Multiple pathways transmit movement commands from the brain down the spinal cord. In mammals, especially in primates, the corticospinal tract is the dominant system. The powerful corticospinal connections enable fine dexterous abilities. An important parallel system involved in posture and gross motor function is called the reticulospinal tract. This tract also contributes to upper limb movement and even to fine hand control. Fisher et al. used electrophysiological recordings in macaques to characterize inputs from the main neocortical motor areas to reticulospinal cells of the medulla. They found extensive convergence from the primary motor cortex, as well as the supplementary motor area in both hemispheres, onto neurons in the reticular formation. This knowledge may become helpful for the development of therapies after stroke.
J. Neurosci. 41, 1005 (2021).