Psychological and physiological responses to stress: a review based on results from PET and MRI studies

A new application for the nuclear imaging techniques is the study of organic responses to stress. Neuroimaging techniques allow the assessment of brain activation changes in association with the metabolic responses to stress. In this paper, a review of general effects of the stress on organic activity is made, emphasizing important advances introduced by studies using PET and fMRI. The importance of the hypothalamus-pituitary-adrenal axis to onset the adequate psychical and organic responses to sustain the homeostasis during the stress is discussed, as well as the possibility of traumatic stressing experiences have negative effects on the brain. (author)