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Abstract:
The cortical mechanisms mediating visual awareness are thought to exploit a large
population of similarly tuned neurons explicitly representing a perceptually dominant visual
pattern through changes in its mean firing rate. However, inherent limitations of population
rate coding schemes such as noise detected in the correlated response variability across
neurons could constrict the encoding power of such a cortical network and thus decrease
the probability of this encoding strategy. Studying the differences in the noise correlation
structure of a tuned population between purely sensory visual stimulation subjective visual
perception could thus provide fundamental insights into the mechanisms of conscious visual
perception. Here we show that in the macaque prefrontal cortex perceptual dominance
under conditions of visual rivalry is accompanied by decorrelated discharges across neurons
sensory tuned to the dominant stimulus, compared to their significantly correlated
fluctuations when the same stimulus is perceived without competition. We propose that
noise decorrelation in prefrontal cortical circuits is optimal for achieving perceptual
dominance during visual awareness by substantially improving the encoding accuracy of the
dominant neuronal ensemble. Our findings also provide the first electrophysiological
demonstration of the contribution of prefrontal cortex to visual consciousness, a hypothesis
previously suggested by theoretical models as well as human functional imaging studies.
