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My research interests center on understanding the neuronal circuitry underlying vision and touch. To map these functions in the brain, we use a high spatial resolution imaging method, called optical imaging of intrinsic cortical signals. Through an implanted 'window' on the brain, pictures of cortical reflectance are taken; these reflectance values correlate with neural activity at high spatial resolution (50-100 um). This method, in conjunction with electrophysiology and anatomical tracing methods, permits the study of fundamental cortical modules in the brain and their connections. We are now studying how different networks of modules are activated by simple and complex visual and somatosensory stimuli. Recently, we adapted this technology for use in the awake, trained animal and are linking cortical activation patterns to visual and somatosensory perception in the behavioral context. |
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Feature Article: Rapid spot imaging method In optical imaging experiments, it is often advantageous to map the field of view and to converge the eyes without electrophysiological recording. We have developed a rapid spot imaging method that can be conducted rapidly and repeatedly throughout an experiment. Using small 0.2° - 0.5° spots, we can quickly map 1) the extent of the imaged field of view and 2) assess eye convergence to within 0.1° resolution. Lu HD*, Chen G*, Ts'o DY, Roe AW (2008) A rapid topographic mapping and eye alignment method using optical imaging in Macaque visual cortex. Neuroimage, /in press/. *equal contributions. |
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| Feature Article: 3D Maps in Visual Area V2 When we open our eyes, the 3D visual world is projected onto the 2D plane of our retina. Our brain reconstructs the third dimension (depth) by comparing inputs from the two eyes. But where in the brain is this third dimension calculated? To answer this question, we have used a high spatial resolution brain imaging method called optical imaging. We find that whereas primary |
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| visual cortex (V1) contains a 2D map of visual space, the third dimension is mapped in the second visual area (V2). This suggests that 3D vision results from a combination of V1 and V2 activations. At right: Layer above is color-coded schematic of orientation map in V1 and V2. Peaks and valleys in V2 indicate maps for near to far in V2 thick stripes. Layer below indicates location of V1 region (light blue), V2 pale stripe (olive), V2 thin stripe (gray), and V2 thick stripe (cream). Chen G, Lu HD, Roe AW (2008) A map of horizontal disparity in primate V2. Neuron, 58:442-450 |
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Feature Article: Yin and Yang of color maps in the brain Macaque monkey visual cortex (areas V1 and V2). Yin (right portion): optical image of V1 & V2 activation while monkey is viewing a color stimulus. Yang (left portion): cytochrome-oxidase (CO) stained brain slice of the imaged region. As shown in Lu and Roe 2008, color-activations in V1 (smaller patches) align with CO blobs in V1, while color-activations in V2 (larger patches) align with CO thin stripes in V2. Lu HD, Roe AW (2008) Functional Organization of Color Domains in V1 and V2 of Macaque Monkey Revealed by Optical Imaging. Cereb Cortex 18(2). |
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| Feature Article: Disparity Channels in Early Vision | ||||||||||||||||||||
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Human beings and many other animals see the world with two eyes. However, each eye has a view which is slightly offset from the other. The brain has taken advantage of this offset, termed binocular disparity, to figure out distance and three dimensional depth information about the world, a capability called stereopsis. The last decade has seen a dramatic increase in our knowledge of the neural basis of stereopsis. New cortical areas have been found to represent binocular disparities, and the first causal links between neural activity and depth perception have been established. Equally exciting is the finding that experience affects how signals are channeled through different brain areas, a flexibility that may be crucial for learning, plasticity, and recovery of function. |
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| Roe AW, Parker AJ, Born RT, DeAngelis GC (2007) Disparity channels in early vision: a mini-review. J Neurosci, 27:11820-11831. |
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| Feature Article: How our brain fills gaps A vase from China's Song dynasty demonstrates the use of very faint contrast borders to create the illusion of shading on a one-color background. The phenomenon is known as edge induction. The image of the vase is overlaid over the Cornsweet illusion, in which the left half of a rectangle divided in two looks lighter and the right area darker. Holding one's hand over the center of the image reveals that the left and the right are in fact the same color. The brain "fills in" the color on the left and the right in response to information from the middle border. |
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| Hung CP, Ramsden RM, Roe AW (2007) A functional circuitry for edge-induced brightness perception. Nature Neurosci,/ /10:1185-1190. See also http://www.vanderbilt.edu/news/releases/2007/8/20/ when-in-doubt-brain-relies-on-precise-timing-to-perceive-brightness. |
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Feature article: The Power of Proximity In Michelangelo's Creation of Adam (Sistine Chapel), God stretches out His right index to the first man. In a return gesture, Adam mirrors the movement, reaching out his own hand to meet the Creator's animating spark. Graphs on either side illustrate activations in somatosensory cortex in response to real and illusory digit tip stimulation.* |
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Chen LM, Turner G, Friedman RM, Gore JC, Roe AW, Avison MJ (2007) High resolution maps of real and illusory tactile activation in SI: intra-individual correlation with fMRI, optical imaging and electrophysiology. J Neurosci,/ /27(34):9181-9191. |
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| Publications & Conferences Laboratory Members Web Links Curriculum Vitae Post doc Position Available |
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