[The dynamic changes in somatosensory input into the cortical motor area after damage to the somatosensory cortical zones in dogs].

Dynamics of changes in the somatosensory evoked potentials (EPs) in the foreleg motor cortex (MI) was studied in awake dogs in chronic experiments following lesions of the forelimb area in the somatosensory cortex (SI) or in area 5. Cortical ablations reduced the amplitude of the primary positive-negative wave of the EPs in ipsilateral MI down to 28-63% of the original one. Within three weeks recovery of the EPs was insignificant or was absent at all. So there was no correlation between the EPs changes and spontaneous recovery of precise avoidance movements of the foreleg which takes place two weeks after local ablation of the SI. After area 5 lesion the EPs in the MI did not recover in spite of complete recovery of the EPs in the adjoining area of SI after its initial reduction down to 53%. The long-lasting EPs reduction was apparently a result of destruction of somatotopic sensory inputs from SI (or area 5) to MI, since EPs in MI of the intact hemisphere and in the hindlimb area of MI on the side of the lesion either did not change or recovered during one or two weeks.