The characteristics of the antidromic discharge of cat dorsal raphe neurons during repetitive activation.
Slowly discharging neurons in the cat dorsal raphe could be classified into 3 types according to the behavior of antidromic spike discharges during repetitive stimulation of the medial forebrain bundle at 10 Hz. In the types 1 and 2, the latency of antidromic discharge was gradually prolonged to reach an asymptote, whereas no marked change occurred in the type 3. The type 2 neurons, which had a slower conduction velocity, showed a greater prolongation than the type 1 neurons. The maximum length of this prolongation was not significantly correlated with the initial latency. During 10 Hz stimulation some neurons showed repeatedly a conduction block after a sequence of initial decrease and later increase in latency. The spontaneous discharge was strongly suppressed during 10 Hz stimulation. During 1 Hz stimulation just after the cessation of 10 Hz stimulation, the prolonged antidromic latency was gradually restored in parallel with the recovery of the spontaneous discharge. Circumstantial evidences seem to be in favor of the idea that hyperpolarization of the axonal and somatic membranes is mainly responsible for the observed behavior of antidromic spikes of type 1 and 2 neurons.
D000818:Animals; D002415:Cats; D004558:Electric Stimulation; D005071:Evoked Potentials; D009474:Neurons / Q000145:classification / Q000502:physiology; D011903:Raphe Nuclei / Q000502:physiology*; D011930:Reaction Time