Reactivation of motor brain areas during explicit memory for actions

Recent functional brain imaging studies have shown that sensory-specific br ain regions that are activated during perception/encoding of sensory-specif ic information are reactivated during memory retrieval of the same informat ion. Here we used PET to examine whether verbal retrieval of action phrases is associated with reactivation of motor brain regions if the actions were overtly or covertly performed during encoding. Compared to a verbal condit ion, encoding by means of overt as well as covert activity was associated w ith differential activity in regions in contralateral somatosensory and mot or cortex. Several of these regions were reactivated during retrieval. Comm on to both the overt and covert conditions was reactivation of regions in l eft ventral motor cortex and left inferior parietal cortex. A direct compar ison of the overt and covert activity conditions showed that activation and reactivation of left dorsal parietal cortex and right cerebellum was speci fic to the overt condition. These results support the reactivation hypothes is by showing that verbal-explicit memory of actions involves areas that ar e engaged during overt and covert motor activity. (C) 2001 Academic Press.