[The involvement of intracellular calcium in the sensitization of command neurons in the defensive behavior of the edible snail].

Examinations carried out on command neurons of defensive behaviour of snail carried out using electrophysiological methods and a chlorotetracycline fluorescent probe have revealed that a single sensitizing action induces alterations of electrical neuronal activity and bound calcium (Ca-C) level in cells. An initial increase of the Ca-c amount (the first 15-20 min after the sensitizing action) coincides in time with depolarization, enhancement of plasma membrane excitability as well as with a decrease of amplitude and duration of the IPSPs induced by sensory stimulations. Repeated pronounced increase of the Ca-c level develops 50-60 min after the sensitizing action and correlates with facilitation of neuronal responses to sensory stimuli. Alteration of the Ca-c level in command neurons of defensive behaviour in the course of sensitization development differed from the previously described Ca-c shifts in the same cells in the course of habituation development in dynamics and direction.