Plasticity and primary motor cortex

One fundamental function of primary motor cortex (MI) is to control volunta ry movements. Recent evidence suggests that this role emerges from distribu ted networks rather than discrete representations and that in adult mammals these networks are capable of modification. Neuronal recordings and activa tion patterns revealed with neuroimaging methods have shown considerable pl asticity of MI representations and cell properties following pathological o r traumatic changes and in relation to everyday experience, including motor -skill learning and cognitive motor actions. The intrinsic horizontal neuro nal connections in MI are a strong candidate substrate for map reorganizati on: They interconnect large regions of MI, they show activity-dependent pla sticity, and they modify in association with skill learning. These findings suggest that MI cortex is not simply a static motor control structure. It also contains a dynamic substrate that participates in motor learning and p ossibly in cognitive events as well.