Neuromodulation and the functional dynamics of piriform cortex

Acetylcholine and norepinephrine have a number of effects at the cellular l evel in the piriform cortex. Acetylcholine causes a depolarization of the m embrane potential of pyramidal cells and interneurons, and suppresses the a ction potential frequency accommodation of pyramidal cells. Acetylcholine a lso haj strong effects on synaptic transmission, suppressing both excitator y and inhibitory synaptic transmission. At the same time as it suppresses s ynaptic transmission, acetylcholine enhances synaptic modification, as demo nstrated by experiments showing enhancement of long-term potentiation. Nore pinephrine has similar effects. In this review, we discuss some of these di fferent cellular effects and provide functional proposals for these individ ual effects in the context of the putative associative memory function of t his structure.