Using fMRI during a fear conditioning paradigm in healthy subjects, amygdalae activation was increased (LaBar et al. 1998). Another investigation showed amygdalae activation on presentation of non-conditioned, fear-related or negatively affect-loaded stimuli, too (Grodd et al. 1995). Gottfried and Dolan (2004) could demonstrate that in humans that orbitofrontal cortex and amygdalae activity were preferably enhanced during extinction learning of previously conditioned aversive stimuli. Etkin et al. (2006) found that activity in the amygdala and dorsomedial and dorsolateral prefrontal cortices reflects the amount of emotional conflict, when a coping-strategy seems not to be directly available. The amygdala activation appears to be personality dependent and correlates with neuroticism (Haas et al. 2007). Final resolution of the emotional conflict goes in line with anterior cingulate cortex (ACC) activity and correlates with reduction of amygdalae activity (top-down inhibition). Herry et al. (2007) suggested that amygdala function increases with the unpredictability of a stimulus or situation. Paulus et al. (2004), however, implied that activation of the ACC and medial prefrontal cortex was significantly higher in high trait-anxiety subjects and was correlated with trait but not state anxiety. Possibly, this feature characterizes subjects who scan their environment more thoroughly for anxiety inducing stimuli but also for coping factors. According to (Phelps et al. 2004), ventromedial prefrontal cortex activation (anterior cingulate) seems to be primarily linked to expression of fear learning during delayed tests of extinction.
Panic disorder is a condition characterized by repeated limited episodes of intense somatic and psychic anxiety symptoms. Symptoms such as dyspnea, palpitations, tachycardia, sweating, tremor, nausea and depersonalization, fear of losing control or dying emerge in specific situations or “out of the blue” and increase within a few minutes. Such panic attacks usually result in an intense and ongoing fear of the next expected attack (phobophobia). This may lead to avoidance behaviour with patients refraining situations in which they may become helplessly panicky. Panic disorder very often is associated with agoraphobia, a fear of certain situations (such as elevators, wide places, crows of people, theatres) from which fleeing is expected to be difficult.