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Developing Predictive Measures of Sensorimotor Adaptability to Produce Customized Countermeasure Prescriptions

Principal Investigator:
Jacob J. Bloomberg, Ph.D.

NASA Johnson Space Center

NASA Taskbook Entry

Technical Summary

This research project seeks to develop a set of predictive measures capable of identifying individual differences in sensorimotor adaptability and to use this information to design sensorimotor adaptability training countermeasures that are customized for each crewmember’s individual sensory bias and adaptive capacity.

The researchers have been developing a sensorimotor adaptability (SA) training program to facilitate rapid adaptation to novel gravitational environments. Information from this study will allow the researchers to customize the SA training program based on a crewmember's individual sensory biases and adaptive capacity optimizing the efficacy of the countermeasure prescription.

Specific Aims
1) Determine whether behavioral metrics of individual sensory bias predicts sensorimotor adaptability. For this aim, subjects will perform tests that will delineate individual sensory bias in tests of visual, vestibular and proprioceptive function. They will then be tested to determine if these metrics predict how quickly they adapt to a novel discordant sensory environment.

2) Determine if individual capability for strategic and plastic-adaptive responses predicts sensorimotor adaptability. The transition from one sensorimotor state to another consists of two main mechanisms: strategic and plastic-adaptive. Strategic modifications represent immediate and transitory changes in control that are employed to deal with short-term changes in the prevailing environment. If these changes are prolonged then plastic-adaptive changes are evoked that modify central nervous system function to automate new behavioral responses. For this aim, each subject’s strategic and plastic-adaptive motor learning abilities will be assessed using two tests of locomotor function designed specifically to delineate both mechanisms. Subjects will then be tested to determine if these measures predict how quickly they adapt to a novel discordant sensory environment.

3) Develop predictors of sensorimotor adaptability using brain structural and functional metrics. The researchers will measure 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). Subjects will then be tested to determine if these metrics predict how fast they behaviorally adapt to a novel discordant sensory environment.

4) Determine if individualized training prescriptions based on predictive metrics can be used to optimize sensorimotor adaptability training countermeasures. To achieve this aim, the research team will examine a test case focusing on improving adaptive performance of visually dependent subjects. Subjects identified in Aim 1 as being visually dependent with reduced adaptive capability will receive individualized training prescriptions designed to reduce their dependence on vision and increase their ability to use vestibular information for control of movement. As part of a specialized training program, subjects will walk on a treadmill-motion base system while experiencing discordant visual scenes along with increased support surface motion. During this training, subjects will receive stimuli to enhance vestibular signal detection to aid in dynamic balance control. Training efficacy will be assessed by comparing the performance of trained and control subjects on how quickly they adapt to a novel discordant sensory environment.