The eCB - anandamide and 2-arachidonoylglycerol (2-AG) - and their attending cannabinoid (CB) receptors which are found in high densities in a fear circuitry involving the amygdala, hippocampus, the anterior cingulate cortex and prefrontal cortex serve important functions in the regulation of stress-coping behaviors. Besides eCB regulation there is strong evidence from ongoing research of the investigators group and others suggesting an important role for glucocorticoid signaling as an endpoint of the biochemical sequelae initiated by stressful or aversive stimuli. One of the long-term research goals of our lab is to understand such functions and determine their relevance to the pathogenesis of PTSD and to provide a more integrative view on neurobiological mechanisms that are involved in the regulation of the neuroadaptive response to stress. The objective of the proposed translational study is to test a model, based upon basic science studies, exploring multisystem impairments in PTSD including eCB and glucocorticoids in the modulation of fear memories by examining the CB1 receptor in a PTSD fear circuit as well as glucocorticoid function. The investigators propose that impaired eCB signaling in PTSD resulting in the maladaptive neurobehavioral response to the stressor is associated with an upregulation of the CB1 receptors and insufficient glucocorticoid signaling.