A new pathway from primary afferents to the red nucleus.

Evidence is provided that rubrospinal neurons receive feedback information from the periphery via pathways which bypass both the cerebellum and the cerebral cortex. It appears that the primary afferent fibers which ascend in the dorsal columns of the spinal cord give off collaterals via which they activate ascending tracts with axons in the ventral quandrants of the spinal cord. The existence of such pathways indicates that the red nucleus is part of a long feedback loop assisting the ongoing movement.