Abstract
Discharge activity was recorded extracellularly from individual neurons of the nucleus locus coeruleus in anesthetized squirrel monkeys. These cells exhibited long-duration (2–3 ms) action potentials and discharged spontaneously in a slow (0.2–2 Hz) irregular fashion. Stimulation of the lateral hypothalamus evoked antidromic responses at latencies of 10–20 ms, indicating conduction velocities of over 1 m/s in some cases. The mean refractory period for these axons was 2.6 ms. When the rate of hypothalamic stimulation was increased from 1 to 10 Hz there was a 15–20% increase in antidromic latencies. These properties are similar to those previously observed for rat LC neurons, except that conduction velocities are higher in monkey.