Red nucleus

The red nucleus has a somatotopic map. Its activity leads intentional movements and associates with parameters like velocity, force, and direction, much similar to corticospinal tract neurons. Moreover, most of the primates rubrospinal axons have similar distribution to proximal and distal limb motor neurons as the corticospinal tract and their activity moves separate digits. Though, in humans the distinction among the two lateral pathways seems not to be as significant as in many mammals, and the rubrospinal tract is included in gross limb movements not fine ones.

However the two pathways emerge strikingly similar, studies in sub-human primates recommend that they operate in various contexts. Whereas the rubrospinal tract is active whenever formerly learnt automated movements are executed, the corticospinal tract is needed whenever novel movements are being learnt. The other pathway acts to switch activity among the two lateral motor systems. As a new movement is effectively learnt its execution is switched from the corticospinal tract to rubrospinal tract control. The switch functions in the opposite direction when an automatic movement requires being adapted. It is since of the switch that each lateral motor system can reimburse for the loss of the other. A corticospinal tract lesion consists of a more severe and protracted effect than rubrospinal tract lesions as new movements cannot be executed and only the old rubrospinal tract repertoire can be called ahead. The switch pathway includes the inferior olive, one of the functions is to detect and accurate errors in motor performance.