Open AccessIdentification of early visual evoked potential generators by retinotopic and topographic analyses
Author(s) -
Clark Vincent P.,
Fan Silu,
Hillyard Steven A.
Publication year - 1994
Publication title -
human brain mapping
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.005
H-Index - 191
eISSN - 1097-0193
pISSN - 1065-9471
DOI - 10.1002/hbm.460020306
Subject(s) - extrastriate cortex , stimulus (psychology) , neuroscience , visual cortex , retinotopy , visual field , striate cortex , visual system , visual n1 , orientation column , psychology , visual perception , perception , cognitive psychology
This study investigated the cortical sources of the early (50‐250 ms) components of the pattern‐onset visual evoked potential (VEP). VEPs were recorded in response to a small circular checkerboard stimulus that was flashed over a range of visual field positions. Temporally and spatially overlapping VEP components were distinguished by differences in retinotopic sensitivity and scalp topography, and by inverse dipole modeling. The C1 component (50‐80 ms) was found to change its polarity and topography systematically as a function of stimulus position in a manner consistent with the retinotopic organization of the striate cortex. The P1 component (comprised of the P75 and P100 subcomponents) had a time course that overlapped the C1 but could be distinguished from the C1 by its differing topography and reduced sensitivity to stimulus position. The P1 generators were localized to the lateral extrastriate cortex. Inverse dipole models were consistent with these striate and extrastriate source locations for the C1 and P1, respectively. The N1 component (120‐180 ms) was found to originate from several spatially distinct generators that differed in their retinotopic organization. © 1995 Wiley‐Liss, Inc.