Detection of common synaptic inputs shared by populations of motor neurons innervating different muscles: Methodology and considerations for neuroprosthetic treatment of tremor

A large proportion of tremor patients do not benefit from any treatment. This is partly motivated by the fact that current therapies may not be sufficiently specific because the pathophysiology of each type of tremor is not fully understood. In particular, the ultimate mechanisms (common synaptic inputs) that generate the tremorogenic muscle activity are yet unknown. Therefore, in this paper we present a novel methodology to investigate whether motor neuron pools innervating different muscles receive the same common synaptic inputs, and what are their properties. We illustrate the potential of the approach by demonstrating that motor neuron pools innervating antagonist muscles of one essential tremor and one parkinsonian patient share the same common synaptic input at the tremor frequency. We finish discussing what are the potential implications of our findings when designing a neuroprosthesis for tremor suppression based on the stimulation of afferent pathways.