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Investigating the role of occipital cortex in tactile processing: In search of a meta-modal brain
Multiple Paper Presentation
Lotfi B. Merabet
Department of Neurology, Harvard Medical School
Jessica Andrews
Department of Neurology, Harvard Medical School Hugo Theoret
Department of Neurology, Harvard Medical School Alvaro Pascual-Leone
Department of Neurology, Harvard Medical School Abstract ID Number: 43
Abstract
Neuroimaging studies have demonstrated that the occipital (visual) cortex is recruited during tactile discrimination tasks in both normally sighted and blind subjects. Furthermore, disruption of visual cortex in early blind subjects (using TMS) impairs performance in tactile discrimination tasks. We have further investigated the possible role of occipital cortex in tactile performance implicating fine spatial discrimination (using arrays of raised dots of different inter-dot spacing). Normally sighted subjects were asked to separately rate the subjective roughness and distance spacing between dots for a series of patterns presented randomly. Application of repetitive TMS (rTMS) to the contralateral somatosensory cortex disrupted the amount of overall roughness perceived (i.e. flattening the roughness judgment curve) while distance judgment was not impaired. Conversely, rTMS to the occipital cortex did not affect judgments of roughness but rather disrupted distance perception. Subjects tended to scale increasing inter-dot spacing with less perceived distance compared to the control condition. Investigation of the effects of selective cortical disruption in early and late blind subjects are currently in progress. These results support the notion of meta-modal sensory processing within the occipital cortex in that this region can decode spatial information regardless of input modality.
To be Presented at the Following Symposium:
Consequences of sensory loss
Other papers in this Symposium:
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