Neural pathways for regulating fear responses depending on the perceived level of threat and safety

While it is normal to experience fear in certain situations, we can adjust our fear responses depending on our knowledge and circumstances. Many brain regions are known to be involved in processing perceived danger and mediating fear reactions, nevertheless the mechanisms of how these reactions are controlled are still unclear. Such control is crucial since its impairment can lead to anxiety disorders such as phobias or post-traumatic stress disorder, in which the circuits in the brain associated with fear and anxiety are thought to become overactive, leading to pathologically increased fear responses. Brain circuits in the ventral lateral geniculate nucleus (vLGN) have been shown to have strong control over fear reactions. I will test the hypothesis that the vLGN is a crucial hub for integrating external sensory signals with the internal state and knowledge of an animal, in order to regulate fear-related behaviour depending on the perceived threat level. I will determine how information about sensory signals, present circumstances and previous knowledge converge on and are integrated by vLGN circuits, and what information is conveyed by neuromodulatory inputs. This will allow me to elucidate the neural circuit-mechanisms of how the level of perceived threat can regulate fear responses.