Binocular rivalry-like neural activities in anesthetized macaque V1

Abstract

While the binocular rivalry (BR) stimulus is processed over multiple cortical areas, it is unclear how much the neural activities in area V1 contribute to its perception. To investigate this, we examined whether V1 neural activities when deprived of top-down attention control, alternate like the typical BR perception. Intrinsic signal optical imaging was employed to measure population response from V1 of anesthetized and paralyzed macaque monkeys. The BR stimulus comprised a pair of 45 and 135 deg gratings (diameter: 1.5-3.5 deg, spatial frequency: 2 cpd; speed: 3 deg/sec) in green and red colors. The imaging pattern from each 0.25-second frame over a 60-second stimulation period was evaluated for its similarity to either the left or right eye alone activation pattern, from which we derived the eye-dominance score. Accordingly, by classifying each frame as left or right eye dominance, we are able to reveal a clear alternation of eye dominance over time. We estimated the mean eye dominance duration to be in the range of 2 to 8 seconds. Also revealing is the difference (subtraction) between the classified left and right eye dominance image maps. We found the subtracted map closely matches the ocular dominance column map, confirming the eye-of-origin specificity of the estimated eye dominance status. Finally, these characteristic optical imaging patterns (ocular dominance map) are not observed in a control condition where the monkeys viewed a non-rivaling binocular stimulus (e.g., random dot patterns or plaids). Overall, our findings demonstrate that there exist eye specific neural activities in V1 that alternate during BR stimulation and occur without conscious top-down attention modulation.

Meeting abstract presented at VSS 2012