The great repertoire of movements in higher order mammals comes courtesy of the corticospinal tract (CST) which is able to initiate precise movement of the entire musculature of the axial and limb muscle groups. It forms the longest axonal trajectory in the mammalian central nervous system and its axons must navigate the entire length of the central nervous system--from its origins in the deeper layers of the cerebral cortex down through the cerebral peduncles and brainstem and along the entire length of the spinal cord. This period of navigation is incredibly complex, and relies upon the coordinated regulation of a collection of molecular guidance cues - coming from all of the known major families of guidance cues - the ephrins, slits, Netrins and Semaphorins - that work together to steer the growing axonal tips through the brain and spinal cord. As such a long tract, the CST forms an excellent experimental model to investigate the nature of molecular cues that sequentially guide axons through the central nervous system. Using the rodent as a model system, this review discusses each step of axonal guidance through the major brain regions--starting from the decision to grow ventrally out of the cortical plate to the eventual activity-dependent refinement of circuitry in the spinal grey matter. In recent years, the identification of these guidance cues and their proposed mode of action is beginning to give us a picture at a molecular level of how the CST is guided so accurately over such a long distance.

Item Type:	Refereed Article
Research Division:	Biomedical and Clinical Sciences
Research Group:	Neurosciences
Research Field:	Central nervous system
Objective Division:	Health
Objective Group:	Clinical health
Objective Field:	Clinical health not elsewhere classified
UTAS Author:	Canty, A (Associate Professor Alison Canty)
ID Code:	69928
Year Published:	2008
Web of Science® Times Cited:	66
Deposited By:	Medicine
Deposited On:	2011-05-25
Last Modified:	2011-05-26
Downloads:	0