2016 — 2017 |
White, Alexander Lindley |
F32Activity Code Description: To provide postdoctoral research training to individuals to broaden their scientific background and extend their potential for research in specified health-related areas. |
The Cortical Mechanisms of Divided Attention in Word Recognition @ University of Washington
? DESCRIPTION (provided by applicant): Written language is a crowning achievement of the human brain: it allows the thoughts of one person to flow into the mind of another despite great time and distance between them. For most readers, this information transfer happens effortlessly. Nevertheless, there are limits to how much text can be understood at once; for instance, you do not yet know what the next sentence says. This project uses a combination of behavioral testing and brain imaging to answer the following questions: Is it possible to recognize two words simultaneously? If not, what internal bottlenecks constrain the processing of printed text? Human observers will make judgments about various aspects of words that are flashed simultaneously on both sides of a computer screen. In addition, the observers will either focus attention on one location or divide attention between words at both locations. While they do that, their brain activity will be recorded with functional magnetic resonance imaging. Of particular interest are the visual areas of the brain, including one that responds selectively to words. Some brain areas may respond less strongly when attention is divided than focused, indicating that those areas play a role in determining behavioral accuracy. Furthermore, by varying the demands of the task, this project will uncover the particular stages of visual word processing-from extracting the features of individual letters to retrieving the semantic meaning-that impose the greatest limits on reading ability. The results will enhance our understanding of the limitations of the human brain, setting the stage for further research applied to learning disabilities. Dyslexia impairs reading for up to 10 percent of the population, and it may have multiple causes including difficulties with word sounds (phonology). In some theories, reading is slowed by failures to select small chunks of text in the correct order, or by improper division of attention across the page. Therefore, by studying how visual attention works in typical readers, this project may elucidate the mechanisms of dyslexia and impairments caused by brain damage. That knowledge can help design interventions targeted to each individual according to the challenges he or she faces.
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0.918 |
2018 — 2021 |
White, Alexander Lindley |
K99Activity Code Description: To support the initial phase of a Career/Research Transition award program that provides 1-2 years of mentored support for highly motivated, advanced postdoctoral research scientists. R00Activity Code Description: To support the second phase of a Career/Research Transition award program that provides 1 -3 years of independent research support (R00) contingent on securing an independent research position. Award recipients will be expected to compete successfully for independent R01 support from the NIH during the R00 research transition award period. |
Capacity Limits in the Neural Circuitry of Visual Word Recognition @ University of Washington
Project Summary / Abstract For most literate adults, reading feels effortless. However, visual word recognition is a complex process performed by specialized circuits in the brain, and for millions of people it never becomes easy. Even skilled readers have to process a page of text in small chunks, due to poor peripheral vision and inherent capacity limits for sensory information processing. It is difficult to recognize even just two clearly visible words at once. This project investigates the underlying neuronal basis for capacity limits in visual word recognition and how they differ across individuals. Specific research goals: (1) To test the hypothesis that a particular occipito- temporal brain area, the putative `visual word form area' (VWFA), is a bottleneck to word recognition. Observers will view flashing pairs of words in an MRI scanner that records both functional activity and structural connections between brain areas. To trace out the flow of information from early visual cortex into the language system, this study will manipulate which aspects of the stimuli the observers attend to. (2) To vary the task demands in order to hone in on the particular stage of word recognition (e.g., orthographic, lexical) where there is a processing bottleneck. (3) To test the hypothesis that individual differences in reading ability are related to capacity limits in particular processing stages, and to relate those capacity limits to white matter tracts that are hypothesized to control the flow of visual information during reading. Candidate: Dr. Alex White is a postdoctoral researcher seeking to establish himself as a uniquely skilled cognitive neuroscientist and launch his own laboratory to study visual perception and the neural foundations of literacy. In his prior training, he investigated the mechanisms of selective attention with psychophysics, eye-tracking, and fMRI. In his most recent work he discovered that skilled readers can semantically recognize only one word at a time, and now seeks to fully explain that finding. To accomplish these goals he needs more training in advanced neuroimaging, especially diffusion-weighted MRI (dMRI), to assay the white matter tracts in the reading circuitry. The Pathway to Independence Award will allow him to reach his goals by funding additional training at the University of Washington and facilitating his transition to a faculty position. Training plan: Dr. White has assembled a first-rate team of mentors: Dr. Jason Yeatman, who develops sophisticated imaging methods to study the neural circuits related to reading and dyslexia; Dr. Geoff Boynton, an expert in fMRI and the effects of attention in human visual cortex; and Dr. John Palmer, who develops mathematical models for capacity limits in perception. In the K99 phase of this award, these mentors will train Dr. White in advanced fMRI analysis techniques, dMRI and modeling. They will support the execution of the first set of proposed studies and prepare him to become an effective principal investigator. When he carries on this work independently in his own lab, he hopes to open new avenues of applied research that will alleviate reading impairments in diverse populations.
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0.931 |