Habenula volume in post-traumatic stress disorder measured with high-resolution MRI

High-resolution images (resolution of approximately 0.4 mm3) were acquired using a 3T scanner and a pulse sequence optimized for tissue contrast resolution. The habenula was manually segmented by one rater blind to diagnosis. PTSD and HC participants did not differ significantly in absolute or normalized habenula volume. Post hoc analyses controlling for the effects of comorbid major depressive disorder (MDD) and type and age of trauma exposure were not significant. Further, there was no association between PTSD severity and habenula volume.Our data suggest that PTSD is not associated with robust structural changes in the habenula. The modest size of the PTSD sample may have reduced statistical power thereby accounting for the negative results obtained.Post-traumatic stress disorder (PTSD) is associated with an impaired ability to extinguish conditioned fear responses to threatening stimuli. This deficit attributed is hypothesized to reflect deficient inhibition of the amygdala by the ventromedial prefrontal cortex (vmPFC) [1-3]. Nevertheless, additional neurocircuitry likely is involved in the pathophysiology of PTSD. The habenula receives projections from limbic regions, including the vmPFC, and modulates cortical function via its projections to the raphe and ventral tegmental area (VTA) [4]. Conditioned aversive stimuli have been shown to activate the habenula, inhibiting VTA-mediated dopamine release and potentially both inhibiting and facilitating raphe-mediated serotonin release [4]. Conceivably, therefore, the habenula may a key role in the inhibition of conditioned fear, and by extension, PTSD.The extant preclinical data appear consistent with this hypothesis. Rats exposed to chronic stress or undergoing dopamine depletion showed elevated glucose metabolism in the lateral habenula that was prevented by administration of an antidepressant [5]. Similarly, rats exposed to inescapable shock no longer developed learned helplessness after lesioning of the habenula