[Experimental tremor induced by VMT lesion in monkeys--neuroanatomical study]

Ventromedial portion of the mesencephalic tegmentum in a monkey is known as one of the major target to produce experimental tremor. By Ohye's method, we made lesions at the above mentioned target in 18 monkeys. Out of them, 5 showed hemiparesis and cubital joint flexion on the contralateral side which are known as precursors of experimental tremor of this kind. In these 5 monkeys, we made neuroanatomical studies on various relating nuclei and neural pathways by Nissl and silver impregnation methods. Results are as follows: 1. The lesion involved at the parvocellular part of red nucleus and the area located ventromedial to the red nucleus. 2. Silver impregnation revealed degenerated nerve fibers and terminals in the ipsilateral globus pallidus, putamen, nucleus olivaris inferior (major accessorius medialis), thalamus (VA, VPL, Cn. Md, Pcn, Cl major VL, X, VI) and bilateral substantia nigra. In conclusion, blocking of projecting fibers to VI, VL and X seems to elicit an experimental tremor.