Gnashing induced by electrical stimulation of rabbit brain cortex

¹ Department of Physiology, Dental School, Osaka University, Osaka, Japan

Gnashing was induced in rabbits by high-frequency cortical stimulation. The frequencies ranged from 60 to 1000 cycle/sec. Strictly circumscribed anteromedial cortical areas were responsive to stimulation. These loci are similar to those which induced chewing movements with low-frequency stimulation (30 cycle/ sec). Electrical stimulation within the above-described range induced gnashing of a constant rhythm of 3–4 cycle/sec that was almost independent of the stimulation frequency. The rate of experimentally induced gnashing is slower than the rate of experimentally induced chewing movements of 5–6 cycle/sec. Gnashing motion of the lower jaw consisted of the vertical and dominant lateral movements; the lateral deflection was more predominant than that of the chewing movement. Gnashing was readily induced with low-frequency stimulation after topical application of a 0.5% solution of strychnine nitrate on the cortical jaw motor area.