Extinguishing trauma
Trauma induced by events such as military combat, car accidents, physical or sexual assault can lead to debilitating anxiety and post-traumatic stress disorder (PTSD). Fear induces activation of the amygdala, almond-shaped structures deep in the temporal lobes of the brain. Here, memory of emotional reaction is processed, leading to response from the amygdala and stress effects when confronted with a fear situation. Normally, changes in the brain are temporary but in cases like PTSD, recovery can be absent after many years. Fear extinction is one therapy on offer based on exposure to the object without the previously paired aversive stimulus. However, in persistent cases, fear learning is resistant to extinction processes. To tackle anxiety disorders faced by many millions of people worldwide, one approach is to identify key neural mechanisms involved in extinction processes. The EU-funded 'Neurobiology of the persistence of traumatic memories' (Fear and Trauma) project is investigating the basolateral amygdala (BLA) under high emotional stress. In particular, the team has focused on release of the hormone corticotrophin releasing factor (CRF) and a CRF modulating system involving glutamatergic receptors. Fear and Trauma scientists investigated synaptic proteins. One theory is that fear extinction involves profound modifications to relevant synapses (junctions between nerve endings). Whether fear extinction is achieved is a matter of competition between fear consolidation and extinction acquisition and a fear experience would therefore render the amygdala over activated and unresponsive to correction. Previous work with rats has established that it is the timing of fear extinction therapy with relation to the actual fear conditioning. Project researchers have to date successfully designed the experimental framework to establish a rat model of impaired fear extinction where extinction deficits depend on the time after the trauma. The work of the Fear and Trauma project will continue to include studies on the effects of experiences in early life. When applied to psychological and psychiatric practice, successful fear extinction will help to make the lives of many people more bearable and less prone to resulting in depression.
