Patterns of regional brain activation associated with different forms of motor learning

To examine the variations in regional cerebral blood flow during execution and learning of reaching movements, we employed a family of kinematically a nd dynamically controlled motor tasks in which cognitive, mnemonic and exec utive features of performance were differentiated and characterized quantit atively. During O-15-labeled water positron emission tomography (PET) scans , twelve right-handed subjects moved their dominant hand on a digitizing ta blet:From a central location to equidistant targets displayed with a cursor on a computer screen in synchrony with a tone. In the preceding week, all subjects practiced three motor tasks: 1) movements to a predictable sequenc e of targets; 2) learning of new visuomotor transformations in which screen cursor motion was rotated by 30 degrees-60 degrees; 3) learning new target sequences by trial and error, by using previously acquired routines in a t ask placing heavy load on spatial working memory. The control condition was observing screen and audio displays. Subtraction images were analyzed with Statistical Parametric Mapping to identify significant brain activation fo ci. Execution of predictable sequences was characterized by a modest decrea se in movement time and spatial error. The underlying pattern of activation involved primary motor and sensory areas, cerebellum, basal ganglia. Adapt ation to a rotated reference frame, a form of procedural learning, was asso ciated with decrease in the imposed directional bias. This task was associa ted with activation in the right posterior parietal cortex. New sequences w ere learned explicitly. Significant activation was found in dorsolateral pr efrontal and anterior cingulate cortices. In this study, we have introduced a series of flexible motor tasks with similar kinematic characteristics an d different spatial attributes. These tasks can be used to assess specific aspects of motor learning with imaging in health and disease. (C) 2000 Else vier Science B.V. All rights reserved.