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. Author manuscript; available in PMC: 2006 Apr 20.
Published in final edited form as: J Neurophysiol. 2004 Dec 29;93(5):2950–2958. doi: 10.1152/jn.00784.2004

Fig. 5.

Fig. 5

A possible scheme for the ipsilateral motor systems originating from the PcG. Both premotor cortex and M1 may control the ipsilateral hand below age 10 (childhood). The ipsilateral M1 function is gradually suppressed in the course of the normal development of inhibitory systems such as the transcallosal inhibition from the contralateral M1. In normal adults, only the premotor cortex usually controls ipsilateral or bilateral distal limb movements (adulthood). Withdrawal of the inhibitory inputs due to acquired lesions might lead to the reemergence of ipsilateral M1 function (pathologic).