Offline tDCS modulates prefrontal cortical–subcortical cerebellar fear pathways in delayed fear extinction [article]

Ana Ganho Avila, Raquel Guiomar, Daniela Valerio, Oscar F. Goncalves, Jorge Almeida
2019 bioRxiv   pre-print
Transcranial direct current stimulation (tDCS) has been studied as an add-on enhancer of extinction-based treatments for anxiety disorders. However, previous studies have failed to address one issue of translational significance: the to-be extinguished fear memory must be consolidated. Additionally, extant literature shows conflicting results about the anxiolytic effect of tDCS delivered to the right dorsolateral prefrontal cortex. To address these issues, we recruited thirty-four female
more » ... pants to participate in a two-day fear conditioning procedure. On Day 1, laboratory fear acquisition was confirmed by self-reported contingency ratings. On Day 2, participants were randomly assigned to either the control group (n=18; completed the extinction session) or the tDCS group (n=16; whom received 20min tDCS session of 1mA [cathode: F4; anode: contralateral deltoid immediately before extinction). Functional magnetic resonance imagining data showed that tDCS modulates the late phase of the delayed extinction process. In particular, neural activity of the frontal middle cortex, the left frontal superior cortex, and the left and right paracentral and postcentral cortices is increased during the processing of the CS-, supporting the processing of uncertainty. Furthermore, during the processing of threat, tDCS leads to an increased information flow from the contralateral prefrontal cortex along the cortical amygdalo hippocampal cerebellar pathways. Thus, the boosted processing of uncertainty and the stronger coupling during threat processing might well be the mechanisms by which tDCS boosts stimuli discrimination, leading to decreased symptoms and enhanced clinical gains.
doi:10.1101/2019.12.18.880658 fatcat:zd6kzpnsordgbka2h6a6a7cnzq