Developmental plasticity of descending motor pathways.

Juvenile animal brains are highly plastic and thus often achieve better functional recovery after injury compared with adult brains. Recently, Umeda et al. (Umeda T, Takahashi M, Isa K, Isa T. J Neurophysiol 104: 1707-1716, 2010) have shown that the remodeling of both corticospinal and extra-pyramidal pathways can contribute to the recovery of grasping and reaching ability in hemidecorticated juvenile rats. They have further unveiled the strengthening of the cortico-reticulo-spinal pathway after injury, that mediates the fast excitation of ipsilateral motoneurons for functional recovery.