Neurological correlates of unilateral and bilateral "strokes" of the middle cerebral artery in the rat.

Rats with unilateral lesions of the middle cerebral artery (MCA) were tested for the ability to detect (touch) and remove a square of adhesive tape from each forepaw, and for performance on a number of neurological tests (e.g., placing and hopping reflexes, activity). Rats with MCA damage showed deficits in both touching and removing the tape from the paw contralateral to the damage, but not ipsilateral to the damage, while performing within normal limits on the other tests. After scores of the MCA rats dropped into the control group range on the adhesive tape test, they sustained damage to the opposite MCA. This did not reinstate the original deficit, suggesting that the recovery seen after the unilateral lesion was not mediated by the opposite cortex. The second lesion, however, caused a deficit in removing the adhesive tape from the limb opposite the new stroke. Some of the rats that originally had sham operations received bilateral MCA lesions at this time. These animals showed much more severe deficits on the adhesive tape test than the rats with sequential strokes. Rats with bilateral MCA damage (simultaneous or sequential) also slipped on a long narrow plank more often than control animals. Nimodipine did not enhance recovery on any of the behavioral measures.