Dissociating the Role of the Dorsolateral Prefrontal and Anterior Cingulate Cortex in Cognitive Control by MacDonald III et al.

The Link Between DLPFC and ACC in Cognitive Regulation

The authors wonder if the dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC) are linked to cognitive regulation. The matter is crucial to investigate because prior research on the subject has yielded contradictory results about the associative or associative participation of the two areas in modifying cognitive functions and performances. As a result, the framing of the inquiry was prompted by the necessity to confirm the relative dissociations of the two regions.

Hypothesis and Theory

Besides, they use the theory that cognitive control is accorded by the establishment of appropriate stimulus-response mapping to guide their investigations. As a result, they hypothesized that the DLPFC and the ACC are relatively dissociated in cognitive control. The hypothesis formulation was informed by previous neuroimaging studies that intimated relative dissociations between the two regions modulating cognitive activities. For instance, the DLPFC is activated in maintaining simple cues over a delay while ACC is activated in tasks requiring divided attention, overcoming a prepotent response and related reactions. Besides, the theory of mapping appropriate stimulus responses to cognitive functions justifies the need to delineate possible dissociations in cognitive control involving the two areas.

Experimental Design and Variables

For the instruction-related experiment, the independent variable is the task stimulus (color/word naming), while in the response-related activity, it is the Stroop interference (response reaction interval). The rationale for manipulating the task stimulus is to determine the rate and extent of producing fast and accurate responses, while that one for controlling the Stroop interference is to evaluate the extent to which participants use cognitive control mechanisms to modulate reactions to specific stimuli. Despite these constructs, the dependent variable for the instruction-related activity is the rate and extent of congruence to word/color naming, while for the response-related investigation, the dependent variable is the rate and degree of incongruence to the colored word-color match. Nonetheless, both of the variables were measured by the response time intervals and changes in the MRI activities from the baseline.

Findings and Conclusion

Despite these constructs, for the instruction-related part, significant changes in the MRI activity occurred in the left DLPFC compared to the ACC, which is consistent with representing and maintaining task-related stimuli in working memory. However, regarding the response-related experiment, the findings showed greater MRI activity in the ACC region compared to the DLPFC area, indicating steadiness in conflict monitoring (cognitive manipulation) that synonymous with the ACC. These findings support the hypothesis regarding the relative dissociation of the two regions in cognitive control.

The authors conclude that the DLPFC represents and maintains the attention demands of tasks, while the ACC directs the evaluate processes, though the two regions are relatively dissociative and complementary in cognitive control. The study demonstrates some weaknesses in defining the wording fonts, which can mediate the participants’ response patterns, and the scope of Stroop interference, which can explain the reaction patterns exhibited in the response-related activity. Nonetheless, an alternative hypothesis could be that the DLPFC and the ACC are associated in cognitive control.

Reference

MacDonald III, A.W., Cohen, J.D., Stenger, V.A., & Carter, C.S. (2000). Dissociating the role of the dorsolateral prefrontal cortex and anterior cingulate cortex in cognitive control. Science, 288, 1835-1838.