Effects of stimulation of the frontoparietal cortex and parafascicular nucleus on locomotion in rats

The spontaneous motor activity and locomotion initiated by electrical stimulation of the lateral hypothalamus were recorded after electrical stimulation (50-500 microA, 10-30 Hz, 0.1 ms pulses) of the frontoparietal cortex (FrPaM) and parafascicular nucleus of the thalamus (PF). Local injection of kainic acid (KA) (0.02 micrograms, 1.0 microliter) was applied to the FrPaM and PF to avoid stimulation of descending fibres of passage. The electrical stimulation and KA application to the FrPaM and PF produced inhibition of locomotion in freely moving rats. In Nembutal-anesthetized (25-30 mg/kg) rats electrical stimulation of the FrPaM and PF inhibitory zones blocked the increase of phasic and tonic electrical activity of hindlimb muscles elicited by electrical stimulation of the lateral hypothalamus (LH) and red nucleus (R). Electrolytic lesion of inhibitory zones of the raphe magnus nucleus (RMg) and adjacent areas of gigantocellular (Gi) reticular nuclei arrested blocking effects of the FrPaM and PF on motor activity and hindlimbs tonus. The results demonstrated a possible role of the FrPaM and PF in initiation of locomotor activity inhibition. Interactions of the FrPaM and PF with the brain stem inhibitory zones are also discussed.