[The dynamic synapse].

The universal principle of brain operation which consists in initial global non-specific reactions and secondary local specific changes is reflected at the behavioral level in the dominant properties of the generalization stage of conditioned reflex and its transition to the specialization 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 inhibitory 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 transition of cells to burst discharge mode of unit activity and is accompanied by pronounced generalized synchronization of slow electrical activity in the theta-rhythm range promotes manifestation of synaptic modifications, which, in turn, determine a specialized conditioned motor act at the terminal stage.