The long-term goal of this project is to improve understanding of how the nervous system selects and executes individuated finger movements. Individuated movements are the first lost and last recovered when neurologic lesions affect the motor cortex or corticospinal tract. The resulting motor deficits impair use of the hand and fingers in everyday tasks. The present application proposes to examine the role of synchrony among primary motor cortex neurons in the learning and performance of skilled finger movements. Studies will focus on changes in synchrony in three, inter-related situations: 1) changes that relate to long-term training at a repertoire of skilled finger movements, 2) changes that depend on which particular movements are performed, and 3) changes that occur when a skilled subject attempts a novel movement. Such changes in synchrony could enable the nervous system to more efficiently activate the varied combinations of muscles needed for execution of skilled movements. Multiple neuron recording and spike-triggered averaging of electromyographic activity will be used together to examine synchrony both between pairs of motor cortex neurons, and among larger ensembles of neurons that provide inputs to spinal motoneuron pools. The proposed studies will address the following specific questions: 1) What is the time course of the increase in synchrony over long-term training? 2) Does synchrony occur during only a subset of finger movements or task time periods? 3) Do patterns of synchrony change when a fully trained subject practices a novel movement? 4) Does synchrony occur predominantly in corticospinal or non-corticospinal primary motor cortex neurons?