Functional organization of the primary motor cortex characterized by event-related fMRI during movement preparation and execution.

Neuronal recording and neuroimaging studies have shown that the primary motor area (M1) not only participates in motor execution, but is also engaged during movement preparation. The purpose of the present study was to map the distribution of the preparation- and execution-related activity within the contralateral M1 using functional magnetic resonance imaging. Eleven subjects performed a delayed sequential finger movement task, in which a CUE signal indicated a movement sequence in advance of an imperative GO signal. The hemodynamic response related to the CUE and GO signals decreased in a linear fashion across the central sulcus, with activity greater along the lateral extent compared to the medial extent. This decrease was especially evident in the epoch following the CUE. Our data reveal a pattern of functional organization within M1 related to the preparation and execution of movement sequences.