Critical features of training that facilitate adaptive generalization of over ground locomotion

{ "0" : "Universities Space Research Association, United States" , "1" : "Bobby R. Alford Department of Otolaryngology, Head and Neck Surgery, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, United States" , "2" : "Neuroscience Laboratories, NASA/Johnson Space Center, United States" , "4" : "Balance therapy" , "5" : "Motor learning" , "6" : "Plasticity" , "7" : "Locomotion" , "8" : "Rehabilitation"}
Gait & posture (Impact Factor: 2.75). 02/2009; 29(2):242-248. DOI: 10.1016/j.gaitpost.2008.08.012


When subjects learn motor tasks under novel visuomotor conditions variations in sensory input during training facilitate adaptive generalization. We tested the hypotheses that training with multiple sensory input variations is more effective than a single or no variation and that training must include critical features of the criterion task. Normal adults were pre- and post-tested on an obstacle avoidance task while wearing visual distortion lenses after treadmill walking (Experiment 1), or balance training (Experiment 2). Subjects were randomized to training groups in which they wore either: (1) three different visual distortion lenses, (2) a single pair of visual distortion lenses, or (3) sham lenses. Post-tests were done while wearing novel lenses. In Experiment 1 subjects who trained with multiple lenses adapted better than single or sham lens groups. The single lens-training group with magnifying lenses adapted better than the other single lens groups. In Experiment 2, training for dynamic balance, alone, did not increase training efficacy. Thus, training for an obstacle avoidance task in a novel visual environment required a critical feature of the criterion task: locomotion. Constant practice with a single lens was successful only if the best lens was selected, but the best lens could not be known ahead of time. Therefore variable practice with multiple lenses on a task that included a critical feature of the criterion task was the best training strategy to enhance adaptive generalization.

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    • "There are more broad-based countermeasures which are geared toward maintaining the spectrum of overall function in different environments (one key environmental factor being tonic g level). These include adaptive generalization (Mulavara et al., 2009) and contextual adaptation (Shelhamer and Zee, "
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    ABSTRACT: Research in the area of sensorimotor and neurovestibular function has played an important role in enabling human space flight. This role, however, is changing. One of the key aspects of sensorimotor function relevant to this role will build on its widespread connections with other physiological and psychological systems in the body. The firm knowledge base in this area can provide a strong platform to explore these interactions, which can also provide for the development of effective and efficient countermeasures to the deleterious effects of space flight.
    Full-text · Article · Aug 2015 · Frontiers in Systems Neuroscience
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    • "Age, adaptation to sensorimotor change, and vestibular disorders are all associated with decreased obstacle avoidance skill. Older adults perform worse than younger adults on such tasks [3] [4] [19] and normals undergoing sensorimotor adaptation perform more poorly than their pre-adaption scores on obstacle avoidance [5] [10] [11]. Our previous work with normals and patients who have vestibular impairments has shown that an obstacle avoidance task is almost as sensitive to vestibular impairments as computerized dynamic posturography and the two tests, combined, are very sensitive [6]. "
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    ABSTRACT: The currently approved objective clinical measure of standing balance in astronauts after space flight is the Sensory Organization Test battery of computerized dynamic posturography. No tests of walking balance are currently approved for standard clinical testing of astronauts. This study determined the sensitivity and specificity of standing and walking balance tests for astronauts before and after long-duration space flight. Astronauts were tested on an obstacle avoidance test known as the Functional Mobility Test (FMT) and on the Sensory Organization Test using sway-referenced support surface motion with eyes closed (SOT 5) before and six months after (n=15) space flight on the International Space Station. They were tested two to seven days after landing. Scores on SOT tests decreased and scores on FMT increased significantly from pre- to post-flight. In other words, post-flight scores were worse than pre-flight scores. SOT and FMT scores were not significantly related. ROC analyses indicated supra-clinical cut-points for SOT 5 and for FMT. The standard clinical cut-point for SOT 5 had low sensitivity to post-flight astronauts. Higher cut-points increased sensitivity to post-flight astronauts but decreased specificity to pre-flight astronauts. Using an FMT cut-point that was moderately highly sensitive and highly specific plus SOT 5 at the standard clinical cut-point was no more sensitive than SOT 5, alone. FMT plus SOT 5 at higher cut-points was more specific and more sensitive. The total correctly classified was highest for FMT, alone, and for FMT plus SOT 5 at the highest cut-point. These findings indicate that standard clinical comparisons are not useful for identifying problems. Testing both standing and walking balance will be more likely to identify balance deficits.
    Full-text · Article · Nov 2012 · Journal of Vestibular Research
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    • "sensorimotor learning; visuomotor rotation; contextual interference; learning to learn; structural learning WHEN HUMANS OR OTHER ANIMALS practice one or more tasks they are often subsequently able to learn related tasks more rapidly. This phenomenon of " transfer learning " or " learning to learn " has been demonstrated for cognitive tasks in animals (Harlow 1949; Warren 1965; Mackintosh and Little 1969; Schrier 1984; Langbein et al. 2007) and humans (Duncan 1960; Halford et al. 1998; Tenenbaum and Griffiths 2001; Kemp and Tenenbaum 2009) and more recently for sensorimotor control tasks in humans (Welch et al. 1993; Roller et al. 2001; Seidler 2004, 2007; Cohen et al. 2005; Seidler 2007; Braun et al. 2009a,b; Mulavara et al. 2009). "
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    ABSTRACT: Motor task variation has been shown to be a key ingredient in skill transfer, retention, and structural learning. However, many studies only compare training of randomly varying tasks to either blocked or null training, and it is not clear how experiencing different nonrandom temporal orderings of tasks might affect the learning process. Here we study learning in human subjects who experience the same set of visuomotor rotations, evenly spaced between -60° and +60°, either in a random order or in an order in which the rotation angle changed gradually. We compared subsequent learning of three test blocks of +30°→-30°→+30° rotations. The groups that underwent either random or gradual training showed significant (P < 0.01) facilitation of learning in the test blocks compared with a control group who had not experienced any visuomotor rotations before. We also found that movement initiation times in the random group during the test blocks were significantly (P < 0.05) lower than for the gradual or the control group. When we fit a state-space model with fast and slow learning processes to our data, we found that the differences in performance in the test block were consistent with the gradual or random task variation changing the learning and retention rates of only the fast learning process. Such adaptation of learning rates may be a key feature of ongoing meta-learning processes. Our results therefore suggest that both gradual and random task variation can induce meta-learning and that random learning has an advantage in terms of shorter initiation times, suggesting less reliance on cognitive processes.
    Preview · Article · Nov 2011 · Journal of Neurophysiology
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