IS 10. What have we learned from motor learning?

Abstract

There are several types of motor learning and here the issue of skill learning will be considered. Skill learning is the development of a new motor ability with practice. The process sequentially consists of initial learning, consolidation, reconsolidation, off line improvement and development of automaticity. Studies with EEG and neuroimaging as well as TMS have illuminated the physiology. Initial learning involves the primary motor cortex, and the capability for learning appears to depend on the state of synaptic excitability within a homeostatic range. For example, TMS methods that increase motor cortex excitability can reduce the ability to learn. Consolidation and reconsolidation depend on continuing activity within motor cortex in a short period following practice. This can be demonstrated by showing a loss of learning with inhibitory TMS immediately following learning. In the long term, there is evidence that the motor program is stored in a parietal-premotor network. Changes in parietal-motor excitability assessed by TMS can also be seen in the short period after practice. In early learning the excitability of the motor cortex rises and then falls; with later learning the activity of the parietal-premotor regions increases, but then decreases with automaticity, together with stronger connectivity. The parietal-premotor network can be studied with a cortico-cortical paired-associative stimulation (PAS) method and that method should be useful in future to probe the changes in this network in the later phases of skilled learning.