Field of study
The motor system is hierarchically structured, but the relative contribution of each of its components to voluntary movement remains unknown. The spinal cord comprises only 2% of the nervous system, but it is a crucial structure in motor control. It is the ultimate gate through which all movement-related commands must pass before reaching the muscles. The segmental circuitry includes an elaborated network of interneurons, which serve as a summing point between descending information from higher brain centers and peripheral sensory inputs. Disruption of any of the inputs converging upon these interneurons interferes with the normal process of integration and results in clear and adverse motor deficits.
In our lab we are studying the way motor command is translated into a detailed pattern of muscle activation. Our working hypothesis is that the cortex does not specifically control individual muscles; rather, it influences the activity of several functionally related groups of muscles. In contrast, spinal neurons (also involved in reflex circuits) integrate all the relevant dynamic parameters arriving from multiple sources (descending and peripheral inputs) and generate the detailed activation of muscles.
To test this hypothesis and to further elucidate the contribution of spinal activity to the planning and execution of volitional movements we are using classical electrophysiological methods combined with more recent computational approach. We are now focusing on the following questions:
• Relation between motor cortical and spinal activity in behaving primates.
• Firing properties of identified spinal neurons and the interactions between these cells.
• Descending impact of motor and pre-motor cortices on spinal activity.