Aging leads to progressive changes in brain metabolism, structure, and function, resulting in declines in motor performance. These changes include reduced cortical inhibition, impaired brain structure, and altered functional connectivity. Consequently, older adults often experience diminished motor ability, postural instability, and increased fall risk, which can negatively affect their quality of life. However, emerging evidence shows that motor learning, such as balance and strength training, can promote neuroplasticity and help mitigate age-related decline. The neural mechanisms supporting motor ability and the brain's adaptations to motor learning remain incompletely understood, particularly regarding the interplay of neurochemical, structural, and functional changes.
This thesis explores the brain mechanisms underlying motor function and the neuroplastic changes associated with motor learning in older adults. The findings are based on data from a longitudinal study in which older adults were assigned to balance training, strength training, or control groups for three months. Participants underwent multimodal neuroimaging before and after the intervention. This design allowed us to assess large-scale brain networks involved in balance and examine training-induced metabolic, structural, and functional changes.
To understand the neural basis of balance, we used connectome-based predictive modeling with baseline data to identify structural and functional brain networks associated with balance performance. Our results show that both structural and functional connectomes predict balance ability. Key networks include motor-subcortical, fronto-parietal, and visual circuits, emphasizing the importance of coordinated activity across these systems in supporting postural control in older adults.
We then examined how balance training drives neural plasticity. Following three months of training, participants showed improved balance, enhanced functional connectivity within sensorimotor networks, and increased cortical inhibition, evidenced by elevated GABA levels in the sensorimotor cortex. These findings suggest that balance training can counteract age-related reductions in connectivity and inhibitory function, underscoring the role of the GABAergic system in neuroplastic adaptation and motor behavior.
While functional changes are important for adaptive motor control, structural changes are also essential. Our third study investigated structural plasticity following balance and strength training. We found that strength training promotes white matter reorganization in key pathways and that both training types counteract age-related structural degeneration in critical brain regions. These results highlight the capacity of motor training to induce beneficial neural plasticity at multiple levels.
In conclusion, this thesis provides evidence that motor learning can drive neuroplastic changes across metabolic, structural, and functional domains in the agin
