Astronauts who return from space flight show significant inter-subject variations in their abilities to readapt to a gravitational environment. The ability to predict the manner and degree to which each individual astronaut will be affected would improve the effectiveness of countermeasure training programs designed to enhance sensorimotor adaptability. For such an approach to succeed, we must develop predictive measures of sensorimotor adaptability that will allow us to determine, before actual space flight, which crewmembers will experience the largest challenges in adaptive capacity. Obtaining this information will allow us to design and implement better sensorimotor adaptability training countermeasures that will be customized for each crewmember’s unique adaptive capabilities. This project will identify and characterize a set of predictive measures that include: 1) behavioral tests to assess sensory bias and adaptability; 2) imaging to determine individual brain morphological and functional features; 3) genotype markers for genetic polymorphisms that play a role in the neural pathways underlying sensorimotor adaptation. Information from this study will help in the design of sensorimotor adaptability training countermeasures that may be customized for each crewmember’s individual characteristics. The study is almost completely retrospective, in that no new bedrest or flight studies are required.
Developing Personalized Countermeasures for Sensorimotor Adaptability: A Bedrest Study
Ajitkumar P. Mulavara, Ph.D.
Universities Space Research Association
To achieve the goals the following Aims will be pursued: 1)Aim 1: Determine whether baseline individual sensory biases and capabilities for strategic and plastic-adaptive responses predict both change and also the ability to re-adapt sensorimotor and functional performance after 70 days bed rest or short/long duration space flight. We will determine if participants’ individual sensory biases in use of vision, vestibular and proprioception as well as tests of strategic and long-term adaption predict the change from pre- to post-tests after bed rest or space flight and determine if those biases predict rates of re-adaptation in sensorimotor performance. 2)Aim 2: Determine if baseline brain morphological and functional metrics predict both change and also the ability to re-adapt sensorimotor and functional performance after 70 days bed rest or short/long duration space flight. We will determine if individual differences in regional brain volumes (structural MRI), white matter integrity (diffusion tensor imaging, or DTI), functional network integrity (resting state functional connectivity MRI), and sensorimotor adaptation task-related functional brain activation (functional MRI) predict pre to post levels of decrements and their rates of re-adaptation in sensorimotor performance.3) Aim 3: Determine if genetic markers predict both change and also the ability to re-adapt sensorimotor and functional performance after 70 days bed rest or short/long duration space flight. We will determine whether genetic polymorphisms in COMT, DRD2, BDNF and genetic polymorphism of α2-adrenergic receptor are associated with pre to post levels of decrements in sensorimotor performance and rates of re-adaptation.
We will be conducting a retrospective study leveraging data already collected from relevant ongoing/completed bed rest and space flight studies. This data will be combined with predictors metrics - behavioral, brain imaging and genomic measures collected from these returning subjects to build models for predicting post-mission (bed rest or space flight) adaptive capability as manifested in their outcome measures. Comparisons of model performance for various groups of predictors will provide insight into how to design subject-specific countermeasures against decrements in post-mission adaptive capability. This ability will allow more efficient use of crew time during training and will optimize training prescriptions for astronauts to ensure expected outcomes.
Developing predictive measures of sensorimotor adaptability will allow us to better design and implement sensorimotor adaptability training/rehabilitation that are customized for each individual’s sensory biases, adaptive capacity, brain structure and functional capacities, and genetic predispositions. This ability will allow more efficient use of individual’s time during training and will optimize training prescriptions for individuals to ensure expected outcomes.