Effect of anodal polarization of deep brain structures on spatial synchronization of cortical potentials during defensive conditioning in rabbits.

Abstract

1. Reversible blocking of some nonspecific thalamic and hypothalamic nuclei differs in its effect on two types of spatial synchronization of cortical potentials (SSCP) formed during defensive conditioned reflex (DCR) formation: Specific local SSCP and conditionedreflex movements disappear, whereas global SSCP remains virtually unchanged under these circumstances in interstimulus periods. 2. By modifying their functional state of these nuclei by anodal polarization it is possible to influence the rate of DCR formation. The effect of polarization depends on the structure to be stimulated and the stage of reflex formation. 3. During temporary blocking of hypothalamic nuclei phasic changes arise in local SSCP, which was never observed after blocking the nonspecific thalamic nuclei. 4. During reversible blockade of subcortical structures synchronization of cortical and subcortical potentials is depressed first. Conditioned-reflex movements appear only when synchronization between cortex and subcortex is recovered. 5. The conclusion can be drawn from the results that the mammillary bodies play an important role in the formation of local SSCP at the beginning of DCR formation and that the nonspecific thalamic nuclei and the posterior hypothalamic nucleus are essential for this form of spatial synchronization to arise on stabilization of the reflex, when definite correlation is observed between the appearance of local, specific SSCP, realization of the reflex, and strengthening of synchronization between the cortex and subcortical formations.