Abstract
An ongoing subject of research in the field of human motor control is the extent of similarities in neural activity underlying overt movement execution compared with imagination and observation of movement. Previous work in this area has focused mainly on the 'active' phase of movement (i.e. the period during which movements are actually executed, imagined or observed). Activation of motor cortical areas has been demonstrated during the active phase of motor imagery and observation suggesting that these alternative modes of movement share underlying neural mechanisms with overt motor execution. This thesis aimed to extend this work by studying the preparatory phase of movement, known to be an important part of the production of a motor response. Using high-density electroencephalography (EEG) recorded in a response-priming paradigm the effects of providing advance information about an upcoming movement were compared in the context of execution, imagination and observation of movement. For imagined movements, similar effects of advance information on preparatory activity were demonstrated to those shown prior to executed movements, providing further support for the theory that motor imagery activates existing neural representations of movement in motor areas of the brain (the neural simulation theory). For observed movements, by contrast, advance information about the upcoming movement did not invoke motor- related preparatory activity suggesting that similarities in motor execution and observation do not extend into the preparatory phase. This was interpreted as reflecting the passive nature of movement observation compared with the willful generation of a motor action in movement imagery and execution. In conclusion, an investigation into the preparatory phase of movement in this thesis suggests that motor imagery, in comparison to motor observation, provides a closer correlate to actual movement execution in terms of shared underlying neural activation.