The mechanism of excitation by acetylcholine in the cerebral cortex

TLDR

Acetylcholine depolarizes cortical neurons via muscarinic receptors, increasing membrane resistance, slowing spike repolarization, and shifting the reversal potential to about −86.7 mV from a resting −56 mV. The authors examine acetylcholine’s potential role in cortical function. The findings suggest that acetylcholine reduces resting and delayed potassium conductances to excite cortical neurons. The abstract includes footnote markers 1–5.

Abstract

1. The muscarinic depolarizing action of ACh on cortical neurones is associated with an increase in membrane resistance (mean Δ V /Δ R = 3·16 mV/MΩ). 2. ACh also promotes repetitive firing by slowing repolarization after spikes. 3. The depolarizing effect has a mean reversal level of −86·7 mV (with mean resting potential −56 mV). 4. It is concluded that as a muscarinic excitatory agent, ACh probably acts by reducing the resting K + conductance of cortical neurones, and also the delayed K + current of the action potential. 5. These results are discussed in relation to the possible role of ACh in cortical function.