Identification of multiple nonprimary motor cortical areas with simple movements

The human cortex reportedly contains at least five nonprimary motor areas: in the frontolateral convexity, the dorsal and ventral premotor cortex (PMd and PMv), and in the frontomesial wall, the presupplementary and supplemen tary motor areas (pre-SMA and SMA), and the rostral, dorsal and ventral cin gulate areas (CMAr, CMAd, and CMAv). Activation of these regions in neuroim aging studies has been generally associated either with the performance of complex motor tasks or with reorganization occurring with motor recovery in the presence of pathology. Recent evidence from neuroimaging studies sugge sts that the same areas are activated with well controlled simple movements in healthy subjects providing support to the observation that their contri bution may be more quantitative rather than exclusively specific to a certa in aspect of motor behaviour. An important consequence of this observation is that activation of multiple nonprimary motor areas during simple motor t asks should not be considered unique to patients with upper or lower motone uron lesions but rather as a normal physiological process. (C) 2001 Elsevie r Science B.V. All rights reserved.