Short-term reorganization of the rat somatosensory cortex following hypodynamia-hypokinesia.

This study was performed to determine if hypodynamia-hypokinesia (HH) could induce a reorganization of the rat somatosensory cortex. The cortical hindpaw representation was determined by stimulating the limb and recording multi-unit cortical activity. The size of the cutaneous receptive fields was also measured. After 14 days of HH, the size of the cortical hindpaw representation was decreased. The proportion of small cutaneous receptive fields decreased while the large ones increased. After 7 days of HH, no change in the two studied parameters was noticed in five animals. In the other rats, a number of sites unresponsive to cutaneous stimulation or with high thresholds was observed. This study provides evidence of a plasticity of the somatosensory cortex induced by a situation that reduces both sensory and motor functions. The cortical reorganization occurs in two stages.