EFFECTS OF SHAPE-DISCRIMINATION TRAINING ON THE SELECTIVITY OF INFEROTEMPORAL CELLS IN ADULT MONKEYS

Through extensive training, humans can become ''visual experts,'' able to visually distinguish subtle differences among similar objects with greater ease than those who are untrained. To understand the neural m echanisms behind this acquired discrimination ability, adult monkeys w ere fully trained to discriminate 28 moderately complex shapes. The tr aining effects on the stimulus selectivity of cells in area TE of the inferotemporal cortex were then examined in anesthetized preparations. Area TE represents a later stage of the ventral visual cortical pathw ay that is known to mediate visual object discrimination and recogniti on. The recordings from the trained monkeys and untrained controls sho wed that the proportion of TE cells responsive to some member of the 2 8 stimuli was significantly greater in the trained monkeys than that i n the control monkeys. Cell responses recorded from the trained monkey s were not sharply tuned to single training stimuli, but rather broadl y covered several training stimuli. The distances among the training s timuli in the response space spanned by responses of the recorded TE c ells were significantly greater in the trained monkeys than those in t he control monkeys. The subset of training stimuli to which individual cells responded differed from cell to cell with only partial overlaps , suggesting that the cells responded to features common to several st imuli. These results are consistent with a model in which visual exper tise is acquired through the development of differential responses by inferotemporal cells to the images of relevant objects.