How Does the Brain Learn New Motor Tasks?

Post by Ewina Pun

What’s motor learning?

Humans possess a remarkable capacity to acquire new motor skills. Some motor skills can be readily transferred to a new task or context. For example, someone who can already play the guitar will have an easier time learning to play the bass, and mastering biking on flat terrain makes it less challenging to tackle mountain biking. However, learning entirely new motor skills can be more difficult. Through practice and repetition, our brain is capable of acquiring and refining those skills. Motor learning involves modifying the nervous system to enable movement generation in response to environmental changes or through practice. This overview highlights some of the neural mechanisms that guide motor learning.

How does the brain change during motor learning?

The brain may reorganize itself on various levels when we learn a new task. First, cortical maps may change over an extended period of deliberate practice. For example, a study revealed skilled musicians have a larger volume of grey matter than non-musicians. Second, learning can also result in short-term and long-term changes in tuning properties of individual neurons, synapses, and functional networks of neurons. Motor learning is complex because these processes may occur simultaneously over different timescales, and typically involve various brain regions depending on the type of learning.

During learning, cortical neurons in the motor cortex and sensorimotor cortex may reuse existing neural patterns for fast skill adaptation or create new neural patterns when learning skills that have not been encountered before. Changes in neural population activity also occur, which can be attributed to synaptic plasticity: synapses being strengthened, pruned, or created, allowing more efficient neural communication. These changes in connections affect the neural population's firing patterns, subsequently influencing behavior.

Reward-based learning in the basal ganglia

Reward-based learning in the basal ganglia plays a crucial role in the acquisition of new motor skills and refining existing ones. Also known as reinforcement learning, this process allows the brain to associate specific motor actions with positive or negative outcomes and adjust behavior to maximize rewards and minimize punishments. The basal ganglia create a feedback loop connecting motor planning and execution from the cerebral cortex with the evaluation of outcomes. This evaluation is facilitated by dopamine-releasing neurons that encode reward prediction information. This process considers rewards independently of sensory and motor aspects and integrates reward information into movement activities.

Error-based learning in the cerebellum

The cerebellum also plays an important role in acquiring and coordinating precise movements through error-based learning. Prediction error refers to the difference between the intended movement and the actual movement produced. To predict and correct errors and fine-tune movements, the cerebellum receives and integrates inputs from sensory systems, such as vision and proprioception (the sense of body position), as well as from the cerebral cortex. Research suggests that the cerebellum is involved in externally driven movements, while the basal ganglia participate in internally generated movements.

Why study motor learning?

Motor learning is an active and ongoing area of research in neuroscience, with many unanswered questions awaiting exploration. Understanding the neural mechanisms underlying movement control and learning is essential, as it holds practical applications in fields such as sports training (to enhance athletic performance) and rehabilitation (new therapies and technologies to help disabled individuals). Furthermore, understanding how we incorporate predictions and errors in the context of motor learning may contribute to the advancement of machine learning algorithms for tackling and solving new tasks. Future research may focus on emerging techniques or technologies, such as brain-computer interfaces, virtual reality, or advanced neuroimaging methods, which could further our understanding of how the brain learns new motor tasks.

References +

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C. S. Li, C. Padoa-Schioppa, E. Bizzi. Neuronal correlates of motor performance and motor learning in the primary motor cortex of monkeys adapting to an external force field. Neuron. (2001).

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