Visual cortical circuitry for building word representations
Abstract/Contents
- Abstract
- Reading is the remarkable human ability to decode the sounds and meaning of language from an intricate combination of strokes of ink. This perceptual capacity is tolerant to changes in size, font, and other visual features of text. Transformations of the neural representation between many neural modules, including primary visual cortex (V1), other retinotopically organized areas, and language regions, are necessary for successful reading. An important focus of previous work has been on characterizing word representations in ventral occipito-temporal cortex, in particular in a left-hemisphere region known as the visual word form area (VWFA). To better understand the transformations occurring between V1 and the VWFA, we measured (using functional magnetic resonance imaging, fMRI) and perturbed (using transcranial magnetic stimulation) neural responses in several visual areas while subjects read words defined by atypical visual features (Chapter 2). We show that VWFA responses are invariant to the visual features that define word stimuli, and we show how flexible neural circuitry accounts for these abstract representations. While these studies contribute to understanding the VWFA's inputs, the inner organization of the VWFA remains unexplored. We describe experiments that use fMRI and electrocorticography (ECoG) in the human brain to show that the VWFA is sensitive to visual field position, and that together with a homologous right-hemisphere region, its inner organization encompasses a retinotopic map (Chapter 3). Information about abstract word forms is in turn transferred from the VWFA to language areas of the brain. This transfer occurs via large white-matter bundles that can be measured with diffusion imaging (DTI). We compare data from a severely dyslexic individual to a group of control subjects and show that the individual's deficits are due to a missing arcuate fasciculus, one of the major pathways important for reading and language (Chapter 4). This set of experiments ties together several fields of neuroscientific inquiry, including early visual processing, complex visual object representations, and language. Ultimately, if we are to understand how spots of light are transformed into sounds and meaning, we must unravel the smaller transformations that occur within all these components of the reading circuitry.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2011 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Rauschecker, Andreas Maximilian | |
|---|---|---|
| Associated with | Stanford University, Department of Neurosciences. | |
| Primary advisor | Wandell, Brian A | |
| Thesis advisor | Wandell, Brian A | |
| Thesis advisor | Newsome, William T | |
| Thesis advisor | Parvizi, Josef | |
| Thesis advisor | Wagner, Anthony David | |
| Advisor | Newsome, William T | |
| Advisor | Parvizi, Josef | |
| Advisor | Wagner, Anthony David |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Andreas Maximilian Rauschecker. |
|---|---|
| Note | Submitted to the Department of Neurosciences. |
| Thesis | Ph.D. Stanford University 2011 |
| Location | electronic resource |
Access conditions
- Copyright
- © 2011 by Andreas Maximilian Rauschecker
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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