Lesion studies suggest that the perirhinai
cortex plays a role in object recognition memory.
To analyze its role, we recorded the activity of
single neurons in the perirhinal cortex in a
rhesus monkey (Macaca mulatta) performing a
delayed matching-to-sample task with up to four
intervening stimuli. Certain neurons (40 of 90
analyzed) showed a smaller response to an image
when it was shown the second time within a trial
(as a match image) than when it had been shown
(as a sample image) the first time. A new finding
was that the perirhinal cortex neurons were
actively reset between trials: when a particular
image was shown as a sample on a succeeding
trial, the response was much larger than when it
had been shown as a match image a short time
previously on the previous trial. This resetting
between trials appears to reflect the operation of
an active working memory process rather than a
passive temporal decay in a neuronal response.
The results thus provide evidence that the
perirhinal cortex plays an active role in visual
working memory, perhaps in association with
other brain areas such as the prefrontal cortex