Abstract
Cognitive control refers to the ability to regulate thought and action in a goal-directed manner and is essential for optimal daily life functioning. Cognitive control can be partitioned into specific functions facilitating efficient control, such as working memory, set-shifting and response inhibition, as well as in the temporal domain into proactive and reactive control. While proactive control refers to the preparation in expectation of an upcoming interfering event, reactive control refers to the processes elicited by the interfering event itself. The preferred control strategy might vary between individuals and task settings. The neural mechanisms underlying reactive control have been investigated extensively over the last two decades, but how these mechanisms interact with proactive control is less known. The current thesis seeks to investigate these control processes by looking at the neural mechanisms underlying proactive and reactive control of response inhibition, a core sub-function of cognitive control. We focused specifically on activity in regions associated with reactive response inhibition, as well as frontal-midline theta (FM-theta) activity measured at the scalp. Further, as resting state activity has been associated with cognitive control performance, it was investigated whether resting state FM-theta activity was associated with proactive and reactive control.
First, we found that proactive control of response inhibition leads to increased activity in some, but not all, of the regions traditionally involved in reactive response inhibition. Importantly, activity within sub-regions of the right inferior frontal gyrus, a proposed core region of the response inhibition network, show functional specialization in response to proactive control. Second, we show that a proposed marker of cognitive control, FM-theta activity, is rather a multidimensional feature, associated with several processes related to the preparation to stop, preparation to respond, as well as reflecting control adjustments across a range of cognitive control tasks beyond mere conflict and novelty. Finally, we did not find evidence for a relationship between resting state theta and proactive or reactive control. However, resting state theta was associated with reaction times in a working memory task, indicating that resting state dynamics may still mediate cognitive control performance. These findings expand the current understanding of cognitive control and are in line with more integrative, domain-general approaches. Importantly, the results of the current thesis have implications for our understanding of cognitive control in both healthy and clinical populations.