About 15 types of retinal ganglion cell, each type tuned to different aspects of the visual scene, independently sample the visual space. About half are coupled via gap junctions to amacrine cells and/or their neighboring ganglion cells of the same type. Very few of these ganglion cell types are well characterized with regard to either their function or what other cells they contact to form their individual circuit. The PI has developed usage of a gap junctional-permeant fluorescent tracer (Hoshi and Mills, 2006) that allows in vivo identification of cells electrically coupled to the injected cell. This tracer, PoPro1, provides the PI with a unique opportunity to examine the properties of coupled ganglion and amacrine cells. This proposal uses this novel technique to investigate this important, but almost completely-unexplored feature of network coupling, namely, the functional consequences of heterologous coupling between amacrine and ganglion cells. The proposal involves (1) recording from a ganglion cell type called the G3 ganglion cell, which preliminary data shows has an orientation bias and determining how this function arises, and (2) discovering the manner in which amacrine cells coupled to ganglion cells participate in synchronized firing of ganglion cells. Synchrony is emerging as an important process in coding and possibly decoding of visual signals. The processes that lead to synchrony are also important in pathologies such as seizures.

Public Health Relevance

The studies in this grant are directed toward two elements pertinent to public health: ganglion cell circuits and gap junctions. The importance of gap junctions has been established in photoreceptor death (the """"""""bystander"""""""" effect), but as the extent and function of gap junctions in ganglion cell circuitry is not well known, the involvement of gap junctions in ganglion cell death in diseases such as glaucoma is a topic worthy of investigation.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
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Biology and Diseases of the Posterior Eye Study Section (BDPE)
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Greenwell, Thomas
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University of Texas Health Science Center Houston
Schools of Medicine
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Marshak, David W; Chuang, Alice Z; Dolino, Drew M et al. (2015) Synaptic connections of amacrine cells containing vesicular glutamate transporter 3 in baboon retinas. Vis Neurosci 32:E006
Marshak, David W; Mills, Stephen L (2014) Short-wavelength cone-opponent retinal ganglion cells in mammals. Vis Neurosci 31:165-75
Mills, Stephen L; Tian, Lian-Ming; Hoshi, Hideo et al. (2014) Three distinct blue-green color pathways in a mammalian retina. J Neurosci 34:1760-8
Mao, Chai-An; Li, Hongyan; Zhang, Zhijing et al. (2014) T-box transcription regulator Tbr2 is essential for the formation and maintenance of Opn4/melanopsin-expressing intrinsically photosensitive retinal ganglion cells. J Neurosci 34:13083-95
Hoshi, Hideo; Tian, Lian-Ming; Massey, Stephen C et al. (2013) Properties of the ON bistratified ganglion cell in the rabbit retina. J Comp Neurol 521:1497-509
Pan, Feng; Keung, Joyce; Kim, In-Beom et al. (2012) Connexin 57 is expressed by the axon terminal network of B-type horizontal cells in the rabbit retina. J Comp Neurol 520:2256-74
Vila, Alejandro; Satoh, Hiromasa; Rangel, Carolina et al. (2012) Histamine receptors of cones and horizontal cells in Old World monkey retinas. J Comp Neurol 520:528-43
Hoshi, Hideo; Tian, Lian-Ming; Massey, Stephen C et al. (2011) Two distinct types of ON directionally selective ganglion cells in the rabbit retina. J Comp Neurol 519:2509-21
Hoshi, Hideo; Mills, Stephen L (2009) Components and properties of the G3 ganglion cell circuit in the rabbit retina. J Comp Neurol 513:69-82
Hoshi, Hideo; Liu, Wei-Li; Massey, Stephen C et al. (2009) ON inputs to the OFF layer: bipolar cells that break the stratification rules of the retina. J Neurosci 29:8875-83

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