title: Functional role of the basal ganglia in the planning and execution of actions.
abstract: OBJECTIVE
  Recent studies of functional brain imaging have shown the involvement of the basal ganglia in executive processes such as planning and set-shifting. However, the specific contributions of the striatum in those processes remain unknown. This study aimed to test the hypothesis that the caudate nucleus is primarily involved in the preparation of a novel action and not in set-shifting per se.
  
  
  METHODS
  In the present event-related functional magnetic resonance imaging (fMRI) study, a new task was developed that permitted, for the first time, to distinguish between shifts in classification when the rule is implicitly given by the task from shifts that require cognitive comparison and planning.
  
  
  RESULTS
  Significantly increased activity in the caudate nucleus and the putamen was observed only in conditions in which cognitive planning was required to perform a set-shift, whereas significant activation was seen in the subthalamic nucleus (another region of the basal ganglia) in all shifting conditions whether or not planning was required.
  
  
  CONCLUSIONS
  We suggest that the caudate nucleus and the putamen are particularly important, respectively, in the planning and the execution of a self-generated novel action, whereas the subthalamic nucleus may be required when a new motor program is solicited independently of the choice of strategy.
authors.affiliation: Functional Neuroimaging Unit, Centre de Recherhe, Institut Universitaire de Gériatrie de Montréal, Québec, Canada. oury.monchi@umontreal.ca
authors.forename: Oury
authors.initials: O
authors.lastname: Monchi
authors.forename: Michael
authors.initials: M
authors.lastname: Petrides
authors.forename: Antonio P
authors.initials: AP
authors.lastname: Strafella
authors.forename: Keith J
authors.initials: KJ
authors.lastname: Worsley
authors.forename: Julien
authors.initials: J
authors.lastname: Doyon
mesh_terms: D000293:Adolescent; D000328:Adult; D001288:Attention / Q000502:physiology*; D001479:Basal Ganglia / Q000033:anatomy & histology / Q000098:blood supply / Q000502:physiology*; D001931:Brain Mapping; D002421:Caudate Nucleus / Q000098:blood supply / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D011939:Mental Recall / Q000502:physiology; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation / Q000379:methods; D011340:Problem Solving / Q000502:physiology*
chemical_list: D010100:Oxygen