The Neural Dynamics of Action Representation for Sound: An investigation of musical training effects on mu suppression

Abstract

Efficient sensorimotor integration is essential for music performance. Musicians undergo extensive training, which enhances established neural links between auditory and motor areas of the brain. Long-term training develops, strengthens and enables flexibility in these connections allowing proficiency in performance. Functional neuroimaging studies have indicated that listening to trained music can result in the activity in premotor areas, even after a short period of training. This suggests that such mappings can be specific, and can rapidly become automatic. It has been argued that although these are abstract associations, these mappings rely on activity in mirror neuron systems (involved generally in imitating and learning actions). It has also been suggested that these systems are heavily dependent on actual sensorimotor experience; however others suggest that humans naturally move to music and therefore actual sensorimotor training is not necessary to demonstrate action representation during listening to music. Electroencephalography (EEG) studies in the actionobservation field have associated changes in mu rhythm activity with the mirror neuron system for observation of actions as well as the more abstract association of observation of musical notation. The overall aims of this current thesis were to extend this visuomotor work into the audiomotor domain, and investigate whether specific sensorimotor training led to action representation for auditory stimuli. Study 1 showed that sensorimotor mu rhythm desynchronisation occurred when pianists listened passively to piano melodies, demonstrating that this spectral analysis method can be used to detect action representation during listening. Study 2 sought to determine if similar action representation during passive listening occurs specifically for newly acquired soundaction mappings after short-term musical training. Somewhat unexpectedly, significant mu suppression was not revealed post-training, for either piano tone stimuli or rhythmic stimuli. In Study 3 spectral coherence methods were used, and it was found that functional connectivity increased after musical training for specific listening tasks. This last finding suggests that there is some degree of specificity in the modulation of task-related coherence due to training, as the increased coherence did not occur for rhythmic stimuli. We consider possible explanations for these varied findings, and discuss the relevance of these studies to brain plasticity, sensorimotor integration and relatively recent developments in musicsupported therapy for stroke rehabilitation.