Dissecting proactive control processes in task-switching: a model-based neuroscience approach

Abstract

Research Doctorate - Doctor of Philosophy (PhD)Cognitive control processes support purposeful, goal-directed behaviour in the presence of conflicting demands from our environment. Given advance information, this type of control can be engaged in anticipation of a change in behaviour. The cued-trials task-switching paradigm can temporally dissociate proactive and reactive cognitive control processes involved in switching between sets of abstract task rules. Typically, there is a performance cost for switch relative to repeat trials, which is attributed partly to proactive control processes required to prepare for a switch in task and partly to reactive control processes required to deal with between-task interference. Despite two decades of research into preparatory processes in task-switching, the cognitive processes and neural substrates that support proactive control remain underspecified. This thesis uses a model-based neuroscience approach to define the temporal and spatial characteristics of cognitive processes that contribute to proactive control in task-switching. Using converging evidence from ERPs, a novel multivariate pattern misclassification analysis of EEG data and cognitive modeling, we showed that a switch-specific preparation process is temporally and spatially distinct from more general task preparation for both switch and repeat trials. Consistent with a conflict control mechanism, we show that this switch-specific preparation process is linked to a right inferior frontal source and is related to upward adjustment of response caution in anticipation of more difficult switch trials. We also used fMRI- and DWI-based analyses to examine the neural basis of these cue-related adjustments in response caution, showing that distinct cortico-basal ganglia networks are associated with the ability to flexibly adjust response caution in anticipation of easy or difficult decisions, as well as intrinsic tendencies to set overall response caution high or low. We discuss implications of these findings for our understanding of the organization and timecourse of cognitive control mechanisms