons in tissue slices. In parallel to E2 negative feedback on LH secretion, E2 decreased the intensity of the EGFP signal and reduced the excitability of NKB neurons in the arcuate nucleus of ovariectomized Tac2-EGFP mice.