Functional neuroanatomical and neurobiological modulators of the interaction of volitionally controlled and automatic behavior

For quite long, volitional control and automaticity have been considered to be opposing processes. In this context, volitional control has long been described as a superior faculty mainly used to modify automatic behavior. Yet, there is mounting evidence that there may not be such a strict hierarchy as volitional control and automaticity seem to interact in both directions. While there has been much research on this interaction at the behavioral level, the neural mechanisms that underlie it have remained largely elusive. The aim of this project within the CRC is to investigate key functional neuroanatomical and neurobiological mechanisms associated with the interaction of volitional control and automatic processes. As a general hypothesis, we assume that factors which up-regulate volitional control also increase its sometimes detrimental effects on automatic processing and lessen the effects of automaticity on controlled processes. Given that the striatum, which plays a key role in response selection, is involved in the application and acquisition of both volitional and automated behavior, all these effects should mainly occur at the response selection level. To tackle these hypotheses, we will employ two complementary experimental paradigms: One has been designed to determine the extent of potential detrimental effects of volitional control on automatic response processes. The other paradigm allows to investigate the opposite, namely the effect of automatic response tendencies on volitionally controlled ones. To examine the effects of potential modulators of the interaction on the response selection level, we will use EEG techniques. We will focus on event-related potentials (especially the N2 and lateralized readiness potentials), theta frequency oscillations and the functional neuroanatomical networks underlying modulations of the interaction of cognitive control and automaticity using source localization methods (i.e. beamforming approaches). Based on the general hypothesis, we put our focus on the potential relevance of fronto-striatal loops (especially the supplementary motor area (SMA), anterior cingulate cortex (ACC), and striatum). This is done because these brain regions are known for their relevance in mediating both cognitive control and automatic processes as well as playing a pivotal role in response selection. We use two different lines of investigation with a focus on the GABAergic, glutamatergic, and dopaminergic systems, which have also been shown to be involved in cognitive control and automaticity. MR spectroscopy will be used to investigate the role of the GABAergic and glutamatergic systems. The relevance of the dopaminergic system will be investigated using complementary approaches targeting short term vs. long term effects of its upregulation using a pharmacological intervention (methylphenidate treatment) and an infection model (latent toxoplasmosis), respectively.

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