Motor Unit Properties and Underlying Determinants in Pathological Tremor

Abstract

Pathological tremors are accepted to originate from the projection of supraspinal pathological oscillations to motor neurons that innervate the affected muscles. These oscillations interact with other neural mechanisms such as reflexes, and, together with the mechanical properties of the limb, determine the characteristics of the tremor. However, much is yet unknown about the exact mechanisms that mediate the different types of tremor, and how they interact. Given that the neural drive to muscle encodes information about all pathways that regulate movement, we are investigating the properties of motor unit activities in tremor patients and the factors that determine them as a means to further our understanding of the disorder. This paper presents a simulation study that supports our departure hypothesis (that tremor is a common cortical projection to the motor neuron pool), and first experimental evidences on a patient with essential tremor. The latter illustrate that the predictions derived from the model provide significant support for the analysis of real data, and demonstrate the potential of the analysis techniques here employed.