The impact of non-invasive stimulation of the ventromedial prefrontal cortex on attentional biases and reward processing: an advanced network approach

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The overarching goal of the proposed research project is to illuminate the presumed cardinal role of the ventromedial prefrontal cortex (vmPFC) on the processing of emotional material and reward. We intend to focus on the vmPFC "at work", while it biases emotional and reward processing, to directly trace its activation but especially trace its functional relationships with other cortical areas. Until now, evidence for the neural mechanisms underlying both types of biases was predominately based on correlational approaches and analyses of particular brain areas in separation. In contrast, we plan to directly and non-invasively modulate vmPFC excitability and plan to introduce a novel network connectivity approach that enables us to track functional brain circuits during exchange of neural information.We propose that the vmPFC modulates other brain regions and gets modulated by them via bidirectional feedback and feedforward connections. Based on the existing literature and previous work of the German and Polish groups, we predict, that neural mechanisms of attentional bias and reward processing will be reflected by a dynamic interaction between vmPFC and other brain areas, specifically dorsolateral prefrontal and temporoparietal cortex regions as well as functional connectivity with the dorsal and ventral attentional networks.In our experiments, we will combine non-invasive transcranial direct-current stimulation (tDCS) with EEG/MEG methodology to increase and decrease vmPFC excitability and monitor brain activity with high temporal resolution. We will employ source localization methods that reconstruct activations of particular brain structures with good spatial resolution. Importantly, to determine dynamic relationships across brain regions during attentional bias and reward processing, causal analyses will be performed using the Directed Transfer Function (DTF) effective connectivity, an innovative network approach which is successfully used and constantly developed by the Polish group.The results of this project will advance current understanding of the neural underpinnings of attentional biases and reward processing. In particular, we aim to unravel the dynamic role of vmPFC during these biases. As disturbed biases in emotional attention and reward processing are considered key symptoms of various psychiatric disorders including depression or addiction, the results of this project will inform theories of corresponding pathophysiology. At the same time, by employing DTF, we will develop a novel pipeline for the analysis of the source-space MEG data.The projects objectives and goals can only be achieved in close collaboration between both groups. The German group provides expertise in implementation of MEG-tDCS studies while the Polish group provides expertise in effective connectivity analyses in sensor and source space. The joint project will enable transfer of knowledge and skills and further strengthen the collaboration of both groups.