Abstract:

PURPOSE: Our visual world is rich in spectral information, and the evolution of separate L / M cone and resultant L—M opponent channels in catarrhine and some platyrrhine primates is indicative that distinguishing "red" from "green" serves a critical purpose. Psychophysical studies in humans, and electrophysiology in both human and non-human primate visual cortices suggests a red dominance in driving neural responses in comparison to other colors. The purpose of this study is to test if there is a neural basis of red dominance at the level of local ?eld potentials (LFP) and multi-unit activity (MUA).
METHODS: Here we used 16-channel laminar probes to record LFP and MUA across the cortical depth for full-field isoluminant color stimuli in both V1 and V4. We computed band-limited power from the LFP during stimulation induced by seven isoluminant colors (red, orange, yellow, green, cyan, blue, purple). As the gamma (γ) band is commonly assumed to be related to attention and stimulus awareness in visual cortex, we hypothesized that red may di?erentially drive gamma band power during visual perception.
RESULTS: Isoluminant red stimulation induced significantly higher power at both the γ–low (30–50Hz) and γ–high bands (50–100Hz) across all laminar depths in both V1 and V4. Even when recording within V4 color domains whose color preference was other than red, or V4 form domains with little color preference, red still drove a higher γ–band power response.
CONCLUSIONS: Red drives a significantly enhanced γ–band response invariant to color or form domain preferences, which is consistant with the perceptual preference to red shown in other studies perceptually.

Key words: Color perception, Oscillations, Laminar analysis