Movement-related cortical potential markers of motor skill learning

In this thesis the cortical processes involved in motor skill learning were examined. Electroencephalography (EEG) was used to record the movement-related cortical potential (MRCP): an event-related potential reflecting the cortical activity involved in motor planning and preparation, prior to performance of a guitar playing task. A series of five experiments was conducted to investigate how the MRCP may vary depending on a performer’s skill level and how it may change with skill learning. In Study 1 a scale-playing task on the guitar, from which it was possible to accurately record the MRCP, was identified. In Study 2, the MRCP was recorded during scale-playing on the guitar from a group of experienced guitarists and a group of non-musicians who had no prior musical training and no experience of playing any musical instrument. Differences in the amplitude and onset times of the MRCP components were compared across groups, with results indicating that the experienced guitarists allocated less cortical activity to planning the performance of the scale than the non-musicians. The purposes of Studies 3, 4, and 5 were to establish the extent to which these between-group differences were the result of training by the experienced guitarists. In Study 3 the effect of short-term practice on movement-related cortical activity was investigated and, contrary to the hypothesis, found an increase in cortical activity involved in movement preparation following practice on the guitar. In Studies 4a and 4b the effect of long-term motor practice on the MRCP was explored. Non-musicians took part in a five and ten week training programme, learning to play the guitar. Study 4a reported a decrease in cortical activity in certain parts of the motor cortex following five weeks of learning to play a scale on the guitar. When the training programme was extended to ten weeks in Study 4b however, an increase in cortical activity was found in certain areas of the motor cortex. Study 4c investigated the effect of a period of de-training on the MRCP in five participants. Results from these participants indicated a decrease in MRCP amplitude following training. This reduced amplitude was also found following a five-week period of de-training. Finally, in Study 5, within-session changes in cortical activity were investigated over an extended ten-week learning period. The combined results of Studies 3 and 5 indicate that there may be an increase in both pre- and primary motor cortex activity during the initial phase of motor skill learning, followed by a decrease in motor cortex activity once the performer becomes competent in the task. From the results of these studies, it was concluded that the process of motor skill learning is likely to be more complex than is currently stated in the literature. Rather than a simple linear decrease in the amount of cortical activity involved in motor planning as a result of learning, it is more likely that fluctuations in cortical activity occur at different stages in the learning period, which may, over time, lead to a reduced activity being required during motor preparation.