Activities in the jaw and tongue muscles by electrical microstimulation of the reticular part of the substantia nigra in rats

Abstract

To localize the sites of reticular part of the substantia nigra (SNr) which induce activity in the muscles of orofacial region, mapping by electrical microstimulation (40 pulses, 333 Hz, 40 μA) was performed in lightly anesthetized rats previously decerebrated. The selected sites were electrolytically marked through an elgiloy microelectrode tip for later histological identification. When the right SNr, 5.5-6.0 mm posterior to Bregma, 2.0 mm lateral to the midline, was stimulated, remarkable EMG activities appeared in the ipsilateral masseter, anterior digastricus, genioglossus, and levator labii superioris muscles. Occasional movements of the contralateral forelimb and ipsilateral eye ball were also observed.