The basal ganglia are thought to play a critical role in adaptive behavior and cognition in general, and movement preparation, initiation, control and sequencing in particular. However, the relative contributions and roles of the various sub-components of the basal ganglia are not known. The overarching goal of this proposal is to characterize the differential contributions of dorsal basal ganglia (dBG) nuclei during the sequential organization of behavior. The proposed study aims to extend and amplify our previous findings of reliable and differential fMRI activation of the anterior caudate, anterior and posterior putamen and globus pallidus during movement sequencing. We plan to investigate in greater detail dBG involvement in various specific components of movement sequencing, and to examine the relationship between dBG activation, overall behavior, and specific behavioral performance measures such as reaction time and accuracy. Although the primary focus of this study is the dBG, the relative signal change, spatial extent and time course of activation in neocortical motor areas and the cerebellum will be also be examined. In addition, functional relations between the posterior putamen and globus pallidus, thalamus, cerebellum and cortical motor areas receiving dBG output will also be examined. Study 1 will investigate dBG function during movement sequencing in relation to specific and measurable changes in behavior. We will examine the effect of rate of movement on dBG activation during sequencing of unpredictable and predictable movements. Study 2 will investigate dBG function in relation to specific components involved in motor control during movement sequencing using event-related fMRI. Together these studies will more convincingly relate dBG to behavior during movement sequencing. More broadly, contrasting the roles of the dBG, motor cortex, SMA, pre-SMA and the cerebellum will yield significant information about distributed brain processes involved in the sequential organization of behavior. Results from the proposed studies will provide additional insights regarding the role of the dBG in adaptive behavior. Furthermore, the proposed research will aid in understanding and treating basal ganglia disorders, such as schizophrenia, ADHD, Huntington's disease, Parkinson's disease, and Tourette's syndrome.
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