Effects of physostigmine on the activity of medullary raphe neurons in anesthetized rats.

Medullary raphe neurons are involved in the control of sympathetic activity during desynchronized sleep. To determine if cholinergic stimulation of these sites has any effect on raphe unit activity, we administered physostigmine to urethane-anesthetized rats. Most of the neurons (68%) were excited by physostigmine, suggesting the existence of cholinergic synapses which are excitatory for the majority of medullary raphe neurons.