The figures to the left and right show intracellular recordings of the membrane potential of a piriform (olfactory) cortex pyramidal cell during a 1 second long current injection. On the left, the neuron fires rapidly at first and then slows firing as activation of a calcium-dependent potassium current causes adaptation. On the right, perfusion of the slice chamber with 20uM carbachol (a cholinergic agonist) causes suppression of the calcium-dependent potassium current, resulting in a decrease in adaptation (and more sustained firing during the current injection. This work is published in Barkai and Hasselmo (1994) J. Neurophysiol. 72:644-658. The suppression of adaptation has been modeled using GENESIS.

This figure shows the performance of an associative memory model of the piriform cortex with different levels of cholinergic suppression of synaptic transmission during learning. Red = high performance (effective learning and recall of multiple patterns). Blue = low performance (usually due to interference between the stored patterns). With low levels of acetylcholine in the model, the function is only good for a brief period before breaking down. With high levels of acetylcholine, the network reaches good performance more slowly but maintains that performance indefinitely. This work has been published in Hasselmo and Bower (1992) J. Neurophysiol. 67: 1222-1229.