Abstract
The extinction of conditioned fear depends on an efficient interplay between the amygdala and the medial prefrontal cortex (mPFC). In rats, high-frequency electrical mPFC stimulation has been shown to improve extinction by means of a reduction of amygdala activity. However, so far it is unclear whether stimulation of homologues regions in humans might have similar beneficial effects. Healthy volunteers received one session of either active or sham repetitive transcranial magnetic stimulation (rTMS) covering the mPFC while undergoing a 2-day fear conditioning and extinction paradigm. Repetitive TMS was applied offline after fear acquisition in which one of two faces (CS+ but not CS−) was associated with an aversive scream (UCS). Immediate extinction learning (day 1) and extinction recall (day 2) were conducted without UCS delivery. Conditioned responses (CR) were assessed in a multimodal approach using fear-potentiated startle (FPS), skin conductance responses (SCR), functional near-infrared spectroscopy (fNIRS), and self-report scales. Consistent with the hypothesis of a modulated processing of conditioned fear after high-frequency rTMS, the active group showed a reduced CS+/CS− discrimination during extinction learning as evident in FPS as well as in SCR and arousal ratings. FPS responses to CS+ further showed a linear decrement throughout both extinction sessions. This study describes the first experimental approach of influencing conditioned fear by using rTMS and can thus be a basis for future studies investigating a complementation of mPFC stimulation to cognitive behavioral therapy (CBT).
Highlights
The extinction of conditioned fear describes the decrement of conditioned responses (CR) after repeatedly presenting a formerly conditioned stimulus (CS) that no longer predicts an unconditioned stimulus (UCS)
This study describes the first experimental approach of influencing conditioned fear by using repetitive transcranial magnetic stimulation (rTMS) and can be a basis for future studies investigating a complementation of medial prefrontal cortex (mPFC) stimulation to cognitive behavioral therapy (CBT)
We hypothesized that if rTMS modulates the processing of conditioned fear, it will correlate with higher mPFC activation in the cluster for which we found a signal increase from early to late extinction learning in a previous study (Guhn et al, 2012)
Summary
The extinction of conditioned fear describes the decrement of conditioned responses (CR) after repeatedly presenting a formerly conditioned stimulus (CS) that no longer predicts an unconditioned stimulus (UCS). At the beginning of the extinction learning, the amygdala shows a profound activation increase to the CS which decreases throughout extinction learning while ventro medial prefrontal cortex (vmPFC) activation increases. This reversed amygdala-vmPFC correlation has been shown to reduce the expression of the conditioned fear response. VmPFC contribution appears to be a precondition for sufficient consolidation and later recall extinction memory in animals (Quirk and Mueller, 2008) as well as in humans (Phelps et al, 2004; Kalisch et al, 2006)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
