The Functional Reorganization Of Hand-area And Facial-area In Human Motor Cortex After Ischemic Nerve Block In Hegu Acupoint

ObjectiveBy observing the change of motor evoked potentials from Hegu acupoint and ora-facial area in the state of pathology, the object is to probe the mechanism of plasticity in across-representation of the cerebral motor cortex, which provides a basic evidence for the Meridian theory.MethodsTranscranial magnetic stimulation was applied to give a beyond threshold’s stimulation to the hand-representation and face-representation in motor cortex before and after the forearm ischemic nerve block. Meanwhile, the electromyography records the motor evoked potentials from the First dorsal interosseus and Orbicularis oculi muscle. Basic on the MEPs, the two-dimensional diagrams of the representations was drawed before and after the INB in order to know the change of the motor cortex from the target muscles.Results1. In physiological conditions, the hand-representation and the face-representation have a range of distribution in Figure2;2. The MEPs from First dorsal interosseus:the latentperiod is21.76±0.45ms, the amplitude is1.26+0.25mV, the Motor threshold is55.83+9.17%; the MEPs from Orbicularis oculi muscle:the latentperiod is4.28±0.23ms, the amplitude is0.65±0.25mV, the Motor threshold is55.0±10.4%;3. In pathological conditions, the block of time is38.61±3.60minutes. With times’extending, the area of hand-representation is narrowing while the face-representation is enlarging, and spreading towards to hand-representation in Figure4;4. The latentperiod and the amplitude are significantly relative to the time of blocking in Figure3.;5. To dislodge ischemic nerve block:after30minutes’INB, both hand area and facial area are recovered.ConclusionAfter the INB, the MEPs from the target muscles show the changes of the amplitude and the amounts of the stimulated points, which to some extend responds Hegu acupoint and ora-facial area to the cortical excitability and cortical area. It may be one of the biological mechanism of "the specific relation of ora-facial area and Hegu acupoint" in physiological condition.