TY - JOUR
T1 - Representation of color surfaces in V1
T2 - Edge enhancement and unfilled holes
AU - Zweig, Shay
AU - Zurawel, Guy
AU - Shapley, Robert
AU - Slovin, Hamutal
PY - 2015/9/2
Y1 - 2015/9/2
N2 - The neuronal mechanism underlying the representation of color surfaces in primary visual cortex (V1) is not well understood. We tested on color surfaces the previously proposed hypothesis that visual perception of uniform surfaces is mediated by an isomorphic, filled-in representation in V1. We used voltage-sensitive-dye imaging in fixating macaque monkeys to measure V1 population responses to spatially uniform chromatic (red, green, or blue) and achromatic (black or white) squares of different sizes (0.5°-8°) presented for 300 ms. Responses to both color and luminance squares early after stimulus onset were similarly edge-enhanced: for squares 1° and larger, regions corresponding to edges were activated much more than those corresponding to the center. At later times after stimulus onset, responses to achromatic squares’ centers increased, partially “filling-in” the V1 representation of the center. The rising phase of the center response was slower for larger squares. Surprisingly, the responses to color squares behaved differently. For color squares of all sizes, responses remained edge-enhanced throughout the stimulus. There was no filling-in of the center. Our results imply that uniform filled-in representations of surfaces in V1 are not required for the perception of uniform surfaces and that chromatic and achromatic squares are represented differently in V1.
AB - The neuronal mechanism underlying the representation of color surfaces in primary visual cortex (V1) is not well understood. We tested on color surfaces the previously proposed hypothesis that visual perception of uniform surfaces is mediated by an isomorphic, filled-in representation in V1. We used voltage-sensitive-dye imaging in fixating macaque monkeys to measure V1 population responses to spatially uniform chromatic (red, green, or blue) and achromatic (black or white) squares of different sizes (0.5°-8°) presented for 300 ms. Responses to both color and luminance squares early after stimulus onset were similarly edge-enhanced: for squares 1° and larger, regions corresponding to edges were activated much more than those corresponding to the center. At later times after stimulus onset, responses to achromatic squares’ centers increased, partially “filling-in” the V1 representation of the center. The rising phase of the center response was slower for larger squares. Surprisingly, the responses to color squares behaved differently. For color squares of all sizes, responses remained edge-enhanced throughout the stimulus. There was no filling-in of the center. Our results imply that uniform filled-in representations of surfaces in V1 are not required for the perception of uniform surfaces and that chromatic and achromatic squares are represented differently in V1.
KW - Color
KW - Monkeys
KW - Population coding
KW - Primary visual cortex
KW - Surfaces
KW - VSDI
UR - http://www.scopus.com/inward/record.url?scp=84940921132&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84940921132&partnerID=8YFLogxK
U2 - 10.1523/JNEUROSCI.1334-15.2015
DO - 10.1523/JNEUROSCI.1334-15.2015
M3 - Article
C2 - 26338322
AN - SCOPUS:84940921132
VL - 35
SP - 12103
EP - 12115
JO - Journal of Neuroscience
JF - Journal of Neuroscience
SN - 0270-6474
IS - 35
ER -