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Two mechanisms for direction selectivity in a model of the primate starburst amacrine cell
- Jiajia Wu, Yeon Jin Kim, Dennis M. Dacey, John B. Troy, Robert G. Smith
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- Journal:
- Visual Neuroscience / Volume 40 / 2023
- Published online by Cambridge University Press:
- 23 May 2023, E003
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In a recent study, visual signals were recorded for the first time in starburst amacrine cells of the macaque retina, and, as for mouse and rabbit, a directional bias observed in calcium signals was recorded from near the dendritic tips. Stimulus motion from the soma toward the tip generated a larger calcium signal than motion from the tip toward the soma. Two mechanisms affecting the spatiotemporal summation of excitatory postsynaptic currents have been proposed to contribute to directional signaling at the dendritic tips of starbursts: (1) a “morphological” mechanism in which electrotonic propagation of excitatory synaptic currents along a dendrite sums bipolar cell inputs at the dendritic tip preferentially for stimulus motion in the centrifugal direction; (2) a “space–time” mechanism that relies on differences in the time-courses of proximal and distal bipolar cell inputs to favor centrifugal stimulus motion. To explore the contributions of these two mechanisms in the primate, we developed a realistic computational model based on connectomic reconstruction of a macaque starburst cell and the distribution of its synaptic inputs from sustained and transient bipolar cell types. Our model suggests that both mechanisms can initiate direction selectivity in starburst dendrites, but their contributions differ depending on the spatiotemporal properties of the stimulus. Specifically, the morphological mechanism dominates when small visual objects are moving at high velocities, and the space–time mechanism contributes most for large visual objects moving at low velocities.
Parasol cell mosaics are unlikely to drive the formation of structured orientation maps in primary visual cortex
- VICTORIA R.A. HORE, JOHN B. TROY, STEPHEN J. EGLEN
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- Journal:
- Visual Neuroscience / Volume 29 / Issue 6 / November 2012
- Published online by Cambridge University Press:
- 30 October 2012, pp. 283-299
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The receptive fields of on- and off-center parasol cell mosaics independently tile the retina to ensure efficient sampling of visual space. A recent theoretical model represented the on- and off-center mosaics by noisy hexagonal lattices of slightly different density. When the two lattices are overlaid, long-range Moiré interference patterns are generated. These Moiré interference patterns have been suggested to drive the formation of highly structured orientation maps in visual cortex. Here, we show that noisy hexagonal lattices do not capture the spatial statistics of parasol cell mosaics. An alternative model based upon local exclusion zones, termed as the pairwise interaction point process (PIPP) model, generates patterns that are statistically indistinguishable from parasol cell mosaics. A key difference between the PIPP model and the hexagonal lattice model is that the PIPP model does not generate Moiré interference patterns, and hence stimulated orientation maps do not show any hexagonal structure. Finally, we estimate the spatial extent of spatial correlations in parasol cell mosaics to be only 200–350 μm, far less than that required to generate Moiré interference. We conclude that parasol cell mosaics are too disordered to drive the formation of highly structured orientation maps in visual cortex.
Contributors
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- By Gregory H. Adkisson, Ozan Akça, Nawar Al-Rawas, John T. Anderson, Richard M. Bednarski, Francesca Bernabè, David G. Bjoraker, Lluis Blanch, Stephan H. Böhm, Edwin A. Bowe, Philip G. Boysen, Justin C. Cahill, Ira M. Cheifetz, David C. Cone, Nancy Craig, Daniel P. Davis, John B. Downs, Ronald Dueck, Jay L. Falk, Roger Fletcher, Michael A. Frakes, Andrea Gabrielli, Thomas J. Gallagher, Geoff Gilmartin, J. S. Gravenstein, Antonino Gullo, Donna Hamel, John W. Huang, Amy V. Isenberg, Michael B. Jaffe, Michael C. K. Khoo, Robert R. Kirby, E. F. Klein, A. Joseph Layon, Umberto Lucangelo, Emilio Maldonado, Paul E. Marik, Alicia E. Meuret, Timothy E. Morey, William Muir, Joseph A. Orr, Mehmet S. Ozcan, Lucía Isabel Passoni, David A. Paulus, Yong G. Peng, Carl W. Peters, George A. Ralls, Adriana G. Scandurra, Peter W. Scherer, Gerd Schmalisch, Adam Seiver, Salvatore Silvestri, Bob Smalhout, Fernando Suarez-Sipmann, Daniel E. Supkis, John Thompson, Patrick Troy, Jonathon D. Truwit, Gerardo Tusman, Joseph Varon, Ajeet G. Vinayak, Kevin R. Ward, Marvin A. Wayne, Charles Weissman, Dafna Willner, Kai Zhao, Christian C. Zuver
- Edited by J. S. Gravenstein, University of Florida, Michael B. Jaffe, Nikolaus Gravenstein, University of Florida, David A. Paulus, University of Florida
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- Book:
- Capnography
- Published online:
- 05 August 2011
- Print publication:
- 17 March 2011, pp ix-xii
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Contributors
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- By Waiel Almoustadi, Brian J. Anderson, David B. Auyong, Michael Avidan, Michael J. Avram, Roland J. Bainton, Jeffrey R. Balser, Juliana Barr, W. Scott Beattie, Manfred Blobner, T. Andrew Bowdle, Walter A. Boyle, Eugene B. Campbell, Laura F. Cavallone, Mario Cibelli, C. Michael Crowder, Ola Dale, M. Frances Davies, Mark Dershwitz, George Despotis, Clifford S. Deutschman, Brian S. Donahue, Marcel E. Durieux, Thomas J. Ebert, Talmage D. Egan, Helge Eilers, E. Wesley Ely, Charles W. Emala, Alex S. Evers, Heidrun Fink, Pierre Foëx, Stuart A. Forman, Helen F. Galley, Josephine M. Garcia-Ferrer, Robert W. Gereau, Tony Gin, David Glick, B. Joseph Guglielmo, Dhanesh K. Gupta, Howard B. Gutstein, Robert G. Hahn, Greg B. Hammer, Brian P. Head, Helen Higham, Laureen Hill, Kirk Hogan, Charles W. Hogue, Christopher G. Hughes, Eric Jacobsohn, Roger A. Johns, Dean R. Jones, Max Kelz, Evan D. Kharasch, Ellen W. King, W. Andrew Kofke, Tom C. Krejcie, Richard M. Langford, H. T. Lee, Isobel Lever, Jerrold H. Levy, J. Lance Lichtor, Larry Lindenbaum, Hung Pin Liu, Geoff Lockwood, Alex Macario, Conan MacDougall, M. B. MacIver, Aman Mahajan, Nándor Marczin, J. A. Jeevendra Martyn, George A. Mashour, Mervyn Maze, Thomas McDowell, Stuart McGrane, Berend Mets, Patrick Meybohm, Charles F. Minto, Jonathan Moss, Mohamed Naguib, Istvan Nagy, Nick Oliver, Paul S. Pagel, Pratik P. Pandharipande, Piyush Patel, Andrew J. Patterson, Robert A. Pearce, Ronald G. Pearl, Misha Perouansky, Kristof Racz, Chinniampalayam Rajamohan, Nilesh Randive, Imre Redai, Stephen Robinson, Richard W. Rosenquist, Carl E. Rosow, Uwe Rudolph, Francis V. Salinas, Robert D. Sanders, Sunita Sastry, Michael Schäfer, Jens Scholz, Thomas W. Schnider, Mark A. Schumacher, John W. Sear, Frédérique S. Servin, Jeffrey H. Silverstein, Tom De Smet, Martin Smith, Joe Henry Steinbach, Markus Steinfath, David F. Stowe, Gary R. Strichartz, Michel M. R. F. Struys, Isao Tsuneyoshi, Robert A. Veselis, Arthur Wallace, Robert P. Walt, David C. Warltier, Nigel R. Webster, Jeanine Wiener-Kronish, Troy Wildes, Paul Wischmeyer, Ling-Gang Wu, Stephen Yang
- Edited by Alex S. Evers, Washington University School of Medicine, St Louis, Mervyn Maze, University of California, San Francisco, Evan D. Kharasch, Washington University School of Medicine, St Louis
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- Book:
- Anesthetic Pharmacology
- Published online:
- 11 April 2011
- Print publication:
- 10 March 2011, pp viii-xiv
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Generation, identification and functional characterization of the nob4 mutation of Grm6 in the mouse
- LAWRENCE H. PINTO, MARTHA H. VITATERNA, KAZUHIRO SHIMOMURA, SANDRA M. SIEPKA, VICTORIA BALANNIK, ERIN L. MCDEARMON, CHIAKI OMURA, STEPHEN LUMAYAG, BRANDON M. INVERGO, BRETT GLAWE, DONALD R. CANTRELL, SAMSOON INAYAT, MARISSA A. OLVERA, KIRSTAN A. VESSEY, MAUREEN A. McCALL, DENNIS MADDOX, CATHERINE W. MORGANS, BRANDON YOUNG, MATHEW T. PLETCHER, ROBERT F. MULLINS, JOHN B. TROY, JOSEPH S. TAKAHASHI
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- Journal:
- Visual Neuroscience / Volume 24 / Issue 1 / January 2007
- Published online by Cambridge University Press:
- 12 April 2007, pp. 111-123
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We performed genome-wide chemical mutagenesis of C57BL/6J mice using N-ethyl-N-nitrosourea (ENU). Electroretinographic screening of the third generation offspring revealed two G3 individuals from one G1 family with a normal a-wave but lacking the b-wave that we named nob4. The mutation was transmitted with a recessive mode of inheritance and mapped to chromosome 11 in a region containing the Grm6 gene, which encodes a metabotropic glutamate receptor protein, mGluR6. Sequencing confirmed a single nucleotide substitution from T to C in the Grm6 gene. The mutation is predicted to result in substitution of Pro for Ser at position 185 within the extracellular, ligand-binding domain and oocytes expressing the homologous mutation in mGluR6 did not display robust glutamate-induced currents. Retinal mRNA levels for Grm6 were not significantly reduced, but no immunoreactivity for mGluR6 protein was found. Histological and fundus evaluations of nob4 showed normal retinal morphology. In contrast, the mutation has severe consequences for visual function. In nob4 mice, fewer retinal ganglion cells (RGCs) responded to the onset (ON) of a bright full field stimulus. When ON responses could be evoked, their onset was significantly delayed. Visual acuity and contrast sensitivity, measured with optomotor responses, were reduced under both photopic and scotopic conditions. This mutant will be useful because its phenotype is similar to that of human patients with congenital stationary night blindness and will provide a tool for understanding retinal circuitry and the role of ganglion cell encoding of visual information.
Risk Adjustment for Surgical Site Infection After Median Sternotomy in Children
- Jessica Kagen, Warren B. Bilker, Ebbing Lautenbach, Louis M. Bell, Susan E. Coffin, Keith H. St. John, Eva Teszner, Troy Dominguez, J. William Gaynor, Samir S. Shah
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- Journal:
- Infection Control & Hospital Epidemiology / Volume 28 / Issue 4 / April 2007
- Published online by Cambridge University Press:
- 02 January 2015, pp. 398-405
- Print publication:
- April 2007
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Objective.
To determine whether the National Nosocomial Infections Surveillance (NNIS) System risk index adequately stratified a population of pediatric patients undergoing cardiac surgery according to the risk of developing surgical site infection (SSI).
Design.A retrospective, case-control study.
Setting.An urban tertiary care children's hospital.
Patients.Patients who had a median sternotomy performed between January 1,1995, and December 31, 2003, were eligible for inclusion in the study. For all case patients, medical records were reviewed to verify that all patients met the case definition for SSI. Control subjects were chosen randomly from among all patients who underwent median sternotomy during the study period who did not develop SSI.
Results.Thirty-eight patients with SSI and 172 patients without SSI were included. One hundred six patients (50%) were male. The median patient age was 4 months. The sensitivity of the NNIS risk index with cutoff scores of 0 to 1 and 2 to 3 was 20%. The distribution of patients with SSI for an NNIS risk index score of 0 was 0%; for a score of 1, 80%; for a score of 2, 20%; and for a score of 3, 0%. The distribution of patients without SSI for a scores of 0 was 4%; for a score of 1, 87%; for a score of 2, 9%; and for a score of 3, 0%. The area under the receiver-operating characteristic curve (AUC) of the original NNIS risk index was 0.57. The modified risk indices did not perform significantly better, with an AUC range of 0.58 to 0.73.
Conclusions.The NNIS risk index did not adequately stratify pediatric patients undergoing median sternotomy according to their risk of developing an SSI. Various modifications to the risk index yielded only slightly higher AUC values.
Homotypic constraints dominate positioning of on- and off-center beta retinal ganglion cells
- STEPHEN J. EGLEN, PETER J. DIGGLE, JOHN B. TROY
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- Journal:
- Visual Neuroscience / Volume 22 / Issue 6 / November 2005
- Published online by Cambridge University Press:
- 03 February 2006, pp. 859-871
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Beta retinal ganglion cells (RGCs) of the cat are classified as either on-center or off-center, according to their response to light. The cell bodies of these on- and off-center RGCs are spatially distributed into regular patterns, known as retinal mosaics. In this paper, we investigate the nature of spatial dependencies between the positioning of on- and off-center RGCs by analysing maps of RGCs and simulating these patterns. We introduce principled approaches to parameter estimation, along with likelihood-based techniques to evaluate different hypotheses. Spatial constraints between cells within-type and between-type are assumed to be controlled by two univariate interaction functions and one bivariate interaction function. By making different assumptions on the shape of the bivariate interaction function, we can compare the hypothesis of statistical independence against the alternative hypothesis of functional independence, where interactions between type are limited to preventing somal overlap. Our findings suggest that the mosaics of on- and off-center beta RGCs are likely to be generated assuming functional independence between the two types. By contrast, allowing a more general form of bivariate interaction function did not improve the likelihood of generating the observed maps. On- and off-center beta RGCs are therefore likely to be positioned subject only to homotypic constraints and the physical constraint that no two somas of opposite type can occupy the same position.
Looking Backward, Looking Forward: MLA Members Speak
- April Alliston, Elizabeth Ammons, Jean Arnold, Nina Baym, Sandra L. Beckett, Peter G. Beidler, Roger A. Berger, Sandra Bermann, J.J. Wilson, Troy Boone, Alison Booth, Wayne C. Booth, James Phelan, Marie Borroff, Ihab Hassan, Ulrich Weisstein, Zack Bowen, Jill Campbell, Dan Campion, Jay Caplan, Maurice Charney, Beverly Lyon Clark, Robert A. Colby, Thomas C. Coleman III, Nicole Cooley, Richard Dellamora, Morris Dickstein, Terrell Dixon, Emory Elliott, Caryl Emerson, Ann W. Engar, Lars Engle, Kai Hammermeister, N. N. Feltes, Mary Anne Ferguson, Annie Finch, Shelley Fisher Fishkin, Jerry Aline Flieger, Norman Friedman, Rosemarie Garland-Thomson, Sandra M. Gilbert, Laurie Grobman, George Guida, Liselotte Gumpel, R. K. Gupta, Florence Howe, Cathy L. Jrade, Richard A. Kaye, Calhoun Winton, Murray Krieger, Robert Langbaum, Richard A. Lanham, Marilee Lindemann, Paul Michael Lützeler, Thomas J. Lynn, Juliet Flower MacCannell, Michelle A. Massé, Irving Massey, Georges May, Christian W. Hallstein, Gita May, Lucy McDiarmid, Ellen Messer-Davidow, Koritha Mitchell, Robin Smiles, Kenyatta Albeny, George Monteiro, Joel Myerson, Alan Nadel, Ashton Nichols, Jeffrey Nishimura, Neal Oxenhandler, David Palumbo-Liu, Vincent P. Pecora, David Porter, Nancy Potter, Ronald C. Rosbottom, Elias L. Rivers, Gerhard F. Strasser, J. L. Styan, Marianna De Marco Torgovnick, Gary Totten, David van Leer, Asha Varadharajan, Orrin N. C. Wang, Sharon Willis, Louise E. Wright, Donald A. Yates, Takayuki Yokota-Murakami, Richard E. Zeikowitz, Angelika Bammer, Dale Bauer, Karl Beckson, Betsy A. Bowen, Stacey Donohue, Sheila Emerson, Gwendolyn Audrey Foster, Jay L. Halio, Karl Kroeber, Terence Hawkes, William B. Hunter, Mary Jambus, Willard F. King, Nancy K. Miller, Jody Norton, Ann Pellegrini, S. P. Rosenbaum, Lorie Roth, Robert Scholes, Joanne Shattock, Rosemary T. VanArsdel, Alfred Bendixen, Alarma Kathleen Brown, Michael J. Kiskis, Debra A. Castillo, Rey Chow, John F. Crossen, Robert F. Fleissner, Regenia Gagnier, Nicholas Howe, M. Thomas Inge, Frank Mehring, Hyungji Park, Jahan Ramazani, Kenneth M. Roemer, Deborah D. Rogers, A. LaVonne Brown Ruoff, Regina M. Schwartz, John T. Shawcross, Brenda R. Silver, Andrew von Hendy, Virginia Wright Wexman, Britta Zangen, A. Owen Aldridge, Paula R. Backscheider, Roland Bartel, E. M. Forster, Milton Birnbaum, Jonathan Bishop, Crystal Downing, Frank H. Ellis, Roberto Forns-Broggi, James R. Giles, Mary E. Giles, Susan Blair Green, Madelyn Gutwirth, Constance B. Hieatt, Titi Adepitan, Edgar C. Knowlton, Jr., Emanuel Mussman, Sally Todd Nelson, Robert O. Preyer, David Diego Rodriguez, Guy Stern, James Thorpe, Robert J. Wilson, Rebecca S. Beal, Joyce Simutis, Betsy Bowden, Sara Cooper, Wheeler Winston Dixon, Tarek el Ariss, Richard Jewell, John W. Kronik, Wendy Martin, Stuart Y. McDougal, Hugo Méndez-Ramírez, Ivy Schweitzer, Armand E. Singer, G. Thomas Tanselle, Tom Bishop, Mary Ann Caws, Marcel Gutwirth, Christophe Ippolito, Lawrence D. Kritzman, James Longenbach, Tim McCracken, Wolfe S. Molitor, Diane Quantic, Gregory Rabassa, Ellen M. Tsagaris, Anthony C. Yu, Betty Jean Craige, Wendell V. Harris, J. Hillis Miller, Jesse G. Swan, Helene Zimmer-Loew, Peter Berek, James Chandler, Hanna K. Charney, Philip Cohen, Judith Fetterley, Herbert Lindenberger, Julia Reinhard Lupton, Maximillian E. Novak, Richard Ohmann, Marjorie Perloff, Mark Reynolds, James Sledd, Harriet Turner, Marie Umeh, Flavia Aloya, Regina Barreca, Konrad Bieber, Ellis Hanson, William J. Hyde, Holly A. Laird, David Leverenz, Allen Michie, J. Wesley Miller, Marvin Rosenberg, Daniel R. Schwarz, Elizabeth Welt Trahan, Jean Fagan Yellin
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- Journal:
- PMLA / Publications of the Modern Language Association of America / Volume 115 / Issue 7 / December 2000
- Published online by Cambridge University Press:
- 23 October 2020, pp. 1986-2078
- Print publication:
- December 2000
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Modeling cat retinal beta-cell arrays
- XUE J. ZHAN, JOHN B. TROY
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- Journal:
- Visual Neuroscience / Volume 17 / Issue 1 / January 2000
- Published online by Cambridge University Press:
- 01 January 2000, pp. 23-39
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There were three objectives to the work undertaken for this paper: (1) to provide a comprehensive characterization of the statistical properties of arrays of β-cell somata; (2) to develop a model that simulates cellular arrays with the same properties; and (3) to use this model to examine whether the array of β-cells should be viewed as one array or as two arrays, one each for its OFF- and ON-center cells. β-cells are morphological correlates of the electrophysiological X-cells and those β-cells whose dendrites stratify within the outer and inner sublamina of the retina's inner plexiform layer correspond, respectively, to OFF- and ON-center X-cells. Arrays of peripheral β-cell somata from two retinas were studied. A Delaunay triangulation and a Voronoi tessellation were generated for each array and measures derived from these constructs used to analyze the arrays' spatial organization. As others have shown previously with a less complete statistical characterization, we found that the arrays of OFF- and ON-center β-cells have similar spatial properties and are more regular than the array of all β-cells. We developed a model to simulate cellular arrays with spatial properties like those of arrays of β-cells. A good fit between model and real arrays was found when the model assumed an explicit spatial dependence between the placement of OFF- and ON-center cells. We propose therefore that a single array of β-cells formed of both OFF- and ON-center cells is consistent with the data currently available for β-cell somatic arrays.