Clinical Pilates in Practice: Age & Motor Adaptation
The authors of this study examined the differences in the brain structure and cognition underlying motor adaptation in a population-based cohort. Results support the hypothesis that sensorimotor adaptation is a composite of multiple learning strategies, which are differentially affected by age, and the authors conclude that "that across the lifespan, motor adaptation declines with age as a result of the deteriorating explicit learning system".
Wolpe N, Ingram J, Tsvetanov K, et al. (2020). Age-related reduction in motor adaptation: brain structural correlates and the role of explicit memory. Neurobiology of Aging 90: 13-23.
Key Points: Age & Motor Adaptation
Adaptation of movement to environmental changes varies across the lifespan.
Motor adaptation is related to individual differences in visuospatial working memory.
The degree of motor adaptation is typically reduced with age,1 although visuomotor adaptation does not necessarily change with age.2
In the classical interpretation of sensorimotor adaptation, an internal forward model predicts the sensory outcome of one’s movement.
Updating of the internal forward model is made possible by a discrepancy between the sensorimotor prediction and sensory feedback.
The medial temporal lobe and hippocampus contribute to motor adaptation. The degree of motor adaptation is related to changes in mean diffusivity of white matter within the medial temporal lobe.
→ This implies that young healthy individuals who show increased white matter integrity can adapt more in a visuomotor learning task.
The hippocampus contributes to the acquisition of motor sequences via connections with higher cortical regions, and may be essential for consolidating motor memories via their interactions with the cerebellum and striatum.
There is evidence that implicit motor adaptation is preserved in older age, while explicit adaptation deteriorates:
→ When an experimental visual perturbation is small and gradual, emphasizing implicit processes, older adults adapt their movement as well as younger adults.3
→ When young and old participants are matched by explicit knowledge of the perturbation, age-related differences largely dissipate.4
Recently, there has been a dissociation between the contribution of implicit and explicit learning to age-related decline in motor adaptation.5
Age-related reduction in grey matter volume in the bilateral premotor and lateral prefrontal cortex is related to reduced adaptation.
→ These clusters overlap with regions that have been suggested to mediate spatial working memory capacity, which is important for motor adaptation.
In humans, striatal activation has been demonstrated during a motor adaption task,6 and is implicated in tasks involving motor sequence learning.
The striatum and basal ganglia complement sensory prediction error-based learning by reinforcing movements that lead to rewarding outcomes, thus contributing to overall adaptation.
→ It is this learning strategy that is impaired in older age.
The sensorimotor system is capable of adapting to external changes that occur in the environment as well as internal changes in neuronal and musculoskeletal dynamics.
This adaptive ability of the sensorimotor system is critical for learning new skills and also adjusting to previously learned movements when presented with new tasks.
Effects of age on motor adaption are explained by the optimal control theory, which proposes that the central nervous system continuously stimulates an individual’s interaction with the environment during the execution of a voluntary movement.
The decline in motor adaptation with age is independent of implicit learning and results from deterioration in explicit learning processes.
The reduction in motor adaptation with age is tightly coupled with the reduction in explicit learning.
→ However, age may not affect cerebellar-based learning mechanisms despite a degree of cerebellar degeneration.
Researchers found that reduction in grey matter volume in the prefrontal cortex and striatum - but not in the cerebellum - was related to adaptation differences with age.
Differences in the medial temporal lobe, including the hippocampus, were also strongly associated with motor adaptation with age.
The anterior hippocampus supports the learning of new environmental layouts.
The medial temporal and anterior hippocampus contribute to the consolidation of motor memories by encoding performance error signals that are critical for the explicit component of motor adaptation.
→ This degeneration with age makes older people prone to motor learning deficits.
Motor adaptation is more positively related to long-term memory scores with age.
→ However, motor adaptation relates to short-term memory measures regardless of age.
Clinical Pilates in practice
Consider age when designing rehabilitation programs - at what stage of the lifespan is your client, and how does this affect their explicit learning systems?
Conscious problem-solving (explicit learning) becomes more difficult with age, therefore look to provide more sensory input for learning feedback:
→ Closed kinetic chain exercises.
→ Joint approximation for proprioception.
→ Visualizations and imagery.
→ Verbal and tactile cueing.
References
1. King, B.R., Fogel, S.M., Albouy, G., Doyon, J., 2013. Neural correlates of the age-related changes in motor sequence learning and motor adaptation in older adults. Front. Hum. Neurosci. 7, 142.
2. Heuer, H., Hegele, M., 2008a. Adaptation to direction-dependent visuo-motor rotations and its decay in younger and older adults. Acta Psychol. (Amst) 127, 369e381.
3. Buch, E.R., Young, S., Contreras-Vidal, J.L., 2003. Visuomotor adaptation in normal aging. Learn Mem. 10, 55e63
4. Heuer, H., Hegele, M., 2008b. Adaptation to visuomotor rotations in younger and older adults. Psychol. Aging 23, 190e202.
5. Vandevoorde, K., Orban de Xivry, J.-J., 2019. Internal model recalibration does not deteriorate with age while motor adaptation does. Neurobiol. Aging 80,138e153
6. Seidler, R.D., Noll, D.C., Chintalapati, P., 2006. Bilateral basal ganglia activation associated with sensorimotor adaptation. Exp. Brain Res. 175, 544e555