Task Progress:
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Summary of Results to Date
As part of the effort to evaluate the gait adaptability-training regimen, we have collected pre and post flight locomotion data from International Space Station Expeditions 5-12 (n =18) who will serve as the Control group.
Functional Mobility Test (FMT)
The time to complete (TCC) the FMT course data from all 18 subjects for each post flight day were averaged and collated for further analysis. A logarithmic curve using a least squares procedure was fit through these points and its intersection with the average ± 95% confidence interval of the mean preflight TCC across all subjects was calculated to determine the duration of time taken to recover functional locomotor performance. Results from FMT of the 18 subjects indicate that the adaptation to space flight led to a significant increase in time to traverse the obstacle course and recovery of function took an average of 2 weeks after their return.
Evaluation of TCC for each individual subject over the days of re-adaptation revealed the presence of two distinct postflight recovery patterns: 1) a rapid learning curve over the first six FMT trials conducted on R+1 and 2) a slower recovery pattern across days (R+1 - R+25). We infer that the learning curve shown within each test day represent strategic learning while the longer recovery period represent adaptive remodeling in sensorimotor function. Subjects were then classified into two groups, the Slow Recovery Group (SRG) and the Fast Recovery Group (FRG), based on the significance of the curve fit results for the data obtained on one day after landing. Comparing the average recovery rates for one day after landing (R+1) and the overall rate (R+1 - R+25) across the subjects in the two groups we see that subjects who demonstrate a fast initial strategic learning effect on R+1 also show a faster overall recovery during the R+1 - R+25 recovery period.
Integrated Treadmill Locomotion Test
The movement of head and torso body segments was measured using a video-based motion measurement system. Six time synchronized CCD cameras, sampling at 60 Hz, were used to obtain the three dimensional positions of light weight retro-reflective markers placed on these body segments. The 3D positions of these markers were used to calculate the head and torso angular orientations. Each 30-second trial period for each of these movement parameters was subjected to Fourier analysis. The amplitude of the predominant frequency in the signals was measured to estimate the contributions of vestibular reflexive mechanisms to head movement control. The temporal variations of the head and trunk roll, pitch and yaw angular orientations were time normalized over the entire gait cycle - heel strike (0%) to the following heel strike (100%) of the right foot - at one percent gait cycle intervals. These time normalized waveforms were used to determine the cross correlation functions between the head and trunk movements about the roll (HRTR), pitch (HPTP) and the yaw (HYTY) planes. The maximum values closest to the zero phase lag were quantified as the estimate of coordination between the head and trunk movements. Each measurement was averaged and its 95% confidence interval (CI) was determined across the six trials pre and post flight. Subjects were then classified into three groups based on the overlap of the Pre and Post flight confidence limits: A) significantly increased, B) no change, and C) significantly decreased, relative to pre-flight. Analyzing the each subject’s amplitude of the predominant frequency for the head angular roll, pitch and yaw orientations with respect to space (deg) we found that after space flight, subjects showed a significant change in the head roll and pitch orientations, respectively, during walking. In contrast, only smaller percentage of subjects showed a significant change in head movement magnitudes in the yaw orientation, during walking. Analyzing each subjects maximum cross correlation values for the HRTR, HPTP and the HYTY functions we found similar results in that after space flight, subjects showed a significant change in coordination between the head and torso in the roll and pitch planes, respectively, with minimal changes in the yaw plane, during walking.
Dynamic visual acuity (DVA) data collected following their long-duration (~6 months) stays in space showed a decrement in walking acuity. For some subjects the decrement was greater than the mean acuity decrement seen in a population of vestibularly impaired patients collected using a similar protocol. In summary, head movements during locomotion showed postflight changes predominantly in the pitch and roll planes presumably due to the central reinterpretation of otolith information. Dynamic visual acuity was decreased followed by an improvement in performance during the post flight recovery period. Adaptation to space flight led to a 50% increase in time to traverse the obstacle course on R+1, and recovery of function took an average of 2 weeks after return. Importantly, alterations in kinematics and dynamic visual acuity were accompanied by commensurate changes in functional mobility.
CONCLUSIONS
Recovery of functional mobility after long-duration space flight is composed of two distinct processes: a rapid on-line strategic change characterized by immediate onset after landing and a slower adaptive change requiring days to complete after landing. Therefore the composition and timing of sensory challenges experienced during gait training sessions need to be optimized to facilitate the acquisition of rapid on-line strategic changes. Further, training that facilitates rapid reorganization of sensorimotor function will allow improved functional performance during the early phase of readaptation to a planetary g-environment.
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Abstracts for Journals and Proceedings
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Mulavara AP, Peters BT, Cohen HS, Richards JT, Miller CA, Brady R, Warren LE, Kozlovskaya IB, Bloomberg JJ. "Development of Testing Methodologies to Evaluate Postflight Locomotor Performance." Presented at the The Seventh Symposium on the Role of the Vestibular Organs in Space Exploration, Noordwijk, the Netherlands, June 7-9, 2006. The Seventh Symposium on the Role of the Vestibular Organs in Space Exploration, ESA, June 2006. , Jun-2006
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Abstracts for Journals and Proceedings
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Bloomberg JJ, Mulavara AP, Peters BT, Cohen HS, Richards JT, Miller CA, Brady R, Warren LE, Ruttley TM, Kozlovskaya IB. "Development of a Countermeasure to Mitigate Postflight Locomotor Dysfunction. " Presented at the The Seventh Symposium on the Role of the Vestibular Organs in Space Exploration, Noordwijk, the Netherlands, June 7-9, 2006. The Seventh Symposium on the Role of the Vestibular Organs in Space Exploration, ESA, June 2006. , Jun-2006
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Abstracts for Journals and Proceedings
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Richards JT, Mulavara AP, Ruttley TM, Peters BT, Warren LE, Bloomberg JJ. "Relative Contributions of Strategic and Adaptive Control Mechanisms in Plastic Recalibration of Locomotor Heading Direction." Presented at the The Seventh Symposium on the Role of the Vestibular Organs in Space Exploration, Noordwijk, the Netherlands, June 7-9, 2006. The Seventh Symposium on the Role of the Vestibular Organs in Space Exploration, ESA, June 2006. , Jun-2006
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Abstracts for Journals and Proceedings
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Warren LE, Mulavara AP, Peters BT, Cohen HS, Richards JT, Miller CA, Brady R, Ruttley TM, Bloomberg JJ. "Assessment of Postflight Locomotor Performance Utilizing a Test of Functional Mobility: Strategic and Adaptive Responses. " Presented at the The Seventh Symposium on the Role of the Vestibular Organs in Space Exploration, Noordwijk, the Netherlands, June 7-9, 2006. The Seventh Symposium on the Role of the Vestibular Organs in Space Exploration, ESA, June 2006. , Jun-2006
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Abstracts for Journals and Proceedings
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Peters BT, Mulavara AP, Brady R, Miller CA, Warren LE, Richards JT, Cohen HS, Bloomberg JJ. "The Use of Dynamic Visual Acuity as a Functional Test of Gaze Stabilization Following Space Flight. " Presented at the The Seventh Symposium on the Role of the Vestibular Organs in Space Exploration, Noordwijk, the Netherlands, June 7-9, 2006. The Seventh Symposium on the Role of the Vestibular Organs in Space Exploration, ESA, June 2006. , Jun-2006
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Abstracts for Journals and Proceedings
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Cohen HS, Kimball KT, Bloomberg JJ, Mulavara AP. "Usefulness of current standardized balance tests for determining if balance-impaired individuals differ from normals. " Presented at the The Seventh Symposium on the Role of the Vestibular Organs in Space Exploration, Noordwijk, the Netherlands, June 7-9, 2006. The Seventh Symposium on the Role of the Vestibular Organs in Space Exploration, ESA, June 2006. , Jun-2006
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Abstracts for Journals and Proceedings
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Oddsson LIE , Bloomberg JJ, Zemkova E, Dwyer A, Chow A, Meyer P, Wall C 3rd. "Development of In-Flight Countermeasures with Multimodal Effects - Muscle Strength and Balance Function." Presented at the The Seventh Symposium on the Role of the Vestibular Organs in Space Exploration, Noordwijk, the Netherlands, June 7-9, 2006. The Seventh Symposium on the Role of the Vestibular Organs in Space Exploration, ESA, June 2006. , Jun-2006
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Abstracts for Journals and Proceedings
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Mulavara AP, Cohen HS, Peters BT, Miller CA, Brady R, Bloomberg JJ. "Locomotor Dysfunction after Spaceflight: Characterization and Countermeasure Development." HSEMB 2006 meeting, University of Houston, Houston, TX, February 9-10, 2006. HSEMB 2006 meeting, February 2006. , Feb-2006
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Abstracts for Journals and Proceedings
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Cohen HS, Kimball KT, Mulavara AP, Paloski WH, Bloomberg JJ. "Usefulness of Current Balance Tests for Identifying Balance-Impaired Individuals. " Presented at the 30th MidWinter Meeting, ARO, Denver, Colorado, Feb. 10 - 15, 2007. ARO (Association for Research in Otolaryngology) MidWinter Meeting, February 2007. , Feb-2007
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Abstracts for Journals and Proceedings
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Bloomberg JJ, Mulavara AP, Peters BT, Cohen HS, Richards JT, Miller CA, Brady R, Warren LE, Ruttley TM, Kozlovskaya IB. "Development of training programs to optimize planetary ambulation. " Presented at the NASA Human Research Program Investigators' Workshop, Houston, Texas, February 12–14, 2007. NASA Human Research Program Investigators' Workshop, February 2007. , Feb-2007
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Articles in Peer-reviewed Journals
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Peters BT, van Emmerik RE, Bloomberg JJ. "Stride cycle influences on goal-directed head movements made during walking." Gait Posture. 2006 Aug;24(1):70-6. PMID: 16099655 , Aug-2006
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Articles in Peer-reviewed Journals
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Moore ST, MacDougall HG, Peters BT, Bloomberg JJ, Curthoys IS, Cohen HS "Modeling locomotor dysfunction following spaceflight with Galvanic vestibular stimulation. " Exp Brain Res. 2006 Oct;174(4):647-59. PMID: 16763834 , Oct-2006
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Articles in Peer-reviewed Journals
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Richards JT , Mulavara AP, Bloomberg JJ. "The interplay between strategic and adaptive control mechanisms in plastic recalibration of locomotor function. " Exp Brain Res. 2007 Apr;178(3):326-38. PMID: 17061092 , Apr-2007
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Dissertations and Theses
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Peters B. "Visual Acuity While Walking and the Collective Contribution of Non-Ocular Gaze Mechanisms." Dissertation, University of Massachusetts, Amherst, February 2006.
, Feb-2006
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Dissertations and Theses
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Ruttley T. "The role of body load-regulating mechanisms in gaze stabilization during locomotion." Dissertation, The University of Texas Medical Branch at Galveston, Galveston, February 2007. , Feb-2007
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Dissertations and Theses
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Buccello-Stout R. "The effects of sensorimotor adaptation training on functional mobility in older adults." Dissertation, The University of Texas Medical Branch at Galveston, Galveston, January 2007. , Jan-2007
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