Effects of binocular flash suppression in awake and anesthetized macaque

The primary visual cortex (V1) was implicated as an important candidate for the site of perceptual suppression in numerous psychophysical and imaging studies (Lehky, 1988; Blake, 1989; Polonsky et al., 2000; Tong and Engel, 2001). However, neurophysiological results in awake monkeys provided evidence for competition mainly between neurons in areas beyond V1 (Leopold and Logothetis, 1996; Sheinberg and Logothetis, 1997). In particular, only a moderate percentage of neurons in V1 was modulated in parallel with perception and the magnitude of their modulation was substantially smaller than the physical preference of these neurons (Keliris et al., 2010). It is yet unclear whether these small modulations are rooted in local circuits in V1 or influenced by higher cognitive states. To address this question we recorded multi-unit spiking activity and local field potentials in area V1 of awake and anesthetized macaque monkeys during the paradigm of binocular flash suppression. The results showed that the pattern of perceptual modulation of neurons in V1 under the conditions of general anesthesia is almost identical to those recorded from awake monkeys. This suggests a role of local processes in V1 in perceptual suppression. Alternatively, these modulations could be caused by feedback from higher areas independent of conscious state