The Brain in Deep Space: Identifying 'Potential' Synergistic Risks to Behavior and Performance from Space Radiation, Isolation and Confinement, and Altered Gravity

摘要

Space exploration beyond the protection of the Van Allen Belt will expose humans to levels of galactic cosmic radiation that are known to cause behavioral performance decrements in animals. Given this evidence, NASA's Johnson Space Center's Human Research Program (HRP) has directed three of its risk areas to integrate their research efforts to assess risk to astronauts' behavioral performance from the combined effects of the three major spaceflight hazards (space radiation; isolated, confined, and extreme environments; altered gravity). This completely integrated approach will systematically identify and investigate the relationships amongst three risks: Risk of Acute (In-flight) and Late Central Nervous System Effects from Radiation (CNS); Risk of Adverse Cognitive or Behavioral Conditions and Psychiatric Disorders (BMed); and Risk of Impaired Control of Spacecraft/Associated Systems and Decreased Mobility Due to Vestibular/Sensorimotor Alterations Associated with Spaceflight (SM). We review relevant animal research on the effects of simulated Galactic Cosmic Ray (GCR), the impacts to the sensorimotor system from simulated gravity modifications such as hindlimb unloading, and the effects of isolation and confinement. We also describe how the integrated research will focus on identifying operationally relevant measures of behavioral performance, along with assessments of brain physiology, neurovascular unit integrity, molecular signalling, and changes in biomarkers, to generate data sets that can be incorporated into computational models. Evidence shows that a number of identified environmental stressors, including altered gravity, sleep loss, radiation exposure, and isolation and confinement can all lead to dysregulation of the brain's structure and microenvironment, leading to imbalanced function of neuronal and glial networks and the neurovascular unit. The magnitude of physical and biological stressors during a space mission is believed to vary by mission phase