Spring Research Day, 2008

Scott L. Rauch, MD
McLean Hospital and Harvard Medical School Belmont, Massachusetts, USA.

Abstract

Neuroimaging and the Neurocircuitry of Posttraumatic Stress Disorder:
A Model Influenced by Fear Conditioning and Extinction

      Contemporary neurocircuitry models of anxiety disorders have been heavily influenced by two lines of research: 1) animal experiments involving fear conditioning and extinction; and 2) human neuroimaging studies. In the current presentation the convergence of these two lines of inquiry will be reviewed, focusing on the example of posttraumatic stress disorder (PTSD). In particular, animal research has delineated a role for the amygdala in mediating conditioned fear acquisition and expression. Moreover, cortical structures, including medial frontal territories and hippocampus, have been implicated in the top-down governance of amygdala responses.

     To elaborate, ventromedial prefrontal territories are implicated in suppressing amygdala responses in the service of extinction recall, while the hippocampus has been shown to mediate contextual information processing to modulate extinction recall. Resonant with this animal literature, neuroimaging studies of PTSD have converged to indicate exaggerated amygdala responses and diminished structure as well as function within the medial prefrontal cortex and hippocampus. The implications of this translational research will be discussed. 

Objectives:
After attending this presentation, participants should have achieved the following objectives --

1) To understand how animal research on fear conditioning has influenced neurocircuitry models of anxiety disorders
2) To understand how neuroimaging can be used to advance models of pathophysiology in psychiatric disorders
3) To understand current neurocircuitry models of PTSD

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