Dorsal striatum mediates cognitive control, not cognitive effort per se, in decision-making: An event-related fMRI study.

Neuroimage. 2015 Apr 7;

Authors: Robertson BD, Hiebert NM, Seergobin KN, Owen AM, MacDonald PA

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. Discriminating smaller physical size differences between a number pair increases cognitive effort, but does not demand 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 control increases errors and response times. Despite similar behavioural profiles, our aim was to determine whether DS simply indexes cognitive effort versus specifically mediates cognitive control, 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 requirements 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., ACC).
INTERPRETATION: 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.

PMID: 25862263 [PubMed - as supplied by publisher]