[Dynamics of the space-time organization of cortical potentials upon extinction of electro-defensive conditioned reflexes in rabbits].

Spatio-temporal distribution of cortical potentials formed by non-reinforced conditioned stimuli in 10 unrestrained rabbits, was studied in the course of extinction of a conditioned defense ear-shaking reaction to flickering light, by means of comparison of successive electroencephalotopograms. The first signs of the extinction were characterized by a periodical reversion of the momentary sagittal gradient of values of simultaneous cortical potentials, going on with the frequency of light stimulation (4 cps). Under these conditions, the probability of motor reaction to light was reduced. At a late stage of the extinction the potential gradient reversion had lower frequency characteristics for passive wakefulness and drowsiness of the rabbits.