Retinotopic representation of visual space is a general feature of mammalian visual cortex. Experiments in this proposal will study whether the retinotopic map is required for the physiological processing of sensory information. Specifically, the proposed work will study the consequences that genetically disrupted retinotopic maps have for receptive field properties, cortical circuits and visual behaviors. Several lines of mutant mice that display mapping errors in their visual cortex will be used, including the mice deficient in the molecular guidance cues ephrin-As, the mice that have disrupted patterns of spontaneous activity in the developing retina, and the mice in which these two disruptive interventions are combined. In addition, retinotopic maps will also be disrupted in wild type mice by misexpressing ephrin-As in the developing visual cortex. Using these mice, the investigators will first determine whether cortical receptive fields are abnormal when retinotopic maps are disrupted. Single-unit recordings will be performed to measure the size, orientation selectivity and spatial tuning of individual cortical neurons. By comparing the receptive field properties of mice that have different degrees of mapping errors, the contribution of topographic maps in shaping receptive fields in the visual cortex will be determined. Second, intracellular whole cell recording will be performed in the intact brain to study the pattern of intracortical synaptic inhibition in the absence of a precise retinotopic map. Finally, using a swimming test of visual discrimination and a test of optomotor response, the investigators will determine whether disruption of retinotopic maps affects visual behaviors. Together, these studies will elucidate the role of retinotopic maps in visual processing and will also help define how precise patterns of synaptic connections contribute to the normal behavioral output of the nervous system in general. Importantly, these experiments will reveal how mis-wired visual systems function at cellular, circuit and behavioral levels. Such knowledge will be useful for the understanding and treatment of disorders resulting from brain injury and from aberrant neuronal connections.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY018621-02
Application #
7561004
Study Section
Central Visual Processing Study Section (CVP)
Program Officer
Steinmetz, Michael A
Project Start
2008-02-01
Project End
2012-01-31
Budget Start
2009-02-01
Budget End
2010-01-31
Support Year
2
Fiscal Year
2009
Total Cost
$377,500
Indirect Cost
Name
Northwestern University at Chicago
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
160079455
City
Evanston
State
IL
Country
United States
Zip Code
60201
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Sarnaik, Rashmi; Chen, Hui; Liu, Xiaorong et al. (2014) Genetic disruption of the On visual pathway affects cortical orientation selectivity and contrast sensitivity in mice. J Neurophysiol 111:2276-86
Liu, Mingna; Wang, Lupeng; Cang, Jianhua (2014) Different roles of axon guidance cues and patterned spontaneous activity in establishing receptive fields in the mouse superior colliculus. Front Neural Circuits 8:23
Sarnaik, Rashmi; Wang, Bor-Shuen; Cang, Jianhua (2014) Experience-dependent and independent binocular correspondence of receptive field subregions in mouse visual cortex. Cereb Cortex 24:1658-70
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Grimbert, François; Cang, Jianhua (2012) New model of retinocollicular mapping predicts the mechanisms of axonal competition and explains the role of reverse molecular signaling during development. J Neurosci 32:9755-68
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Yoshida, Miho; Feng, Liang; Grimbert, Francois et al. (2011) Overexpression of neurotrophin-3 stimulates a second wave of dopaminergic amacrine cell genesis after birth in the mouse retina. J Neurosci 31:12663-73

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