abstract Mats Fredrikson

Mats Fredrikson (Department of Psychology, Uppsala University, Sweden)

The fearful brain: Imaging, conditioning and anxiety

Fearful encounters activate the amygdala in several anxiety disorders including specific phobia, social phobia and posttraumatic stress disorder. In specific and social phobia, exposure to feared objects elicits amygdala activity, associated with increased activity in motor and visual object recognition areas. Fear conditioning in rodents and humans increase amygdala activity suggesting that this could represent an evolutionary conserved etiological mechanism because fear conditioning has been proposed to underlie the acquisition of certain phobias. Recent studies indicate that memory reconsolidation processes are important, but their clinical significance and genetic determination are not yet described. Polymorphisms in serotonergic genes that form conditionability are also associated with amygdale reactivity suggesting that enhanced amygdala reactivity might be a risk factor for phobia development. Conversely, attenuated amygdale reactivity may be associated with treatment responsivity. Some studies indicate that when phobias are treated, a normalization of the original hyperresponsivity in the amygdala occurs. In social phobia this seems to be true both for pharmacological and psychological treatments and also placebo induced anxiety reductions. This illustrates plasticity in the core fear system in the human brain and suggests that attenuated amygdale activity is a final common pathway for therapeutic interventions.