Role of the premotor and the precentral negative motor area in praxis: A direct electrical stimulation study with behavioral analysis

Abstract

Objective: Although the negative motor area (NMA) is defined as the area where electrical cortical stimulation inhibits voluntary movements, detail functions of NMA on praxis have not been elucidated. We investigated its role in praxis by motion analysis during stimulation at a smaller intensity. Methods: Patients were six intractable partial epilepsy patients undergoing implantation of intracranial electrodes. Motion impairments by stimulation were studied in finger tapping, reach-to-grasp, finger gesture, and pantomime of tool use. Results: NMAs were identified on the precentral gyrus (4 patients), ventral premotor area (1), and at their border (1). In patients with precentral NMA, quantitative analysis revealed decreased tapping stroke and grasping aperture, while reaching velocity and pantomime did not change. As for more rostral NMA, quantitative stroke, aperture, and reaching velocity were decreased. One patient showed the arrest of finger gestures and pantomime, and the other had prolongation of reaction time. These two NMAs showed distinct connectivity pattern in connectivity analysis. Conclusions: Precentral NMA seemed to play a role in elementary finger movement control, whereas more rostral NMA in complex movement. The findings indicate functional differences within NMAs. Significance: These findings elucidated the contribution of the human premotor area to the highly skilled hand movements.