@article{EwaldGlotzbachSchoonGerdesetal.2014,
  author    = {Ewald, Heike and Glotzbach-Schoon, Evelyn and Gerdes, Antje B. M. and Andreatta, Marta and M{\"u}ller, Mathias and M{\"u}hlberger, Andreas and Pauli, Paul},
  title     = {Delay and trace fear conditioning in a complex virtual learning environment - neural substrates of extinction},
  series = {Frontiers in Human Neuroscience},
  volume    = {8},
  journal   = {Frontiers in Human Neuroscience},
  number    = {323},
  issn      = {1662-5161},
  doi       = {10.3389/fnhum.2014.00323},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-116230},
  year      = {2014},
  abstract  = {Extinction is an important mechanism to inhibit initially acquired fear responses. There is growing evidence that the ventromedial prefrontal cortex (vmPFC) inhibits the amygdala and therefore plays an important role in the extinction of delay fear conditioning. To our knowledge, there is no evidence on the role of the prefrontal cortex in the extinction of trace conditioning up to now. Thus, we compared brain structures involved in the extinction of human delay and trace fear conditioning in a between-subjects-design in an fMRI study. Participants were passively guided through a virtual environment during learning and extinction of conditioned fear. Two different lights served as conditioned stimuli (CS); as unconditioned stimulus (US) a mildly painful electric stimulus was delivered. In the delay conditioning group (DCG) the US was administered with offset of one light (CS+), whereas in the trace conditioning group (TCG) the US was presented 4s after CS+ offset. Both groups showed insular and striatal activation during early extinction, but differed in their prefrontal activation. The vmPFC was mainly activated in the DCG, whereas the TCG showed activation of the dorsolateral prefrontal cortex (dlPFC) during extinction. These results point to different extinction processes in delay and trace conditioning. VmPFC activation during extinction of delay conditioning might reflect the inhibition of the fear response. In contrast, dlPFC activation during extinction of trace conditioning may reflect modulation of working memory processes which are involved in bridging the trace interval and hold information in short term memory.},
  language  = {en}
}
@article{GuhnDreslerAndreattaetal.2014,
  author    = {Guhn, Anne and Dresler, Thomas and Andreatta, Marta and M{\"u}ller, Laura D. and Hahn, Tim and Tupak, Sara V. and Polak, Thomas and Deckert, J{\"u}rgen and Herrmann, Martin J.},
  title     = {Medial prefrontal cortex stimulation modulates the processing of conditioned fear},
  doi       = {10.3389/fnbeh.2014.00044},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-111309},
  year      = {2014},
  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).},
  language  = {en}
}