Copyright 2012 Aileen M. Echiverri-Cohen - University of Washington

inhibitory inputs and ultimately decrease amygdala responsiveness, in addition to mediating
extinction of fear responding (Quirk & Beer, 2006; Akirav & Maroun, 2007) suggesting PE may
have an additive effect of changing pathological beliefs related to the trauma over SER. In
addition, exposure therapy uses extinction principles in facilitating inhibitory learning (Rauch et
al., 2003) subsequently inhibiting fear responses in PTSD. Therefore it may be more specific in
directly targeting inhibitory processes (Craske et al., 2008) than SER that facilitates serotonin
neurotransmission and is thought to bring about more broad changes in functioning (Brady et al.,
2001; Davidson et al., 2001). Indeed, pharmacological therapies are heavily criticized to
ameliorate target symptoms but not necessarily the underlying cause of the disorder, to suggest
that it may not inhibit the original fear learning (Brady et al., 2001). PE and SER may use
specific pathways on how they bring about therapeutic change, however ultimately follow a final
common pathway in reducing amygdala reactivity (Rausch et al., 2003).
This final common pathway may help explain the general pattern of increased attentional
inhibitory control from pre- to post-treatment being modified by therapeutic modality and
treatment response. Specifically, exposure therapy is thought to bring about therapeutic change
through a top down modulation of amygdala activity whereas sertraline may influence bottom up
modulation by the amygdala (Porto et al., 2009; Brady et al., 2001). In a fMRI study examining
predictors of treatment recovery of cognitive behavioral therapy (CBT) for MDD, Siegle and
colleagues (2006) found reduced subgenual cingulate cortex activity at pre-treatment for
treatment responders of CBT for depression. The authors proposed that responders of CBT were
those individuals with high emotional reactivity; therefore, emotion regulation strategies, a
treatment component of CBT, may have facilitated control and regulation over their emotions.
Similarly, in MDD, DeRubeis et al. (2008) reviewed studies that compared CBT and
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