Neurophysiologic methods to measure stress during survival, evasion, resistance, and escape training

Training in Survival, Evasion, Resistance, and Escape (SERE) is required for U.S. military members at high risk of capture. This physically and psychologically demanding course is considered an analog to the stress imposed by war, captivity, and related events, thus offering a unique and unprecedented medium in which to systematically examine human stress and performance during a realistically intense operational context. Operational stress is multifaceted, manifesting cerebral, neuroendocrine, cardiac, and cognitive characteristics, and necessitating an integration of multiple methods of measurement to appropriately characterize its complexity. Herein we describe some of our present research methods and discuss their applicability to real-time monitoring and predicting of key aspects of human performance. A systems approach is taken, whereby some of the "key players" implicated in the stress response (e.g., cerebral, neuroendocrine, cardiac) are briefly discussed, to which we link corresponding investigative techniques (fMRI, acoustic startle eye-blink reflex, heart rate variability, and neuroendocrine sampling). Background and previous research with each investigative technique and its relationship to the SERE context is briefly reviewed. Ultimately, we discuss the operational applicability of each measure, that is, how each may be integrated with technologies that allow computational systems to adapt to the performer during operational stress.