Fronto-parietal activationduring observation of impossible grasping actions : an fMRI study

Neuroimaging experiments have shown that observation of others\u2019 actions activates a fronto-parietal network in the brain of observers (Broadmann areas 6, 9, 2, 3 and 40). This activation is assumed to be a sensory-motor representation of observed actions, generating an embodied simulation used to understand observed actions and their intentions. Utilizing natural (\u2018palmar\u2019 finger flexion) and impossible (\u2018dorsal\u2019 finger flexion) actions with identical grasping intention, neurophysiological experiments have also shown that motor resonant responses (TMS-evoked motor potentials) in primary motor cortex reflect the specific motor program encoding the movements composing an action rather than its intention. To test the hypothesis that different features of observed actions may be encoded at different levels in the CNS, here we compare brain activation during observation of the same natural and impossible grasping actions performed by an avatar right hand. Twenty right-handed subjects participated in a fMRI experiment; group analyses were performed, identifying areas active in both conditions (\u201cnatural\u201d and \u201cimpossible\u201d; p