Central mechanisms of tremor in some feline and primate models

For several years our interest has been in a postural Parkinson-like tremor at 4-6/sec. which can be produced in the monkey by lesions of the central nervous system. We have also studied the effects of harmaline, a drug which evokes or intensifies the Parkinson-like tremor in lesioned animals and which also induces a fine, generalized tremor at 7-12/sec. in normal animals. The results obtained so far indicate that these two types of tremor are generated by two independent central mechanisms which do not require the integrity of peripheral feedback loops. The experimental Parkinson-like tremor is generated by a thalamo-cortical mechanism while the olivo-cerebellar system is responsible for the faster "physiological" tremor. Similar tremor mechanisms may be involved in some movement disorders in man.