Development of decision-making paradigms using noninvasive brain stimulation and neuroimaging

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We are continuously faced with decisions in our daily life: Poor decision-making may be due to inadequate analysis of choices or an excessively risky (or overly cautious) approach and can have deleterious consequences for health, safety, and financial well-being. The long-term question that we are pursuing in our research program is Why do some individuals eat well, drink moderately, and exercise compared to others? The main goal of the proposed research program is to develop a novel method that combines simultaneously noninvasive brain stimulation and neuroimaging. Specifically, we will deliver transcranial direct current stimulation (tDCS) during task-based functional magnetic resonance imaging (fMRI) to study decision-making mechanisms in humans. This will allow us to test for causal brain-behavior interactions. tDCS can modulate human cognitive functions in vivo. However we know little on how the brain is stimulated when tDCS modulates cognitive functions. Thanks to our previous Discovery grant, we developed protocols that capture, in real time, the cause and effect evidence of tDCS modulating the brain. As an example, we delivered tDCS over the dorsolateral prefrontal cortices in healthy subjects during resting-state fMRI as well as during MR spectroscopy. Resting state functional connectivity was modulated by tDCS, strengthening connectivity between the right prefrontal cortex and posterior cingulate cortex when contrasting real and sham tDCS conditions in healthy subjects. Also, real as compared to sham tDCS elevated striatal glutamate and prefrontal NAA levels during stimulation in healthy adults. This work is among the first demonstrations that tDCS truly modulates human brain substrates during MR acquisition. We propose to pursue this line of work by combining tDCS with task-based fMRI in order to characterize the cognitive and neural roots of decision-making. In terms of cognitive processes, we propose to focus on reward seeking, impulsivity, and inhibitory control in order to maintain feasibility following our previous and ongoing work. We also include real rewards such as money and food in various contexts (food restrictions, experimentally-induced stress and attentional biais training). The drive behind this research program is that decision-making abilities and its associated neural substrates underlie important aspects of wellness, health, security, financial and social choices in our daily life. Decision-making has been extensively studied in the context of economics and from a group perspective, as well as in clinical populations, and little is known on the fundamental processes involved in lifestyle decision-making in contexts representative of real life.