INTER-TRIAL NEURONAL-ACTIVITY IN INFERIOR TEMPORAL CORTEX - A PUTATIVE VEHICLE TO GENERATE LONG-TERM VISUAL ASSOCIATIONS

When monkeys perform a delayed match-to-sample task, some neurons in t he anterior inferotemporal cortex show sustained activity following th e presentation of specific visual stimuli, typically only those that a re shown repeatedly. When sample stimuli are shown in a fixed temporal order, the few images that evoke delay activity in a given neuron are often neighboring stimuli in the sequence, suggesting that this delay activity may be the neural correlate of associative long-term memory. Here we report that stimulus-selective sustained activity is also evi dent following the presentation of the test stimulus in the same task. We use a neural network model to demonstrate that persistent stimulus -selective activity across the intertrial interval can lead to similar mnemonic representations (distributions of delay activity across the neural population) for neighboring visual stimuli. Thus, inferotempora l cortex may contain neural machinery for generating long-term stimulu s-stimulus associations.