[The ultrastructural reorganizations in the formations of the rat endbrain in decreased motor activity not evoking stress].

Ultrastructure of central and lateral nuclei of amygdala, singular gyrus and caudal nucleus was studied in rats subjected to non-stress 90-days-long hypokinesia. Not numerous changes basically reflecting decrease of activity of a series of neurons and synapses were noted in all the formations. Selective nature of the action was demonstrated: in every region examined mostly one certain cell type changes. The data were compared with the results of earlier performed research concerning the action of "hypokinetic stress" on the same brain formations.