Stimulation of the ventromedial prefrontal cortex blocks the return of subcortically mediated fear responses

Abstract

The ventromedial prefrontal cortex (vmPFC) mediates the inhibition of defensive responses upon encounters of cues, that had lost their attribute as a threat signal via previous extinction learning. Here, we investigated whether such fear extinction recall can be facilitated by anodal transcranial direct current stimulation (tDCS). Extinction recall was tested twenty-four hours after previously acquired fear was extinguished. Either anodal tDCS or sham stimulation targeting the vmPFC was applied during this test. After stimulation ceased, we examined return of fear after subjects had been re-exposed to aversive events. Fear was assessed by reports of threat expectancy and modulations of autonomic (skin conductance, heart rate) and protective reflex (startle potentiation) measures, the latter of which are mediated by subcortical defense circuits. While tDCS did not affect initial extinction recall, it abolished the return of startle potentiation and autonomic components of the fear response. Results suggest hierarchical multi-level vmPFC functions in human fear inhibition and indicate, that its stimulation might immunize against relapses into pathological subcortically mediated defensive activation.

The emotion paradox in the aging body and brain

“…Because the vmPFC modulates startle and its gating, 258,[269][270][271] the autonomic compensation model can account for these surprising reversals of how affect modulates startle. Younger adults' low HRV during waking active states 59 (Figure 2) suggests that their vmPFC proparasympathetic regulatory processes are not especially active during these states.…”

The Meltdown Pathway: A Multidisciplinary Account of Autistic Meltdowns

“…Within the insula, this kind of demanding cognitive process could only happen in the anterior insula. By the time neuroceptive cues reach this part of the insula, they have been fully integrated and contextualized by prior knowledge, observational learning cues and other factors from the ventromedial and dorsolateral prefrontal cortex (Gonzalez & Fanselow, 2020;Horga et al, 2011;Penick & Solomon, 1991;Stark et al, 2018;Szeska et al, 2022), anterior cingulate cortex and parietal lobe (Chang et al, 2013;Deen et al, 2011;Gu et al, 2013;Nomi et al, 2016;Uddin et al, 2014). The anterior insula also plays an important role in deciphering and embodying the emotions of others, which allows people to weigh the reactions of those around in their own threat assessments (Gu et al, 2012).…”

The emotion paradox in the aging body and brain

“…Because the vmPFC modulates startle and its gating, 258,[269][270][271] the autonomic compensation model can account for these surprising reversals of how affect modulates startle. Younger adults' low HRV during waking active states 59 (Figure 2) suggests that their vmPFC proparasympathetic regulatory processes are not especially active during these states.…”