Document Detail

Contrast dependency of VEPs as a function of spatial frequency: the parvocellular and magnocellular contributions to human VEPs.
MedLine Citation:
PMID:  11893127     Owner:  NLM     Status:  MEDLINE    
The present study investigated the contrast dependency of visual evoked potentials (VEPs) elicited by phase reversing sine wave gratings of varying spatial frequency. Sixty-five trials were recorded for each of 54 conditions: 6 spatial frequencies (0.8, 1.7, 2.8, 4.0, 8.0 and 16.0 c deg(-1)) each presented at 9 contrast levels (2, 4, 8, 11, 16, 23, 32, 64 and 90%). At the lowest spatial frequency, the waveform contained mainly one peak (P1). For spatial frequencies up to 8 c deg(-1), P1 had a characteristic magnocellular contrast response: it appeared at low contrasts, increased rapidly in amplitude with increasing contrast, and saturated at medium contrasts. With increasing spatial frequency, an additional peak (N1) gradually became the more dominant component of the waveform. N1 had a characteristic parvocellular contrast response: it appeared at medium to high contrasts, increased linearly in amplitude with increasing contrast, and did not appear to saturate. The data suggest the contribution of both magnocellular and parvocellular responses at intermediate spatial frequencies. Only at the lowest and highest spatial frequencies tested did magnocellular and parvocellular responses, respectively, appear to dominate.
D Ellemberg; B Hammarrenger; F Lepore; M S Roy; J P Guillemot
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Spatial vision     Volume:  15     ISSN:  0169-1015     ISO Abbreviation:  Spat Vis     Publication Date:  2001  
Date Detail:
Created Date:  2002-03-14     Completed Date:  2002-10-18     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8602662     Medline TA:  Spat Vis     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  99-111     Citation Subset:  IM    
Groupe de Recherche En Neuropsychologie Expérimentale, Université de Montréal, Québec, Canada.
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MeSH Terms
Contrast Sensitivity / physiology*
Evoked Potentials, Visual*
Pattern Recognition, Visual / physiology*
Vision, Binocular
Visual Pathways / physiology*

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