Control of fine movements mediated by propriospinal neurons.

Studies of the role of the C3/C4 propriospinal system of spinal cord interneurons in the control of fine movements and the processes compensating motor deficiency after lesioning of the cortico- and rubrospinal tracts at the level of segments C2 and C5 were studied in cats. These experiments showed that after lesioning of the cortico- and rubrospinal tracts at the level of C5, the C3/C4 propriospinal system played a key role in recovery processes, while after lesioning at the level of C2, the leading role was played by ipsilateral tracts in the ventral part of the spinal cord. In addition, the propriospinal system demonstrated a significant level of plasticity and was able to provide complete control of a number of fine voluntary movements.