RELEASE OF CEREBRAL ACETYLCHOLINE INCREASES DURING VISUALLY MEDIATED BEHAVIOR IN MONKEYS

EXTRACELLULAR levels of acetylcholine in inferior temporal cortex (IT) , perirhinal cortex (PR), and dentate gyrus (DG) of the hippocampus we re monitored using in vivo microdialysis in rhesus monkeys performing two behavioral tasks. Performance on a visual recognition task was ass ociated with 26%, 41% and 24% increases in acetylcholine overflow in I T, PR and DG, respectively, compared with pre-test baseline levels. Pe rformance on a memory-independent task was associated with increases i n acetylcholine release of 24%, 34% and 7% above baseline in IT, PR an d DG, respectively. The PR-DG differences were significant, but the ot hers were not. The results provide biochemical evidence for cerebral c holinergic system activation during visually mediated behavior in non- human primates, and are consistent with the view that such activation is a prerequisite for visual recognition memory.