for bilateral fast conducting corticospinal pathways. Other patients with an acquired hemiplegia between 9 months and 7 years of age had weaker mirror movement. Magnetic stimulation of the healthy hemisphere induced the usual controlateral answer but also induced an ispsilateral evoked potential which occurred 4 ms later on average than the contralateral one. This ipsilateral answer was also smaller than the contralateral one. These results suggest that in this group another mechanism for mirror movement could be identified which could implicate an oligosynaptic