[Interaction between neurons of the visual and sensomotor areas of the neocortex during elaboration and extinction of a conditioned defense reflex].

Cooperation in activities of pairs of neurones situated in projection cortical areas of conditioned and unconditioned stimuli was studied in rabbits during intertrial intervals at different stages of elaboration and extinction of conditioned defensive response by means of auto- and crosscorrelation analysis of impulse fluxes. At the stage of generalization the number of pairs of neurones discharging in correlation was shown to increase a little (64 per cent) in comparison to that at the initial stage of conditioning (50 per cent) and pseudoconditioning (54 per cent). At the stage of stabilization and during extinction the number of pairs of neurones discharging in correlation decreased correspondingly to 34 and 32 per cent. Parallel analysis of correlation in neuronal discharges and simultaneously recorded electroencephalogram allowed to suppose that excitatory synchronizing influences and inhibitory cortical system play a great part in synchronization of activities of cortical neurones. Participation of these two systems is not the same at different stages of conditioning and extinction.