Abstract
If two different stimuli are presented to corresponding parts of the two retinae, perception alternates between them in a random fashion, a phenomenon called binocular rivalry. A closely related phenomenon called flash suppression consists of the perceptual suppression of one stimulus that was previously presented monocularly to one eye upon flashing a new stimulus to the other eye. Logothetis and colleagues have recorded from neurons in inferotemporal cortex in the macaque that modulate their firing depending on what the animal is seeing. We investigated the neuronal correlates of these perceptual alterations in humans at the single neuron level. Subjects were patients with pharmacologically intractable epilepsy who were implanted with depth electrodes to localize the seizure focus for possible surgical resection. The number of electrodes as well as their position was based exclusively on clinical criteria. We report here the activity of individual units in the entorhinal cortex, amygdala, hippocampus and parahippocampal gyrus while subjects reported what they saw by pressing buttons during binocular rivalry and flash suppression. Our preliminary data shows that there are neurons that change their firing rate according to the percept subjects reported in spite of the fact that the stimulus is constant. Not all the visually selective neurons followed the percept in this manner. Together with our previous results, these preliminary results suggest a correlate at the single neuron level to the seemingly random alterations in these bistable perceptual phenomena.