A Dynamical Approach to Normal and Parkinsonian Tremor

Abstract

Many phenomena in motor control recur at regular or almost regular intervals (gait, tremor, fibrillations) while others occur irregularly (cerebellar gait, fasciculations, myoclonus). Subtle changes in the dynamics of motor control rhythms (i.e., going from regular to irregular or from irregular to regular rhythms) can be of major clinical importance in the early detection of neurodegenerative diseases. Here, we examine the effect of lesions located in the basal ganglia on the amplitude and frequency of tremor. As one of the major reentrant subcortical loop modulating the output of the cerebral cortex through thalamo-cortical projections, the basal ganglia play a major role in sensorimotor integration. Some lesions affecting these neural structures are associated with Parkinson’s disease and produce qualitative changes in tremor dynamics. These tremor dynamics may represent the missing link between the anatomical level (i.e., the lesion) and the behavioral level (i.e., the pathophysiology).