The Hippocampal–Ventral Medial Prefrontal Cortex Neurocircuitry Involvement in the Association of Daily Life Stress With Acute Perceived Stress and Cortisol Responses

Daily life stressors include everyday irritants, hassles, and inconveniences, such as problems in traffic and unexpected work deadlines. A growing body of research has suggested higher daily stress is associated with blunted cortisol response to acute psychosocial stressors. However, so far, the neural mechanism underlying this association has not been elucidated. The current study aimed to examine the role of stress neurocircuitry between the hippocampus and the ventral medial prefrontal cortex in this relationship.To this end, as an index of daily stress in 44 young healthy individuals (23 females; mean [standard deviation] age = 19.07 [1.11] years), the total stressful rating score of daily life stress events that occurred in a 24-hour period was quantified. Individuals were then administered a modified version of the Montreal Imaging Stress Task while undergoing functional magnetic resonance imaging scans, and their saliva samples were collected for assessment of the stress hormone cortisol.Results revealed that a higher level of daily stress was associated with lower salivary cortisol secretion (r = -0.39, p = .008) and lower activation of the left hippocampus (tpeak = -5.51) in response to the Montreal Imaging Stress Task. Furthermore, a higher level of daily stress was associated with stronger functional connectivity between the left hippocampus and the ventral medial prefrontal cortex/subgenual anterior cingulate cortex (tpeak = 4.91, R2= 0.365).Taken together, the current study suggested a possible neurocircuitry of the hippocampus and ventral medial prefrontal cortex in the relationship between daily life stress and acute psychosocial stress.