The neural basis of object perception: dissociating action and semantic processing

This thesis has evaluated the roles of dorsal and ventral processing streams in recognition and use of objects. Four main empirical studies are presented. First, to investigate how the cortical brain processes semantic and action knowledge in different object-related tasks, I examined structural data from stroke patients (Chapter 2) and functional data from healthy individuals (Chapter 3) using a voxel-wise statistical analysis method. Using data of different modalities (structural CT, fMRI) from different sources (patients’ lesions; healthy subjects’ functional activity) handled with a systematic analysis approach, I attempted to find convergent evidence to support the dissociation of semantic and action processing. Second, I also looked into the potential differentiation within the mechanisms underlying object-related action (Chapter 4) and object naming (Chapter 5) separately. Overall, comparable findings were provided from the voxel-based morphometric analysis of patients’ lesion data and the fMRI study with healthy participants: an association was observed between ventral brain structures and the retrieval of semantic knowledge/object recognition while a dorsal fronto-parietal-occipital network was found to support the processing of action knowledge/object-oriented action. Specific dissociations were also observed within the representations for object-oriented actions as well as the mechanisms underlying naming of objects