NORADRENERGIC CONTRIBUTIONS TO LARGE-SCALE BRAIN NETWORK SHIFTS: A PRELIMINARY RESTING-STATE ANALYSIS
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Acute stress prompts noradrenergic activity that is theorized to drive functional brain network shifts resulting in a prioritization of rapid vigilant behaviour over slower top-down functions. Neurocognitive mechanisms underlying these behavioural changes are widely studied, however the intrinsic alterations in noradrenergic system and its contribution to brain networks shifts under acute stress is yet to be investigated in humans. Hence, the aim of the study was to examine the resting-state alterations in the norepinephrine origin region, locus coeruleus (LC) activity and stress-associated shifts in salience (SN), executive control (ECN) and default mode networks (DMN). We expected a strong LC-SN connectivity during the immediate phase of acute stress which was predicted to decrease over time (delayed phase) and vice versa for LCECN and LC-DMN connectivity. An improvised method of LC preprocessing was performed to obtain LC time courses which were linearly regressed with brain network time courses to obtain beta coefficients. Since there were no significant results, we explored the network and whole-brain LC connectivity analysis. LC showed differential connectivity patterns with SN, ECN, DMN, parts of insular cortex and parahippocampal gyrus in acute stress conditions. These results exhibit the inconsistency in the data but also partially align with the theory-based expectations. Overall, due to the methodological and statistical concerns, the present study fails to express a convincing support towards the theory of LC involvement in stress-related brain network shifts, but with future investigation the explorative results could possess replicative potential that might go in line with our hypotheses.
Faculteit der Sociale Wetenschappen