Temporal and task-specific profiles of effort investment

Investment of cognitive effort plays an important role in many aspects of daily life. For example, it can lead to feelings of cognitive fatigue, it is perceived as aversive and therefore avoided if possible, and it is registered as a cost in decision making. Cognitive effort can be invested through the application of cognitive control, which entails a flexible adjustment of behavior to environmental demands. For example, when faced with conflicting response options, we need to adaptively allocate cognitive control to overcome automatic response tendencies in favor of more appropriate behavior. Because cognitive control is effortful, it requires a balance between exerting a sufficient amount (to solve hard tasks), but not too much (to spare costly cognitive effort). This suggests that that cognitive control is best applied at variable time scales: transiently when conflict is rare but in a sustained way when conflict is frequent. In chapter 2, a behavioral quantification of this time scale is introduced. The chapter shows that cognitive control is indeed applied on a short time scale when conflict is rare or the context is volatile, and on a longer time scale when conflict is more frequent. The fMRI study in chapter 3 elaborates on these findings and shows that time scale differences are also mirrored in the neural implication of cognitive control. Increased transient activity was found in fronto-parietal areas when cognitive control was required rarely, while sustained neural activity was found in similar regions when cognitive control was required frequently. These results illuminate how context-dependent transient and sustained control subtend the same brain areas but operate on different time scales. Whereas chapters 2 and 3 deal with the temporal dynamics of cognitive effort through allocation of cognitive control (i.e., they expose when cognitive effort is applied), chapter 4 focuses on how effort investment is implemented neurally. The fMRI study in this chapter shows increased connectivity between dorsal anterior cingulate cortex (dACC) and task-specific cortical areas when effort demand is high. This implies that dACC, together with anterior insula and intraparietal sulcus, constitutes a general effort-responsive circuitry, and that dACC connects to specialized lower-level brain regions, depending on task specifics. Taken together, these studies provide 1) a behavioral and 2) a neural signature of temporal variations in the allocation of effortful control, and 3) show that the neural implementation of cognitive effort involves dACC-initiated sensitization of task-dependent areas.

Jaar van publicatie:2020

Toegankelijkheid:Open