Brain Mechanism Responsible for "the Treatment of Orofacial Diseases by Acupuncture at Hegu Acupoint"

Abstract

treatment of orofacial diseases by acupuncture at (LI4), as a conclusion of ancient physicians before more than 1000 years, exhibits effect of acupuncture at point on orofacial diseases, such as toothache and facial paralysis. However, how to correlate and face and its biological mechanism still remain elusive. Here we investigated relationship of somatosensory cortex areas representing face and hands using single electrode and electrode array recording in macaco monkeys. We found that in 3b area, neurons receiving signals from are neighboring to those areas receiving signals from orofacial receptive field separately; convergent neurons of and lower lip were also found. The somatopographic map based on electrophysiological recordings showed that those units are neighboring to each other but not overlapping in 3b area. Three months after ligations of median nerve and musculospiral nerve, plasticity could be found in neurons adjacent in thumb-orofacial regions in 3b area of cortex; region which was response to orofacial stimulation was significantly enlarged to depth of 1-2 mm in cerebral cortex of thumb, suggesting functional reorganization in cortex of thumb. Therefore, the treatment of orofacial diseases by acupuncture at Hegu exhibits adjacent representing areas receiving signals from and face in 3b somatosensory cortex separately, and functional reorganization as representing area invasion may occur under pathological conditions.