A revised model of visual information processing has begun to emerge from our primate studies on the structure and function of the three segregated, parallel pathways (magnocellular (M), parvocellular (P), and koniocellular (K)) from the lateral geniculate nucleus (LGN) to striate cortex. The parallel inputs are utilized by the laminar and compartmental (i.e., cytochrome oxidase (CO) blob and interblob) circuitry of striate cortex to produce new output pathways appropriate for the next steps of analysis. Just as LGN layers appear to be arranged to optimally distribute information to striate, the interactions within striate cortex may create (or re-encode) visual signals to optimally support the functional requirements of the different extrastriate visual areas. In fight of this model, our project's broad aim is to identify the key components of parallel pathways beginning at the LGN, and to understand how these pathways are transformed within the layers and compartments of primate striate cortex to produce the parallel output pathways.
The specific aims are designed to test hypotheses generated by our model of parallel visual cortical organization.
In Aim I, we will morphologically characterize the classes of LGN cells that project to the CO rich blob, and CO poor interblob zones of the primate striate cortex.
In Aim II, we will investigate the relative contributions of LGN pathways to the physiological properties of CO blob and interblob cells.
In Aim III, we will elucidate the functional significance of anatomical and physiological differences between striate cortical compartments and layers. The results of our proposed studies will contribute important new information on the fundamental understanding of how the brain processes visual information.

National Institute of Health (NIH)
National Eye Institute (NEI)
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Visual Sciences B Study Section (VISB)
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Vanderbilt University Medical Center
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Jiang, Yaoguang; Purushothaman, Gopathy; Casagrande, Vivien A (2015) A computational relationship between thalamic sensory neural responses and contrast perception. Front Neural Circuits 9:54
Jiang, Yaoguang; Yampolsky, Dmitry; Purushothaman, Gopathy et al. (2015) Perceptual decision related activity in the lateral geniculate nucleus. J Neurophysiol 114:717-35
Jiang, Yaoguang; Purushothaman, Gopathy; Casagrande, Vivien A (2015) The functional asymmetry of ON and OFF channels in the perception of contrast. J Neurophysiol 114:2816-29
Purushothaman, Gopathy; Chen, Xin; Yampolsky, Dmitry et al. (2014) Neural mechanisms of coarse-to-fine discrimination in the visual cortex. J Neurophysiol 112:2822-33
Shostak, Yuri; Wenger, Ashley; Mavity-Hudson, Julia et al. (2014) Metabotropic glutamate receptor 5 shows different patterns of localization within the parallel visual pathways in macaque and squirrel monkeys. Eye Brain 6:29-43
Ichida, Jennifer M; Mavity-Hudson, Julia A; Casagrande, Vivien A (2014) Distinct patterns of corticogeniculate feedback to different layers of the lateral geniculate nucleus. Eye Brain 2014:57-73
Marion, Roan; Li, Keji; Purushothaman, Gopathy et al. (2013) Morphological and neurochemical comparisons between pulvinar and V1 projections to V2. J Comp Neurol 521:813-32
Li, K; Patel, J; Purushothaman, G et al. (2013) Retinotopic maps in the pulvinar of bush baby (Otolemur garnettii). J Comp Neurol 521:3432-50
Purushothaman, Gopathy; Casagrande, Vivien A (2013) A Generalized ideal observer model for decoding sensory neural responses. Front Psychol 4:617
Purushothaman, Gopathy; Marion, Roan; Li, Keji et al. (2012) Gating and control of primary visual cortex by pulvinar. Nat Neurosci 15:905-12

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