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Title: The organisation of the ventral temporal object processing stream
Author: Acres, L.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2009
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A first study used a new pattern analysis method to examine the differential patterns of fMRI activity for object pairs that were perceptually or conceptually related (or unrelated) at different points along the stream. As hypothesised, perceptually related objects generated more similar activation patterns than unrelated objects in posterior ventral temporal cortex. This study was repeated using a new spin echo sequence minimising signal drop-out in anterior temporal lobes, where conceptual effects were predicted. The signal was weak and the results were not conclusive. A third study investigated release from repetition suppression by perceptually or semantically related objects. The degree of release from suppression was determined by the factors that each voxel responds to. A fourth study focussed on how conceptual variables affect object processing in the ventral temporal stream. This study entered principal components of conceptual variables and visual variables as repressors in analyses of fMRI activity associated with picture naming. The results provided suggestive support for a distributed neurocognitive model of object representations. Finally, I investigated the hypothesised functional laterality of the ventral stream, with object naming purportedly relying on left and object recognition on right anterior temporal regions. Patients with temporal lobe damage were administered the same task, once with words and once pictures, and behaviour was correlated with a voxel-based measure of neural integrity. The right anterior temporal lobe was associated with object recognition and the left anterior temporal lobe with conceptual retrieval from the object name. This research confirms that posterior sections of the object processing stream are organised according to perceptual factors and provides suggestive evidence that anteromedial regions may be organised according to semantic factors.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available