Q1ABSTRACT: The research showing how exposure to extreme stress affectsbrain function is making important contributions to understanding thenature of traumatic stress.Reminders of traumatic experiences activate brain regions thatsupport intense emotions, and decrease activation in the central nervoussystem (CNS) regions involved in (a) the integration of sensory inputwith motor output, (b) the modulation of physiological arousal, and (c)the capacity to communicate experience in words.This includes the notion that traumatizedindividuals are vulnerable to react to sensory information with subcor-tically initiated responses that are irrelevant, and often harmful, in thepresent.