Mapping of Hand and Face Representations Areas in Cerebral Cortex with Transcranial Magnetic Stimulation

Transcranial Magnetic Stimulation is a noninvasive magnetic stimulation of the motor cortex and motor pathways. Responses obtained from the target muscles through TMS can be evaluated electrophysiologically. There are 20 healthy volunteers who use the right hand actively in the study. There are active right hand 20 healthy volunteers in the study. Two sEMG electrodes are placed in the Abductor Pollicis Brevis (APB) and Orbicularis Oris (O.oris) muscles. APB muscle constitutes a hand representative in the cortical motor mapping. O.Oris muscle constitutes a face representative in the cortical motor mapping. The position, amplitude and latency values of muscular action potentialsinduced by magnetic stimulation are determined by signal processing methods. The results are mapped on 3-D human model. When the right-hand representation map is examined, the hot spot of the APB muscle is found as the C1. While the motor potential of the hot spot is 6.89(±1.67) mV, the latency time is 20.98(±0.87) ms. When the right-face representation map is examined, the hot spot of the O.Oris muscle's found as the F5. While the motor potential of the hot spot is 2.83(±1.81) mV, the latency time is 4.95(±0.05) ms. Moreover, the face representation intersects with the hand representation at some points and is active at distances close to the hand representation.