[Primary and repeated exposure to hypergravity: ultrastructure of the somatosensory cortex in rats].

Nineteen-day centrifugation of rats at 2 G and ensuing 30-d readaptation to 1 g caused changes in the somatosensory cortex (SSC) ultrastructure pointing to intensification of the afferent input and functional activity of SSC neurons during hypergravity, and recovery of these processes in the course of readaptation. Repeated 5-d centrifugation of the rats at 2 G produced changes in ultrastructure of SSC layers 3 and 4 evidencing a more effective cortex functioning aimed at facilitation of adaptation to hypergravity repeated after the lengthy delay.