Neural regulation of endocrine and autonomic stress responses

The response of mammals to external or internal challenge involves engagement of multiple physiological systems, prominently including the hypothalamic-pituitary-adrenocortical (HPA) axis and the autonomic nervous system (ANS).Autonomic and HPA axis responses to systemic stressors are initiated by brainstem and hypothalamic structures that receive direct and indirect homeostatic feedback.Psychological stress responses are activated and inhibited by limbic system structures, such as the medial prefrontal cortex, the hippocampus and the amygdala, which send multisynaptic input to brainstem and hypothalamic activators of the HPA axis and the ANS.'Psychological' information and homeostatic information are integrated by telencephalic and diencephalic relays prior to the elaboration of HPA axis or ANS responses.HPA axis and ANS components of the stress response are probably encoded in distinct yet highly interconnected limbic subregions.Chronic stress induces neuroplasticity in central stress-processing networks, causing sensitization as well as habituation of HPA axis and ANS responses.Limbic stress response networks overlap extensively with memory and reward circuitry, allowing stress responses to be coloured by prior experience and expected outcomes.