An anterior-posterior gradient of cognitive control within the dorsomedial striatum.

Lateral prefrontal cortex and basal ganglia work together to mediate working memory and top-down regulation of cognition. This circuit regulates the balance and interactions between automatic and high-order control responses. Using ultra-high-field high-resolution functional magnetic resonance imaging (7T-fMRI), the present study examined the role of subcortical structures in cognitive control during language processing. Participants were asked to judge the grammaticality of unambiguous, ungrammatical and ambiguous sentences. Grammatical unambiguous sentences should elicit an automatic response, while ambiguous and ungrammatical sentences should conflict with the automatic response and, hence, require a high-order control response. Within the control response domain, ambiguity and ungrammaticality represent two different dimensions of conflict resolution, while for a temporarily ambiguous sentence a correct interpretation is available, that is not the case for ungrammatical sentences. Our results reveal an anterior-posterior axis in the dorsomedial striatum with more rostral regions supporting higher levels of cognitive processing. This functional architecture mirrors the rostrocaudal hierarchical organization evidenced within the lateral prefrontal cortex.