Control of species-dependent cortico-motoneuronal connections underlying manual dexterity

Abstract

The disappearance of fine motor control Manual skills are much better developed in primates than in rodents. This difference is in part due to species-specific differences in the control of motoneurons by the brain. Gu et al. used a range of approaches to evaluate potential corticospinal tract projections in neonatal mice. These projections exist immediately after birth but disappear within the first 2 postnatal weeks owing to the actions of plexin A, a member of the semaphorin receptor family. Targeted deletion of semaphorin receptors in mutant mice prevented elimination of corticospinal tract projection and loss of functional monosynaptic input to spinal motoneurons. Science , this issue p. 400