title: Dorsal striatum mediates cognitive control, not cognitive effort per se, in decision-making: An event-related fMRI study.
abstract: OBJECTIVE
  Whether the dorsal striatum (DS) mediates cognitive control or cognitive effort per se in decision-making is unclear given that these effects are highly correlated. As the cognitive control requirements of a neuropsychological task intensify, cognitive effort increases proportionately. We implemented a task that disentangled cognitive control and cognitive effort to specify the particular function DS mediates in decision-making.
  
  
  METHODS
  Sixteen healthy young adults completed a number Stroop task with simultaneous blood-oxygenation-level-dependent response (BOLD) measurement using functional magnetic resonance imaging. Participants selected the physically larger number of a pair of single-digit integers. Discriminating smaller versus larger physical size differences between a number pair requires greater cognitive effort, but does not require greater cognitive control. We also investigated the effect of conflict between the physical and numerical dimensions of targets (e.g., 2 6). Selections in this incongruent case are more cognitively effortful and require greater cognitive control to suppress responding to the irrelevant dimension. Enhancing cognitive effort or cognitive control demands increases errors and response times. Despite similar behavioural profiles, our aim was to determine whether DS mediates cognitive control or simply indexes cognitive effort, using the same data set.
  
  
  RESULTS
  As expected, behavioural interference effects occurred for both enhanced cognitive control and/or cognitive effort conditions. Despite similar degrees of behavioural interference, DS BOLD signal only correlated with interference arising due to increased cognitive control demands in the incongruent case. DS was not preferentially activated for discriminations of smaller relative to larger physical size differences between number pairs, even when using liberal statistical criteria. However, our incongruent and physical size effects conjointly activated regions related to effortful processing (e.g., anterior cingulate cortex).
  
  
  CONCLUSIONS
  We interpret these findings as support for the increasingly accepted notion that DS mediates cognitive control specifically and does not simply index cognitive effort per se.
authors: Brain and Mind Institute, The Natural Sciences Centre, University of Western Ontario, London, Ontario, Canada N6A 5B7; Department of Physiology and Pharmacology, Medical Sciences Building, Room 216, University of Western Ontario, London, Ontario, Canada N6A 5C1.
authors: Brian D
authors: BD
authors: Robertson
authors: Brain and Mind Institute, The Natural Sciences Centre, University of Western Ontario, London, Ontario, Canada N6A 5B7; Department of Physiology and Pharmacology, Medical Sciences Building, Room 216, University of Western Ontario, London, Ontario, Canada N6A 5C1.
authors: Nole M
authors: NM
authors: Hiebert
authors: Brain and Mind Institute, The Natural Sciences Centre, University of Western Ontario, London, Ontario, Canada N6A 5B7.
authors: Ken N
authors: KN
authors: Seergobin
authors: Brain and Mind Institute, The Natural Sciences Centre, University of Western Ontario, London, Ontario, Canada N6A 5B7; Department of Physiology and Pharmacology, Medical Sciences Building, Room 216, University of Western Ontario, London, Ontario, Canada N6A 5C1.
authors: Adrian M
authors: AM
authors: Owen
authors: Brain and Mind Institute, The Natural Sciences Centre, University of Western Ontario, London, Ontario, Canada N6A 5B7; Department of Physiology and Pharmacology, Medical Sciences Building, Room 216, University of Western Ontario, London, Ontario, Canada N6A 5C1; Clinical Neurological Sciences, London Health Sciences Centre, University Hospital, 339 Windermere Road, London, Ontario, Canada N6A 5A5. Electronic address: penny.macdonald@gmail.com.
authors: Penny A
authors: PA
authors: MacDonald
mesh_terms: D000328:Adult; D001931:Brain Mapping; D003071:Cognition / Q000502:physiology*; D003657:Decision Making / Q000502:physiology*; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D017072:Neostriatum / Q000502:physiology*; D011930:Reaction Time; D057190:Stroop Test; D055815:Young Adult
keywords: Cognitive control; Cognitive effort; Striatum; Stroop; fMRI