Attention refers to the cognitive processes that prioritise a subset of available sensory information for enhanced processing, and which can be directed towards spatial locations, object features, time, or other aspects of the environment. While the majority of research has focused on studying attention within sensory modalities, a growing body of evidence has demonstrated that attention interact with multisensory processes. Several neuroimaging studies have shown that higher cortical regions activated during attention to multiple sensory modalities overlap significantly with the dorsal and ventral frontoparietal regions activated during visual attention tasks. This evidence has led some researchers to propose the existence of supramodal frontoparietal system that controls the deployment of attention across various sensory modalities. Although influential, this hypothesis has been challenged by other studies that discovered evidence for modality-specific regions in the parietal cortex. In this thesis, I investigated the generality and specificity of the frontoparietal network associated with multisensory spatial and feature-based attention, in vision and touch, by applying multivoxel pattern analysis (MVPA) to fMRI data. Recent studies have successfully demonstrated that MVPA methods could be used to discriminate various experimental conditions from weak distributed patterns of activity within overlapping cortical regions found by univariate fMRI analysis. Here, I applied similar logic to examine overlapping frontoparietal regions activated during multisensory attention. Contrary to the supramodal hypothesis, the results supported the existence of modality-specific systems in the posterior parietal cortex during both attention to spatial locations and stimulus features. Additional evidence for modality-specific processes was also indicated in the patterns of top-down modulatory activity in visual cortex. Overall, the current findings supported the view that both modality-specific and potentially supramodal frontoparietal regions work in concert to selectively bias activity in sensory cortical regions during various states of attention.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:567424 |
| Date | January 2012 |
| Creators | Kurniawan, Veldri |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/40755/ |
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