Conditioning and sensitization in the snail: neurophysiological and metabolic characteristics.

The changes in the electrophysiological indices as well as the intravital dynamics of the content of bound calcium (Cab) during the development of sensitization and of food aversion conditioned reflex were investigated in the command neurons of the snail. The most essential electrophysiological distinction of conditioning from sensitization was the later appearance of the response to the conditional stimulus as compared with the emergence of long-term sensitization: the facilitation of the responses of the neuron to test sensory stimulations appeared 50-60 min after the application of the first sensitizing stimulation, whereas the reaction to the conditional stimulus appeared 30 min later. The analysis of the dynamics of Cab suggests that the differences in the electrophysiological effects may be associated with the pronounced differences in calcium-dependent metabolism during the development of these acquired capacities.