[The molecular cellular mechanisms of the formation of long-term memory in the snail]

Experimental data concerning molecular and cellular mechanisms of the nonassociative and associative forms of learning (sensitization and classical conditioning) in snail Helix lucorum are reviewed. Results of our investigations and data obtained in other laboratories support hypothesis about activation during conditioning of complex metabolic reactions which are specific for each reflex. Integration of different neural signals by single neuron not only activates second messengers system in the neuron but initiates also synthesis of specific (during conditioning) or relatively specific (during sensitization) for definite synaptic inputs protein molecules with short time of half-life (1-3 hours). After weak consolidation effect of conditioning probably coincide with time of half-life of the protein molecules and disappears after catabolism of the molecules. Strong consolidation initiates selfsupport synthesis of the protein molecules and effect of conditioning lasts a long time.