| Summary: | This thesis comprises a collection of papers that describe a process of hypothesis development, followed by testing, and ending in revision. The hypothesis developed in the first paper is that dysfunction of ‘mirror neurons’ might explain the cluster of symptoms that characterise autism. Mirror neurons are located primarily in ventral preomotor and parietal cortex. They are characterised by a property of firing in response to the observation of specific actions, and also when those same actions are executed. Mirror neurons offer a potential mechanism of connecting neural processes that serve action perception with those that serve action execution. It is proposed that mirror neuron function is important for the development of normal imitation skills, ‘theory of mind’ and joint attention. This was investigated taking several approaches. A systematic literature review revealed strong evidence for impaired imitation ability in autism and suggested that imitation of gesture might be more impaired than imitation of object-directed action. Functioning of the mirror neuron system in autism during imitation was investigated using functional magnetic resonance imaging (fMRI). This revealed evidence for mirror neuron dysfunction, but also, dysfunction of associated neural systems. An fMRI study of joint attention, an important ability that is disrupted in autism, found that joint attention, an important ability that is disrupted in autism, found that joint attention relies on medial frontal cortex and superior frontal gyrus function. The superior frontal gyral function matched onto an area of grey matter abnormality that we identified in a voxel-based morphometry study of autism. A study of auditory visual integration in autism investigated another facet of the hypothesis. The final two chapters are review articles that synthesise recent evidence from studies that are relevant to the mirror neuron hypothesis of autism. The final chapter represents the latest and most comprehensive review of the mirror neuron hypothesis and presents a reformulation and novel hypotheses for future work.
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