Article

In maturity, motor skills depend on the corticospinal tract (CST) and brainstem
pathways that together synapse on interneurons and motoneurons in the spinal
cord. Descending signals to spinal neurons that mediate voluntary control can be
distinguished from peripheral sensory signals, primarily for feedback control.
These motor system circuits depend initially on developmental genetic mechanisms
to establish their connections and neural activity- and use-dependent synaptic
refinement during the early postnatal period to enable motor skills to develop.
In this review we consider four key activity-dependent developmental mechanisms
that provide insights into how the motor systems establish the proper connections
for skilled movement control and how the same mechanisms also inform the
mechanisms of motor impairments and developmental plasticity after corticospinal
system injury: (1) synaptic competition between the CSTs from each hemisphere;
(2) interactions between the CST and spinal cord neurons; (3) synaptic
competition between the CST and proprioceptive sensory fibres; and (4)
interactions between the developing corticospinal motor system and the
rubrospinal tract. Our findings suggest that the corticospinal motor system
effectively 'oversees' development of its subcortical targets through synaptic
competition and trophic-like interactions and this has important implications for
motor impairments after perinatal cortical stroke. WHAT THIS PAPER ADDS: Neural
activity-dependent processes inform the brain and spinal cord response to injury.
The corticospinal motor system may 'oversee' development of its downstream
subcortical targets through activity, trophic-like interactions, and synaptic
competition.
CI - (c) 2017 Mac Keith Press.

Langue : ANGLAIS