Samuel M. Wu - US grants

DESCRIPTION (provided by applicant): The overall objective of our research is to understand detailed synaptic mechanisms underlying the center-surround antagonistic receptive field (CSARF) organization of retinal bipolar cells (BCs), and how BCs form parallel information channels for signal processing in the retina. We will use microelectrode voltage recording techniques to study BC receptive field properties in the flat-mounted retina, and use single or dual whole-cell patch clamp techniques to study light-, current/voltage- or neurotransmitter-elicited signals in individual or pairs of morphologically identified cells in retinal slices. These two approaches compensate each other's limitations, and with the new knowledge and technical advances developed during the past grant period, we will use the salamander retina as a model system to study synaptic mechanisms underlying CSARF organization of the four major types of BCs (rod- and cone-dominated depolarizing and hyperpolarizing bipolar cells (DBC-R, DBC-C, HBC-R and HBC-C)) found in most vertebrates. This application addresses 4 specific aims focused on 4 key sets of BC receptive field properties: (1) relative center/surround response strength, receptive field size, degree of coupling and response conductance changes, (2) horizontal cell (HC)-mediated surround inputs in the outer retina (HC-cone feedback and HCBC feedforward synapses, and whether these synapses are chemical or electrical), (3) amacrine cell (AC)-mediated surround inputs in the inner retina (GABAA-, GABAC- and glycine-receptor-mediated AC signals and stratum-by-stratum distributions), and (4) properties of presynaptic voltage-evoked excitatory postsynaptic currents (veEPSCs) in output synapses to ganglion cells. Results obtained will provide a detailed description on how different synaptic pathways mediate the center and surround responses of different types of BCs in the retina, and the differences may render possible explanations for several controversial issues in the BC CSARF synaptic circuitry. As similarities in functional, anatomical and neurochemical organizations between salamander and mammalian retinas become increasingly evident, knowledge obtained from this project will facilitate our understanding on how BC parallel information channels in mammalian and human retinas are organized, and provide important clues for developing animal models for various retinal diseases.

digital imaging; confocal scanning microscopy; vision; biomedical facility;

? DESCRIPTION (provided by applicant): The objective of the Core Grant for Vision Research is to provide support and facilities which are not available and cannot be obtained through individual grants exclusively for vision research and NEI-funded projects at Baylor College of Medicine (BCM). The Core also provides space, support personnel and capital equipment to facilitate state-of-the-art vision research and collaborations among vision research laboratories in the College. The Vision Research Core at BCM currently has 25 vision research investigators, carrying 17 eligible NEI R01s, 1 NEI P41, 1 NEI PN2, 1 NEI K08, 1 NEI DP1, 1 NEI R21, 2 NEI T32s, 8 NIH R01s from other NIH institutes and 2 DOD grants, and their research areas cover the structure, function and pathogenesis of the entire visual system, from the cornea and lens to the retina and to the central visual centers. Their research disciplines include biochemistry, molecular genetics, electrophysiology, genomic/bioinformatic analysis, psychophysics, computational visual neuroscience and developmental biology. These investigators form a vibrant and highly interactive vision research group, and have published more than 400 papers in the past 5 years, and 259 of which have benefited directly from the usage of this Vision Core during this grant period. In this competing renewal application, we report our highly successful and productive past usage of the Core facilities, and seek continued support for four Resource/Service Modules: the Microscopy, Digital Imaging and Histology Module, the Instrumentation Module, the Small Animal Visual System Analysis Module and the Genomic and Bioinformatics Module. These modules contain equipment worth over $5M purchased with the Department of Ophthalmology and the College funds (in 2014 alone, over $1.2M new equipment was purchased to update and expand the Core's research capacities). The Specific Aims of the Vision Core are: (1) To provide three scanning confocal microscope and one electron microscope services for high-resolution three-dimensional imaging of tissues and cells labeled with fluorescent dyes and for ultrastructural analysis of ocular and neural tissues, and to provide histological facilities, services and training for both confocal and electrn microscopy. (2) To provide in-house, custom-designed machine, electronic, optics and computer services to the Vision Core investigators who need special apparatuses that are not commercially available. (3) To provide access to structural, physiological, biochemical, and behavior testing facilities, such as OCT, ERG, HPLC, mass spectrometry and OKR, to study mouse, rat and rabbit visual system function, dysfunction, and structural/genetic defects. (4) To provide state-of-the-art genomic technologies and critical bioinformatics support to Vision Core labs by leveraging the expertise, technologies, and resources of the BCM Human Genome Sequencing Center. (5) To foster interactions and collaborations among various vision research and to provide a vibrant research environment for vision research faculty and student recruitment and retention at BCM.

Program Director/Principal Investigator (Last, First, Middle): Abstract The Instrumentation Module provides design, fabrication and modification capabilities for project-specific, customized and software-flexible vision research apparatuses that are not commercially available. During the past five years, the Module fabricated many in-house, tailor-fitted and specially-designed devices that have played crucial roles in generating many high-impact and innovative vision research results. In the next grant period, this Module will continue its indispensable role in supporting vision research projects by providing new mechanical, electronic, optic and computer-based design and fabrication services and to develop highly innovative, high-impact research tools, such as the chronically implanted tetrode array recording chambers, the virtual reality visual-vestibular stimulating system, and the forced-choice, Bayesian adaptive protocol-driven optokinetic reflex machine. All these devices will be constructed and repeatedly modified, fitted and adjusted before and during experiments by the in-house machine shop and electronic/optics/computer shop. Therefore the Instrumentation Module is not only a necessity of many Vision Core labs, but also an integrated part of the research process and scientific progress. PHS 398/2590 (Rev. 11/07) Page Continuation Format Page