Magnetic stimulation study during observation of motor tasks

The aim of the study was to assess if the observation of single or more com plex muscle movements activates the premotor cortex in man. We stimulated b y transcranial magnetic stimulation the right and left motor cortex recordi ng from the abductor pollicis brevis of right normal subjects, during obser vation of different movements performed by the examiner: (1) single movemen ts: thumb abduction, arm elevation, (2) motor sequences: finger opposing mo vements performed in an ordinate sequence: 1-2, 1-3, 1-4, 1-5, 1-2..., and in a non-consecutive non-repetitive order: 1-3, 1-5, 1-3,1-2, 1-5, 1-2... W e found an increased excitability of the right cortex during observation of isolated muscle movement regardless of which muscle is moved. At the stimu lation of the left cortex, MEPs were significantly increased during observa tion of complex muscular synergies. (C) 2000 Elsevier Science B.V. All righ ts reserved.