Selective form of an excitable membrane plasticity.

This work describes the change in an active electrogenesis of the command neurons responsible for defensive closure of a snail's pneumostome during elaborating, extinction and restoration of a classical conditioned defensive reflex to a tactile stimulus. Tactile stimulations applied to different parts of a snail's body served as a differential stimulus. As the biological value of a conditioned stimulus increases due to learning, the excitability of command neurons in response to conditioned stimulus rises. At the same time the neurons demonstrated a reduced excitability in response to a differentiating stimulus.