Articles de revues : « Visual oscillations »

1

Young, M. P., K. Tanaka et S. Yamane. « On oscillating neuronal responses in the visual cortex of the monkey ». Journal of Neurophysiology 67, n^o 6 (1 juin 1992) : 1464–74. http://dx.doi.org/10.1152/jn.1992.67.6.1464.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

2

Benedetto, Alessandro, Donatella Spinelli et M. Concetta Morrone. « Rhythmic modulation of visual contrast discrimination triggered by action ». Proceedings of the Royal Society B : Biological Sciences 283, n^o 1831 (25 mai 2016) : 20160692. http://dx.doi.org/10.1098/rspb.2016.0692.

Texte intégral

Résumé :

Recent evidence suggests that ongoing brain oscillations may be instrumental in binding and integrating multisensory signals. In this experiment, we investigated the temporal dynamics of visual–motor integration processes. We show that action modulates sensitivity to visual contrast discrimination in a rhythmic fashion at frequencies of about 5 Hz (in the theta range), for up to 1 s after execution of action. To understand the origin of the oscillations, we measured oscillations in contrast sensitivity at different levels of luminance, which is known to affect the endogenous brain rhythms, boosting the power of alpha-frequencies. We found that the frequency of oscillation in sensitivity increased at low luminance, probably reflecting the shift in mean endogenous brain rhythm towards higher frequencies. Importantly, both at high and at low luminance, contrast discrimination showed a rhythmic motor-induced suppression effect, with the suppression occurring earlier at low luminance. We suggest that oscillations play a key role in sensory–motor integration, and that the motor-induced suppression may reflect the first manifestation of a rhythmic oscillation.

Styles APA, Harvard, Vancouver, ISO, etc.

3

Welle, Cristin G., et Diego Contreras. « Sensory-driven and spontaneous gamma oscillations engage distinct cortical circuitry ». Journal of Neurophysiology 115, n^o 4 (1 avril 2016) : 1821–35. http://dx.doi.org/10.1152/jn.00137.2015.

Texte intégral

Résumé :

Gamma oscillations are a robust component of sensory responses but are also part of the background spontaneous activity of the brain. To determine whether the properties of gamma oscillations in cortex are specific to their mechanism of generation, we compared in mouse visual cortex in vivo the laminar geometry and single-neuron rhythmicity of oscillations produced during sensory representation with those occurring spontaneously in the absence of stimulation. In mouse visual cortex under anesthesia (isoflurane and xylazine), visual stimulation triggered oscillations mainly between 20 and 50 Hz, which, because of their similar functional significance to gamma oscillations in higher mammals, we define here as gamma range. Sensory representation in visual cortex specifically increased gamma oscillation amplitude in the supragranular (L2/3) and granular (L4) layers and strongly entrained putative excitatory and inhibitory neurons in infragranular layers, while spontaneous gamma oscillations were distributed evenly through the cortical depth and primarily entrained putative inhibitory neurons in the infragranular (L5/6) cortical layers. The difference in laminar distribution of gamma oscillations during the two different conditions may result from differences in the source of excitatory input to the cortex. In addition, modulation of superficial gamma oscillation amplitude did not result in a corresponding change in deep-layer oscillations, suggesting that superficial and deep layers of cortex may utilize independent but related networks for gamma generation. These results demonstrate that stimulus-driven gamma oscillations engage cortical circuitry in a manner distinct from spontaneous oscillations and suggest multiple networks for the generation of gamma oscillations in cortex.

Styles APA, Harvard, Vancouver, ISO, etc.

4

Ro, Tony. « Alpha Oscillations and Feedback Processing in Visual Cortex for Conscious Perception ». Journal of Cognitive Neuroscience 31, n^o 7 (juillet 2019) : 948–60. http://dx.doi.org/10.1162/jocn_a_01397.

Texte intégral

Résumé :

Variability in perception between individuals may be a consequence of different inherent neural processing speeds. To assess whether alpha oscillations systematically reflect a feedback pacing mechanism for cortical processing during visual perception, comparisons were made between alpha oscillations, visual suppression from TMS, visual evoked responses, and metacontrast masking. Peak alpha oscillation frequencies, measured through scalp EEG recordings, significantly correlated with the optimum latencies for visual suppression from TMS of early visual cortex. Individuals with shorter alpha periods (i.e., higher peak alpha frequencies) processed visual information faster than those with longer alpha periods (i.e., lower peak alpha frequencies). Moreover, peak alpha oscillation periods and optimum TMS visual suppression latencies predicted the latencies of late but not early visual evoked responses. Together, these findings demonstrate an important role of alpha oscillatory and late feedback activity in visual cortex for conscious perception. They also show that the timing for visual awareness varies across individuals, depending on the pace of one's endogenous oscillatory cycling frequency.

Styles APA, Harvard, Vancouver, ISO, etc.

5

Wang, Wei, Kaiming Yang et Yu Zhu. « Optimal Frequency and Amplitude of Vertical Viewpoint Oscillation for Improving Vection Strength and Reducing Neural Constrains on Gait ». Entropy 23, n^o 5 (28 avril 2021) : 541. http://dx.doi.org/10.3390/e23050541.

Texte intégral

Résumé :

Inducing self-motion illusions referred as vection are critical for improving the sensation of walking in virtual environments (VE). Adding viewpoint oscillations to a constant forward velocity in VE is effective for improving vection strength under static conditions. However, the effects of oscillation frequency and amplitude on vection strength under treadmill walking conditions are still unclear. Besides, due to the visuomotor entrainment mechanism, these visual oscillations would affect gait patterns and be detrimental for achieving natural walking if not properly designed. This study was aimed at determining the optimal frequency and amplitude of vertical viewpoint oscillations for improving vection strength and reducing gait constraints. Seven subjects walked on a treadmill while watching a visual scene. The visual scene presented a constant forward velocity equal to the treadmill velocity with different vertical viewpoint oscillations added. Five oscillation patterns with different combinations of frequency and amplitude were tested. Subjects gave verbal ratings of vection strength. The mediolateral (M-L) center of pressure (CoP) complexity was calculated to indicate gait constraints. After the experiment, subjects were asked to give the best and the worst oscillation pattern based on their walking experience. The oscillation frequency and amplitude had strong positive correlations with vection strength. The M-L CoP complexity was reduced under oscillations with low frequency. The medium oscillation amplitude had greater M-L CoP complexity than the small and large amplitude. Besides, subjects preferred those oscillation patterns with large gait complexity. We suggested that the oscillation amplitude with largest M-L CoP complexity should first be chosen to reduce gait constraints. Then, increasing the oscillation frequency to improve vection strength until individual preference or the boundary of motion sickness. These findings provide important guidelines to promote the sensation of natural walking in VE.

Styles APA, Harvard, Vancouver, ISO, etc.

6

Mureşan, Raul C., Ovidiu F. Jurjuţ, Vasile V. Moca, Wolf Singer et Danko Nikolić. « The Oscillation Score : An Efficient Method for Estimating Oscillation Strength in Neuronal Activity ». Journal of Neurophysiology 99, n^o 3 (mars 2008) : 1333–53. http://dx.doi.org/10.1152/jn.00772.2007.

Texte intégral

Résumé :

We present a method that estimates the strength of neuronal oscillations at the cellular level, relying on autocorrelation histograms computed on spike trains. The method delivers a number, termed oscillation score, that estimates the degree to which a neuron is oscillating in a given frequency band. Moreover, it can also reliably identify the oscillation frequency and strength in the given band, independently of the oscillation in other frequency bands, and thus it can handle superimposed oscillations on multiple scales ( theta, alpha, beta, gamma, etc.). The method is relatively simple and fast. It can cope with a low number of spikes, converging exponentially fast with the number of spikes, to a stable estimation of the oscillation strength. It thus lends itself to the analysis of spike-sorted single-unit activity from electrophysiological recordings. We show that the method performs well on experimental data recorded from cat visual cortex and also compares favorably to other methods. In addition, we provide a measure, termed confidence score, that determines the stability of the oscillation score estimate over trials.

Styles APA, Harvard, Vancouver, ISO, etc.

7

Sánchez-Arias, Mônica Del Rosario, Ana Francisca Rozin Kleiner, Ágata Yoko Yasue Hamanaka, Paulo Roberto Pereira Santiago, Lilian Teresa Bucken Gobbi et Florindo Stella. « Visual restriction and anterior-posterior body oscillations in Parkinson’s disease ». Acta Fisiátrica 19, n^o 3 (9 septembre 2012) : 161–66. http://dx.doi.org/10.11606/issn.2317-0190.v19i3a103709.

Texte intégral

Résumé :

With their vision restricted, sufferers of Parkinson’s disease (PD) make few anticipatory and/or compensatory adjustments in their posture and the evidence of these adjustments is even less when the disease progresses and body oscillations are considered. Objective: The aim of this study was to demonstrate the effects of visual restriction on the anterior-posterior body oscillation angles in parkinsonian stance considering the early stages of this disease. Method: Ten elderly PD patients with Hoehn & Yahr (HY) stage 2 remained standing still for 30 seconds to measure the body oscillation angles with and without restricted vision. Results: Two-way ANOVA analyses with repeated measurements revealed the main effect of vision (F(1,7) = 8.931, p < 0.02). Conclusion: The angles of the anterior-posterior body oscillations without visibility were greater than with visibility. They did not differ in correlation with the HY stages and visibility conditions interfered with the postural control regardless of the PD evolution stage.

Styles APA, Harvard, Vancouver, ISO, etc.

8

Mathewson, Kyle E., Christopher Prudhomme, Monica Fabiani, Diane M. Beck, Alejandro Lleras et Gabriele Gratton. « Making Waves in the Stream of Consciousness : Entraining Oscillations in EEG Alpha and Fluctuations in Visual Awareness with Rhythmic Visual Stimulation ». Journal of Cognitive Neuroscience 24, n^o 12 (décembre 2012) : 2321–33. http://dx.doi.org/10.1162/jocn_a_00288.

Texte intégral

Résumé :

Rhythmic events are common in our sensory world. Temporal regularities could be used to predict the timing of upcoming events, thus facilitating their processing. Indeed, cognitive theories have long posited the existence of internal oscillators whose timing can be entrained to ongoing periodic stimuli in the environment as a mechanism of temporal attention. Recently, recordings from primate brains have shown electrophysiological evidence for these hypothesized internal oscillations. We hypothesized that rhythmic visual stimuli can entrain ongoing neural oscillations in humans, locking the timing of the excitability cycles they represent and thus enhancing processing of subsequently predictable stimuli. Here we report evidence for entrainment of neural oscillations by predictable periodic stimuli in the alpha frequency band and show for the first time that the phase of existing brain oscillations cannot only be modified in response to rhythmic visual stimulation but that the resulting phase-locked fluctuations in excitability lead to concomitant fluctuations in visual awareness in humans. This entrainment effect was dependent on both the amount of spontaneous alpha power before the experiment and the level of 12-Hz oscillation before each trial and could not be explained by evoked activity. Rhythmic fluctuations in awareness elicited by entrainment of ongoing neural excitability cycles support a proposed role for alpha oscillations as a pulsed inhibition of cortical activity. Furthermore, these data provide evidence for the quantized nature of our conscious experience and reveal a powerful mechanism by which temporal attention as well as perceptual snapshots can be manipulated and controlled.

Styles APA, Harvard, Vancouver, ISO, etc.

9

Goldreich, D., R. J. Krauzlis et S. G. Lisberger. « Effect of changing feedback delay on spontaneous oscillations in smooth pursuit eye movements of monkeys ». Journal of Neurophysiology 67, n^o 3 (1 mars 1992) : 625–38. http://dx.doi.org/10.1152/jn.1992.67.3.625.

Texte intégral

Résumé :

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)

Styles APA, Harvard, Vancouver, ISO, etc.

10

Garcia, Javier O., Emily D. Grossman et Ramesh Srinivasan. « Evoked potentials in large-scale cortical networks elicited by TMS of the visual cortex ». Journal of Neurophysiology 106, n^o 4 (octobre 2011) : 1734–46. http://dx.doi.org/10.1152/jn.00739.2010.

Texte intégral

Résumé :

Single pulses of transcranial magnetic stimulation (TMS) result in distal and long-lasting oscillations, a finding directly challenging the virtual lesion hypothesis. Previous research supporting this finding has primarily come from stimulation of the motor cortex. We have used single-pulse TMS with simultaneous EEG to target seven brain regions, six of which belong to the visual system [left and right primary visual area V1, motion-sensitive human middle temporal cortex, and a ventral temporal region], as determined with functional MRI-guided neuronavigation, and a vertex “control” site to measure the network effects of the TMS pulse. We found the TMS-evoked potential (TMS-EP) over visual cortex consists mostly of site-dependent theta- and alphaband oscillations. These site-dependent oscillations extended beyond the stimulation site to functionally connected cortical regions and correspond to time windows where the EEG responses maximally diverge (40, 200, and 385 ms). Correlations revealed two site-independent oscillations ∼350 ms after the TMS pulse: a theta-band oscillation carried by the frontal cortex, and an alpha-band oscillation over parietal and frontal cortical regions. A manipulation of stimulation intensity at one stimulation site (right hemisphere V1-V3) revealed sensitivity to the stimulation intensity at different regions of cortex, evidence of intensity tuning in regions distal to the site of stimulation. Together these results suggest that a TMS pulse applied to the visual cortex has a complex effect on brain function, engaging multiple brain networks functionally connected to the visual system with both invariant and site-specific spatiotemporal dynamics. With this characterization of TMS, we propose an alternative to the virtual lesion hypothesis. Rather than a technique that simulates lesions, we propose TMS generates natural brain signals and engages functional networks.

Styles APA, Harvard, Vancouver, ISO, etc.

11

Chen, Yvonne Y., et 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, n^o 1 (janvier 2017) : 183–202. http://dx.doi.org/10.1162/jocn_a_01033.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

12

Prechtl, J. C. « Visual motion induces synchronous oscillations in turtle visual cortex. » Proceedings of the National Academy of Sciences 91, n^o 26 (20 décembre 1994) : 12467–71. http://dx.doi.org/10.1073/pnas.91.26.12467.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

13

Mulligan, J. B. « Assessing visual delays using pupil oscillations ». Journal of Vision 11, n^o 11 (23 septembre 2011) : 504. http://dx.doi.org/10.1167/11.11.504.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

14

Ishikane, H., M. Gangi, S. Honda, S. Usui et M. Tachibana. « Visual information coding by synchronized oscillations ». Journal of Vision 6, n^o 6 (24 mars 2010) : 63. http://dx.doi.org/10.1167/6.6.63.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

15

Moldakarimov, Samat, Julianne E. Rollenhagen, Carl R. Olson et Carson C. Chow. « Competitive Dynamics in Cortical Responses to Visual Stimuli ». Journal of Neurophysiology 94, n^o 5 (novembre 2005) : 3388–96. http://dx.doi.org/10.1152/jn.00159.2005.

Texte intégral

Résumé :

Neurons in the visual cortex of the macaque monkey exhibit a variety of competitive behaviors, including normalization and oscillation, when presented with multiple visual stimuli. Here we argue that a biophysically plausible cortical circuit with opponent inhibition, spike-frequency adaptation, and synaptic depression can account for the full range of behaviors. The governing parameter is the strength of inhibition between competing neuronal pools. As the strength of inhibition is increased, the pattern of network behavior shifts from normalization mode to oscillatory mode, with oscillations occurring at progressively lower frequency until, at the extreme, winner-take-all behavior appears.

Styles APA, Harvard, Vancouver, ISO, etc.

16

Assaiante, Christine, et Bernard Amblard. « Visual Factors in the Child's Gait : Effects on Locomotor Skills ». Perceptual and Motor Skills 83, n^o 3 (décembre 1996) : 1019–41. http://dx.doi.org/10.2466/pms.1996.83.3.1019.

Texte intégral

Résumé :

This kinematic study investigated the effects of visual factors on the angular oscillations of the head and trunk during various locomotor tasks in 3- to 8-yr.-old children and adults. The oscillations of the head under normal vision were limited and changed little across ages Oscillations of both head and trunk about the roll axis were the most sensitive to difficulty in maintaining lateral equilibrium. On narrow supports, the lateral oscillations of the trunk increased between the ages of 3 and 6 years, with a maximum amplitude at the latter age and then decreased up to adulthood, suggesting a transition phase around the age of 6 years. Visual restriction had little effect on the control of angular oscillations of the head in children or adults. On a narrow support in darkness, adults increased oscillations of the trunk but reduced oscillations of the head. It can be concluded that, regardless of the age, control of locomotor equilibrium aims at limiting the angular oscillations of the head. Vision seems to contribute little to stabilization of the head.

Styles APA, Harvard, Vancouver, ISO, etc.

17

Savino, Gustavo, Anna Dickmann, Fabrizio Ottaviani, Walter Di Nardo, Luigi Scullica et Stefano Di Girolamo. « The role of ocular oscillations upon visually dependent postural stabilization in patients affected by congenital nystagmus ». Journal of Vestibular Research 10, n^o 4-5 (1 novembre 2000) : 201–6. http://dx.doi.org/10.3233/ves-2000-104-504.

Texte intégral

Résumé :

Visually dependent postural stabilization decreases as a consequence of a long-standing reduction of visual cues in patients affected by congenital nystagmus. The aim of the present study was to verify whether the changes in postural control in this group of patients are due to ocular oscillations or to reduced visual acuity. Therefore, postural control was evaluated when the nystagmus was blocked by the blocking position or by prisms and compared with the postural score observed in a group of normal controls whose visual acuity had been artificially reduced to the same level as that of the patients using Bangerter's filters. The results show a statistically significant improvement of visually dependent postural stabilization when ocular oscillations are inhibited either by the gaze blocking position or by prisms. They also show that postural control in normal subjects with Bangerter's filters is reduced, but is still significantly better than that observed when ocular oscillations are inhibited in patients affected by congenital nystagmus. Our data strongly support the role of ocular oscillations in visually dependent postural control, since postural impairment recovered under any condition in which ocular oscillations were abolished, despite differences in visual acuity. Our data also show that reduced visual acuity decreases visually dependent postural control to a lesser degree than ocular oscillations. This could be due to the fact that ocular oscillations are a disturbing input, usually inhibited centrally, in order to avoid oscillopsia. This mechanism is probably responsible for the reduced role of visual cues in the postural control in this group of patients. The reduction of visual acuity, by comparison, merely causes a decrease in visual cues, depending on the degree of visual loss. It can be concluded that the impaired postural control in patients affected by congenital nystagmus is mainly due to ocular oscillations, with reduced visual acuity creating a secondary effect.

Styles APA, Harvard, Vancouver, ISO, etc.

18

Yener, Görsev G., Bahar Güntekin, Elif Tülay et Erol Başar. « A comparative analysis of sensory visual evoked oscillations with visual cognitive event related oscillations in Alzheimer's disease ». Neuroscience Letters 462, n^o 3 (septembre 2009) : 193–97. http://dx.doi.org/10.1016/j.neulet.2009.07.036.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

19

Stenner, Max-Philipp, Markus Bauer, Patrick Haggard, Hans-Jochen Heinze et Ray Dolan. « Enhanced Alpha-oscillations in Visual Cortex during Anticipation of Self-generated Visual Stimulation ». Journal of Cognitive Neuroscience 26, n^o 11 (novembre 2014) : 2540–51. http://dx.doi.org/10.1162/jocn_a_00658.

Texte intégral

Résumé :

The perceived intensity of sensory stimuli is reduced when these stimuli are caused by the observer's actions. This phenomenon is traditionally explained by forward models of sensory action–outcome, which arise from motor processing. Although these forward models critically predict anticipatory modulation of sensory neural processing, neurophysiological evidence for anticipatory modulation is sparse and has not been linked to perceptual data showing sensory attenuation. By combining a psychophysical task involving contrast discrimination with source-level time–frequency analysis of MEG data, we demonstrate that the amplitude of alpha-oscillations in visual cortex is enhanced before the onset of a visual stimulus when the identity and onset of the stimulus are controlled by participants' motor actions. Critically, this prestimulus enhancement of alpha-amplitude is paralleled by psychophysical judgments of a reduced contrast for this stimulus. We suggest that alpha-oscillations in visual cortex preceding self-generated visual stimulation are a likely neurophysiological signature of motor-induced sensory anticipation and mediate sensory attenuation. We discuss our results in relation to proposals that attribute generic inhibitory functions to alpha-oscillations in prioritizing and gating sensory information via top–down control.

Styles APA, Harvard, Vancouver, ISO, etc.

20

Bellet, Joachim, Chih-Yang Chen et Ziad M. Hafed. « Sequential hemifield gating of α- and β-behavioral performance oscillations after microsaccades ». Journal of Neurophysiology 118, n^o 5 (1 novembre 2017) : 2789–805. http://dx.doi.org/10.1152/jn.00253.2017.

Texte intégral

Résumé :

Microsaccades are tiny saccades that occur during gaze fixation. Even though visual processing has been shown to be strongly modulated close to the time of microsaccades, both at central and peripheral eccentricities, it is not clear how these eye movements might influence longer term fluctuations in brain activity and behavior. Here we found that visual processing is significantly affected and, in a rhythmic manner, even several hundreds of milliseconds after a microsaccade. Human visual detection efficiency, as measured by reaction time, exhibited coherent rhythmic oscillations in the α- and β-frequency bands for up to ~650–700 ms after a microsaccade. Surprisingly, the oscillations were sequentially pulsed across visual hemifields relative to microsaccade direction, first occurring in the same hemifield as the movement vector for ~400 ms and then the opposite. Such pulsing also affected perceptual detection performance. Our results suggest that visual processing is subject to long-lasting oscillations that are phase locked to microsaccade generation, and that these oscillations are dependent on microsaccade direction. NEW & NOTEWORTHY We investigated long-term microsaccadic influences on visual processing and found rhythmic oscillations in behavioral performance at α- and β-frequencies (~8–20 Hz). These oscillations were pulsed at a much lower frequency across visual hemifields, first occurring in the same hemifield as the microsaccade direction vector for ~400 ms before switching to the opposite hemifield for a similar interval. Our results suggest that saccades temporally organize visual processing and that such organization can sequentially switch hemifields.

Styles APA, Harvard, Vancouver, ISO, etc.

21

Forget, Joachim, Marco Buiatti et Stanislas Dehaene. « Temporal Integration in Visual Word Recognition ». Journal of Cognitive Neuroscience 22, n^o 5 (mai 2010) : 1054–68. http://dx.doi.org/10.1162/jocn.2009.21300.

Texte intégral

Résumé :

When two displays are presented in close temporal succession at the same location, how does the brain assign them to one versus two conscious percepts? We investigate this issue using a novel reading paradigm in which the odd and even letters of a string are presented alternatively at a variable rate. The results reveal a window of temporal integration during reading, with a nonlinear boundary around ∼80 msec of presentation duration. Below this limit, the oscillating stimulus is easily fused into a single percept, with all characteristics of normal reading. Above this limit, reading times are severely slowed and suffer from a word-length effect. ERPs indicate that, even at the fastest frequency, the oscillating stimulus elicits synchronous oscillations in posterior visual cortices, while late ERP components sensitive to lexical status vanish beyond the fusion threshold. Thus, the fusion/segregation dilemma is not resolved by retinal or subcortical filtering, but at cortical level by at most 300 msec. The results argue against theories of visual word recognition and letter binding that rely on temporal synchrony or other fine temporal codes.

Styles APA, Harvard, Vancouver, ISO, etc.

22

Clayton, Michael S., Nick Yeung et Roi Cohen Kadosh. « The many characters of visual alpha oscillations ». European Journal of Neuroscience 48, n^o 7 (6 novembre 2017) : 2498–508. http://dx.doi.org/10.1111/ejn.13747.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

23

Webster, Kelly, et Tony Ro. « Visual Modulation of Resting State α Oscillations ». eneuro 7, n^o 1 (13 décembre 2019) : ENEURO.0268–19.2019. http://dx.doi.org/10.1523/eneuro.0268-19.2019.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

24

Thoss, Franz, Bengt Bartsch et Joachim Stebel. « Analysis of oscillations of the visual sensitivity ». Vision Research 38, n^o 1 (janvier 1998) : 139–42. http://dx.doi.org/10.1016/s0042-6989(97)00150-8.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

25

Huang, J., et R. Sekuler. « -oscillations and the fidelity of visual memory ». Journal of Vision 10, n^o 7 (11 août 2010) : 715. http://dx.doi.org/10.1167/10.7.715.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

26

Tikhonov, Alexander, Barbara Händel, Thomas Haarmeier, Werner Lutzenberger et Peter Thier. « Gamma oscillations underlying the visual motion aftereffect ». NeuroImage 38, n^o 4 (décembre 2007) : 708–19. http://dx.doi.org/10.1016/j.neuroimage.2007.07.055.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

27

Schroeder, Charles E., Peter Lakatos, Yoshinao Kajikawa, Sarah Partan et Aina Puce. « Neuronal oscillations and visual amplification of speech ». Trends in Cognitive Sciences 12, n^o 3 (mars 2008) : 106–13. http://dx.doi.org/10.1016/j.tics.2008.01.002.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

28

San Juan, R. M. « Oscillations of the Early Modern Visual Imagination ». Oxford Art Journal 30, n^o 3 (27 juillet 2007) : 521–24. http://dx.doi.org/10.1093/oxartj/kcm017.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

29

Petrauskiene, Vilma, Rita Palivonaite, Algiment Aleksa et Minvydas Ragulskis. « Dynamic visual cryptography based on chaotic oscillations ». Communications in Nonlinear Science and Numerical Simulation 19, n^o 1 (janvier 2014) : 112–20. http://dx.doi.org/10.1016/j.cnsns.2013.06.002.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

30

Cabral-Calderin, Y., C. Schmidt-Samoa et M. Wilke. « Role of gamma oscillations in visual awareness. » Journal of Vision 13, n^o 9 (25 juillet 2013) : 1030. http://dx.doi.org/10.1167/13.9.1030.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

31

Loesel, Rudi, et Uwe Homberg. « Sustained oscillations in an insect visual system ». Naturwissenschaften 85, n^o 5 (mai 1998) : 238–40. http://dx.doi.org/10.1007/s001140050490.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

32

Ghose, G. M., et R. D. Freeman. « Oscillatory discharge in the visual system : does it have a functional role ? » Journal of Neurophysiology 68, n^o 5 (1 novembre 1992) : 1558–74. http://dx.doi.org/10.1152/jn.1992.68.5.1558.

Texte intégral

Résumé :

1. The discharge of individual neurons in the visual cortex and lateral geniculate nucleus (LGN) of anesthetized and paralyzed cats and kittens was examined for the presence of oscillatory activity. Neural firing was evoked through the monoptic or dichoptic presentation of drifting gratings and random sequences of flashed bars. The degree to which different oscillatory frequencies were present in neural discharge was quantified by computation of the power spectra of impulse train responses. 2. Action potentials from single cells were recorded extracellularly and isolated on the basis of amplitude. Receptive-field properties of the neurons under study were characterized initially by their discharge in response to gratings of sinusoidal luminance. By varying orientation and spatial frequency, optimal stimulus characteristics were determined. Oscillation analysis was performed on spike trains acquired during repeated presentations of the optimal stimulus by identification of power spectra peaks in the frequency range of rhythmic potentials observed in electroencephalograph studies (30-80 Hz). The amplitude and frequency of the largest peak in this range was used to characterize oscillatory strength and frequency. All discharge in which the peak amplitude exceeded the high-frequency noise by a factor > 1.5 was classified as oscillatory. 3. Of the 342 cortical cells examined, 147 cells displayed oscillatory activity in the 30 to 80-Hz range during portions of their visual response. Sixty out of 169 simple cells, 82 out of 166 complex cells, and 5 out of 7 special complex cells exhibited oscillations. There was no laminar bias in the distribution of oscillatory cells; the proportions of oscillatory cells were similar in all layers. All oscillatory discharge was variable with respect to frequency and strength between successive presentations of the same optimal stimulus. In as little as 10 s, for example, peak frequencies shifted by a factor of two. For many cells, these trial-to-trial variations obscured detectable oscillations when all trials were averaged together. 4. The potential role of neuronal maturation in the generation of oscillatory activity was investigated by studying neuronal responses from kittens at 4 wk postnatal. Of the 80 kitten cells studied, 27 exhibited oscillatory discharge. Although oscillations in the kitten visual cortex spanned the same frequency range as that seen in the adult, oscillations in the midfrequency range (36-44 Hz) are more common in the adult cortex. 5. To explore the possibility that oscillations might play a functional role in vision, we investigated the dependence of oscillations on different stimulus parameters.(ABSTRACT TRUNCATED AT 400 WORDS)

Styles APA, Harvard, Vancouver, ISO, etc.

33

Rouhinen, Santeri, Felix Siebenhühner, J. Matias Palva et Satu Palva. « Spectral and Anatomical Patterns of Large-Scale Synchronization Predict Human Attentional Capacity ». Cerebral Cortex 30, n^o 10 (2 juin 2020) : 5293–308. http://dx.doi.org/10.1093/cercor/bhaa110.

Texte intégral

Résumé :

Abstract The capacity of visual attention determines how many visual objects may be perceived at any moment. This capacity can be investigated with multiple object tracking (MOT) tasks, which have shown that it varies greatly between individuals. The neuronal mechanisms underlying capacity limits have remained poorly understood. Phase synchronization of cortical oscillations coordinates neuronal communication within the fronto-parietal attention network and between the visual regions during endogenous visual attention. We tested a hypothesis that attentional capacity is predicted by the strength of pretarget synchronization within attention-related cortical regions. We recorded cortical activity with magneto- and electroencephalography (M/EEG) while measuring attentional capacity with MOT tasks and identified large-scale synchronized networks from source-reconstructed M/EEG data. Individual attentional capacity was correlated with load-dependent strengthening of theta (3–8 Hz), alpha (8–10 Hz), and gamma-band (30–120 Hz) synchronization that connected the visual cortex with posterior parietal and prefrontal cortices. Individual memory capacity was also preceded by crossfrequency phase–phase and phase–amplitude coupling of alpha oscillation phase with beta and gamma oscillations. Our results show that good attentional capacity is preceded by efficient dynamic functional coupling and decoupling within brain regions and across frequencies, which may enable efficient communication and routing of information between sensory and attentional systems.

Styles APA, Harvard, Vancouver, ISO, etc.

34

Adjamian, Peyman, Ian E. Holliday, Gareth R. Barnes, Arjan Hillebrand, Avgis Hadjipapas et Krish D. Singh. « Induced visual illusions and gamma oscillations in human primary visual cortex ». European Journal of Neuroscience 20, n^o 2 (juillet 2004) : 587–92. http://dx.doi.org/10.1111/j.1460-9568.2004.03495.x.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

35

Hoseini, Mahmood S., Jeff Pobst, Nathaniel Wright, Wesley Clawson, Woodrow Shew et Ralf Wessel. « Induced cortical oscillations in turtle cortex are coherent at the mesoscale of population activity, but not at the microscale of the membrane potential of neurons ». Journal of Neurophysiology 118, n^o 5 (1 novembre 2017) : 2579–91. http://dx.doi.org/10.1152/jn.00375.2017.

Texte intégral

Résumé :

Bursts of oscillatory neural activity have been hypothesized to be a core mechanism by which remote brain regions can communicate. Such a hypothesis raises the question to what extent oscillations are coherent across spatially distant neural populations. To address this question, we obtained local field potential (LFP) and membrane potential recordings from the visual cortex of turtle in response to visual stimulation of the retina. The time-frequency analysis of these recordings revealed pronounced bursts of oscillatory neural activity and a large trial-to-trial variability in the spectral and temporal properties of the observed oscillations. First, local bursts of oscillations varied from trial to trial in both burst duration and peak frequency. Second, oscillations of a given recording site were not autocoherent; i.e., the phase did not progress linearly in time. Third, LFP oscillations at spatially separate locations within the visual cortex were more phase coherent in the presence of visual stimulation than during ongoing activity. In contrast, the membrane potential oscillations from pairs of simultaneously recorded pyramidal neurons showed smaller phase coherence, which did not change when switching from black screen to visual stimulation. In conclusion, neuronal oscillations at distant locations in visual cortex are coherent at the mesoscale of population activity, but coherence is largely absent at the microscale of the membrane potential of neurons. NEW & NOTEWORTHY Coherent oscillatory neural activity has long been hypothesized as a potential mechanism for communication across locations in the brain. In this study we confirm the existence of coherent oscillations at the mesoscale of integrated cortical population activity. However, at the microscopic level of neurons, we find no evidence for coherence among oscillatory membrane potential fluctuations. These results raise questions about the applicability of the communication through coherence hypothesis to the level of the membrane potential.

Styles APA, Harvard, Vancouver, ISO, etc.

36

Agadagba, Stephen Kugbere, et Leanne Lai Hang Chan. « Modulation of narrowband and broadband gamma connectivity in retinal degeneration mice according to electrical stimulation pulse width ». Special Issue with Awarded and Shortlisted Papers from the HKIE Outstanding Paper Award for Young Engineers/Researchers 2020 27, n^o 4 (11 janvier 2021) : 148–55. http://dx.doi.org/10.33430/thie-2020-0006.

Texte intégral

Résumé :

Brain connectivity involves the structural, functional and effective communication between neurons across brain regions and is expressed in neuronal oscillations. Previous research has reported the evidence of two types of gamma oscillations namely the broadband gamma (30 Hz - 90 Hz) and narrowband gamma (55 Hz - 70 Hz) oscillations which have been implicated in excitatory and inhibitory network transmission. There is presently no systematic investigation of the relationship between electrical stimulation pulse width and narrow or broadband gamma oscillations in visual-deficient mice. In the current study, we set out to bridge this gap in knowledge by exploring the modulation of brain connectivity indices in broadband gamma and narrowband gamma oscillations in response to varying electrical stimulation pulse width in retinal degeneration (rd) mice. The results revealed that a low pulse width (0.5 ms/phase) strongly enhances coherence and directional connectivity of broadband and narrowband gamma oscillations in contra visual cortex and contra prefrontal cortex of rd mice. This study serves a crucial role in the design and utilisation of visual prostheses by contributing to the understanding of information transmission between different brain regions under retinal electrical stimulation in visual-deficit population.

Styles APA, Harvard, Vancouver, ISO, etc.

37

Agadagba, Stephen Kugbere, et Leanne Lai Hang Chan. « Modulation of narrowband and broadband gamma connectivity in retinal degeneration mice according to electrical stimulation pulse width ». Special Issue with Awarded and Shortlisted Papers from the HKIE Outstanding Paper Award for Young Engineers/Researchers 2020 27, n^o 4 (11 janvier 2021) : 148–55. http://dx.doi.org/10.33430/thie-2020-0006.

Texte intégral

Résumé :

Brain connectivity involves the structural, functional and effective communication between neurons across brain regions and is expressed in neuronal oscillations. Previous research has reported the evidence of two types of gamma oscillations namely the broadband gamma (30 Hz - 90 Hz) and narrowband gamma (55 Hz - 70 Hz) oscillations which have been implicated in excitatory and inhibitory network transmission. There is presently no systematic investigation of the relationship between electrical stimulation pulse width and narrow or broadband gamma oscillations in visual-deficient mice. In the current study, we set out to bridge this gap in knowledge by exploring the modulation of brain connectivity indices in broadband gamma and narrowband gamma oscillations in response to varying electrical stimulation pulse width in retinal degeneration (rd) mice. The results revealed that a low pulse width (0.5 ms/phase) strongly enhances coherence and directional connectivity of broadband and narrowband gamma oscillations in contra visual cortex and contra prefrontal cortex of rd mice. This study serves a crucial role in the design and utilisation of visual prostheses by contributing to the understanding of information transmission between different brain regions under retinal electrical stimulation in visual-deficit population.

Styles APA, Harvard, Vancouver, ISO, etc.

38

Agadagba, Stephen Kugbere, et Leanne Lai Hang Chan. « Modulation of narrowband and broadband gamma connectivity in retinal degeneration mice according to electrical stimulation pulse width ». Special Issue with Awarded and Shortlisted Papers from the HKIE Outstanding Paper Award for Young Engineers/Researchers 2020 27, n^o 4 (11 janvier 2021) : 148–55. http://dx.doi.org/10.33430/v27n4thie-2020-0006.

Texte intégral

Résumé :

Brain connectivity involves the structural, functional and effective communication between neurons across brain regions and is expressed in neuronal oscillations. Previous research has reported the evidence of two types of gamma oscillations namely the broadband gamma (30 Hz - 90 Hz) and narrowband gamma (55 Hz - 70 Hz) oscillations which have been implicated in excitatory and inhibitory network transmission. There is presently no systematic investigation of the relationship between electrical stimulation pulse width and narrow or broadband gamma oscillations in visual-deficient mice. In the current study, we set out to bridge this gap in knowledge by exploring the modulation of brain connectivity indices in broadband gamma and narrowband gamma oscillations in response to varying electrical stimulation pulse width in retinal degeneration (rd) mice. The results revealed that a low pulse width (0.5 ms/phase) strongly enhances coherence and directional connectivity of broadband and narrowband gamma oscillations in contra visual cortex and contra prefrontal cortex of rd mice. This study serves a crucial role in the design and utilisation of visual prostheses by contributing to the understanding of information transmission between different brain regions under retinal electrical stimulation in visual-deficit population.

Styles APA, Harvard, Vancouver, ISO, etc.

39

López-Caneda, Eduardo, Socorro Rodríguez Holguín, Ángeles Correas, Carina Carbia, Alberto González-Villar, Fernando Maestú et Fernando Cadaveira. « Binge drinking affects brain oscillations linked to motor inhibition and execution ». Journal of Psychopharmacology 31, n^o 7 (7 février 2017) : 873–82. http://dx.doi.org/10.1177/0269881116689258.

Texte intégral

Résumé :

Introduction: Neurofunctional studies have shown that binge drinking patterns of alcohol consumption during adolescence and youth are associated with anomalies in brain functioning. Recent evidence suggests that event-related oscillations may be an appropriate index of neurofunctional damage associated with alcoholism. However, there is no study to date that has evaluated the effects of binge drinking on oscillatory brain responses related to task performance. The purpose of the present study was to examine brain oscillations linked to motor inhibition and execution in young binge drinkers (BDs) compared with age-matched controls. Methods: Electroencephalographic activity was recorded from 64 electrodes while 72 university students (36 controls and 36 BDs) performed a visual Go/NoGo task. Event-related oscillations along with the Go-P3 and NoGo-P3 event-related potential components were analysed. Results: While no significant differences between groups were observed regarding event-related potentials, event-related oscillation analysis showed that BDs displayed a lower oscillatory response than controls in delta and theta frequency ranges during Go and NoGo conditions. Conclusions: Findings are congruent with event-related oscillation studies showing reduced delta and/or theta oscillations in alcoholics during Go/NoGo tasks. Thus, BDs appear to show disruptions in neural oscillations linked to motor inhibition and execution similar to those observed in alcohol-dependent subjects. Finally, these results are the first to evidence that oscillatory brain activity may be a sensitive indicator of underlying brain anomalies in young BDs, which could complement standard event-related potential measures.

Styles APA, Harvard, Vancouver, ISO, etc.

40

Wu, Wenfeng, Xiaojiaqi Huang, Xin Qi et Yongbiao Lu. « Bias of Attentional Oscillations in Individuals with Subthreshold Depression : Evidence from a Pre-Cueing Facial Expression Judgment Task ». International Journal of Environmental Research and Public Health 19, n^o 21 (6 novembre 2022) : 14559. http://dx.doi.org/10.3390/ijerph192114559.

Texte intégral

Résumé :

Background: Study results regarding attentional bias in depressed individuals are inconsistent. Recent studies have found that attention is a discrete process, alternating between periods of either enhanced or diminished attention sensitivity. Whether a visual target can be detected depends on when it occurs relative to these oscillation rhythms. We infer that the inconsistency of attentional bias may be related to the abnormality of attentional oscillations in depressed individuals. Methods: A pre-cueing attentional task was used. We set 48 levels of stimulus onset asynchrony (SOA) between cues and targets and measured the response time (RT) of participants, as well as their EEG signals. Results: The RTs showed patterns of behavioral oscillations. Repeated-measure ANOVA indicated that subthreshold depressed participants had significantly higher RTs for negative expressions than for neutral but significantly lower RTs for positive than for neutral. The frequency analysis indicated that the RT oscillational frequency of subthreshold depressed participants to negative/positive expressions was different from that to neutral. The EEG time–frequency analysis showed that when faced with negative expressions, the intensity of the neural alpha oscillatory power of subthreshold depressed participants was significantly lower than that of normal controls. When faced with positive expressions, the intensity of neural alpha oscillatory power was significantly higher than that of normal controls. Conclusion: Compared to normal persons, subthreshold depressed individuals may have biases in both the amplitude and frequency of attentional oscillations. These attentional biases correspond to the intensity of their neural alpha wave rhythms.

Styles APA, Harvard, Vancouver, ISO, etc.

41

Cabral-Calderin, Yuranny, et Melanie Wilke. « Probing the Link Between Perception and Oscillations : Lessons from Transcranial Alternating Current Stimulation ». Neuroscientist 26, n^o 1 (7 février 2019) : 57–73. http://dx.doi.org/10.1177/1073858419828646.

Texte intégral

Résumé :

Brain oscillations are regarded as important for perception as they open and close time windows for neural spiking to enable the effective communication within and across brain regions. In the past, studies on perception primarily relied on the use of electrophysiological techniques for probing a correlative link between brain oscillations and perception. The emergence of noninvasive brain stimulation techniques such as transcranial alternating current stimulation (tACS) provides the possibility to study the causal contribution of specific oscillatory frequencies to perception. Here, we review the studies on visual, auditory, and somatosensory perception that employed tACS to probe the causality of brain oscillations for perception. The current literature is consistent with a causal role of alpha and gamma oscillations in parieto-occipital regions for visual perception and theta and gamma oscillations in auditory cortices for auditory perception. In addition, the sensory gating by alpha oscillations applies not only to the visual but also to the somatosensory domain. We conclude that albeit more refined perceptual paradigms and individualized stimulation practices remain to be systematically adopted, tACS is a promising tool for establishing a causal link between neural oscillations and perception.

Styles APA, Harvard, Vancouver, ISO, etc.

42

van Diepen, Rosanne M., Michael X. Cohen, Damiaan Denys et Ali Mazaheri. « Attention and Temporal Expectations Modulate Power, Not Phase, of Ongoing Alpha Oscillations ». Journal of Cognitive Neuroscience 27, n^o 8 (août 2015) : 1573–86. http://dx.doi.org/10.1162/jocn_a_00803.

Texte intégral

Résumé :

The perception of near-threshold visual stimuli has been shown to depend in part on the phase (i.e., time in the cycle) of ongoing alpha (8–13 Hz) oscillations in the visual cortex relative to the onset of that stimulus. However, it is currently unknown whether the phase of the ongoing alpha activity can be manipulated by top–down factors such as attention or expectancy. Using three variants of a cross-modal attention paradigm with constant predictable stimulus onsets, we examined if cues signaling to attend to either the visual or the auditory domain influenced the phase of alpha oscillations in the associated sensory cortices. Importantly, intermixed in all three experiments, we included trials without a target to estimate the phase at target presentation without contamination from the early evoked responses. For these blank trials, at the time of expected target and distractor onset, we examined (1) the degree of the uniformity in phase angles across trials, (2) differences in phase angle uniformity compared with a pretarget baseline, and (3) phase angle differences between visual and auditory target conditions. Across all three experiments, we found that, although the cues induced a modulation in alpha power in occipital electrodes, neither the visual condition nor the auditory cue condition induced any significant phase-locking across trials during expected target or distractor presentation. These results suggest that, although alpha power can be modulated by top–down factors such as attention and expectation, the phase of the ongoing alpha oscillation is not under such control.

Styles APA, Harvard, Vancouver, ISO, etc.

43

Schroeter, Matthias L., Ole Schmiedel et D. Yves von Cramon. « Spontaneous Low-Frequency Oscillations Decline in the Aging Brain ». Journal of Cerebral Blood Flow & ; Metabolism 24, n^o 10 (octobre 2004) : 1183–91. http://dx.doi.org/10.1097/01.wcb.0000135231.90164.40.

Texte intégral

Résumé :

It is well known that aging leads to a degeneration of the vascular system. Hence, one may hypothesize that spontaneous oscillations decrease in the cerebral microvasculature with aging. Accordingly, the authors investigated the age dependency of spontaneous oscillations in the visual cortex during rest and functional activation. Functional near-infrared spectroscopy was used because it is particularly sensitive to the microvasculature. Visual stimulation led to an increase of oxyhemoglobin, total hemoglobin, and a decrease of deoxyhemoglobin, without any influence of age. Peaks of normalized power spectral density were detected for spontaneous low-frequency (0.07 to 0.11 Hz) and very-low-frequency (0.01 to 0.05 Hz) oscillations, with a higher amplitude for oxyhemoglobin than for deoxyhemoglobin. Spontaneous low-frequency oscillations of oxyhemoglobin and deoxyhemoglobin declined strongly with aging during both rest and visual stimulation. Reduction of spontaneous low-frequency oscillations might indicate a declining spontaneous activity in microvascular smooth muscle cells, in conjunction with an increased vessel stiffness with aging.

Styles APA, Harvard, Vancouver, ISO, etc.

44

Murty, Dinavahi V. P. S., Vinay Shirhatti, Poojya Ravishankar et Supratim Ray. « Large Visual Stimuli Induce Two Distinct Gamma Oscillations in Primate Visual Cortex ». Journal of Neuroscience 38, n^o 11 (9 février 2018) : 2730–44. http://dx.doi.org/10.1523/jneurosci.2270-17.2017.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

45

Samaha, Jason, Luca Iemi, Saskia Haegens et Niko Busch. « Spontaneous brain oscillations and visual perceptual decision making ». Journal of Vision 20, n^o 11 (20 octobre 2020) : 1729. http://dx.doi.org/10.1167/jov.20.11.1729.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

46

Spillmann, Lothar, Stuart Anstis, Anne Kurtenbach et Ian Howard. « Reversed Visual Motion and Self-Sustaining Eye Oscillations ». Perception 26, n^o 7 (juillet 1997) : 823–30. http://dx.doi.org/10.1068/p260823.

Texte intégral

Résumé :

A random-dot field undergoing counterphase flicker paradoxically appears to move in the same direction as head and eye movements, ie opposite to the optic-flow field. The effect is robust and occurs over a wide range of flicker rates and pixel sizes. The phenomenon can be explained by reversed phi motion caused by apparent pixel movement between successive retinal images. The reversed motion provides a positive feedback control of the display, whereas under normal conditions retinal signals provide a negative feedback. This altered polarity invokes self-sustaining eye movements akin to involuntary optokinetic nystagmus.

Styles APA, Harvard, Vancouver, ISO, etc.

47

Luo, Huan. « Behavioral oscillations : hidden temporal dynamics in visual attention ». Journal of Vision 15, n^o 12 (1 septembre 2015) : 1400. http://dx.doi.org/10.1167/15.12.1400.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

48

Nelli, Stephanie, Sarah Fraley et John Serences. « Post-stimulus alpha oscillations influence visual discrimination performance ». Journal of Vision 15, n^o 12 (1 septembre 2015) : 225. http://dx.doi.org/10.1167/15.12.225.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

49

Ro, Tony, et Jeremy Fesi. « Alpha Oscillations Reflect Feedback Processing for Visual Awareness ». Journal of Vision 17, n^o 10 (31 août 2017) : 1100. http://dx.doi.org/10.1167/17.10.1100.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

50

Mulligan, J. B., et S. B. Stevenson. « Spontaneous oculomotor oscillations induced by delayed visual feedback ». Journal of Vision 7, n^o 9 (19 mars 2010) : 320. http://dx.doi.org/10.1167/7.9.320.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Articles de revues sur le sujet « Visual oscillations »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres