DYNAMICAL SYNAPSE

The universal principle of brain operation which consists in initial g lobal non-specific reactions and secondary local specific changes is r eflected at the behavioral level in the dominant properties of the gen eralization stage of conditioned reflex and its transition to the spec ialization stage, These phenomena correspond at the cellular level to a temporary increase in excitability of cortical neurons and long-term modifications of synaptic efficacy in interneuronal excitatory and in hibitory connections, Such a sequence of events is largely determined by the dynamics of hypothalamic-cortical integration and operation of N-methyl-D-aspartate (NMDA) receptor-channel complex, Increase in cell excitability which results at the initial stage of learning in a tran sition of cells to burst discharge mode of unit activity and is accomp anied by pronounced generalized synchronization of slow electrical act ivity in the theta-rhythm range promotes manifestation of synaptic mod ifications, which, in turn, determine a specialized conditioned motor act at the terminal stage.