[Effects of intracortical microstimulation on the muscle activity of the extremities in waking rabbits].

Intracortical microstimulation (IM) revealed separate sites of motor representation (MR) for contralateral limbs in the rabbit neocortex. The site of wrist control is in the MR center surrounded by the antebrachial and brachial sites. No isolated finger responses to the IM could be obtained. A more caudal MR for the hindlimb where the IM evoked separated responses of the crus and femoral muscles, revealed no geometric regularity of organization. The minimal thresholds of IM in the brachial and antebrachial MRs reached 3-10 microA and in the crus and femoral MRs 30-200 microA. Latencies of the EMG brachial, antebrachial, crus and femoral responses were, respectively, 25-52, 24-73, 36-71 and 32-54 msec. The organization of cortical regulation of limb movements is concluded to be primitive in rabbits, particularly for hindlimbs.