A Mapping Of Rat Facial Motor Cortex By Intracortical Microstimulation

Objectives The organization of the facial motor cortex was mapped with Intracortical Micro stimulation. Further studies can be performed to find out the relationships between the facial nerve and the facial motor cortex with this outcomes.Methods 25 female Wistar rats weighted 250-350 gram were studied. In light anaesthetized (ketamine), the electrode was inserted perpendicular to the cortical surface at a depth of 1.5～1.7mm with a stereotaxic frame . Thirty-ms duration trains of negative constant current pulses of 0.25ms duration were delivered at a frequency of 300Hz. The distance between two successive penetrations was usually 500 μ m and the interval between two stimulations was at least 5s. The facial motor effects (eyelid moving, vibrissae moving, pinna moving) were observed, and the threshold of intensity for movement were recorded by electromyography. Consider the bregma as the origin, the ant-post middle line as x axis and endo-lateral line as y axis. Record coordinates of all the stimulated points and threshold intensity. Then reconsruct the facial motor map.Results The rat facial motor cortex appears to be organized into irregularly shaped patches of cortex devoted to particular movements. The subdivisions stand alone each other, and are not successive. The successive position in the body isn't...