The electrical characteristics of command and motor neurons during acquisition of a conditioned defensive reflex and formation of long-term sensitization in snails.

The mechanisms of the acquisition of a conditioned defensive reflex and formation of long-term sensitization were studied at the level of an analysis of the electrical characteristics of defensive behavior command neurons and motor neurons which open and close the pneumostoma. Significant decreases in membrane and threshold potentials were seen in command neurons in response to acquisition of the conditioned defensive reflex and formation of long-term sensitization, along with further decreases in these parameters in snails which were trained after long-term sensitization. Changes in the critical level of depolarization and amplitude of action potentials were insignificant. The changes observed here provide evidence for an increase in the membrane excitability of command neurons. Similar changes were not seen in motor neurons.