Neuroplasticity in Motor Learning in Young Adults Under Variable and Constant Practice Conditions

Variable practice involving the practice of several variations of motor skill benefits learning differently than practice in constant conditions, i.e., practice that involves only one variation of a skill. The variable practice results in better retention and transfer. The performance of a skill practiced in variable conditions is more accurate and stable. In contrast, practicing only one variation of a skill better refines the recall schema. It means that the motor program (which serves as an "example" while executing a movement) is developed better. The trained variation of a skill (in constant practice), produces an advantage in performance compared to the same variation of the skill that was practiced in variable conditions (assuming that variable and constant practice had similar capacity).

This finding has an important implication for those who want to master their skills and it does not matter whether this skill refers to sport, driving, piloting, or rehabilitation. If one wants to be good at performing only one variation of a skill, one should practice in constant conditions, whereas if one wants to be good in more than one variation of skill and wants to generalize the experience to novel situations an individual should practice in variable conditions. As one can see, this implication is practical, although the mechanisms underlying this distinction and differences are unknown.

On the other hand, it is unquestioned today that learning new motor skills dynamically changes brain, i.e., brain is neuroplastic. The neuroplasticity of the brain is specifically conspicuous in the progression of motor learning. As it was reported in previous research, cortico-striatal and cortico-cerebellar systems play an important role in motor skill acquisition. However, both of these systems differ in terms of the role they play as learning progresses. Cortico-striatal system (associative/premotor brain regions) is primarily engaged in the initial phase of learning, i.e., in cognitive functioning and sensory processing. Cortico-cerebellar system (sensorimotor network) is becoming more active in the later phase of motor learning. However, none of the previous research focused on what role these systems play in learning under different conditions and how the different roles the systems may play affect structural neuroplasticity, including grey and white matter.

It may be also interesting to look at the functional neuroplasticity. A lesser degree of cognitive involvement during the execution of movements may be associated with lower activation in the sensorimotor cortex. On the other hand, increased cognitive involvement may be expected in variable conditions due to, e.g., stimulus identification or decision making. Therefore, the assumption that decreased cognitive involvement and, as a result, decreased prefrontal cortex activation in constant practice conditions sounds reasonable. Moreover, it may be hypothesized that practicing and learning in constant conditions will be characterized by lower sensorimotor cortex activation since there will be decreased control during the motor performance, which leads to more adaptive motor performance.