Abstract
Behavioral priming improves performance in psychophysical tasks. To investigate the neural mechanisms of visual priming, we recorded neural spiking and field potentials across all layers of area V4 in monkeys performing priming of popout visual search. Response accuracy increases and response time decreases with repeated presentation of the same singleton in a search array (e.g., red among green), and performance is impaired when feature assignments change. Neurophysiological substrates of these behavioral changes have been described in the frontal eye field (FEF) (Bichot & Schall 2002 J Neurosci). We investigated whether area V4 contributes to priming of popout. Two monkeys performed a color popout task with sequences of trials organized to elicit consistent priming. Linear microelectrode arrays were introduced into V4 and recorded neural activity across the layers during task performance. Both synaptic activations, measured through current source density (CSD), and neural spiking were measured. We found that priming coincided with earlier target selection measured across all layers of V4 in neural spiking and in the supragranular layers in CSD sinks. The laminar specificity of the changes in target selection time in the CSD suggest that V4 either generates the priming effect or inherits it from higher cortical areas, perhaps FEF, rather than through bottom-up changes in visual processing from earlier visual areas. These results provide new information about the mechanisms of visual memory and provide new constraints on the generation of event-related potential indices of visual attention like the N2pc.