BMI Progress Reports 2021 // Prof. Hummel's Lab: P. Maceira - Optimization of motor skill acquisition in healthy older adults using neuromodulation

Ageing often results in functional and structural changes in the brain, gradually diminishing the ability to acquire new knowledge or novel motor skills. Understanding the underlying mechanisms impairing these abilities and developing methods to maintain or improve them in older adults are crucial goals of translational neuroscience. We first quantified the dynamics of learning a new motor sequence and determined the impact of differential chunking strategies in young, middle-aged, and older adults. We found that the young learned the fastest by excellent chunking and benefited from consolidation occurring overnight, which were both absent in the other two older groups (i.e., middle-aged and old). To address the age-related deficits, we applied learning-enhancing non-invasive brain stimulation during training of an explicit motor sequence for a week. The application of verum stimulation, but not placebo, significantly boosted learning in the older group, especially in the most impaired participants, by driving chunking mechanisms towards young-like improving accuracy of movements. These improvements were associated to the efficiency of inhibitory interneuronal circuits within the motor cortex. These results provide an insight into the foundation of age-related motor skill acquisition deficits, how they can be addressed by interventional strategies based on non-invasive brain stimulation and how this can impact behavior. This approach is capable of influencing interneuronal dynamics and resulting chunking strategies to improve learning, especially in individuals with neuroplastically imbalanced brains and most significant behavioral impairment.