The neurocircuitry of fear and PTSD

Abstract

Research on the neurocircuitry of post-traumatic stress disorder (PTSD) has its roots in animal models of fear conditioning. In vivo imaging studies have revealed that the same basic circuitry involved in rodent contextual fear conditioning and extinction is dysfunctional in humans with PTSD. In this chapter, we briefly describe the paradigms and methods used in functional neuroimaging studies of PTSD and review functional neuroimaging findings in this disorder. In general, the amygdala is hyperresponsive, and the ventromedial prefrontal cortex (vmPFC) is hyporesponsive in PTSD, likely reflecting a failure of the vmPFC to inhibit fear responses. In addition, the dorsal anterior cingulate cortex (dACC) and insula are hyperresponsive. The hippocampus functions abnormally in PTSD, although the direction of this abnormality varies across studies. Hypotheses and implications regarding these functional deficits are discussed.