Visual Evoked Potentials to Gratings and Noise

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 355-355
Author(s):  
Y E Shelepin ◽  
A K Harauzov ◽  
N N Krasilnikov ◽  
S V Pronin
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
Evoked Potentials ◽  
White Noise ◽  
Visual Evoked Potentials ◽  
Occipital Cortex ◽  
Normal Subjects ◽  
Sine Wave ◽  
Frequency Characteristics ◽  
Visual Evoked

Visual evoked potentials were recorded in a study of the spatial-frequency characteristics of the human visual system. Stimuli were gratings with and without superposition of white noise. Evoked potentials were recorded in normal subjects from different areas of the occipital cortex, from the temporal and parietal lobes, according to the ‘ten-twenty’ electrode system. A set of black-and-white sine-wave gratings was used with eight different spatial frequencies in the range 0.45 to 14.4 cycles deg−1. The gratings were presented with binary quasi-white noise or with a uniform grey field with mean luminance equal to that of the noise. The amplitudes of the N1, P1, N2, and P2 response components were compared under the two stimulation conditions. Changes in the form of responses as well as changes in spatial-frequency characteristics were found when white noise was superimposed. The results obtained are discussed in terms of the presence and location of matched filtering in the visual system.

Nonlinear Analysis of Visual Evoked Potentials Elicited by Color Stimulation

1997 ◽  
Vol 36 (04/05) ◽  
pp. 315-318 ◽  
Author(s):  
K. Momose ◽  
K. Komiya ◽  
A. Uchiyama
Keyword(s):  
Visual System ◽  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Normal Subjects ◽  
Second Order ◽  
First Order ◽  
The Relationship ◽  
Perceived Color ◽  
Second Order Nonlinearity ◽  
Visual Evoked

Abstract:The relationship between chromatically modulated stimuli and visual evoked potentials (VEPs) was considered. VEPs of normal subjects elicited by chromatically modulated stimuli were measured under several color adaptations, and their binary kernels were estimated. Up to the second-order, binary kernels obtained from VEPs were so characteristic that the VEP-chromatic modulation system showed second-order nonlinearity. First-order binary kernels depended on the color of the stimulus and adaptation, whereas second-order kernels showed almost no difference. This result indicates that the waveforms of first-order binary kernels reflect perceived color (hue). This supports the suggestion that kernels of VEPs include color responses, and could be used as a probe with which to examine the color visual system.

Spatial-Frequency Characteristics of Different Areas of Human Cortex

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 167-167
Author(s):  
A K Harauzov ◽  
Y E Shelepin ◽  
S V Pronin
Keyword(s):  
Spatial Frequency ◽  
Temporal Frequency ◽  
Receptive Fields ◽  
Occipital Lobe ◽  
Occipital Cortex ◽  
Normal Subjects ◽  
Sine Wave ◽  
Electrode System ◽  
Frequency Characteristics ◽  
Spatial Frequencies

We recorded visual evoked potentials in normal subjects from different areas of the occipital cortex, from the temporal and parietal lobes according to the ‘ten - twenty’ electrode system. Stimuli were black-and-white sine-wave gratings with eight different spatial frequencies in the range 0.45 to 14.4 cycles deg−1, presented at four different temporal frequencies (1, 2, 4, 8 Hz). Stimulation was either contrast-reversal or onset. VEPs were analysed both by component analysis and by Fourier transformation. Spatial characteristics were measured from the dependence of the amplitudes and latencies of the main response components (N1, P1, N2, P2) on the contrast and spatial frequency of the gratings. The characteristics obtained in the occipital lobe are in accordance with earlier experimental data [Regan, 1989 Human Electrophysiology (Amsterdam: Elsevier)]. When the temporal frequency of stimulation was increased, the maximum of the spatial-frequency curves shifted to lower spatial frequencies. However, we found differences in the spatial-frequency characteristics of different cortical areas. The results are discussed in terms of differences in the spatial and temporal tuning of the receptive fields of neurons in these areas.

scholarly journals Cortical Contrast Processing in Retinitis Pigmentosa: Evidence of PVEPs Spatial Functions

2020 ◽  
Vol 10 (4) ◽  
pp. 1010-1019
Author(s):  
Rafael Mancebo-Azor ◽  
José Antonio Sáez-Moreno ◽  
José Manuel Rodríguez-Ferrer
Keyword(s):  
Retinitis Pigmentosa ◽  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Normal Subjects ◽  
Pattern Reversal ◽  
Check Size ◽  
Low Contrast ◽  
Control Subjects ◽  
The Right ◽  
Visual Evoked

Objective: To study the effect of check width size of the stimuli on the amplitude and latency of the P100 component of visual evoked potentials recorded in patients with retinitis pigmentosa (RP). Methods: Pattern reversal visual evoked potentials (PVEPs) were recorded in 16 RP patients and 20 visually normal subjects. Pattern reversal stimuli with five different check widths and 100% of contrast were projected in the right eye of both patients and control subjects. PVEPs induced by stimuli with 78%, 16%, and 6% of contrast were also recorded in 10 of the control subjects. Results: In RP patients, the amplitude of P100 was smaller than controls in all check sized used and the peak P100 amplitude was obtained with a larger check width than in controls. P100 was also delayed in RP patients in all check sizes studied. The P100 amplitude- and latency-check size functions of RP patients were like those found in control subjects with low contrast stimuli of 16% and 6%. Conclusion: The PVEPs spatial functions of RP patients show quantitative and qualitative changes, suggesting disease induced alteration in the neural processing of stimulus contrast.

Multifocal visual-evoked potentials in patients with schizophrenia during treatment

2011 ◽  
Vol 23 (1) ◽  
pp. 31-34 ◽  
Author(s):  
Mariko Yamada ◽  
Eiichi Yukawa ◽  
Futoshi Taketani ◽  
Toyoaki Matsuura ◽  
Yoshiaki Hara
Keyword(s):  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Normal Subjects ◽  
Subject Group ◽  
Recording Apparatus ◽  
Multifocal Visual Evoked Potentials ◽  
Psychotropic Agents ◽  
Schizophrenic Patients ◽  
Conventional Perimetry ◽  
Visual Evoked

Aim: Investigation of responses of multifocal visual-evoked potentials (mfVEPs) in schizophrenic patients under treatment in whom no abnormality was detected on the conventional perimetry.Methods: Recordings of mfVEPs were performed in 31 schizophrenic patients and 30 normal subjects using a VERIS Junior Science recording apparatus (Mayo, Aichi, Japan). Responses from eight sites in each subject were divided into four quadrants (superior and inferior temporal quadrants, and superior and inferior nasal quadrants). In each quadrant, two response waves were grouped and averaged, and the latency and amplitude of main waveforms that appeared near 100 ms were evaluated.Results: The peak latency was about 7–9 ms prolonged and the amplitude was reduced by about 2–5 nV/deg2 in the schizophrenic patient group compared to those in the normal subject group, and significant differences were noted in both parameters in all quadrants.Conclusion: In schizophrenic patients under treatment with psychotropic agents, prolongation of the latency and amplitude reduction were noted in mfVEPs even though no abnormality was detected on the conventional perimetry.

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