Modulation of neuronal fear circuits through transcranial direct current stimulation (tDCS).

Fear is a physiological response to threats but it can become excessive to the point of interfering with daily life. Exposure-based psychotherapy is a first choice treatment for anxiety disorders, but a third of the patients do not achieve full recovery. We propose transcranial direct current stimulation (tDCS) as a strategy to improve the long-term efficacy of psychotherapy. The tDCS technique is based on the short-term delivery of a constant direct current to the brain via scalp electrodes. The potential advantages of tDCS are compelling, notably its portable and non-invasive nature. However, it remains poorly understood how tDCS influences brain circuit activity, and how this may further alter fear memory. We will investigate the effects of tDCS on fear extinction in mice and we will use immuno(histo)chemical methods to assess the role of brain-derived neurotrophic factor (BDNF) in these effects. These experiments will enable us to formulate optimal tDCS application strategies. We will go beyond the descriptive level and will use a viral knockdown strategy to investigate whether observed changes in BDNF expression are causal to observed effects on fear extinction. Ultimately, our studies may improve psychotherapy for anxiety disorders.