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Beltrán González AN, López Pazos MI, Del Vas M, Calvo DJ. Negative modulation of the GABA Aρ1 receptor function by histamine. Eur J Pharmacol 2023; 955:175880. [PMID: 37406850 DOI: 10.1016/j.ejphar.2023.175880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 06/12/2023] [Accepted: 06/26/2023] [Indexed: 07/07/2023]
Abstract
Besides its function as a local mediator of the immune response, histamine can play a role as a neurotransmitter and neuromodulator. Histamine actions are classically mediated through four different G protein-coupled receptor subtypes but non-classical actions were also described, including effects on many ligand-gated ion channels. Previous evidence indicated that histamine acts as a positive modulator on diverse GABAA receptor subtypes, such as GABAAα1β2γ2, GABAAα2β3γ2, GABAAα3β3γ2, GABAAα4β3γ2 and GABAAα5β3γ2. Meanwhile, its effects on GABAAρ1 receptors, known to stand for tonic currents in retinal neurons, had not been examined before. The effects of histamine on the function of human homomeric GABAAρ1 receptors were studied here, using heterologous expression in Xenopus laevis oocytes followed by the electrophysiological recording of GABA-evoked Cl- currents. Histamine inhibited GABAAρ1 receptor-mediated responses. Effects were reversible, independent of the membrane potential, and strongly dependent on both histamine and GABA concentration. A rightward parallel shift in the concentration-response curve for GABA was observed in the presence of histamine, without substantial change in the maximal response or the Hill coefficient. Results were compatible with a competitive antagonism of histamine on the GABAAρ1 receptors. This is the first report of inhibitory actions exerted by histamine on an ionotropic GABA receptor.
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Affiliation(s)
- Andrea N Beltrán González
- Laboratorio de Neurobiología Celular y Molecular, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIByNE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires (UBA), Ciudad Autónoma de Buenos Aires, Argentina
| | - Manuel I López Pazos
- Laboratorio de Neurobiología Celular y Molecular, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIByNE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires (UBA), Ciudad Autónoma de Buenos Aires, Argentina
| | - Mariana Del Vas
- Instituto de Agrobiotecnología y Biología Molecular (IABIMO), Instituto Nacional de Tecnología Agropecuaria (INTA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Daniel J Calvo
- Laboratorio de Neurobiología Celular y Molecular, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIByNE), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires (UBA), Ciudad Autónoma de Buenos Aires, Argentina.
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2
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Ganczer A, Szarka G, Balogh M, Hoffmann G, Tengölics ÁJ, Kenyon G, Kovács-Öller T, Völgyi B. Transience of the Retinal Output Is Determined by a Great Variety of Circuit Elements. Cells 2022; 11:cells11050810. [PMID: 35269432 PMCID: PMC8909309 DOI: 10.3390/cells11050810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 02/06/2023] Open
Abstract
Retinal ganglion cells (RGCs) encrypt stimulus features of the visual scene in action potentials and convey them toward higher visual centers in the brain. Although there are many visual features to encode, our recent understanding is that the ~46 different functional subtypes of RGCs in the retina share this task. In this scheme, each RGC subtype establishes a separate, parallel signaling route for a specific visual feature (e.g., contrast, the direction of motion, luminosity), through which information is conveyed. The efficiency of encoding depends on several factors, including signal strength, adaptational levels, and the actual efficacy of the underlying retinal microcircuits. Upon collecting inputs across their respective receptive field, RGCs perform further analysis (e.g., summation, subtraction, weighting) before they generate the final output spike train, which itself is characterized by multiple different features, such as the number of spikes, the inter-spike intervals, response delay, and the rundown time (transience) of the response. These specific kinetic features are essential for target postsynaptic neurons in the brain in order to effectively decode and interpret signals, thereby forming visual perception. We review recent knowledge regarding circuit elements of the mammalian retina that participate in shaping RGC response transience for optimal visual signaling.
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Affiliation(s)
- Alma Ganczer
- Szentágothai Research Centre, University of Pécs, H-7624 Pécs, Hungary; (A.G.); (G.S.); (M.B.); (G.H.); (Á.J.T.); (T.K.-Ö.)
- Department of Experimental Zoology and Neurobiology, University of Pécs, H-7624 Pécs, Hungary
- MTA-PTE NAP 2 Retinal Electrical Synapses Research Group, H-7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, H-7624 Pécs, Hungary
| | - Gergely Szarka
- Szentágothai Research Centre, University of Pécs, H-7624 Pécs, Hungary; (A.G.); (G.S.); (M.B.); (G.H.); (Á.J.T.); (T.K.-Ö.)
- Department of Experimental Zoology and Neurobiology, University of Pécs, H-7624 Pécs, Hungary
- MTA-PTE NAP 2 Retinal Electrical Synapses Research Group, H-7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, H-7624 Pécs, Hungary
| | - Márton Balogh
- Szentágothai Research Centre, University of Pécs, H-7624 Pécs, Hungary; (A.G.); (G.S.); (M.B.); (G.H.); (Á.J.T.); (T.K.-Ö.)
- Department of Experimental Zoology and Neurobiology, University of Pécs, H-7624 Pécs, Hungary
- MTA-PTE NAP 2 Retinal Electrical Synapses Research Group, H-7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, H-7624 Pécs, Hungary
| | - Gyula Hoffmann
- Szentágothai Research Centre, University of Pécs, H-7624 Pécs, Hungary; (A.G.); (G.S.); (M.B.); (G.H.); (Á.J.T.); (T.K.-Ö.)
- Department of Experimental Zoology and Neurobiology, University of Pécs, H-7624 Pécs, Hungary
- MTA-PTE NAP 2 Retinal Electrical Synapses Research Group, H-7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, H-7624 Pécs, Hungary
| | - Ádám Jonatán Tengölics
- Szentágothai Research Centre, University of Pécs, H-7624 Pécs, Hungary; (A.G.); (G.S.); (M.B.); (G.H.); (Á.J.T.); (T.K.-Ö.)
- Department of Experimental Zoology and Neurobiology, University of Pécs, H-7624 Pécs, Hungary
- MTA-PTE NAP 2 Retinal Electrical Synapses Research Group, H-7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, H-7624 Pécs, Hungary
| | - Garrett Kenyon
- Los Alamos National Laboratory, Computer & Computational Science Division, Los Alamos, NM 87545, USA;
| | - Tamás Kovács-Öller
- Szentágothai Research Centre, University of Pécs, H-7624 Pécs, Hungary; (A.G.); (G.S.); (M.B.); (G.H.); (Á.J.T.); (T.K.-Ö.)
- Department of Experimental Zoology and Neurobiology, University of Pécs, H-7624 Pécs, Hungary
- MTA-PTE NAP 2 Retinal Electrical Synapses Research Group, H-7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, H-7624 Pécs, Hungary
| | - Béla Völgyi
- Szentágothai Research Centre, University of Pécs, H-7624 Pécs, Hungary; (A.G.); (G.S.); (M.B.); (G.H.); (Á.J.T.); (T.K.-Ö.)
- Department of Experimental Zoology and Neurobiology, University of Pécs, H-7624 Pécs, Hungary
- MTA-PTE NAP 2 Retinal Electrical Synapses Research Group, H-7624 Pécs, Hungary
- Center for Neuroscience, University of Pécs, H-7624 Pécs, Hungary
- Correspondence:
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3
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Vlasiuk A, Asari H. Feedback from retinal ganglion cells to the inner retina. PLoS One 2021; 16:e0254611. [PMID: 34292988 PMCID: PMC8297895 DOI: 10.1371/journal.pone.0254611] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 06/29/2021] [Indexed: 11/19/2022] Open
Abstract
Retinal ganglion cells (RGCs) are thought to be strictly postsynaptic within the retina. They carry visual signals from the eye to the brain, but do not make chemical synapses onto other retinal neurons. Nevertheless, they form gap junctions with other RGCs and amacrine cells, providing possibilities for RGC signals to feed back into the inner retina. Here we identified such feedback circuitry in the salamander and mouse retinas. First, using biologically inspired circuit models, we found mutual inhibition among RGCs of the same type. We then experimentally determined that this effect is mediated by gap junctions with amacrine cells. Finally, we found that this negative feedback lowers RGC visual response gain without affecting feature selectivity. The principal neurons of the retina therefore participate in a recurrent circuit much as those in other brain areas, not being a mere collector of retinal signals, but are actively involved in visual computations.
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Affiliation(s)
- Anastasiia Vlasiuk
- Epigenetics and Neurobiology Unit, EMBL Rome, European Molecular Biology Laboratory, Monterotondo, Rome, Italy
- Collaboration for joint PhD degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Hiroki Asari
- Epigenetics and Neurobiology Unit, EMBL Rome, European Molecular Biology Laboratory, Monterotondo, Rome, Italy
- * E-mail:
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Abstract
In addition to the role that our visual system plays in determining what we are seeing right now, visual computations contribute in important ways to predicting what we will see next. While the role of memory in creating future predictions is often overlooked, efficient predictive computation requires the use of information about the past to estimate future events. In this article, we introduce a framework for understanding the relationship between memory and visual prediction and review the two classes of mechanisms that the visual system relies on to create future predictions. We also discuss the principles that define the mapping from predictive computations to predictive mechanisms and how downstream brain areas interpret the predictive signals computed by the visual system. Expected final online publication date for the Annual Review of Vision Science, Volume 7 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Nicole C Rust
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104;
| | - Stephanie E Palmer
- Department of Organismal Biology and Anatomy, University of Chicago, Illinois 60637;
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5
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Wang C, Lian R, Dong X, Mi Y, Wu S. A Neural Network Model With Gap Junction for Topological Detection. Front Comput Neurosci 2020; 14:571982. [PMID: 33178003 PMCID: PMC7591819 DOI: 10.3389/fncom.2020.571982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 10/02/2020] [Indexed: 11/26/2022] Open
Abstract
Visual information processing in the brain goes from global to local. A large volume of experimental studies has suggested that among global features, the brain perceives the topological information of an image first. Here, we propose a neural network model to elucidate the underlying computational mechanism. The model consists of two parts. The first part is a neural network in which neurons are coupled through gap junctions, mimicking the neural circuit formed by alpha ganglion cells in the retina. Gap junction plays a key role in the model, which, on one hand, facilitates the synchronized firing of a neuron group covering a connected region of an image, and on the other hand, staggers the firing moments of different neuron groups covering disconnected regions of the image. These two properties endow the network with the capacity of detecting the connectivity and closure of images. The second part of the model is a read-out neuron, which reads out the topological information that has been converted into the number of synchronized firings in the retina network. Our model provides a simple yet effective mechanism for the neural system to detect the topological information of images in ultra-speed.
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Affiliation(s)
- Chaoming Wang
- Peking-Tsinghua Center for Life Sciences, School of Electronics Engineering and Computer Science, IDG/McGovern Institute for Brain Research, Peking University, Academy for Advanced Interdisceplinary Studies, Beijing, China.,Hefei Comprehensive National Science Center, Institute of Artificial Intelligence, Hefei, China.,Chinese Institute for Brain Research, Beijing, China
| | - Risheng Lian
- Peking-Tsinghua Center for Life Sciences, School of Electronics Engineering and Computer Science, IDG/McGovern Institute for Brain Research, Peking University, Academy for Advanced Interdisceplinary Studies, Beijing, China
| | - Xingsi Dong
- Peking-Tsinghua Center for Life Sciences, School of Electronics Engineering and Computer Science, IDG/McGovern Institute for Brain Research, Peking University, Academy for Advanced Interdisceplinary Studies, Beijing, China
| | - Yuanyuan Mi
- Center for Neurointelligence, School of Medicine, Chongqing University, Chongqing, China
| | - Si Wu
- Peking-Tsinghua Center for Life Sciences, School of Electronics Engineering and Computer Science, IDG/McGovern Institute for Brain Research, Peking University, Academy for Advanced Interdisceplinary Studies, Beijing, China.,Hefei Comprehensive National Science Center, Institute of Artificial Intelligence, Hefei, China
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6
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Rozenblit F, Gollisch T. What the salamander eye has been telling the vision scientist's brain. Semin Cell Dev Biol 2020; 106:61-71. [PMID: 32359891 PMCID: PMC7493835 DOI: 10.1016/j.semcdb.2020.04.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/16/2020] [Accepted: 04/16/2020] [Indexed: 12/30/2022]
Abstract
Salamanders have been habitual residents of research laboratories for more than a century, and their history in science is tightly interwoven with vision research. Nevertheless, many vision scientists - even those working with salamanders - may be unaware of how much our knowledge about vision, and particularly the retina, has been shaped by studying salamanders. In this review, we take a tour through the salamander history in vision science, highlighting the main contributions of salamanders to our understanding of the vertebrate retina. We further point out specificities of the salamander visual system and discuss the perspectives of this animal system for future vision research.
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Affiliation(s)
- Fernando Rozenblit
- Department of Ophthalmology, University Medical Center Göttingen, 37073, Göttingen, Germany; Bernstein Center for Computational Neuroscience Göttingen, 37077, Göttingen, Germany
| | - Tim Gollisch
- Department of Ophthalmology, University Medical Center Göttingen, 37073, Göttingen, Germany; Bernstein Center for Computational Neuroscience Göttingen, 37077, Göttingen, Germany.
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7
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Appleby TR, Manookin MB. Selectivity to approaching motion in retinal inputs to the dorsal visual pathway. eLife 2020; 9:e51144. [PMID: 32091390 PMCID: PMC7080407 DOI: 10.7554/elife.51144] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 02/18/2020] [Indexed: 11/13/2022] Open
Abstract
To efficiently navigate through the environment and avoid potential threats, an animal must quickly detect the motion of approaching objects. Current models of primate vision place the origins of this complex computation in the visual cortex. Here, we report that detection of approaching motion begins in the retina. Several ganglion cell types, the retinal output neurons, show selectivity to approaching motion. Synaptic current recordings from these cells further reveal that this preference for approaching motion arises in the interplay between presynaptic excitatory and inhibitory circuit elements. These findings demonstrate how excitatory and inhibitory circuits interact to mediate an ethologically relevant neural function. Moreover, the elementary computations that detect approaching motion begin early in the visual stream of primates.
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Affiliation(s)
- Todd R Appleby
- Graduate Program in Neuroscience, University of WashingtonSeattleUnited States
- Department of Ophthalmology, University of WashingtonSeattleUnited States
- Vision Science Center, University of WashingtonSeattleUnited States
| | - Michael B Manookin
- Department of Ophthalmology, University of WashingtonSeattleUnited States
- Vision Science Center, University of WashingtonSeattleUnited States
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8
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Abstract
Inhibition shapes activity and signal processing in neural networks through numerous mechanisms mediated by many different cell types. Here, we examined how one type of GABAergic interneuron in the retina, the A17 amacrine cell, influences visual information processing. Our results suggest that A17s, which make reciprocal feedback inhibitory synapses onto rod bipolar cell (RBC) synaptic terminals, extend the luminance range over which RBC synapses compute temporal contrast and enhance the reliability of contrast signals over this range. Inhibition from other amacrine cells does not influence these computational features. Although A17-mediated feedback is mediated by both GABAA and GABAC receptors, the latter plays the primary role in extending the range of contrast computation. These results identify specific functions for an inhibitory interneuron subtype, as well as specific synaptic receptors, in a behaviorally relevant neural computation.
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Affiliation(s)
- Nicholas W. Oesch
- Synaptic Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, MD 20892-3701
- Present address: University of California, San Diego, Department of Psychology, Department of Ophthalmology, 9500 Gilman Drive MC#0109, La Jolla, CA 92093-0109
| | - Jeffrey S. Diamond
- Synaptic Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, MD 20892-3701
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9
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Murphy-Baum BL, Taylor WR. Diverse inhibitory and excitatory mechanisms shape temporal tuning in transient OFF α ganglion cells in the rabbit retina. J Physiol 2018; 596:477-495. [PMID: 29222817 DOI: 10.1113/jp275195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 11/23/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Neurons combine excitatory and inhibitory signals to perform computations. In the retina, interactions between excitation and inhibition enable neurons to detect specific visual features. We describe how several excitatory and inhibitory mechanisms work together to allow transient OFF α ganglion cells in the rabbit retina to respond selectively to high temporal frequencies and thus detect faster image motion. The weightings of these different mechanisms change with the contrast and spatiotemporal properties of the visual input, and thereby support temporal tuning in α cells over a range of visual conditions. The results help us understand how ganglion cells selectively integrate excitatory and inhibitory signals to extract specific information from the visual input. ABSTRACT The 20 to 30 types of ganglion cell in the mammalian retina represent parallel signalling pathways that convey different information to the brain. α ganglion cells are selective for high temporal frequencies in visual inputs, which makes them particularly sensitive to rapid motion. Although α ganglion cells have been studied in several species, the synaptic basis for their selective temporal tuning remains unclear. Here, we analyse excitatory synaptic inputs to transient OFF α ganglion cells (t-OFF α GCs) in the rabbit retina. We show that convergence of excitatory and inhibitory synaptic inputs within the bipolar cell terminals presynaptic to the t-OFF α GCs shifts the temporal tuning to higher temporal frequencies. GABAergic inhibition suppresses the excitatory input at low frequencies, but potentiates it at high frequencies. Crossover glycinergic inhibition and sodium channel activity in the presynaptic bipolar cells also potentiate high frequency excitatory inputs. We found differences in the spatial and temporal properties, and contrast sensitivities of these mechanisms. These differences in stimulus selectivity allow these mechanisms to generate bandpass temporal tuning of t-OFF α GCs over a range of visual conditions.
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Affiliation(s)
- Benjamin L Murphy-Baum
- Casey Eye Institute, Department of Ophthalmology, Oregon Health and Science University, 3375 SW Terwilliger Boulevard, Portland, OR, 97239, USA
| | - W Rowland Taylor
- Casey Eye Institute, Department of Ophthalmology, Oregon Health and Science University, 3375 SW Terwilliger Boulevard, Portland, OR, 97239, USA
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10
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Beltrán González AN, Vicentini F, Calvo DJ. Negative modulation of the GABA A ρ1 receptor function by l-cysteine. J Neurochem 2017; 144:50-57. [PMID: 29023772 DOI: 10.1111/jnc.14237] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/12/2017] [Accepted: 10/04/2017] [Indexed: 11/28/2022]
Abstract
l-Cysteine is an endogenous sulfur-containing amino acid with multiple and varied roles in the central nervous system, including neuroprotection and the maintenance of the redox balance. However, it was also suggested as an excitotoxic agent implicated in the pathogenesis of neurological disorders such as Parkinson's and Alzheimer's disease. l-Cysteine can modulate the activity of ionic channels, including voltage-gated calcium channels and glutamatergic NMDA receptors, whereas its effects on GABAergic neurotransmission had not been studied before. In the present work, we analyzed the effects of l-cysteine on responses mediated by homomeric GABAA ρ1 receptors, which are known for mediating tonic γ-aminobutyric acid (GABA) responses in retinal neurons. GABAA ρ1 receptors were expressed in Xenopus laevis oocytes and GABA-evoked chloride currents recorded by two-electrode voltage-clamp in the presence or absence of l-cysteine. l-Cysteine antagonized GABAA ρ1 receptor-mediated responses; inhibition was dose-dependent, reversible, voltage independent, and susceptible to GABA concentration. Concentration-response curves for GABA were shifted to the right in the presence of l-cysteine without a substantial change in the maximal response. l-Cysteine inhibition was insensitive to chemical protection of the sulfhydryl groups of the ρ1 subunits by the irreversible alkylating agent N-ethyl maleimide. Our results suggest that redox modulation is not involved during l-cysteine actions and that l-cysteine might be acting as a competitive antagonist of the GABAA ρ1 receptors.
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Affiliation(s)
- Andrea N Beltrán González
- Laboratorio de Neurobiología Celular y Molecular, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Florencia Vicentini
- Laboratorio de Neurobiología Celular y Molecular, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Daniel J Calvo
- Laboratorio de Neurobiología Celular y Molecular, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres" (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
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11
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Mohammadi E, Shamsizadeh A, Salari E, Fatemi I, Allahtavakoli M, Roohbakhsh A. Effect of TPMPA (GABACreceptor antagonist) on neuronal response properties in rat barrel cortex. Somatosens Mot Res 2017; 34:108-115. [DOI: 10.1080/08990220.2017.1317240] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Elham Mohammadi
- Physiology–Pharmacology Research Center, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
- Department of Physiology and Pharmacology, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
| | - Ali Shamsizadeh
- Physiology–Pharmacology Research Center, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
- Department of Physiology and Pharmacology, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
| | - Elham Salari
- Physiology–Pharmacology Research Center, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
- Department of Physiology and Pharmacology, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
| | - Iman Fatemi
- Physiology–Pharmacology Research Center, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
- Department of Physiology and Pharmacology, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
| | - Mohammad Allahtavakoli
- Physiology–Pharmacology Research Center, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
- Department of Physiology and Pharmacology, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
| | - Ali Roohbakhsh
- Pharmaceutical Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
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12
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Popova E, Kupenova P. Interaction between the serotoninergic and GABAergic systems in frog retina as revealed by electroretinogram. Acta Neurobiol Exp (Wars) 2017. [DOI: 10.21307/ane-2017-067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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13
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Grabner CP, Ratliff CP, Light AC, DeVries SH. Mechanism of High-Frequency Signaling at a Depressing Ribbon Synapse. Neuron 2016; 91:133-45. [PMID: 27292536 DOI: 10.1016/j.neuron.2016.05.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 02/26/2016] [Accepted: 05/05/2016] [Indexed: 12/21/2022]
Abstract
Ribbon synapses mediate continuous release in neurons that have graded voltage responses. While mammalian retinas can signal visual flicker at 80-100 Hz, the time constant, τ, for the refilling of a depleted vesicle release pool at cone photoreceptor ribbons is 0.7-1.1 s. Due to this prolonged depression, the mechanism for encoding high temporal frequencies is unclear. To determine the mechanism of high-frequency signaling, we focused on an "Off" cone bipolar cell type in the ground squirrel, the cb2, whose transient postsynaptic responses recovered following presynaptic depletion with a τ of ∼0.1 s, or 7- to 10-fold faster than the τ for presynaptic pool refilling. The difference in recovery time course is caused by AMPA receptor saturation, where partial refilling of the presynaptic pool is sufficient for a full postsynaptic response. By limiting the dynamic range of the synapse, receptor saturation counteracts ribbon depression to produce rapid recovery and facilitate high-frequency signaling.
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Affiliation(s)
- Chad P Grabner
- Departments of Ophthalmology and Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Charles P Ratliff
- Departments of Ophthalmology and Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Adam C Light
- Departments of Ophthalmology and Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Steven H DeVries
- Departments of Ophthalmology and Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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14
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Mazade RE, Eggers ED. Light adaptation alters inner retinal inhibition to shape OFF retinal pathway signaling. J Neurophysiol 2016; 115:2761-78. [PMID: 26912599 DOI: 10.1152/jn.00948.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 02/20/2016] [Indexed: 12/18/2022] Open
Abstract
The retina adjusts its signaling gain over a wide range of light levels. A functional result of this is increased visual acuity at brighter luminance levels (light adaptation) due to shifts in the excitatory center-inhibitory surround receptive field parameters of ganglion cells that increases their sensitivity to smaller light stimuli. Recent work supports the idea that changes in ganglion cell spatial sensitivity with background luminance are due in part to inner retinal mechanisms, possibly including modulation of inhibition onto bipolar cells. To determine how the receptive fields of OFF cone bipolar cells may contribute to changes in ganglion cell resolution, the spatial extent and magnitude of inhibitory and excitatory inputs were measured from OFF bipolar cells under dark- and light-adapted conditions. There was no change in the OFF bipolar cell excitatory input with light adaptation; however, the spatial distributions of inhibitory inputs, including both glycinergic and GABAergic sources, became significantly narrower, smaller, and more transient. The magnitude and size of the OFF bipolar cell center-surround receptive fields as well as light-adapted changes in resting membrane potential were incorporated into a spatial model of OFF bipolar cell output to the downstream ganglion cells, which predicted an increase in signal output strength with light adaptation. We show a prominent role for inner retinal spatial signals in modulating the modeled strength of bipolar cell output to potentially play a role in ganglion cell visual sensitivity and acuity.
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Affiliation(s)
- Reece E Mazade
- Departments of Physiology and Biomedical Engineering, University of Arizona, Tucson, Arizona
| | - Erika D Eggers
- Departments of Physiology and Biomedical Engineering, University of Arizona, Tucson, Arizona
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15
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Yan RJ, Gong HQ, Zhang PM, He SG, Liang PJ. Temporal properties of dual-peak responses of mouse retinal ganglion cells and effects of inhibitory pathways. Cogn Neurodyn 2016; 10:211-23. [PMID: 27275377 DOI: 10.1007/s11571-015-9374-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 12/08/2015] [Accepted: 12/24/2015] [Indexed: 11/26/2022] Open
Abstract
Dual-peak responses of retinal ganglion cells (RGCs) are observed in various species, previous researches suggested that both response peaks were involved in retinal information coding. In the present study, we investigated the temporal properties of the dual-peak responses recorded in mouse RGCs elicited by spatially homogeneous light flashes and the effect of the inhibitory inputs mediated by GABAergic and/or glycinergic pathways. We found that the two peaks in the dual-peak responses exhibited distinct temporal dynamics, similar to that of short-latency and long-latency single-peak responses respectively. Pharmacological studies demonstrated that the application of exogenous GABA or glycine greatly suppressed or even eliminated the second peak of the cells' firing activities, while little change was induced in the first peak. Co-application of glycine and GABA led to complete elimination of the second peak. Moreover, application of picrotoxin or strychnine induced dual-peak responses in some cells with transient responses by unmasking a second response phase. These results suggest that both GABAergic and glycinergic pathways are involved in the dual-peak responses of the mouse RGCs, and the two response peaks may arise from distinct pathways that would converge on the ganglion cells.
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Affiliation(s)
- Ru-Jia Yan
- School of Biomedical Engineering, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai, 200240 China
| | - Hai-Qing Gong
- School of Biomedical Engineering, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai, 200240 China
| | - Pu-Ming Zhang
- School of Biomedical Engineering, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai, 200240 China
| | - Shi-Gang He
- School of Biomedical Engineering, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai, 200240 China
| | - Pei-Ji Liang
- School of Biomedical Engineering, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai, 200240 China
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16
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The Synaptic and Morphological Basis of Orientation Selectivity in a Polyaxonal Amacrine Cell of the Rabbit Retina. J Neurosci 2015; 35:13336-50. [PMID: 26424882 DOI: 10.1523/jneurosci.1712-15.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Much of the computational power of the retina derives from the activity of amacrine cells, a large and diverse group of GABAergic and glycinergic inhibitory interneurons. Here, we identify an ON-type orientation-selective, wide-field, polyaxonal amacrine cell (PAC) in the rabbit retina and demonstrate how its orientation selectivity arises from the structure of the dendritic arbor and the pattern of excitatory and inhibitory inputs. Excitation from ON bipolar cells and inhibition arising from the OFF pathway converge to generate a quasi-linear integration of visual signals in the receptive field center. This serves to suppress responses to high spatial frequencies, thereby improving sensitivity to larger objects and enhancing orientation selectivity. Inhibition also regulates the magnitude and time course of excitatory inputs to this PAC through serial inhibitory connections onto the presynaptic terminals of ON bipolar cells. This presynaptic inhibition is driven by graded potentials within local microcircuits, similar in extent to the size of single bipolar cell receptive fields. Additional presynaptic inhibition is generated by spiking amacrine cells on a larger spatial scale covering several hundred microns. The orientation selectivity of this PAC may be a substrate for the inhibition that mediates orientation selectivity in some types of ganglion cells. Significance statement: The retina comprises numerous excitatory and inhibitory circuits that encode specific features in the visual scene, such as orientation, contrast, or motion. Here, we identify a wide-field inhibitory neuron that responds to visual stimuli of a particular orientation, a feature selectivity that is primarily due to the elongated shape of the dendritic arbor. Integration of convergent excitatory and inhibitory inputs from the ON and OFF visual pathways suppress responses to small objects and fine textures, thus enhancing selectivity for larger objects. Feedback inhibition regulates the strength and speed of excitation on both local and wide-field spatial scales. This study demonstrates how different synaptic inputs are regulated to tune a neuron to respond to specific features in the visual scene.
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17
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Walker MT, Rupp A, Elsaesser R, Güler AD, Sheng W, Weng S, Berson DM, Hattar S, Montell C. RdgB2 is required for dim-light input into intrinsically photosensitive retinal ganglion cells. Mol Biol Cell 2015; 26:3671-8. [PMID: 26269578 PMCID: PMC4603936 DOI: 10.1091/mbc.e15-05-0288] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 07/30/2015] [Accepted: 08/06/2015] [Indexed: 12/21/2022] Open
Abstract
A subset of retinal ganglion cells is intrinsically photosensitive (ipRGCs) and contributes directly to the pupillary light reflex and circadian photoentrainment under bright-light conditions. ipRGCs are also indirectly activated by light through cellular circuits initiated in rods and cones. A mammalian homologue (RdgB2) of a phosphoinositide transfer/exchange protein that functions in Drosophila phototransduction is expressed in the retinal ganglion cell layer. This raised the possibility that RdgB2 might function in the intrinsic light response in ipRGCs, which depends on a cascade reminiscent of Drosophila phototransduction. Here we found that under high light intensities, RdgB2(-/-) mutant mice showed normal pupillary light responses and circadian photoentrainment. Consistent with this behavioral phenotype, the intrinsic light responses of ipRGCs in RdgB2(-/-) were indistinguishable from wild-type. In contrast, under low-light conditions, RdgB2(-/-) mutants displayed defects in both circadian photoentrainment and the pupillary light response. The RdgB2 protein was not expressed in ipRGCs but was in GABAergic amacrine cells, which provided inhibitory feedback onto bipolar cells. We propose that RdgB2 is required in a cellular circuit that transduces light input from rods to bipolar cells that are coupled to GABAergic amacrine cells and ultimately to ipRGCs, thereby enabling ipRGCs to respond to dim light.
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Affiliation(s)
- Marquis T Walker
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Alan Rupp
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218
| | - Rebecca Elsaesser
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Ali D Güler
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218 Department of Biology, University of Virginia, Charlottesville, VA 22903
| | - Wenlong Sheng
- Institute of Neurobiology, Institute of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200032, China
| | - Shijun Weng
- Institute of Neurobiology, Institute of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200032, China Department of Neuroscience, Brown University, Providence, RI 02912
| | - David M Berson
- Department of Neuroscience, Brown University, Providence, RI 02912
| | - Samer Hattar
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218
| | - Craig Montell
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205 Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara CA 93106
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18
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Tadavarty R, Hwang J, Rajput P, Soja P, Kumar U, Sastry B. Are presynaptic GABA-Cρ2 receptors involved in anti-nociception? Neurosci Lett 2015; 606:145-50. [DOI: 10.1016/j.neulet.2015.08.049] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 08/25/2015] [Accepted: 08/26/2015] [Indexed: 11/24/2022]
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19
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All spiking, sustained ON displaced amacrine cells receive gap-junction input from melanopsin ganglion cells. Curr Biol 2015; 25:2763-2773. [PMID: 26441349 DOI: 10.1016/j.cub.2015.09.018] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 08/15/2015] [Accepted: 09/05/2015] [Indexed: 11/22/2022]
Abstract
Retinal neurons exhibit sustained versus transient light responses, which are thought to encode low- and high-frequency stimuli, respectively. This dichotomy has been recognized since the earliest intracellular recordings from the 1960s, but the underlying mechanisms are not yet fully understood. We report that in the ganglion cell layer of rat retinas, all spiking amacrine interneurons with sustained ON photoresponses receive gap-junction input from intrinsically photosensitive retinal ganglion cells (ipRGCs), recently discovered photoreceptors that specialize in prolonged irradiance detection. This input presumably allows ipRGCs to regulate the secretion of neuromodulators from these interneurons. We have identified three morphological varieties of such ipRGC-driven displaced amacrine cells: (1) monostratified cells with dendrites terminating exclusively in sublamina S5 of the inner plexiform layer, (2) bistratified cells with dendrites in both S1 and S5, and (3) polyaxonal cells with dendrites and axons stratifying in S5. Most of these amacrine cells are wide field, although some are medium field. The three classes respond to light differently, suggesting that they probably perform diverse functions. These results demonstrate that ipRGCs are a major source of tonic visual information within the retina and exert widespread intraretinal influence. They also add to recent evidence that ganglion cells signal not only to the brain.
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20
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Popova E. GABAergic neurotransmission and retinal ganglion cell function. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2015; 201:261-83. [PMID: 25656810 DOI: 10.1007/s00359-015-0981-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 01/19/2015] [Accepted: 01/21/2015] [Indexed: 01/13/2023]
Abstract
Ganglion cells are the output retinal neurons that convey visual information to the brain. There are ~20 different types of ganglion cells, each encoding a specific aspect of the visual scene as spatial and temporal contrast, orientation, direction of movement, presence of looming stimuli; etc. Ganglion cell functioning depends on the intrinsic properties of ganglion cell's membrane as well as on the excitatory and inhibitory inputs that these cells receive from other retinal neurons. GABA is one of the most abundant inhibitory neurotransmitters in the retina. How it modulates the activity of different types of ganglion cells and what is its significance in extracting the basic features from visual scene are questions with fundamental importance in visual neuroscience. The present review summarizes current data concerning the types of membrane receptors that mediate GABA action in proximal retina; the effects of GABA and its antagonists on the ganglion cell light-evoked postsynaptic potentials and spike discharges; the action of GABAergic agents on centre-surround organization of the receptive fields and feature related ganglion cell activity. Special emphasis is put on the GABA action regarding the ON-OFF and sustained-transient ganglion cell dichotomy in both nonmammalian and mammalian retina.
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Affiliation(s)
- E Popova
- Department of Physiology, Medical Faculty, Medical University, 1431, Sofia, Bulgaria,
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21
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Abstract
To make up for delays in visual processing, retinal circuitry effectively predicts that a moving object will continue moving in a straight line, allowing retinal ganglion cells to anticipate the object's position. However, a sudden reversal of motion triggers a synchronous burst of firing from a large group of ganglion cells, possibly signaling a violation of the retina's motion prediction. To investigate the neural circuitry underlying this response, we used a combination of multielectrode array and whole-cell patch recordings to measure the responses of individual retinal ganglion cells in the tiger salamander to reversing stimuli. We found that different populations of ganglion cells were responsible for responding to the reversal of different kinds of objects, such as bright versus dark objects. Using pharmacology and designed stimuli, we concluded that ON and OFF bipolar cells both contributed to the reversal response, but that amacrine cells had, at best, a minor role. This allowed us to formulate an adaptive cascade model (ACM), similar to the one previously used to describe ganglion cell responses to motion onset. By incorporating the ON pathway into the ACM, we were able to reproduce the time-varying firing rate of fast OFF ganglion cells for all experimentally tested stimuli. Analysis of the ACM demonstrates that bipolar cell gain control is primarily responsible for generating the synchronized retinal response, as individual bipolar cells require a constant time delay before recovering from gain control.
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22
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Moore-Dotson JM, Klein JS, Mazade RE, Eggers ED. Different types of retinal inhibition have distinct neurotransmitter release properties. J Neurophysiol 2015; 113:2078-90. [PMID: 25568157 DOI: 10.1152/jn.00447.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 01/06/2015] [Indexed: 01/27/2023] Open
Abstract
Neurotransmitter release varies between neurons due to differences in presynaptic mechanisms such as Ca(2+) sensitivity and timing. Retinal rod bipolar cells respond to brief dim illumination with prolonged glutamate release that is tuned by the differential release of GABA and glycine from amacrine cells in the inner retina. To test if differences among types of GABA and glycine release are due to inherent amacrine cell release properties, we directly activated amacrine cell neurotransmitter release by electrical stimulation. We found that the timing of electrically evoked inhibitory currents was inherently slow and that the timecourse of inhibition from slowest to fastest was GABAC receptors > glycine receptors > GABAA receptors. Deconvolution analysis showed that the distinct timing was due to differences in prolonged GABA and glycine release from amacrine cells. The timecourses of slow glycine release and GABA release onto GABAC receptors were reduced by Ca(2+) buffering with EGTA-AM and BAPTA-AM, but faster GABA release on GABAA receptors was not, suggesting that release onto GABAA receptors is tightly coupled to Ca(2+). The differential timing of GABA release was detected from spiking amacrine cells and not nonspiking A17 amacrine cells that form a reciprocal synapse with rod bipolar cells. Our results indicate that release from amacrine cells is inherently asynchronous and that the source of nonreciprocal rod bipolar cell inhibition differs between GABA receptors. The slow, differential timecourse of inhibition may be a mechanism to match the prolonged rod bipolar cell glutamate release and provide a way to temporally tune information across retinal pathways.
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Affiliation(s)
- Johnnie M Moore-Dotson
- Department of Physiology, University of Arizona, Tucson, Arizona; Department of Biomedical Engineering, University of Arizona, Tucson, Arizona; and
| | - Justin S Klein
- Department of Physiology, University of Arizona, Tucson, Arizona; Department of Biomedical Engineering, University of Arizona, Tucson, Arizona; and
| | - Reece E Mazade
- Graduate Interdisciplinary Program in Physiological Sciences, University of Arizona, Tucson, Arizona
| | - Erika D Eggers
- Department of Physiology, University of Arizona, Tucson, Arizona; Department of Biomedical Engineering, University of Arizona, Tucson, Arizona; and
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23
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Beltrán González AN, Gasulla J, Calvo DJ. An intracellular redox sensor for reactive oxygen species at the M3-M4 linker of GABAA ρ1 receptors. Br J Pharmacol 2014; 171:2291-9. [PMID: 24428763 DOI: 10.1111/bph.12581] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 11/08/2013] [Accepted: 11/14/2013] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND AND PURPOSE Reactive oxygen species (ROS) are normally involved in cell oxidative stress but also play a role as cellular messengers in redox signalling; for example, modulating the activity of neurotransmitter receptors and ion channels. However, the direct actions of ROS on GABAA receptors were not previously demonstrated. In the present work, we studied the effects of ROS on GABAA ρ1 receptor function. EXPERIMENTAL APPROACH GABAA ρ1 receptors were expressed in oocytes and GABA-evoked responses electrophysiologically recorded in the presence or absence of ROS. Chemical protection of cysteines by selective sulfhydryl reagents and site-directed mutagenesis studies were used to identify protein residues involved in ROS actions. KEY RESULTS GABAA ρ1 receptor-mediated responses were significantly enhanced in a concentration-dependent and reversible manner by H₂O₂. Potentiating effects were attenuated by a free radical scavenger, lipoic acid or an inhibitor of the Fenton reaction, deferoxamine. Each ρ1 subunit contains only three cysteine residues, two extracellular at the Cys-loop (C¹⁷⁷ and C¹⁹¹) and one intracellular (C³⁶⁴) at the M3-M4 linker. Mutant GABAA ρ1 receptors in which C³⁶⁴ was exchanged by alanine were completely insensitive to modulation, implying that this site, rather than a cysteine in the Cys-loop, is essential for ROS modulation. CONCLUSION AND IMPLICATIONS Our results show that the function of GABAA ρ1 receptors is enhanced by ROS and that the intracellular C³⁶⁴ is the sensor for ROS actions.
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24
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Popova E. Ionotropic GABA Receptors and Distal Retinal ON and OFF Responses. SCIENTIFICA 2014; 2014:149187. [PMID: 25143858 PMCID: PMC4131092 DOI: 10.1155/2014/149187] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 04/24/2014] [Accepted: 05/27/2014] [Indexed: 05/27/2023]
Abstract
In the vertebrate retina, visual signals are segregated into parallel ON and OFF pathways, which provide information for light increments and decrements. The segregation is first evident at the level of the ON and OFF bipolar cells in distal retina. The activity of large populations of ON and OFF bipolar cells is reflected in the b- and d-waves of the diffuse electroretinogram (ERG). The role of gamma-aminobutyric acid (GABA), acting through ionotropic GABA receptors in shaping the ON and OFF responses in distal retina, is a matter of debate. This review summarized current knowledge about the types of the GABAergic neurons and ionotropic GABA receptors in the retina as well as the effects of GABA and specific GABAA and GABAC receptor antagonists on the activity of the ON and OFF bipolar cells in both nonmammalian and mammalian retina. Special emphasis is put on the effects on b- and d-waves of the ERG as a useful tool for assessment of the overall function of distal retinal ON and OFF channels. The role of GABAergic system in establishing the ON-OFF asymmetry concerning the time course and absolute and relative sensitivity of the ERG responses under different conditions of light adaptation in amphibian retina is also discussed.
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Affiliation(s)
- E. Popova
- Department of Physiology, Medical Faculty, Medical University, 1431 Sofia, Bulgaria
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25
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Asari H, Meister M. The projective field of retinal bipolar cells and its modulation by visual context. Neuron 2014; 81:641-52. [PMID: 24507195 DOI: 10.1016/j.neuron.2013.11.029] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2013] [Indexed: 10/25/2022]
Abstract
The receptive field of a sensory neuron spells out all the receptor inputs it receives. To understand a neuron's role in the circuit, one also needs to know its projective field, namely the outputs it sends to all downstream cells. Here we present the projective fields of the primary excitatory neurons in a sensory circuit. We stimulated single bipolar cells of the salamander retina and recorded simultaneously from a population of ganglion cells. Individual bipolar cell signals diverge through polysynaptic pathways into ganglion cells of many different types and over surprisingly large distance. However, the strength and polarity of the projection depend on the cell types involved. Furthermore, visual stimulation strongly modulates the bipolar cell projective field, in opposite direction for different cell types. In this way, the context from distant parts of the visual field can control the routing of signals in the inner retina.
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Affiliation(s)
- Hiroki Asari
- Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Markus Meister
- Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
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26
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Toychiev AH, Yee CW, Sagdullaev BT. Correlated spontaneous activity persists in adult retina and is suppressed by inhibitory inputs. PLoS One 2013; 8:e77658. [PMID: 24204906 PMCID: PMC3812233 DOI: 10.1371/journal.pone.0077658] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 09/04/2013] [Indexed: 11/29/2022] Open
Abstract
Spontaneous rhythmic activity is a hallmark feature of the developing retina, where propagating retinal waves instruct axonal targeting and synapse formation. Retinal waves cease around the time of eye-opening; however, the fate of the underlying synaptic circuitry is unknown. Whether retinal waves are unique to the developing retina or if they can be induced in adulthood is not known. Combining patch-clamp techniques with calcium imaging, we demonstrate that propagative events persist in adult mouse retina when it is deprived of inhibitory input. This activity originates in bipolar cells, resembling glutamatergic stage III retinal waves. We find that, as it develops, the network interactions progressively curtail this activity. Together, this provides evidence that the correlated propagative neuronal activity can be induced in adult retina following the blockade of inhibitory interactions.
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Affiliation(s)
- Abduqodir H Toychiev
- Department of Neurology, Weill Medical College of Cornell University, New York, New York, United States of America ; Department of Ophthalmology, Weill Medical College of Cornell University, New York, New York, United States of America
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27
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Identifying cell class specific losses from serially generated electroretinogram components. BIOMED RESEARCH INTERNATIONAL 2013; 2013:796362. [PMID: 24089688 PMCID: PMC3781995 DOI: 10.1155/2013/796362] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 07/08/2013] [Indexed: 11/18/2022]
Abstract
Purpose. Processing of information through the cellular layers of the retina occurs in a serial manner. In the electroretinogram (ERG), this complicates interpretation of inner retinal changes as dysfunction may arise from “upstream” neurons or may indicate a direct loss to that neural generator. We propose an approach that addresses this issue by defining ERG gain relationships. Methods. Regression analyses between two serial ERG parameters in a control cohort of rats are used to define gain relationships. These gains are then applied to two models of retinal disease. Results. The PIIIamp to PIIamp gain is unity whereas the PIIamp to pSTRamp and PIIamp to nSTRamp gains are greater than unity, indicating “amplification” (P < 0.05). Timing relationships show amplification between PIIIit to PIIit and compression for PIIit to pSTRit and PIIit to nSTRit, (P < 0.05). Application of these gains to ω-3-deficiency indicates that all timing changes are downstream of photoreceptor changes, but a direct pSTR amplitude loss occurs (P < 0.05). Application to diabetes indicates widespread inner retinal dysfunction which cannot be attributed to outer retinal changes (P < 0.05). Conclusions. This simple approach aids in the interpretation of inner retinal ERG changes by taking into account gain characteristics found between successive ERG components of normal animals.
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28
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Freifeld L, Clark DA, Schnitzer MJ, Horowitz MA, Clandinin TR. GABAergic lateral interactions tune the early stages of visual processing in Drosophila. Neuron 2013; 78:1075-89. [PMID: 23791198 DOI: 10.1016/j.neuron.2013.04.024] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/28/2013] [Indexed: 11/19/2022]
Abstract
Early stages of visual processing must capture complex, dynamic inputs. While peripheral neurons often implement efficient encoding by exploiting natural stimulus statistics, downstream neurons are specialized to extract behaviorally relevant features. How do these specializations arise? We use two-photon imaging in Drosophila to characterize a first-order interneuron, L2, that provides input to a pathway specialized for detecting moving dark edges. GABAergic interactions, mediated in part presynaptically, create an antagonistic and anisotropic center-surround receptive field. This receptive field is spatiotemporally coupled, applying differential temporal processing to large and small dark objects, achieving significant specialization. GABAergic circuits also mediate OFF responses and balance these with responses to ON stimuli. Remarkably, the functional properties of L2 are strikingly similar to those of bipolar cells, yet emerge through different molecular and circuit mechanisms. Thus, evolution appears to have converged on a common strategy for processing visual information at the first synapse.
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Affiliation(s)
- Limor Freifeld
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
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29
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Tanaka M, Tachibana M. Independent control of reciprocal and lateral inhibition at the axon terminal of retinal bipolar cells. J Physiol 2013; 591:3833-51. [PMID: 23690563 DOI: 10.1113/jphysiol.2013.253179] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Bipolar cells (BCs), the second order neurons in the vertebrate retina, receive two types of GABAergic feedback inhibition at their axon terminal: reciprocal and lateral inhibition. It has been suggested that two types of inhibition may be mediated by different pathways. However, how each inhibition is controlled by excitatory BC output remains to be clarified. Here, we applied single/dual whole cell recording techniques to the axon terminal of electrically coupled BCs in slice preparation of the goldfish retina, and found that each inhibition was regulated independently. Activation voltage of each inhibition was different: strong output from a single BC activated reciprocal inhibition, but could not activate lateral inhibition. Outputs from multiple BCs were essential for activation of lateral inhibition. Pharmacological examinations revealed that composition of transmitter receptors and localization of Na(+) channels were different between two inhibitory pathways, suggesting that different amacrine cells may mediate each inhibition. Depending on visual inputs, each inhibition could be driven independently. Model simulation showed that reciprocal and lateral inhibition cooperatively reduced BC outputs as well as background noise, thereby preserving high signal-to-noise ratio. Therefore, we conclude that excitatory BC output is efficiently regulated by the dual operating mechanisms of feedback inhibition without deteriorating the quality of visual signals.
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Affiliation(s)
- Masashi Tanaka
- Department of Psychology, Graduate School of Humanities and Sociology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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30
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Eggers ED, Klein JS, Moore-Dotson JM. Slow changes in Ca2(+) cause prolonged release from GABAergic retinal amacrine cells. J Neurophysiol 2013; 110:709-19. [PMID: 23657284 DOI: 10.1152/jn.00913.2012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The timing of neurotransmitter release from neurons can be modulated by many presynaptic mechanisms. The retina uses synaptic ribbons to mediate slow graded glutamate release from bipolar cells that carry photoreceptor inputs. However, many inhibitory amacrine cells, which modulate bipolar cell output, spike and do not have ribbons for graded release. Despite this, slow glutamate release from bipolar cells is modulated by slow GABAergic inputs that shorten the output of bipolar cells, changing the timing of visual signaling. The time course of light-evoked inhibition is slow due to a combination of receptor properties and prolonged neurotransmitter release. However, the light-evoked release of GABA requires activation of neurons upstream from the amacrine cells, so it is possible that prolonged release is due to slow amacrine cell activation, rather than slow inherent release properties of the amacrine cells. To test this idea, we directly activated primarily action potential-dependent amacrine cell inputs to bipolar cells with electrical stimulation. We found that the decay of GABAC receptor-mediated electrically evoked inhibitory currents was significantly longer than would be predicted by GABAC receptor kinetics, and GABA release, estimated by deconvolution analysis, was inherently slow. Release became more transient after increasing slow Ca(2+) buffering or blocking prolonged L-type Ca(2+) channels and Ca(2+) release from intracellular stores. Our results suggest that GABAergic amacrine cells have a prolonged buildup of Ca(2+) in their terminals that causes slow, asynchronous release. This could be a mechanism of matching the time course of amacrine cell inhibition to bipolar cell glutamate release.
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Affiliation(s)
- Erika D Eggers
- Department of Physiology, University of Arizona, Tucson, AZ 85724, USA.
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31
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Eggers ED, Mazade RE, Klein JS. Inhibition to retinal rod bipolar cells is regulated by light levels. J Neurophysiol 2013; 110:153-61. [PMID: 23596335 DOI: 10.1152/jn.00872.2012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The retina responds to a wide range of light stimuli by adaptation of retinal signaling to background light intensity and the use of two different photoreceptors: rods that sense dim light and cones that sense bright light. Rods signal to rod bipolar cells that receive significant inhibition from amacrine cells in the dark, especially from a rod bipolar cell-activated GABAergic amacrine cell. This inhibition modulates the output of rod bipolar cells onto downstream neurons. However, it was not clear how the inhibition of rod bipolar cells changes when rod signaling is limited by an adapting background light and cone signaling becomes dominant. We found that both light-evoked and spontaneous rod bipolar cell inhibition significantly decrease with light adaptation. This suggests a global decrease in the activity of amacrine cells that provide input to rod bipolar cells with light adaptation. However, inhibition to rod bipolar cells is also limited by GABAergic connections between amacrine cells, which decrease GABAergic input to rod bipolar cells. When we removed this serial inhibition, the light-evoked inhibition to rod bipolar cells remained after light adaptation. These results suggest that decreased inhibition to rod bipolar cells after light adaptation is due to decreased rod pathway activity as well as an active increase in inhibition between amacrine cells. Together these serve to limit rod bipolar cell inhibition after light adaptation, when the rod pathway is inactive and modulation of the signal is not required. This suggests an efficiency mechanism in the retina to limit unnecessary signaling.
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Affiliation(s)
- Erika D Eggers
- Department of Physiology, University of Arizona, Tucson, Arizona 85724, USA.
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Gasulla J, Beltrán González AN, Calvo DJ. Nitric oxide potentiation of the homomeric ρ1 GABA(C) receptor function. Br J Pharmacol 2013; 167:1369-77. [PMID: 22747884 DOI: 10.1111/j.1476-5381.2012.02087.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND AND PURPOSE NO is a highly diffusible and reactive gas produced in the nervous system, which acts as a neuronal signal mediating physiological or pathological mechanisms. NO can modulate the activity of neurotransmitter receptors and ion channels, including NMDA and GABA(A) receptors. In the present work, we examined whether GABA(C) receptor function can also be regulated by NO. EXPERIMENTAL APPROACH Homomeric ρ1 GABA(C) receptors were expressed in oocytes and GABA-evoked responses electrophysiologically recorded in the presence or absence of the NO donor DEA. Chemical protection of cysteines by selective sulfhydryl reagents and site-directed mutagenesis were used to determine the protein residues involved in the actions of NO. KEY RESULTS GABAρ1 receptor responses were significantly enhanced in a dose-dependent, fast and reversible manner by DEA and the specific NO scavenger CPTIO prevented these potentiating effects. The ρ1 subunits contain only three cysteine residues, two extracellular at the Cys-loop (C177 and C191) and one intracellular (C364). Mutations of C177 and C191 render the ρ1 GABA receptors non-functional, but C364 can be safely exchanged by alanine (C364A). NEM, N-ethyl maleimide and (2-aminoethyl) methanethiosulfonate prevented the effects of DEA on GABAρ1 receptors. Meanwhile, the potentiating effects of DEA on mutant GABAρ1(C364A) receptors were similar to those observed on wild-type receptors. CONCLUSIONS AND IMPLICATIONS Our results suggest that the function of GABA(C) receptors can be enhanced by NO acting at the extracellular Cys-loop.
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Affiliation(s)
- J Gasulla
- Laboratorio de Neurobiología Celular y Molecular, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
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Abstract
Previous studies have shown that motion onset is very effective at capturing attention and is more salient than smooth motion. Here, we find that this salience ranking is present already in the firing rate of retinal ganglion cells. By stimulating the retina with a bar that appears, stays still, and then starts moving, we demonstrate that a subset of salamander retinal ganglion cells, fast OFF cells, responds significantly more strongly to motion onset than to smooth motion. We refer to this phenomenon as an alert response to motion onset. We develop a computational model that predicts the time-varying firing rate of ganglion cells responding to the appearance, onset, and smooth motion of a bar. This model, termed the adaptive cascade model, consists of a ganglion cell that receives input from a layer of bipolar cells, represented by individual rectified subunits. Additionally, both the bipolar and ganglion cells have separate contrast gain control mechanisms. This model captured the responses to our different motion stimuli over a wide range of contrasts, speeds, and locations. The alert response to motion onset, together with its computational model, introduces a new mechanism of sophisticated motion processing that occurs early in the visual system.
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Sustained and Transient Contributions to the Rat Dark-Adapted Electroretinogram b-Wave. J Ophthalmol 2013; 2013:352917. [PMID: 23533706 PMCID: PMC3606803 DOI: 10.1155/2013/352917] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 01/31/2013] [Indexed: 11/23/2022] Open
Abstract
The most dominant feature of the electroretinogram, the b-wave, is thought to reflect ON-bipolar cell responses. However, a number of studies suggest that the b-wave is made up of several components. We consider the composition of the rat b-wave by subtracting corneal negative components obtained using intravitreal application of pharmacological agents to remove postreceptoral responses. By analyzing the intensity-response characteristic of the PII across a range of fixed times during and after a light step, we find that the rat isolated PII has 2 components. The first has fast rise and decay characteristics with a low sensitivity to light. GABAc-mediated inhibitory pathways enhance this transient-ON component to manifest increased and deceased sensitivity to light at shorter (<160 ms) and longer times, respectively. The second component has slower temporal characteristics but is more sensitive to light. GABAc-mediated inhibition enhances this sustained-ON component but has little effect on its sensitivity to light. After stimulus offset, both transient and sustained components return to baseline, and a long latency sustained positive component becomes apparent. The light sensitivities of transient-ON and sustained-OFF components are consistent with activity arising from cone ON- and OFF-bipolar cells, whereas the sustained-ON component is likely to arise from rod bipolar cells.
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35
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Asari H, Meister M. Divergence of visual channels in the inner retina. Nat Neurosci 2012; 15:1581-9. [PMID: 23086336 DOI: 10.1038/nn.3241] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 09/20/2012] [Indexed: 11/09/2022]
Abstract
Bipolar cells form parallel channels that carry visual signals from the outer to the inner retina. Each type of bipolar cell is thought to carry a distinct visual message to select types of amacrine cells and ganglion cells. However, the number of ganglion cell types exceeds that of the bipolar cells providing their input, suggesting that bipolar cell signals diversify on transmission to ganglion cells. We explored in the salamander retina how signals from individual bipolar cells feed into multiple ganglion cells and found that each bipolar cell was able to evoke distinct responses among ganglion cells, differing in kinetics, adaptation and rectification properties. This signal divergence resulted primarily from interactions with amacrine cells that allowed each bipolar cell to send distinct signals to its target ganglion cells. Our findings indicate that individual bipolar cell-ganglion cell connections have distinct transfer functions. This expands the number of visual channels in the inner retina and enhances the computational power and feature selectivity of early visual processing.
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Affiliation(s)
- Hiroki Asari
- Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, Massachusetts, USA
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Hilgen G, Huebner AK, Tanimoto N, Sothilingam V, Seide C, Garrido MG, Schmidt KF, Seeliger MW, Löwel S, Weiler R, Hübner CA, Dedek K. Lack of the sodium-driven chloride bicarbonate exchanger NCBE impairs visual function in the mouse retina. PLoS One 2012; 7:e46155. [PMID: 23056253 PMCID: PMC3467262 DOI: 10.1371/journal.pone.0046155] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 08/27/2012] [Indexed: 11/22/2022] Open
Abstract
Regulation of ion and pH homeostasis is essential for normal neuronal function. The sodium-driven chloride bicarbonate exchanger NCBE (Slc4a10), a member of the SLC4 family of bicarbonate transporters, uses the transmembrane gradient of sodium to drive cellular net uptake of bicarbonate and to extrude chloride, thereby modulating both intracellular pH (pH(i)) and chloride concentration ([Cl(-)](i)) in neurons. Here we show that NCBE is strongly expressed in the retina. As GABA(A) receptors conduct both chloride and bicarbonate, we hypothesized that NCBE may be relevant for GABAergic transmission in the retina. Importantly, we found a differential expression of NCBE in bipolar cells: whereas NCBE was expressed on ON and OFF bipolar cell axon terminals, it only localized to dendrites of OFF bipolar cells. On these compartments, NCBE colocalized with the main neuronal chloride extruder KCC2, which renders GABA hyperpolarizing. NCBE was also expressed in starburst amacrine cells, but was absent from neurons known to depolarize in response to GABA, like horizontal cells. Mice lacking NCBE showed decreased visual acuity and contrast sensitivity in behavioral experiments and smaller b-wave amplitudes and longer latencies in electroretinograms. Ganglion cells from NCBE-deficient mice also showed altered temporal response properties. In summary, our data suggest that NCBE may serve to maintain intracellular chloride and bicarbonate concentration in retinal neurons. Consequently, lack of NCBE in the retina may result in changes in pH(i) regulation and chloride-dependent inhibition, leading to altered signal transmission and impaired visual function.
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Affiliation(s)
- Gerrit Hilgen
- Department of Neurobiology, University Oldenburg, Oldenburg, Germany
| | - Antje K. Huebner
- Institute of Human Genetics, University Hospital Jena, Jena, Germany
| | - Naoyuki Tanimoto
- Division of Ocular Neurodegeneration, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Vithiyanjali Sothilingam
- Division of Ocular Neurodegeneration, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Christina Seide
- Division of Ocular Neurodegeneration, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Marina Garcia Garrido
- Division of Ocular Neurodegeneration, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Karl-Friedrich Schmidt
- Institut für Allgemeine Zoologie und Tierphysiologie, Friedrich-Schiller-Universität Jena, Jena, Germany
| | - Mathias W. Seeliger
- Division of Ocular Neurodegeneration, Centre for Ophthalmology, Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Siegrid Löwel
- Institut für Allgemeine Zoologie und Tierphysiologie, Friedrich-Schiller-Universität Jena, Jena, Germany
| | - Reto Weiler
- Department of Neurobiology, University Oldenburg, Oldenburg, Germany
| | | | - Karin Dedek
- Department of Neurobiology, University Oldenburg, Oldenburg, Germany
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Buldyrev I, Taylor WR. Inhibitory mechanisms that generate centre and surround properties in ON and OFF brisk-sustained ganglion cells in the rabbit retina. J Physiol 2012; 591:303-25. [PMID: 23045347 DOI: 10.1113/jphysiol.2012.243113] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Lateral inhibition produces the centre-surround organization of retinal receptive fields, in which inhibition driven by the mean luminance enhances the sensitivity of ganglion cells to spatial and temporal contrast. Surround inhibition is generated in both synaptic layers; however, the synaptic mechanisms within the inner plexiform layer are not well characterized within specific classes of retinal ganglion cell. Here, we compared the synaptic circuits generating concentric centre-surround receptive fields in ON and OFF brisk-sustained ganglion cells (BSGCs) in the rabbit retina. We first characterized the synaptic inputs to the centre of ON BSGCs, for comparison with previous results from OFF BSGCs. Similar to wide-field ganglion cells, the spatial extent of the excitatory centre and inhibitory surround was larger for the ON than the OFF BSGCs. The results indicate that the surrounds of ON and OFF BSGCs are generated in both the outer and the inner plexiform layers. The inner plexiform layer surround inhibition comprised GABAergic suppression of excitatory inputs from bipolar cells. However, ON and OFF BSGCs displayed notable differences. Surround suppression of excitatory inputs was weaker in ON than OFF BSGCs, and was mediated largely by GABA(C) receptors in ON BSGCs, and by both GABA(A) and GABA(C) receptors in OFF BSGCs. Large ON pathway-mediated glycinergic inputs to ON and OFF BSGCs also showed surround suppression, while much smaller GABAergic inputs showed weak, if any, spatial tuning. Unlike OFF BSGCs, which receive strong glycinergic crossover inhibition from the ON pathway, the ON BSGCs do not receive crossover inhibition from the OFF pathway. We compare and discuss possible roles for glycinergic inhibition in the two cell types.
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Affiliation(s)
- Ilya Buldyrev
- Casey Eye Institute, Department of Ophthalmology, School of Medicine, Oregon Health and Science University, Portland, OR 97239, USA
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Abstract
Amacrine cells are a morphologically and functionally diverse group of inhibitory interneurons. Morphologically, they have been divided into approximately 30 types. Although this diversity is probably important to the fine structure and function of the retinal circuit, the amacrine cells have been more generally divided into two subclasses. Glycinergic narrow-field amacrine cells have dendrites that ramify close to their somas, cross the sublaminae of the inner plexiform layer, and create cross talk between its parallel ON and OFF pathways. GABAergic wide-field amacrine cells have dendrites that stretch long distances from their soma but ramify narrowly within an inner plexiform layer sublamina. These wide-field cells are thought to mediate inhibition within a sublamina and thus within the ON or OFF pathway. The postsynaptic targets of all amacrine cell types include bipolar, ganglion, and other amacrine cells. Almost all amacrine cells use GABA or glycine as their primary neurotransmitter, and their postsynaptic receptor targets include the most common GABA(A), GABA(C), and glycine subunit receptor configurations. This review addresses the diversity of amacrine cells, the postsynaptic receptors on their target cells in the inner plexiform layer of the retina, and some of the inhibitory mechanisms that arise as a result. When possible, the effects of GABAergic and glycinergic inputs on the visually evoked responses of their postsynaptic targets are discussed.
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Light-evoked lateral GABAergic inhibition at single bipolar cell synaptic terminals is driven by distinct retinal microcircuits. J Neurosci 2011; 31:15884-93. [PMID: 22049431 DOI: 10.1523/jneurosci.2959-11.2011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Inhibitory amacrine cells (ACs) filter visual signals crossing the retina by modulating the excitatory, glutamatergic output of bipolar cells (BCs) on multiple temporal and spatial scales. Reciprocal feedback from ACs provides focal inhibition that is temporally locked to the activity of presynaptic BC activity, whereas lateral feedback originates from ACs excited by distant BCs. These distinct feedback mechanisms permit temporal and spatial computation at BC terminals. Here, we used a unique preparation to study light-evoked IPSCs recorded from axotomized terminals of ON-type mixed rod/cone BCs (Mb) in goldfish retinal slices. In this preparation, light-evoked IPSCs could only reach axotomized BC terminals via the lateral feedback pathway, allowing us to study lateral feedback in the absence of overlapping reciprocal feedback components. We found that light evokes ON and OFF lateral IPSCs (L-IPSCs) in Mb terminals having different temporal patterns and conveyed via distinct retinal pathways. The relative contribution of rods versus cones to ON and OFF L-IPSCs was light intensity dependent. ACs presynaptic to Mb BC terminals received inputs via AMPA/KA- and NMDA-type receptors in both the ON and OFF pathways, and used TTX-sensitive sodium channels to boost signal transfer along their processes. ON and OFF L-IPSCs, like reciprocal feedback IPSCs, were mediated by both GABA(A) and GABA(C) receptors. However, our results suggest that lateral and reciprocal feedback do not cross-depress each other, and are therefore mediated by distinct populations of ACs. These findings demonstrate that retinal inhibitory circuits are highly specialized to modulate BC output at different light intensities.
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40
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Nonlinear interactions between excitatory and inhibitory retinal synapses control visual output. J Neurosci 2011; 31:15102-12. [PMID: 22016544 DOI: 10.1523/jneurosci.1801-11.2011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The visual system is highly sensitive to dynamic features in the visual scene. However, it is not known how or where this enhanced sensitivity first occurs. We investigated this phenomenon by studying interactions between excitatory and inhibitory synapses in the second synaptic layer of the mouse retina. We found that these interactions showed activity-dependent changes that enhanced signaling of dynamic stimuli. Excitatory signaling from cone bipolar cells to ganglion cells exhibited strong synaptic depression, attributable to reduced glutamate release from bipolar cells. This depression was relieved by amacrine cell inhibitory feedback that activated presynaptic GABA(C) receptors. We found that the balance between excitation and feedback inhibition depended on stimulus frequency; at short interstimulus intervals, excitation was enhanced, attributable to reduced inhibitory feedback. This dynamic interplay may enrich visual processing by enhancing retinal responses to closely spaced temporal events, representing rapid changes in the visual environment.
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Kaur T, Nawy S. Characterization of Trpm1 desensitization in ON bipolar cells and its role in downstream signalling. J Physiol 2011; 590:179-92. [PMID: 22041187 DOI: 10.1113/jphysiol.2011.218974] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
ON bipolar cells invert the sign of light responses from hyperpolarizing to depolarizing before passing them on to ganglion cells. Light responses are generated when a cation channel, recently identified as Trpm1, opens. The amplitude of the light response rapidly decays due to desensitization of Trpm1 current. The role of Trpm1 desensitization in shaping light responses both in bipolar and downstream ganglion cells has not been well characterized. Here we show that two parameters, the amount and the rate of recovery from desensitization, depend on the strength of the presynaptic stimulus. Stimuli that activate less than 20% of the maximum Trpm1 current did not promote any detectable desensitization, even for prolonged periods. Beyond this threshold there was a linear relationship between the amount of desensitization and the fractional Trpm1 current. In response to stimuli that open all available channels, desensitization reduced the response to approximately 40% of the peak, with a time constant of 1 s, and recovery was slow, with a time constant of more than 20 s. In dye-filled bipolar cells classified as transient or sustained using morphological criteria, there were no significant differences in Trpm1 desensitization parameters. Trpm1 activation evoked robust EPSCs in ganglion cells, and removal of Trpm1 desensitization strongly augmented a sustained component of the ganglion cell EPSC irrespective of whether ganglion cells were of the ON or ON/OFF type. We conclude that Trpm1 desensitization impacts the kinetics of ganglion cell EPSCs, but does not underlie the sustained/transient dichotomy of neurons in the ON pathway.
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Affiliation(s)
- Tejinder Kaur
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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42
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Abstract
Ionotropic GABA receptors (GABA(A) and GABA(C)) belong to the Cys-loop receptor family of ligand-gated ion channels. GABA(C) receptors are highly expressed in the retina, mainly localized at the axon terminals of bipolar cells. Ascorbic acid, an endogenous redox agent, modulates the function of diverse proteins, and basal levels of ascorbic acid in the retina are very high. However, the effect of ascorbic acid on retinal GABA receptors has not been studied. Here we show that the function of GABA(C) and GABA(A) receptors is regulated by ascorbic acid. Patch-clamp recordings from bipolar cell terminals in goldfish retinal slices revealed that GABA(C) receptor-mediated currents activated by tonic background levels of extracellular GABA, and GABA(C) currents elicited by local GABA puffs, are both significantly enhanced by ascorbic acid. In addition, a significant rundown of GABA puff-evoked currents was observed in the absence of ascorbic acid. GABA-evoked Cl(-) currents mediated by homomeric ρ(1) GABA(C) receptors expressed in Xenopus laevis oocytes were also potentiated by ascorbic acid in a concentration-dependent, stereo-specific, reversible, and voltage-independent manner. Studies involving the chemical modification of sulfhydryl groups showed that the two Cys-loop cysteines and histidine 141, all located in the ρ(1) subunit extracellular domain, each play a key role in the modulation of GABA(C) receptors by ascorbic acid. Additionally, we show that retinal GABA(A) IPSCs and heterologously expressed GABA(A) receptor currents are similarly augmented by ascorbic acid. Our results suggest that ascorbic acid may act as an endogenous agent capable of potentiating GABAergic neurotransmission in the CNS.
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43
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de Vries SEJ, Baccus SA, Meister M. The projective field of a retinal amacrine cell. J Neurosci 2011; 31:8595-604. [PMID: 21653863 PMCID: PMC3130123 DOI: 10.1523/jneurosci.5662-10.2011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 02/20/2011] [Accepted: 04/04/2011] [Indexed: 11/21/2022] Open
Abstract
In sensory systems, neurons are generally characterized by their receptive field, namely the sensitivity to activity patterns at the input of the circuit. To assess the role of the neuron in the system, one must also know its projective field, namely the spatiotemporal effects the neuron exerts on all of the outputs of the circuit. We studied both the receptive and projective fields of an amacrine interneuron in the salamander retina. This amacrine type has a sustained OFF response with a small receptive field, but its output projects over a much larger region. Unlike other amacrine cells, this type is remarkably promiscuous and affects nearly every ganglion cell within reach of its dendrites. Its activity modulates the sensitivity of visual responses in ganglion cells but leaves their kinetics unchanged. The projective field displays a center-surround structure: depolarizing a single amacrine suppresses the visual sensitivity of ganglion cells nearby and enhances it at greater distances. This change in sign is seen even within the receptive field of one ganglion cell; thus, the modulation occurs presynaptically on bipolar cell terminals, most likely via GABA(B) receptors. Such an antagonistic projective field could contribute to the mechanisms of the retina for predictive coding.
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Affiliation(s)
- Saskia E. J. de Vries
- Department of Molecular and Cellular Biology and Center for Brain Science and
- Program in Neurosciences, Harvard University, Cambridge, Massachusetts 02138
| | - Stephen A. Baccus
- Department of Molecular and Cellular Biology and Center for Brain Science and
| | - Markus Meister
- Department of Molecular and Cellular Biology and Center for Brain Science and
- Program in Neurosciences, Harvard University, Cambridge, Massachusetts 02138
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Abstract
Bipolar cells (BCs) are critical relay neurons in the retina that are organized into parallel signaling pathways. The three main signaling pathways in the mammalian retina are the rod, ON cone, and OFF cone BCs. Rod BCs mediate incrementing dim light signals from rods, and ON cone and OFF cone BCs mediate incrementing and decrementing brighter light signals from cones, respectively. The outputs of BCs are shaped by inhibitory inputs from GABAergic and glycinergic amacrine cells in the inner plexiform layer, mediated by three distinct types of inhibitory receptors: GABA(A), GABA(C), and glycine receptors. The three main BC pathways receive distinct forms of inhibition from these three receptors that shape their light-evoked inhibitory signals. Rod BC inhibition is dominated by slow GABA(C) receptor inhibition, while OFF cone BCs are dominated by glycinergic inhibition. The inhibitory inputs to BCs are also shaped by serial inhibitory connections between GABAergic amacrine cells that limit the spatial profile of BC inhibition. We discuss our recent studies on how inhibitory inputs to BCs are shaped by receptor expression, receptor properties, and neurotransmitter release properties and how these affect the output of BCs.
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Affiliation(s)
- Erika D Eggers
- Department of Physiology, University of Arizona, Tucson, Arizona 85724, USA.
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45
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Zheng W, Zhao X, Wang J, Lu L. Retinal vascular leakage occurring in GABA Rho-1 subunit deficient mice. Exp Eye Res 2010; 90:634-40. [PMID: 20193681 DOI: 10.1016/j.exer.2010.02.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Revised: 02/11/2010] [Accepted: 02/22/2010] [Indexed: 11/18/2022]
Abstract
Recent studies demonstrate that GABAergic activity elicits relaxation of retinal arterioles leading to an increase in blood flow. It has also been found that GABAnergic activity in the retina of mice with diabetic retinopathy is suppressed. In this study, we provide further evidence that lack of GABAergic activity significantly alters vasculature development as well as the hypoxia-induced angiogenic response. Using GABA(C) receptor rho(1) subunit-knockout mice (rho-1(-/-)), our results demonstrate that in hypoxia-induced retinas a severe vascular leakage occurred in 2 week-old rho-1(-/-) mice compared with their wildtype counterparts. In addition, our results also showed that all of the rho-1(-/-) mice developed significant retinal vascular leakages by 48 weeks-of-age. Microarray and real-time PCR experiments revealed a unique angiogenesis-related gene expression pattern. This suggests that retinal vascular disorders of rho-1(-/-) mice results from significant up-regulation of angiogenic genes and concomitant down-regulation of anti-angiogenic genes. The study results are consistent with the pathological changes of the retinal vascular leakage seen in diabetic retinopathy. Our data indicate that the GABA(C) rho(1) subunit plays a role in maintaining both homeostasis and balance of retinal neurotransmitter function. Knockout of the retinal GABA(C) rho(1)-subunit leads to changes in vascular permeability similar to the pathological changes induced by retinal hypoxic conditions.
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Affiliation(s)
- Wei Zheng
- Division of Molecular Medicine, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Torrance, CA 90502, USA
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Ke JB, Chen W, Yang XL, Wang Z. Characterization of spontaneous inhibitory postsynaptic currents in cultured rat retinal amacrine cells. Neuroscience 2010; 165:395-407. [DOI: 10.1016/j.neuroscience.2009.10.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 10/04/2009] [Indexed: 11/29/2022]
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47
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Jiang Z, Shen W. Role of neurotransmitter receptors in mediating light-evoked responses in retinal interplexiform cells. J Neurophysiol 2009; 103:924-33. [PMID: 20018830 DOI: 10.1152/jn.00876.2009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Interplexiform (IP) cells are a long-neglected group of retinal neurons the function of which is yet to be determined. Anatomical study indicates that IP cells are located in the inner nuclear layer, juxtaposed with the third-order neurons. However, the synaptic transmission of IP cells in the inner retina is poorly understood. Using whole cell patch-clamp and pharmacological techniques, we extensively studied synaptic receptors in IP cells. The IP cells in amphibian retinal slices were identified by electrical and morphological properties with voltage-clamp recording and Lucifer yellow dialysis. We find that light-evoked excitatory postsynaptic currents (L-EPSCs) are mediated by AMPA and N-methyl-d-aspartate receptors in IP cells. Although both receptors contributed to the amplitude and kinetics of L-EPSCs, AMPA receptor desensitization substantially shaped L-EPSCs in the neurons, similar to those found in the third-order neurons. The light-evoked inhibitory postsynaptic currents (L-IPSCs) in IP cells were primarily mediated by strychnine-sensitive glycine receptors with a small component of GABA(C) receptors. GABA(C) receptor rho2 subunits were detected in IP cells with single-cell RT-PCR assays. Expression of GABA(C) receptors is one of the special features for IP cells, distinct from most of the third-order neurons that depend on GABA(A) and glycine receptors to relay the inhibitory signals. However, GABA(A) receptors in IP cells acted like nonsynaptic receptors that were activated by exogenous GABA application. Furthermore, L-IPSCs in IP cells were inhibited by the serial inhibitions between amacrine cells in the inner retina. In addition, application of neurotransmitters on the axon terminals of IP cells had no significant current generated in the cells, indicating that the synaptic inputs of IP cells are mainly from the inner retina. This study demonstrates the important role that light signals are encoded by both experiment of inhibitory receptors in IP cells.
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Affiliation(s)
- Zheng Jiang
- College of Biomedical Science, Florida Atlantic University, Boca Raton, Florida, USA
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48
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Eggers ED, Lukasiewicz PD. Interneuron circuits tune inhibition in retinal bipolar cells. J Neurophysiol 2009; 103:25-37. [PMID: 19906884 DOI: 10.1152/jn.00458.2009] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
While connections between inhibitory interneurons are common circuit elements, it has been difficult to define their signal processing roles because of the inability to activate these circuits using natural stimuli. We overcame this limitation by studying connections between inhibitory amacrine cells in the retina. These interneurons form spatially extensive inhibitory networks that shape signaling between bipolar cell relay neurons to ganglion cell output neurons. We investigated how amacrine cell networks modulate these retinal signals by selectively activating the networks with spatially defined light stimuli. The roles of amacrine cell networks were assessed by recording their inhibitory synaptic outputs in bipolar cells that suppress bipolar cell output to ganglion cells. When the amacrine cell network was activated by large light stimuli, the inhibitory connections between amacrine cells unexpectedly depressed bipolar cell inhibition. Bipolar cell inhibition elicited by smaller light stimuli or electrically activated feedback inhibition was not suppressed because these stimuli did not activate the connections between amacrine cells. Thus the activation of amacrine cell circuits with large light stimuli can shape the spatial sensitivity of the retina by limiting the spatial extent of bipolar cell inhibition. Because inner retinal inhibition contributes to ganglion cell surround inhibition, in part, by controlling input from bipolar cells, these connections may refine the spatial properties of the retinal output. This functional role of interneuron connections may be repeated throughout the CNS.
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Affiliation(s)
- Erika D Eggers
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA
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Neuroligin 2 controls the maturation of GABAergic synapses and information processing in the retina. J Neurosci 2009; 29:8039-50. [PMID: 19553444 DOI: 10.1523/jneurosci.0534-09.2009] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
In the present study, we investigated the role of Neuroligin 2 (NL2) in synaptic transmission and network function using the mouse retina as a model circuit. We show that NL2 is preferentially located at GABAergic rather than glycinergic or glutamatergic postsynapses. The absence of NL2 from the retina resulted in a severe reduction of GABA(A) receptor clustering, and in subtle alterations of the retinal circuitry. Light processing was impaired accordingly, and retinal ganglion cells, the output neurons of the retina, showed increased basal activity and altered coding of visual information. Together, our data indicate that NL2 is essential for the functional integrity of GABAergic signaling and as a consequence, for information processing in the retina.
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c-Fos expression in the visual system of the tree shrew (Tupaia belangeri). J Chem Neuroanat 2009; 37:214-28. [DOI: 10.1016/j.jchemneu.2009.03.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2008] [Revised: 03/24/2009] [Accepted: 03/24/2009] [Indexed: 11/23/2022]
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