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Cognitive control  jointly aligns our actions with contextual circumstances and long-term objectives.

Working memory is the mental space that forms the basis of rational thought.

Directed Interactions Supporting Cognitive Control

From the classroom, to social events, to conversing with our parents, we engage in different sets of actions depending upon what is appropriate for the context. To do so, we must constantly select the best course of action while jointly considering our long-term plans and immediate circumstances. This is cognitive control and it requires a massive integration of information on the one hand, and the guidance of action on the other. To understand this process, and how it goes awry in psychiatric disorders, we need to identify the direct interactions that link the functions of brain regions to one another and ultimately behavior. We are using fMRI to examine the brain during cognitive control and computational techniques to model directed interactions. We are using TMS to causally test these models, observing the effect of stimulating one brain region on downstream regions, and how they collectively affect behavior. With directed models in hand, we will be better-positioned to predict and rehabilitate mental dysfunction.

Mechanisms of Mental Prioritization

Our minds are a maelstrom of thoughts. Irrelevant thoughts must be silenced to focus on tasks at hand, while other thoughts must be organized into those that are immediately relevant and those that will be relevant sometime in the near future. Appropriately prioritizing our thoughts is an essential aspect of working memory and at the heart of higher-level abilities such as problem solving and reasoning. We are using experimental psychology to determine the degree to which prioritizing working memory representations draws upon resources similar to external attention. We are using fMRI and techniques for tracking mental representations in the brain to detail how representations are altered by different priority states. We are using TMS to mimic the brain's endogenous prioritization mechanisms to causally induce mental priority shifts. Such data will facilitate our understanding of basic mechanisms and foster treatments of mental disorganization.

Non-invasive stimulation of sub-cortex

All aspects of cognition rely on sub-cortex. Sub-cortical dysfunction is a debilitating feature of numerous psychiatric and neurological disorders. In some cases, invasive treatments (i.e. deep brain stimulation) can remediate symptoms in these disorders, but invasive treatments are rife with side effects. TMS can non-invasively alter brain function with low incidence of side-effects, but TMS pulses themselves cannot penetrate into the sub-cortex. However, all sub-cortical areas have projections from cortical areas. Guided by anatomy and functional connectivity, we are delivering TMS to cortical sites with strong projections to sub-cortical areas of interest. Through a combination of behavioral measurement, and post-TMS EEG and fMRI, we are examining the effects of cortical TMS on sub-cortical function. Current projects are focused on reward processing, and anhedonia with the hope that the research will lead to novel, non-invasive treatments of sub-cortical dysfunction.

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