1
|
Hellevik AM, Mardoum P, Hahn J, Kölsch Y, D'Orazi FD, Suzuki SC, Godinho L, Lawrence O, Rieke F, Shekhar K, Sanes JR, Baier H, Baden T, Wong RO, Yoshimatsu T. Ancient origin of the rod bipolar cell pathway in the vertebrate retina. Nat Ecol Evol 2024; 8:1165-1179. [PMID: 38627529 DOI: 10.1038/s41559-024-02404-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 03/20/2024] [Indexed: 04/30/2024]
Abstract
Vertebrates rely on rod photoreceptors for vision in low-light conditions. The specialized downstream circuit for rod signalling, called the primary rod pathway, is well characterized in mammals, but circuitry for rod signalling in non-mammals is largely unknown. Here we demonstrate that the mammalian primary rod pathway is conserved in zebrafish, which diverged from extant mammals ~400 million years ago. Using single-cell RNA sequencing, we identified two bipolar cell types in zebrafish that are related to mammalian rod bipolar cell (RBCs), the only bipolar type that directly carries rod signals from the outer to the inner retina in the primary rod pathway. By combining electrophysiology, histology and ultrastructural reconstruction of the zebrafish RBCs, we found that, similar to mammalian RBCs, both zebrafish RBC types connect with all rods in their dendritic territory and provide output largely onto amacrine cells. The wiring pattern of the amacrine cells postsynaptic to one RBC type is strikingly similar to that of mammalian RBCs and their amacrine partners, suggesting that the cell types and circuit design of the primary rod pathway emerged before the divergence of teleost fish and mammals. The second RBC type, which forms separate pathways, was either lost in mammals or emerged in fish.
Collapse
Affiliation(s)
- Ayana M Hellevik
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Philip Mardoum
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Joshua Hahn
- Department of Chemical and Biomolecular Engineering; Helen Wills Neuroscience Institute; Vision Sciences Graduate Program; California Institute of Quantitative Biosciences (QB3), University of California Berkley, Berkeley, CA, USA
| | - Yvonne Kölsch
- Department Genes - Circuits - Behavior, Max Planck Institute for Biological Intelligence, Martinsried, Germany
| | - Florence D D'Orazi
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Sachihiro C Suzuki
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Leanne Godinho
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
| | - Owen Lawrence
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Fred Rieke
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA
- Vision Science Center, University of Washington, Seattle, WA, USA
| | - Karthik Shekhar
- Department of Chemical and Biomolecular Engineering; Helen Wills Neuroscience Institute; Vision Sciences Graduate Program; California Institute of Quantitative Biosciences (QB3), University of California Berkley, Berkeley, CA, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Joshua R Sanes
- Department of Molecular and Cellular Biology, and Center for Brain Science, Harvard University, Cambridge, MA, USA
| | - Herwig Baier
- Department Genes - Circuits - Behavior, Max Planck Institute for Biological Intelligence, Martinsried, Germany
| | - Tom Baden
- School of Life Sciences, University of Sussex, Brighton, UK
- Institute of Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Rachel O Wong
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Takeshi Yoshimatsu
- Department of Ophthalmology and Visual Sciences, Washington University in St Louis School of Medicine, St Louis, MO, USA.
- BioRTC, Yobe State University, Damatsuru, Yobe, Nigeria.
| |
Collapse
|
2
|
Sun Y, Hao M, Wu H, Zhang C, Wei D, Li S, Song Z, Tao Y. Unveiling the role of CaMKII in retinal degeneration: from biological mechanism to therapeutic strategies. Cell Biosci 2024; 14:59. [PMID: 38725013 PMCID: PMC11084033 DOI: 10.1186/s13578-024-01236-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Accepted: 04/18/2024] [Indexed: 05/12/2024] Open
Abstract
Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a family of broad substrate specificity serine (Ser)/threonine (Thr) protein kinases that play a crucial role in the Ca2+-dependent signaling pathways. Its significance as an intracellular Ca2+ sensor has garnered abundant research interest in the domain of neurodegeneration. Accumulating evidences suggest that CaMKII is implicated in the pathology of degenerative retinopathies such as diabetic retinopathy (DR), age-related macular degeneration (AMD), retinitis pigmentosa (RP) and glaucoma optic neuropathy. CaMKII can induce the aberrant proliferation of retinal blood vessels, influence the synaptic signaling, and exert dual effects on the survival of retinal ganglion cells and pigment epithelial cells. Researchers have put forth multiple therapeutic agents, encompassing small molecules, peptides, and nucleotides that possess the capability to modulate CaMKII activity. Due to its broad range isoforms and splice variants therapeutic strategies seek to inhibit specifically the CaMKII are confronted with considerable challenges. Therefore, it becomes crucial to discern the detrimental and advantageous aspects of CaMKII, thereby facilitating the development of efficacious treatment. In this review, we summarize recent research findings on the cellular and molecular biology of CaMKII, with special emphasis on its metabolic and regulatory mechanisms. We delve into the involvement of CaMKII in the retinal signal transduction pathways and discuss the correlation between CaMKII and calcium overload. Furthermore, we elaborate the therapeutic trials targeting CaMKII, and introduce recent developments in the zone of CaMKII inhibitors. These findings would enrich our knowledge of CaMKII, and shed light on the development of a therapeutic target for degenerative retinopathy.
Collapse
Affiliation(s)
- Yuxin Sun
- Department of Ophthalmology, Henan Eye Hospital, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, 450003, China
- College of Medicine, Zhengzhou University, Zhengzhou, 450001, China
| | - Mengyu Hao
- Department of Ophthalmology, Henan Eye Hospital, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, 450003, China
- College of Medicine, Zhengzhou University, Zhengzhou, 450001, China
| | - Hao Wu
- Department of Ophthalmology, Henan Eye Hospital, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, 450003, China
- College of Medicine, Zhengzhou University, Zhengzhou, 450001, China
| | - Chengzhi Zhang
- Department of Ophthalmology, Henan Eye Hospital, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, 450003, China
- College of Medicine, Zhengzhou University, Zhengzhou, 450001, China
| | - Dong Wei
- Department of Ophthalmology, Henan Eye Hospital, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, 450003, China
- College of Medicine, Zhengzhou University, Zhengzhou, 450001, China
| | - Siyu Li
- Department of Ophthalmology, Henan Eye Hospital, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, 450003, China
- College of Medicine, Zhengzhou University, Zhengzhou, 450001, China
| | - Zongming Song
- Department of Ophthalmology, Henan Eye Hospital, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, 450003, China.
| | - Ye Tao
- Department of Ophthalmology, Henan Eye Hospital, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, 450003, China.
- College of Medicine, Zhengzhou University, Zhengzhou, 450001, China.
| |
Collapse
|
3
|
Pang JJ. The Variety of Mechanosensitive Ion Channels in Retinal Neurons. Int J Mol Sci 2024; 25:4877. [PMID: 38732096 PMCID: PMC11084373 DOI: 10.3390/ijms25094877] [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: 02/27/2024] [Revised: 04/16/2024] [Accepted: 04/20/2024] [Indexed: 05/13/2024] Open
Abstract
Alterations in intraocular and external pressure critically involve the pathogenesis of glaucoma, traumatic retinal injury (TRI), and other retinal disorders, and retinal neurons have been reported to express multiple mechanical-sensitive channels (MSCs) in recent decades. However, the role of MSCs in visual functions and pressure-related retinal conditions has been unclear. This review will focus on the variety and functional significance of the MSCs permeable to K+, Na+, and Ca2+, primarily including the big potassium channel (BK); the two-pore domain potassium channels TRAAK and TREK; Piezo; the epithelial sodium channel (ENaC); and the transient receptor potential channels vanilloid TRPV1, TRPV2, and TRPV4 in retinal photoreceptors, bipolar cells, horizontal cells, amacrine cells, and ganglion cells. Most MSCs do not directly mediate visual signals in vertebrate retinas. On the other hand, some studies have shown that MSCs can open in physiological conditions and regulate the activities of retinal neurons. While these data reasonably predict the crossing of visual and mechanical signals, how retinal light pathways deal with endogenous and exogenous mechanical stimulation is uncertain.
Collapse
Affiliation(s)
- Ji-Jie Pang
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX 77030, USA
| |
Collapse
|
4
|
Rodríguez-Arzate CA, Noguez-Imm R, Reyes-Ortega P, Rodríguez-Ortiz LR, García-Peña MF, Ordaz RP, Vélez-Uriza F, Cisneros-Mejorado A, Arellano RO, Pérez CI, Hernández-Zimbrón LF, Dégardin J, Simonutti M, Picaud S, Thébault SC. Potential contributions of the intrinsic retinal oscillations recording using non-invasive electroretinogram to bioelectronics. Front Cell Neurosci 2024; 17:1224558. [PMID: 38269118 PMCID: PMC10806452 DOI: 10.3389/fncel.2023.1224558] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 12/15/2023] [Indexed: 01/26/2024] Open
Abstract
Targeted electric signal use for disease diagnostics and treatment is emerging as a healthcare game-changer. Besides arrhythmias, treatment-resistant epilepsy and chronic pain, blindness, and perhaps soon vision loss, could be among the pathologies that benefit from bioelectronic medicine. The electroretinogram (ERG) technique has long demonstrated its role in diagnosing eye diseases and early stages of neurodegenerative diseases. Conspicuously, ERG applications are all based on light-induced responses. However, spontaneous, intrinsic activity also originates in retinal cells. It is a hallmark of degenerated retinas and its alterations accompany obesity and diabetes. To the extent that variables extracted from the resting activity of the retina measured by ERG allow the predictive diagnosis of risk factors for type 2 diabetes. Here, we provided a comparison of the baseline characteristics of intrinsic oscillatory activity recorded by ERGs in mice, rats, and humans, as well as in several rat strains, and explore whether zebrafish exhibit comparable activity. Their pattern was altered in neurodegenerative models including the cuprizone-induced demyelination model in mice as well as in the Royal College of Surgeons (RCS-/-) rats. We also discuss how the study of their properties may pave the way for future research directions and treatment approaches for retinopathies, among others.
Collapse
Affiliation(s)
- Cynthia Alejandra Rodríguez-Arzate
- Laboratorio de Investigación Traslacional en Salud Visual D-13, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Ramsés Noguez-Imm
- Laboratorio de Investigación Traslacional en Salud Visual D-13, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Pamela Reyes-Ortega
- Laboratorio de Investigación Traslacional en Salud Visual D-13, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Luis Roberto Rodríguez-Ortiz
- Laboratorio de Neurobiología Molecular y Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - María Fernanda García-Peña
- Laboratorio de Neurobiología Molecular y Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Rainald Pablo Ordaz
- Laboratorio de Neurofisiología Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Fidel Vélez-Uriza
- Laboratorio de Neurofisiología Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Abraham Cisneros-Mejorado
- Laboratorio de Neurofisiología Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Rogelio O. Arellano
- Laboratorio de Neurofisiología Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Claudia I. Pérez
- Laboratorio de Neurofisiología de los Hábitos, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Luis Fernando Hernández-Zimbrón
- Clínica de Salud Visual, Escuela Nacional de Estudios Superiores, Unidad León, Universidad Nacional Autonóma de México (UNAM), León, Guanajuato, Mexico
| | - Julie Dégardin
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Manuel Simonutti
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Serge Picaud
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Stéphanie C. Thébault
- Laboratorio de Investigación Traslacional en Salud Visual D-13, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| |
Collapse
|
5
|
Hellevik AM, Mardoum P, Hahn J, Kölsch Y, D’Orazi FD, Suzuki SC, Godinho L, Lawrence O, Rieke F, Shekhar K, Sanes JR, Baier H, Baden T, Wong RO, Yoshimatsu T. Ancient origin of the rod bipolar cell pathway in the vertebrate retina. RESEARCH SQUARE 2023:rs.3.rs-3411693. [PMID: 37886445 PMCID: PMC10602083 DOI: 10.21203/rs.3.rs-3411693/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2023]
Abstract
Vertebrates rely on rod photoreceptors for vision in low-light conditions. Mammals have a specialized downstream circuit for rod signaling called the primary rod pathway, which comprises specific cell types and wiring patterns that are thought to be unique to this lineage. Thus, it has been long assumed that the primary rod pathway evolved in mammals. Here, we challenge this view by demonstrating that the mammalian primary rod pathway is conserved in zebrafish, which diverged from extant mammals ~400 million years ago. Using single-cell RNA-sequencing, we identified two bipolar cell (BC) types in zebrafish that are related to mammalian rod BCs (RBCs) of the primary rod pathway. By combining electrophysiology, histology, and ultrastructural reconstruction of the zebrafish RBCs, we found that, like mammalian RBCs, both zebrafish RBC types connect with all rods in their dendritic territory, and provide output largely onto amacrine cells. The wiring pattern of the amacrine cells post-synaptic to one RBC type is strikingly similar to that of mammalian RBCs, suggesting that the cell types and circuit design of the primary rod pathway have emerged before the divergence of teleost fish and amniotes. The second RBC type, which forms separate pathways, is either lost in mammals or emerged in fish.
Collapse
Affiliation(s)
- Ayana M Hellevik
- Department of Biological Structure, University of Washington, Seattle, WA 98195, USA
| | - Philip Mardoum
- Department of Biological Structure, University of Washington, Seattle, WA 98195, USA
| | - Joshua Hahn
- Department of Chemical and Biomolecular Engineering; Helen Wills Neuroscience Institute; Vision Sciences Graduate Program; California Institute of Quantitative Biosciences (QB3), University of California Berkley, Berkeley, CA 94720, USA
| | - Yvonne Kölsch
- Department of Molecular & Cellular Biology and Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
- Max Planck Institute for Biological Intelligence, Department Genes – Circuits – Behavior, 82152 Martinsried, Germany
| | - Florence D D’Orazi
- Department of Biological Structure, University of Washington, Seattle, WA 98195, USA
| | - Sachihiro C. Suzuki
- Department of Biological Structure, University of Washington, Seattle, WA 98195, USA
| | - Leanne Godinho
- Institute of Neuronal Cell Biology, Technische Universität München, 80802 Munich, Germany
| | - Owen Lawrence
- Department of Biological Structure, University of Washington, Seattle, WA 98195, USA
| | - Fred Rieke
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
- Vision Science Center, University of Washington, Seattle, WA 98195, USA
| | - Karthik Shekhar
- Department of Chemical and Biomolecular Engineering; Helen Wills Neuroscience Institute; Vision Sciences Graduate Program; California Institute of Quantitative Biosciences (QB3), University of California Berkley, Berkeley, CA 94720, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Joshua R Sanes
- Department of Molecular & Cellular Biology and Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Herwig Baier
- Max Planck Institute for Biological Intelligence, Department Genes – Circuits – Behavior, 82152 Martinsried, Germany
| | - Tom Baden
- School of Life Sciences, University of Sussex, Brighton, BN1 9QG, UK
- Institute of Ophthalmic Research, University of Tübingen, Tübingen, 72076, Germany
| | - Rachel O Wong
- Department of Biological Structure, University of Washington, Seattle, WA 98195, USA
| | - Takeshi Yoshimatsu
- Department of Ophthalmology & Visual Sciences, Washington University in St Louis School of Medicine, St Louis, MO 63110, USA
- BioRTC, Yobe State University, Damatsuru, Yobe 620101, Nigeria
| |
Collapse
|
6
|
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.
Collapse
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:
| |
Collapse
|
7
|
Zeng FG, Tran P, Richardson M, Sun S, Xu Y. Human Sensation of Transcranial Electric Stimulation. Sci Rep 2019; 9:15247. [PMID: 31649289 PMCID: PMC6813324 DOI: 10.1038/s41598-019-51792-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 10/08/2019] [Indexed: 01/22/2023] Open
Abstract
Noninvasive transcranial electric stimulation is increasingly being used as an advantageous therapy alternative that may activate deep tissues while avoiding drug side-effects. However, not only is there limited evidence for activation of deep tissues by transcranial electric stimulation, its evoked human sensation is understudied and often dismissed as a placebo or secondary effect. By systematically characterizing the human sensation evoked by transcranial alternating-current stimulation, we observed not only stimulus frequency and electrode position dependencies specific for auditory and visual sensation but also a broader presence of somatic sensation ranging from touch and vibration to pain and pressure. We found generally monotonic input-output functions at suprathreshold levels, and often multiple types of sensation occurring simultaneously in response to the same electric stimulation. We further used a recording circuit embedded in a cochlear implant to directly and objectively measure the amount of transcranial electric stimulation reaching the auditory nerve, a deep intercranial target located in the densest bone of the skull. We found an optimal configuration using an ear canal electrode and low-frequency (<300 Hz) sinusoids that delivered maximally ~1% of the transcranial current to the auditory nerve, which was sufficient to produce sound sensation even in deafened ears. Our results suggest that frequency resonance due to neuronal intrinsic electric properties need to be explored for targeted deep brain stimulation and novel brain-computer interfaces.
Collapse
Affiliation(s)
- Fan-Gang Zeng
- Center for Hearing Research, Departments of Anatomy and Neurobiology, Biomedical Engineering, Cognitive Sciences, Otolaryngology - Head and Neck Surgery, University of California Irvine, Irvine, California, 92697, USA.
| | - Phillip Tran
- Center for Hearing Research, Departments of Anatomy and Neurobiology, Biomedical Engineering, Cognitive Sciences, Otolaryngology - Head and Neck Surgery, University of California Irvine, Irvine, California, 92697, USA
| | - Matthew Richardson
- Center for Hearing Research, Departments of Anatomy and Neurobiology, Biomedical Engineering, Cognitive Sciences, Otolaryngology - Head and Neck Surgery, University of California Irvine, Irvine, California, 92697, USA
| | - Shuping Sun
- Center for Hearing Research, Departments of Anatomy and Neurobiology, Biomedical Engineering, Cognitive Sciences, Otolaryngology - Head and Neck Surgery, University of California Irvine, Irvine, California, 92697, USA
- Department of Otolaryngology - Head and Neck Surgery, The First Affiliated Hospital, Zhengzhou University, Henan, 450052, China
| | - Yuchen Xu
- Center for Hearing Research, Departments of Anatomy and Neurobiology, Biomedical Engineering, Cognitive Sciences, Otolaryngology - Head and Neck Surgery, University of California Irvine, Irvine, California, 92697, USA
- Department of Precision Instrument, Tsinghua University, Beijing, 100084, China
| |
Collapse
|
8
|
Van Hook MJ, Nawy S, Thoreson WB. Voltage- and calcium-gated ion channels of neurons in the vertebrate retina. Prog Retin Eye Res 2019; 72:100760. [PMID: 31078724 PMCID: PMC6739185 DOI: 10.1016/j.preteyeres.2019.05.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/25/2019] [Accepted: 05/01/2019] [Indexed: 02/06/2023]
Abstract
In this review, we summarize studies investigating the types and distribution of voltage- and calcium-gated ion channels in the different classes of retinal neurons: rods, cones, horizontal cells, bipolar cells, amacrine cells, interplexiform cells, and ganglion cells. We discuss differences among cell subtypes within these major cell classes, as well as differences among species, and consider how different ion channels shape the responses of different neurons. For example, even though second-order bipolar and horizontal cells do not typically generate fast sodium-dependent action potentials, many of these cells nevertheless possess fast sodium currents that can enhance their kinetic response capabilities. Ca2+ channel activity can also shape response kinetics as well as regulating synaptic release. The L-type Ca2+ channel subtype, CaV1.4, expressed in photoreceptor cells exhibits specific properties matching the particular needs of these cells such as limited inactivation which allows sustained channel activity and maintained synaptic release in darkness. The particular properties of K+ and Cl- channels in different retinal neurons shape resting membrane potentials, response kinetics and spiking behavior. A remaining challenge is to characterize the specific distributions of ion channels in the more than 100 individual cell types that have been identified in the retina and to describe how these particular ion channels sculpt neuronal responses to assist in the processing of visual information by the retina.
Collapse
Affiliation(s)
- Matthew J Van Hook
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA
| | - Scott Nawy
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA; Department Pharmacology & Experimental Neuroscience(2), University of Nebraska Medical Center, Omaha, NE, USA
| | - Wallace B Thoreson
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA; Department Pharmacology & Experimental Neuroscience(2), University of Nebraska Medical Center, Omaha, NE, USA.
| |
Collapse
|
9
|
Lipin MY, Vigh J. Quantifying the effect of light activated outer and inner retinal inhibitory pathways on glutamate release from mixed bipolar cells. Synapse 2018; 72:e22028. [PMID: 29360185 DOI: 10.1002/syn.22028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 01/19/2018] [Accepted: 01/21/2018] [Indexed: 11/12/2022]
Abstract
Inhibition mediated by horizontal and amacrine cells in the outer and inner retina, respectively, are fundamental components of visual processing. Here, our purpose was to determine how these different inhibitory processes affect glutamate release from ON bipolar cells when the retina is stimulated with full-field light of various intensities. Light-evoked membrane potential changes (ΔVm ) were recorded directly from axon terminals of intact bipolar cells receiving mixed rod and cone inputs (Mbs) in slices of dark-adapted goldfish retina. Inner and outer retinal inhibition to Mbs was blocked with bath applied picrotoxin (PTX) and NBQX, respectively. Then, control and pharmacologically modified light responses were injected into axotomized Mb terminals as command potentials to induce voltage-gated Ca2+ influx (QCa ) and consequent glutamate release. Stimulus-evoked glutamate release was quantified by the increase in membrane capacitance (ΔCm ). Increasing depolarization of Mb terminals upon removal of inner and outer retinal inhibition enhanced the ΔVm /QCa ratio equally at a given light intensity and inhibition did not alter the overall relation between QCa and ΔCm . However, relative to control, light responses recorded in the presence of PTX and PTX + NBQX increased ΔCm unevenly across different stimulus intensities: at dim stimulus intensities predominantly the inner retinal GABAergic inhibition controlled release from Mbs, whereas the inner and outer retinal inhibition affected release equally in response to bright stimuli. Furthermore, our results suggest that non-linear relationship between QCa and glutamate release can influence the efficacy of inner and outer retinal inhibitory pathways to mediate Mb output at different light intensities.
Collapse
Affiliation(s)
- Mikhail Y Lipin
- Department of Biomedical Sciences, Colorado State University, 1617 Campus Delivery, Fort Collins, Colorado, 80523-1617
| | - Jozsef Vigh
- Department of Biomedical Sciences, Colorado State University, 1617 Campus Delivery, Fort Collins, Colorado, 80523-1617
| |
Collapse
|
10
|
Frolov D, Li GL. Probing electrical tuning of hair cells with a Zap current method in the intact amphibian papilla of bullfrogs. Synapse 2016; 71. [PMID: 27680688 DOI: 10.1002/syn.21942] [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: 08/25/2016] [Revised: 09/18/2016] [Accepted: 09/22/2016] [Indexed: 12/30/2022]
Abstract
Most, if not all, modern vertebrate species have evolved exquisite inner ears to discriminate acoustic signals of different frequencies, through a process called frequency tuning. For non-mammalian species, at least part of frequency tuning has been attributed to intrinsic electrical properties of hair cells, i.e. electrical tuning. Since it was first discovered, the traditional method to assess electrical tuning has been to inject step current into hair cells and examine dampened membrane voltage oscillation. However, this method is not applicable for hair cells that do not oscillate. In this study, we developed a Zap current method that can be unbiasedly applied to all hair cells regardless of their oscillating behavior. Similar to a chirp sound in acoustic stimulation, a Zap current is a sinusoidal current with the frequency increased linearly with time. We first validated this new method with the traditional step current method on hair cells with dampened membrane voltage oscillation, and then applied it to all hair cells in the intact amphibian papilla of bullfrogs. We found that while hair cells with dampened membrane voltage oscillation are sharply tuned, non-oscillating hair cells are broadly tuned. In addition, we found a third type of hair cells, which oscillate continuously and are extremely sharply tuned, with multiple peaks that are reminiscent of harmonics in the mammalian cochlea. In conclusion, the new Zap current method provides an unbiased way to assess electrical tuning, and it reveals an underappreciated heterogeneity of electrical tuning in the bullfrog amphibian papilla.
Collapse
Affiliation(s)
- Daniil Frolov
- Neuroscience and Behavior Graduate Program, University of Massachusetts Amherst, 611 N Pleasant St, Amherst, Massachusetts, 01003, USA
| | - Geng-Lin Li
- Neuroscience and Behavior Graduate Program, University of Massachusetts Amherst, 611 N Pleasant St, Amherst, Massachusetts, 01003, USA.,Biology Department, University of Massachusetts Amherst, 611 N Pleasant St, Amherst, Massachusetts, 01003, USA
| |
Collapse
|
11
|
Abstract
Large conductance Ca(2+)- and voltage-activated K(+) (BK) channels are widely distributed in the postnatal central nervous system (CNS). BK channels play a pleiotropic role in regulating the activity of brain and spinal cord neural circuits by providing a negative feedback mechanism for local increases in intracellular Ca(2+) concentrations. In neurons, they regulate the timing and duration of K(+) influx such that they can either increase or decrease firing depending on the cellular context, and they can suppress neurotransmitter release from presynaptic terminals. In addition, BK channels located in astrocytes and arterial myocytes modulate cerebral blood flow. Not surprisingly, both loss and gain of BK channel function have been associated with CNS disorders such as epilepsy, ataxia, mental retardation, and chronic pain. On the other hand, the neuroprotective role played by BK channels in a number of pathological situations could potentially be leveraged to correct neurological dysfunction.
Collapse
|
12
|
Rosa JM, Ruehle S, Ding H, Lagnado L. Crossover Inhibition Generates Sustained Visual Responses in the Inner Retina. Neuron 2016; 90:308-19. [PMID: 27068790 PMCID: PMC4848346 DOI: 10.1016/j.neuron.2016.03.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 01/21/2016] [Accepted: 03/02/2016] [Indexed: 12/23/2022]
Abstract
In daylight, the input to the retinal circuit is provided primarily by cone photoreceptors acting as band-pass filters, but the retinal output also contains neuronal populations transmitting sustained signals. Using in vivo imaging of genetically encoded calcium reporters, we investigated the circuits that generate these sustained channels within the inner retina of zebrafish. In OFF bipolar cells, sustained transmission was found to depend on crossover inhibition from the ON pathway through GABAergic amacrine cells. In ON bipolar cells, the amplitude of low-frequency signals was regulated by glycinergic amacrine cells, while GABAergic inhibition regulated the gain of band-pass signals. We also provide the first functional description of a subset of sustained ON bipolar cells in which synaptic activity was suppressed by fluctuations at frequencies above ∼0.2 Hz. These results map out the basic circuitry by which the inner retina generates sustained visual signals and describes a new function of crossover inhibition.
Collapse
Affiliation(s)
- Juliana M Rosa
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Sabine Ruehle
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Huayu Ding
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Leon Lagnado
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK; School of Life Sciences, University of Sussex, Brighton, BN1 9QG, UK.
| |
Collapse
|
13
|
Abstract
The first synapses transmitting visual information contain an unusual organelle, the ribbon, which is involved in the transport and priming of vesicles to be released at the active zone. The ribbon is one of many design features that allow efficient refilling of the active zone, which in turn enables graded changes in membrane potential to be transmitted using a continuous mode of neurotransmitter release. The ribbon also plays a key role in supplying vesicles for rapid and transient bursts of release that signal fast changes, such as the onset of light. We increasingly understand how the physiological properties of ribbon synapses determine basic transformations of the visual signal and, in particular, how the process of refilling the active zone regulates the gain and adaptive properties of the retinal circuit. The molecular basis of ribbon function is, however, far from clear.
Collapse
Affiliation(s)
- Leon Lagnado
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, United Kingdom;
| | - Frank Schmitz
- Department of Neuroanatomy, Institute for Anatomy and Cell Biology, Medical School Saarland University, Homburg/Saar, Germany;
| |
Collapse
|
14
|
Trenholm S, Awatramani GB. Origins of spontaneous activity in the degenerating retina. Front Cell Neurosci 2015; 9:277. [PMID: 26283914 PMCID: PMC4518194 DOI: 10.3389/fncel.2015.00277] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 07/06/2015] [Indexed: 01/10/2023] Open
Abstract
Sensory deafferentation resulting from the loss of photoreceptors during retinal degeneration (rd) is often accompanied by a paradoxical increase in spontaneous activity throughout the visual system. Oscillatory discharges are apparent in retinal ganglion cells in several rodent models of rd, indicating that spontaneous activity can originate in the retina. Understanding the biophysical mechanisms underlying spontaneous retinal activity is interesting for two main reasons. First, it could lead to strategies that reduce spontaneous retinal activity, which could improve the performance of vision restoration strategies that aim to stimulate remnant retinal circuits in blind patients. Second, studying emergent network activity could offer general insights into how sensory systems remodel upon deafferentation. Here we provide an overview of the work describing spontaneous activity in the degenerating retina, and outline the current state of knowledge regarding the cellular and biophysical properties underlying spontaneous neural activity.
Collapse
Affiliation(s)
- Stuart Trenholm
- Friedrich Miescher Institute for Biomedical Research Basel, Switzerland
| | | |
Collapse
|
15
|
Pelassa I, Zhao C, Pasche M, Odermatt B, Lagnado L. Synaptic vesicles are "primed" for fast clathrin-mediated endocytosis at the ribbon synapse. Front Mol Neurosci 2014; 7:91. [PMID: 25520613 PMCID: PMC4248811 DOI: 10.3389/fnmol.2014.00091] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 11/03/2014] [Indexed: 11/13/2022] Open
Abstract
Retrieval of synaptic vesicles can occur 1-10 s after fusion, but the role of clathrin during this process has been unclear because the classical mode of clathrin-mediated endocytosis (CME) is an order of magnitude slower, as during retrieval of surface receptors. Classical CME is thought to be rate-limited by the recruitment of clathrin, which raises the question: how is clathrin recruited during synaptic vesicle recycling? To investigate this question we applied total internal reflection fluorescence microscopy (TIRFM) to the synaptic terminal of retinal bipolar cells expressing fluorescent constructs of clathrin light-chain A. Upon calcium influx we observed a fast accumulation of clathrin within 100 ms at the periphery of the active zone. The subsequent loss of clathrin from these regions reflected endocytosis because the application of a potent clathrin inhibitor Pitstop2 dramatically slowed down this phase by ~3 fold. These results indicate that clathrin-dependent retrieval of synaptic vesicles is unusually fast, most probably because of a "priming" step involving a state of association of clathrin with the docked vesicle and with the endosomes and cisternae surrounding the ribbons. Fluorescence correlation spectroscopy (FCS) and fluorescence recovery after photobleaching (FRAP) showed that the majority of clathrin is moving with the same kinetics as synaptic vesicle proteins. Together, these results indicate that the fast endocytic mechanism operating to retrieve synaptic vesicles differs substantially from the classical mode of CME operating via formation of a coated pit.
Collapse
Affiliation(s)
| | | | | | | | - Leon Lagnado
- Medical Research Council Laboratory of Molecular Biology, Neurobiology DivisionCambridge, UK
| |
Collapse
|
16
|
Lipin MY, Vigh J. Calcium spike-mediated digital signaling increases glutamate output at the visual threshold of retinal bipolar cells. J Neurophysiol 2014; 113:550-66. [PMID: 25339710 DOI: 10.1152/jn.00378.2014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Most retinal bipolar cells (BCs) transmit visual input from photoreceptors to ganglion cells using graded potentials, but some also generate calcium or sodium spikes. Sodium spikes are thought to increase temporal precision of light-evoked BC signaling; however, the role of calcium spikes in BCs is not fully understood. Here we studied how calcium spikes and graded responses mediate neurotransmitter release from Mb-type BCs, known to produce both. In dark-adapted goldfish retinal slices, light induced spikes in 40% of the axon terminals of intact Mbs; in the rest, light generated graded responses. These light-evoked membrane potentials were used to depolarize axotomized Mb terminals where depolarization-evoked calcium current (ICa) and consequent exocytosis-associated membrane capacitance increases (ΔCm) could be precisely measured. When evoked by identical dim light intensities, spiking responses transferred more calcium (Q(Ca)) and triggered larger exocytosis with higher efficiency (ΔCm/Q(Ca)) than graded potentials. Q(Ca) was translated into exocytosis linearly when transferred with spikes and supralinearly when transferred with graded responses. At the Mb output (ΔCm), spiking responses coded light intensity with numbers and amplitude whereas graded responses coded with amplitude, duration, and steepness. Importantly, spiking responses saturated exocytosis within scotopic range but graded potentials did not. We propose that calcium spikes in Mbs increase signal input-output ratio by boosting Mb glutamate release at threshold intensities. Therefore, spiking Mb responses are suitable to transfer low-light-intensity signals to ganglion cells with higher gain, whereas graded potentials signal for light over a wider range of intensities at the Mb output.
Collapse
Affiliation(s)
- Mikhail Y Lipin
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Jozsef Vigh
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| |
Collapse
|
17
|
A synaptic mechanism for temporal filtering of visual signals. PLoS Biol 2014; 12:e1001972. [PMID: 25333637 PMCID: PMC4205119 DOI: 10.1371/journal.pbio.1001972] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 09/10/2014] [Indexed: 12/22/2022] Open
Abstract
The visual system transmits information about fast and slow changes in light intensity through separate neural pathways. We used in vivo imaging to investigate how bipolar cells transmit these signals to the inner retina. We found that the volume of the synaptic terminal is an intrinsic property that contributes to different temporal filters. Individual cells transmit through multiple terminals varying in size, but smaller terminals generate faster and larger calcium transients to trigger vesicle release with higher initial gain, followed by more profound adaptation. Smaller terminals transmitted higher stimulus frequencies more effectively. Modeling global calcium dynamics triggering vesicle release indicated that variations in the volume of presynaptic compartments contribute directly to all these differences in response dynamics. These results indicate how one neuron can transmit different temporal components in the visual signal through synaptic terminals of varying geometries with different adaptational properties.
Collapse
|
18
|
|
19
|
|
20
|
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.
Collapse
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
| | | | | |
Collapse
|
21
|
Chang L, He S. Light adaptation increases response latency of alpha ganglion cells via a threshold-like nonlinearity. Neuroscience 2013; 256:101-16. [PMID: 24144626 DOI: 10.1016/j.neuroscience.2013.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 09/18/2013] [Accepted: 10/04/2013] [Indexed: 01/26/2023]
Abstract
Adaptation is an important process of sensory systems to adjust sensitivity to ensure the appropriate information encoding. Sensitivity and kinetics of retinal ganglion cell (RGC) responses have been studied extensively using a brief flash superimposed on different but steady backgrounds. However, it is still unclear if light adaptation exerts any effect on more complex response properties, such as response nonlinearity. In this study, we found that the latency of spike responses to a repeated flashing spot stimulation increased by 30 ms in the mouse ON α RGCs (An ON-type RGC is excited when a spot is turned on in the center of its receptive field). A single dimming event preceding the test flash on a steady adapting background could also produce similar effect in increasing latency of light responses. A simple computational model with a linear transformation of the light stimulus and a threshold-like nonlinearity could account for the experimental data. Moreover, the strength of the measured nonlinearity and the response latency were affected by the duration of light adaptation. The possible biological processes underlying this nonlinearity were explored. Voltage clamp recording revealed the presence of the increase in latency and threshold-like nonlinearity in the excitatory input of RGCs. However, no comparable nonlinearity was observed in the light responses of the ON cone bipolar cells. We further excluded GABAergic and glycinergic inhibition, N-methyl-D-aspartate receptor rectification and voltage-gated Na(+) channels as potential sources of this nonlinearity by pharmacological experiments. Our results indicate the bipolar cell terminals as the potential site of nonlinearity. Computational modeling constrained by experimental data supports that conclusion and suggests the voltage-sensitive Ca(++) channels and Ca(++)-dependent vesicle release in the bipolar cell terminals as mechanistic basis.
Collapse
Affiliation(s)
- L Chang
- State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China; University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China.
| | - S He
- State Key Laboratory of Brain and Cognitive Sciences, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China; School of Biomedical Engineering, Bio-X Research Center and Institute of Natural Sciences, Shanghai Jiao Tong University, 800 Dong-Chuan Road, Shanghai 200240, China.
| |
Collapse
|
22
|
Esposti F, Johnston J, Rosa JM, Leung KM, Lagnado L. Olfactory stimulation selectively modulates the OFF pathway in the retina of zebrafish. Neuron 2013; 79:97-110. [PMID: 23849198 PMCID: PMC3710973 DOI: 10.1016/j.neuron.2013.05.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/01/2013] [Indexed: 01/11/2023]
Abstract
Cross-modal regulation of visual performance by olfactory stimuli begins in the retina, where dopaminergic interneurons receive projections from the olfactory bulb. However, we do not understand how olfactory stimuli alter the processing of visual signals within the retina. We investigated this question by in vivo imaging activity in transgenic zebrafish expressing SyGCaMP2 in bipolar cell terminals and GCaMP3.5 in ganglion cells. The food-related amino acid methionine reduced the gain and increased sensitivity of responses to luminance and contrast transmitted through OFF bipolar cells but not ON. The effects of olfactory stimulus were blocked by inhibiting dopamine uptake and release. Activation of dopamine receptors increased the gain of synaptic transmission in vivo and potentiated synaptic calcium currents in isolated bipolar cells. These results indicate that olfactory stimuli alter the sensitivity of the retina through the dopaminergic regulation of presynaptic calcium channels that control the gain of synaptic transmission through OFF bipolar cells. Olfactory stimuli regulate transmission of signals through retinal bipolar cells Modulation of synaptic gain and sensitivity occur in OFF bipolar cells but not ON An inhibitor of dopamine uptake blocks odor-induced changes in synaptic gain Dopamine potentiates presynaptic calcium channels in isolated bipolar cells
Collapse
Affiliation(s)
- Federico Esposti
- Laboratory of Molecular Biology, Medical Research Council, Cambridge CB2 0QH, UK
| | | | | | | | | |
Collapse
|
23
|
Abstract
At certain temporal frequencies, the human cone flicker electroretinogram (ERG) contains multiple additional responses following the termination of a flicker train. The purpose of this study was to determine whether these poststimulus responses are a continuing response to the terminated flicker train or represent the oscillation of a resonant system. ERGs were recorded from 10 visually normal adults in response to full-field sinusoidally modulated flicker trains presented against a short-wavelength rod-saturating adapting field. The amplitude and timing properties of the poststimulus responses were evaluated within the context of a model of a second-order resonant system. At stimulus frequencies between 41.7 and 71.4 Hz, the majority of subjects showed at least three additional ERG responses following the termination of the flicker train. The interval between the poststimulus responses was approximately constant across stimulus frequency, with a mean of 14.4 ms, corresponding to a frequency of 69.4 Hz. The amplitude and timing characteristics of the poststimulus ERG responses were well described by an underdamped second-order system with a resonance frequency of 70.3 Hz. The observed poststimulus ERG responses may represent resonant oscillations of retinal ON bipolar cells, as has been proposed for electrophysiological recordings of poststimulus responses from retinal ganglion cells. However, further investigation is required to determine the types of retinal neurons involved in the generation of the poststimulus responses of the human flicker ERG.
Collapse
|
24
|
Amperometric resolution of a prespike stammer and evoked phases of fast release from retinal bipolar cells. J Neurosci 2013; 33:8144-58. [PMID: 23658155 DOI: 10.1523/jneurosci.5062-12.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The neurotransmitter glutamate is used by most neurons in the brain to activate a multitude of different types of glutamate receptors and transporters involved in fast and relatively slower signaling. Synaptic ribbons are large presynaptic structures found in neurons involved in vision, balance, and hearing, which use a large number of glutamate-filled synaptic vesicles to meet their signaling demands. To directly measure synaptic vesicle release events, the ribbon-type presynaptic terminals of goldfish retinal bipolar cells were coaxed to release a false transmitter that could be monitored with amperometry by placing the carbon fiber directly on the larger synaptic terminal. Spontaneous secretion events formed a unimodal charge distribution, but single spike properties were heterogeneous. Larger events rose exponentially without interruption (τ ∼ 30 μs), and smaller events exhibited a stammer in their rising phase that is interpreted as a brief pause in pore dilation, a characteristic commonly associated with large dense core granule fusion pores. These events were entirely Ca(2+)-dependent. Holding the cells at -60 mV halted spontaneous release; and when the voltage was stepped to >-40 mV, secretion ensued. When stepping the voltage to 0 mV, novel kinetic phases of vesicle recruitment were revealed. Approximately 14 vesicles were released per ribbon in two kinetic phases with time constants of 1.5 and 16 ms, which are proposed to represent different primed states within the population of docked vesicles.
Collapse
|
25
|
Baden T, Euler T, Weckström M, Lagnado L. Spikes and ribbon synapses in early vision. Trends Neurosci 2013; 36:480-8. [DOI: 10.1016/j.tins.2013.04.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 04/18/2013] [Accepted: 04/18/2013] [Indexed: 01/01/2023]
|
26
|
Toychiev AH, Sagdullaev B, Yee CW, Ivanova E, Sagdullaev BT. A time and cost efficient approach to functional and structural assessment of living neuronal tissue. J Neurosci Methods 2013; 214:105-12. [PMID: 23370309 DOI: 10.1016/j.jneumeth.2013.01.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 01/16/2013] [Accepted: 01/18/2013] [Indexed: 11/18/2022]
Abstract
In this manuscript, we describe a protocol for capturing both physiological and structural properties of living neuronal tissue. An essential aspect of this method is its flexibility and fast turnaround time. It is a streamlined process that includes recording of electrophysiological neuronal activity, calcium imaging, and structural analysis. This is accomplished by placing intact tissue on a modified Millicell Biopore insert. The Biopore membrane suspends the tissue in the perfusion solution, allowing for complete access to nutrients, oxygen, and pharmacological agents. The ring that holds the membrane ensures its structural stability; forceps can be used to grip the ring without contacting the filter or the tissue, for easy transfer between multiple setups. We show that tissue readily adheres to the surface of the membrane, its entire surface is visible in transmitted light and accessible for recording and imaging, and remains responsive to physiological stimuli for extended periods of time.
Collapse
Affiliation(s)
- Abduqodir H Toychiev
- Department of Ophthalmology, Weill Medical College of Cornell University, Burke Medical Research Institute, White Plains, NY 10605, USA
| | | | | | | | | |
Collapse
|
27
|
Jang JH, Park JB, Kim SD, Lee SY, Hong SJ, Ryu PD. Property of large conductance Ca(2+)-activated K+ channels from Fasciola hepatica incorporated into planar lipid bilayer. Vet Parasitol 2012; 186:281-8. [PMID: 22154253 DOI: 10.1016/j.vetpar.2011.11.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 11/09/2011] [Accepted: 11/14/2011] [Indexed: 11/26/2022]
Abstract
Fasciola hepatica causes biliary epithelial hyperplasia and obstructive jaundice in humans and animals. Using a planar lipid bilayer technique, we further characterized the single channel property of large conductance K(+)-permeable channels that were previously identified from F. hepatica. The single channel conductance was 254.7±17.9 pS under a symmetrical 200/200 mM (cis/trans) KCl gradient. Open state probability (P(o)) varied from channel to channel at a given membrane potential and Ca(2+) concentration, but increased with voltage (-60 to +40 mV) and cis Ca(2+) (1-200 μM). Under a near bi-ionic condition of 200 mM [K(+)](cis)/200 mM [Na(+)](trans), the permeability ratio of K(+) to Na(+) was 5.0. Charybdotoxin (1 μM) inhibited P(o), whereas tetraethylammonium reduced the conductance (K(D)=67.8mM). Taken together, the results show that the single channel properties of the large conductance K(+)-permeable channels in F. hepatica are similar to those of large conductance Ca(2+)-activated K(+) (BK) channels in general, but distinct from typical BK channels in the extent of voltage- and Ca(2+)-dependence, as well as permeability to Na(+). This study further reveals a variant BK channel in F. hepatica that could serve as a new drug target to treat fascioliasis.
Collapse
Affiliation(s)
- Jung Hee Jang
- Department of Pharmacology, Research Institute of Veterinary Science, College of Veterinary Medicine, Seoul National University, 599 Gwanank-ro, Gwanak-gu, Seoul 151-742, Republic of Korea
| | | | | | | | | | | |
Collapse
|
28
|
Encoding of luminance and contrast by linear and nonlinear synapses in the retina. Neuron 2012; 73:758-73. [PMID: 22365549 PMCID: PMC3314971 DOI: 10.1016/j.neuron.2011.12.023] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2011] [Indexed: 01/01/2023]
Abstract
Understanding how neural circuits transmit information is technically challenging because the neural code is contained in the activity of large numbers of neurons and synapses. Here, we use genetically encoded reporters to image synaptic transmission across a population of sensory neurons-bipolar cells in the retina of live zebrafish. We demonstrate that the luminance sensitivities of these synapses varies over 10(4) with a log-normal distribution. About half the synapses made by ON and OFF cells alter their polarity of transmission as a function of luminance to generate a triphasic tuning curve with distinct maxima and minima. These nonlinear synapses signal temporal contrast with greater sensitivity than linear ones. Triphasic tuning curves increase the dynamic range over which bipolar cells signal light and improve the efficiency with which luminance information is transmitted. The most efficient synapses signaled luminance using just 1 synaptic vesicle per second per distinguishable gray level.
Collapse
|
29
|
Trenholm S, Borowska J, Zhang J, Hoggarth A, Johnson K, Barnes S, Lewis TJ, Awatramani GB. Intrinsic oscillatory activity arising within the electrically coupled AII amacrine-ON cone bipolar cell network is driven by voltage-gated Na+ channels. J Physiol 2012; 590:2501-17. [PMID: 22393249 DOI: 10.1113/jphysiol.2011.225060] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In the rd1 mouse model for retinal degeneration, the loss of photoreceptors results in oscillatory activity (∼10–20 Hz) within the remnant electrically coupled network of retinal ON cone bipolar and AII amacrine cells. We tested the role of hyperpolarization-activated currents (I(h)), voltage-gated Na(+) channels and gap junctions in mediating such oscillatory activity. Blocking I(h) (1 mm Cs(+)) hyperpolarized the network and augmented activity, while antagonizing voltage-dependent Na(+) channels (1 μm TTX) abolished oscillatory activity in the AII amacrine-ON cone bipolar cell network. Voltage-gated Na(+) channels were only observed in AII amacrine cells, implicating these cells as major drivers of activity. Pharmacologically uncoupling the network (200 μm meclofenamic acid (MFA)) blocked oscillations in all cells indicating that Na(+) channels exert their influence over multiple cell types within the network. In wt retina, occluding photoreceptor inputs to bipolar cells (10 μm NBQX and 50 μm l-AP4) resulted in a mild (∼10 mV) hyperpolarization and the induction of oscillatory activity within the AII amacrine-ON cone bipolar cell network. These oscillations had similar properties to those observed in rd1 retina, suggesting that no major degeneration-induced network rewiring is required to trigger spontaneous oscillations. Finally, we constructed a simplified computational model that exhibited Na(+) channel-dependent network oscillations. In this model, mild heterogeneities in channel densities between individual neurons reproduced our experimental findings. These results indicate that TTX-sensitive Na(+) channels in AII amacrine cells trigger degeneration-induced network oscillations, which provide a persistent synaptic drive to downstream remnant neurons, thus appearing to replace photoreceptors as the principal drivers of retinal activity.
Collapse
Affiliation(s)
- Stuart Trenholm
- Department of Anatomy, Dalhousie University, Halifax, NS, Canada B3H 1X5
| | | | | | | | | | | | | | | |
Collapse
|
30
|
Yee CW, Toychiev AH, Sagdullaev BT. Network deficiency exacerbates impairment in a mouse model of retinal degeneration. Front Syst Neurosci 2012; 6:8. [PMID: 22383900 PMCID: PMC3285818 DOI: 10.3389/fnsys.2012.00008] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 02/06/2012] [Indexed: 11/23/2022] Open
Abstract
Neural oscillations play an important role in normal brain activity, but also manifest during Parkinson’s disease, epilepsy, and other pathological conditions. The contribution of these aberrant oscillations to the function of the surviving brain remains unclear. In recording from retina in a mouse model of retinal degeneration (RD), we found that the incidence of oscillatory activity varied across different cell classes, evidence that some retinal networks are more affected by functional changes than others. This aberrant activity was driven by an independent inhibitory amacrine cell oscillator. By stimulating the surviving circuitry at different stages of the neurodegenerative process, we found that this dystrophic oscillator further compromises the function of the retina. These data reveal that retinal remodeling can exacerbate the visual deficit, and that aberrant synaptic activity could be targeted for RD treatment.
Collapse
Affiliation(s)
- Christopher W Yee
- Department of Ophthalmology, Burke Medical Research Institute, Weill Medical College of Cornell University White Plains, NY, USA
| | | | | |
Collapse
|
31
|
Baden T, Esposti F, Nikolaev A, Lagnado L. Spikes in retinal bipolar cells phase-lock to visual stimuli with millisecond precision. Curr Biol 2011; 21:1859-69. [PMID: 22055291 PMCID: PMC3235547 DOI: 10.1016/j.cub.2011.09.042] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 09/19/2011] [Accepted: 09/26/2011] [Indexed: 01/14/2023]
Abstract
Background The conversion of an analog stimulus into the digital form of spikes is a fundamental step in encoding sensory information. Here, we investigate this transformation in the visual system of fish by in vivo calcium imaging and electrophysiology of retinal bipolar cells, which have been assumed to be purely graded neurons. Results Synapses of all major classes of retinal bipolar cell encode visual information by using a combination of spikes and graded signals. Spikes are triggered within the synaptic terminal and, although sparse, phase-lock to a stimulus with a jitter as low as 2–3 ms. Spikes in bipolar cells encode a visual stimulus less reliably than spikes in ganglion cells but with similar temporal precision. The spike-generating mechanism does not alter the temporal filtering of a stimulus compared with the generator potential. The amplitude of the graded component of the presynaptic calcium signal can vary in time, and small fluctuations in resting membrane potential alter spike frequency and even switch spiking on and off. Conclusions In the retina of fish, the millisecond precision of spike coding begins in the synaptic terminal of bipolar cells. This neural compartment regulates the frequency of digital signals transmitted to the inner retina as well as the strength of graded signals.
Collapse
Affiliation(s)
- Tom Baden
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - Federico Esposti
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - Anton Nikolaev
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - Leon Lagnado
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
- Corresponding author
| |
Collapse
|
32
|
Dreosti E, Esposti F, Baden T, Lagnado L. In vivo evidence that retinal bipolar cells generate spikes modulated by light. Nat Neurosci 2011; 14:951-2. [PMID: 21706020 PMCID: PMC3232443 DOI: 10.1038/nn.2841] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 04/14/2011] [Indexed: 01/08/2023]
Abstract
Retinal bipolar cells have been assumed to generate purely graded responses to light. To test this idea we imaged the presynaptic calcium transient in live zebrafish. We found that ON, OFF, transient and sustained bipolar cells are all capable of generating fast 'all-or-none' calcium transients modulated by visual stimulation.
Collapse
Affiliation(s)
| | | | - Tom Baden
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - Leon Lagnado
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| |
Collapse
|
33
|
Francis AA, Mehta B, Zenisek D. Development of new peptide-based tools for studying synaptic ribbon function. J Neurophysiol 2011; 106:1028-37. [PMID: 21653726 DOI: 10.1152/jn.00255.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Synaptic ribbons are proteinaceous specialized electron-dense presynaptic structures found in nonspiking sensory cells of the vertebrate nervous system. Understanding the function of these structures is an active area of research (reviewed in Matthews G, Fuchs P. Nat Rev Neurosci 11: 812-822, 2010). Previous work had shown that ribbons could be effectively labeled and visualized using peptides that bind to the synaptic ribbon protein RIBEYE via a PXDLS motif (Zenisek D, Horst NK, Merrifield C, Sterling P, Matthews G. J Neurosci 24: 9752-9759, 2004). Here, we expand on the previous work to develop new tools and strategies for 1) better visualizing synaptic ribbons, and 2) monitoring and manipulating calcium on the synaptic ribbon. Specifically, we developed a new higher-affinity peptide-based label for visualizing ribbons in live cells and two strategies for localizing calcium indicators to the synaptic ribbon.
Collapse
Affiliation(s)
- Adam A Francis
- Department of Cellular and Molecular Physiology, Ophthalmology and Visual Sciences and the Center for Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06520, USA
| | | | | |
Collapse
|
34
|
Borowska J, Trenholm S, Awatramani GB. An intrinsic neural oscillator in the degenerating mouse retina. J Neurosci 2011; 31:5000-12. [PMID: 21451038 PMCID: PMC6622979 DOI: 10.1523/jneurosci.5800-10.2011] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 01/24/2011] [Accepted: 02/01/2011] [Indexed: 11/21/2022] Open
Abstract
The loss of photoreceptors during retinal degeneration (RD) is known to lead to an increase in basal activity in remnant neural networks. To identify the source of activity, we combined two-photon imaging with patch-clamp techniques to examine the physiological properties of morphologically identified retinal neurons in a mouse model of RD (rd1). Analysis of activity in rd1 ganglion cells revealed sustained oscillatory (∼10 Hz) synaptic activity in ∼30% of all classes of cells. Oscillatory activity persisted after putative inputs from residual photoreceptor, rod bipolar cell, and inhibitory amacrine cell synapses were pharmacologically blocked, suggesting that presynaptic cone bipolar cells were intrinsically active. Examination of presynaptic rd1 ON and OFF bipolar cells indicated that they rested at relatively negative potentials (less than -50 mV). However, in approximately half the cone bipolar cells, low-amplitude membrane oscillation (∼5 mV, ∼10 Hz) were apparent. Such oscillations were also observed in AII amacrine cells. Oscillations in ON cone bipolar and AII amacrine cells exhibited a weak apparent voltage dependence and were resistant to blockade of synaptic receptors, suggesting that, as in wild-type retina, they form an electrically coupled network. In addition, oscillations were insensitive to blockers of voltage-gated Ca(2+) channels (0.5 mm Cd(2+) and 0.5 mm Ni(2+)), ruling out known mechanisms that underlie oscillatory behavior in bipolar cells. Together, these results indicate that an electrically coupled network of ON cone bipolar/AII amacrine cells constitutes an intrinsic oscillator in the rd1 retina that is likely to drive synaptic activity in downstream circuits.
Collapse
Affiliation(s)
- Joanna Borowska
- Departments of Anatomy and Neurobiology, Neuroscience Institute, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada
| | - Stuart Trenholm
- Departments of Anatomy and Neurobiology, Neuroscience Institute, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada
| | - Gautam B. Awatramani
- Departments of Anatomy and Neurobiology, Neuroscience Institute, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada
| |
Collapse
|
35
|
Abstract
PURPOSE To investigate changes in cytokine levels in tears of type 2 diabetics with or without retinopathy. METHODS Tears were collected from 15 type 2 diabetics without retinopathy (DNR), 15 patients with retinopathy (DR), and 15 age and gender matched non-diabetic controls. Tear concentrations of 27 cytokines were measured by multiplex bead immunoassay. Cytokine differences between groups, ratios of type-1 T helper (Th1)/type-2 T helper (Th2) cytokines and anti-angiogenic/pro-angiogenic cytokines were analyzed statistically. RESULTS The most abundant cytokine detected in tears was interferon-induced protein-10 (IP-10). In comparison with controls, IP-10 and monocyte chemoattracant protein-1 (MCP-1) levels were significantly elevated in DR (p=0.016 and 0.036, respectively) and DNR groups (p=0.021 and 0.026, respectively). Interleukin-1 (IL-1) receptor antagonist (IL-1ra) levels were significantly increased in DNR (p=0.016). Th1/Th2 cytokines interferon-gamma (IFN-γ)/IL-5 and IL-2/IL-5 ratios were significantly increased in DR compared to controls (p=0.037 and 0.031, respectively). Anti-angiogenic/angiogenic cytokines IFN-γ/MCP-1 and IL-4/MCP-1 ratios in DR and DNR were significantly decreased compared to controls (p<0.05). IL-4/IL-8 and IL-12p70/IL-8 ratios were also significantly decreased in DR compared to controls (p=0.02 and 0.045, respectively). No significant correlation was demonstrated between tear cytokine concentrations and glycosylated hemoglobin (HbA1c) or fasting plasma glucose (FPG). CONCLUSIONS Diabetic tears exhibited elevated levels of IP-10 and MCP-1. The Th1/Th2 cytokine balance may shift to a predominantly Th1 state in DR patients. Pro-angiogenic cytokines are more highly represented than anti-angiogenic cytokines in the tears of diabetic patients.
Collapse
|
36
|
Abstract
AbstractZebrafish are an existing model for genetic and developmental studies due to their rapid external development and transparent embryos, which allow easy manipulation and observation of early developmental stages. The application of the zebrafish model to vision research has allowed for examination of retinal development and the characteristics of different retinal cell types, including bipolar cells. In particular, bipolar cell development, including differentiation, maturation, and gene expression, has been documented, as has physiological properties, such as voltage- and ligand-gated currents, and neurotransmitter receptor and ion channel expression. Mutant strains and transgenic lines have been used to document how bipolar cell connections and/or development may be altered, and toxicological studies examining how environmental factors may impact bipolar cell activity have been performed. The purpose of this paper was to review the existing literature on zebrafish bipolar cells, to provide a comprehensive overview of current information pertaining to this retinal cell type.
Collapse
|
37
|
Abstract
Gap junctions are frequently observed in the adult vertebrate retina. It has been shown that gap junctions function as passive electrotonic pathways and play various roles, such as noise reduction, synchronization of electrical activities, regulation of the receptive field size, and transmission of rod signals to cone pathways. The presence of gap junctions between bipolar cells has been reported in various species but their functions are not known. In the present study, we applied dual whole-cell clamp techniques to the adult goldfish retina to elucidate the functions of gap junctions between ON-type bipolar cells with a giant axon terminal (Mb1-BCs). Electrophysiological and immunohistochemical experiments revealed that Mb1-BCs were coupled with each other through gap junctions that were located at the distal dendrites. The coupling conductance between Mb1-BCs under light-adapted conditions was larger than that under dark-adapted conditions. The gap junctions showed neither rectification nor voltage dependence, and behaved as a low-pass filter. Mb1-BCs could generate Ca(2+) spikes in response to depolarization, especially under dark-adapted conditions. The Ca(2+) spike evoked electrotonic depolarization through gap junctions in neighboring Mb1-BCs, and the depolarization in turn could trigger Ca(2+) spikes with a time lag. A brief depolarizing pulse applied to an Mb1-BC evoked a long-lasting EPSC in the postsynaptic ganglion cell. The EPSC was shortened in duration when gap junctions were pharmacologically or mechanically impaired. These results suggest that the spread of Ca(2+) spikes through gap junctions between bipolar cells may play a key role in lateral interactions in the adult retina.
Collapse
|
38
|
Dorostkar MM, Dreosti E, Odermatt B, Lagnado L. Computational processing of optical measurements of neuronal and synaptic activity in networks. J Neurosci Methods 2010; 188:141-50. [PMID: 20152860 PMCID: PMC2849931 DOI: 10.1016/j.jneumeth.2010.01.033] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 01/27/2010] [Accepted: 01/28/2010] [Indexed: 12/20/2022]
Abstract
Imaging of optical reporters of neural activity across large populations of neurones is a widely used approach for investigating the function of neural circuits in slices and in vivo. Major challenges in analysing such experiments include the automatic identification of neurones and synapses, extraction of dynamic signals, and assessing the temporal and spatial relationships between active units in relation to the gross structure of the circuit. We have developed an integrated set of software tools, named SARFIA, by which these aspects of dynamic imaging experiments can be analysed semi-automatically. Key features are image-based detection of structures of interest using the Laplace operator, determining the positions of units in a layered network, clustering algorithms to classify units with similar functional responses, and a database to store, exchange and analyse results across experiments. We demonstrate the use of these tools to analyse synaptic activity in the retina of live zebrafish by multi-photon imaging of SyGCaMP2, a genetically encoded synaptically localised calcium reporter. By simultaneously recording activity across tens of bipolar cell terminals distributed throughout the IPL we made a functional map of the ON and OFF signalling channels and found that these were only partially separated. The automated detection of signals across many neurones in the retina allowed the reliable detection of small populations of neurones generating “ectopic” signals in the “ON” and “OFF” sublaminae. This software should be generally applicable for the analysis of dynamic imaging experiments across hundreds of responding units.
Collapse
|
39
|
Differential expression of three T-type calcium channels in retinal bipolar cells in rats. Vis Neurosci 2009; 26:177-87. [PMID: 19275782 DOI: 10.1017/s0952523809090026] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Retinal bipolar cells convey visual information from photoreceptors to retinal third-order neurons, amacrine and ganglion cells, with graded potentials through diversified cell types. To understand the possible role of voltage-dependent T-type Ca2+ currents in retinal bipolar cells, we investigated the pharmacological and biophysical properties of T-type Ca2+ currents in acutely dissociated retinal cone bipolar cells from rats using whole-cell patch-clamp recordings. We observed a broad group of cone bipolar cells with prominent T-type Ca2+ currents (T-rich) and another group with prominent L-type Ca2+ currents (L-rich). Based on the pharmacological and biophysical properties of the T-type Ca2+ currents, T-rich cone bipolar cells could be divided into three subgroups. Each subgroup appeared to express a single dominant T-type Ca2+ channel subunit. The T-type calcium currents could generate low-threshold regenerative potentials or spikes. Our results suggest that T-type Ca2+ channels may play an active and distinct signaling role in second-order neurons of the visual system, in contrast to the common signaling by L-rich bipolar cells.
Collapse
|
40
|
Gao J, Schwartz G, Berry MJ, Holmes P. An oscillatory circuit underlying the detection of disruptions in temporally-periodic patterns. NETWORK (BRISTOL, ENGLAND) 2009; 20:106-135. [PMID: 19568983 PMCID: PMC2752637 DOI: 10.1080/09548980902991705] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Neurons in diverse brain areas can respond to the interruption of a regular stimulus pattern by firing bursts of spikes. Here we describe a simple model, which permits such responses to periodic stimuli over a substantial frequency range. Focusing on the omitted stimulus response (OSR) in isolated retinas subjected to periodic patterns of dark flashes, we develop a biophysically-realistic model which accounts for resonances in ON bipolar cells. The bipolar cell terminal contains an LRC oscillator whose inductance is modulated by a transient calcium concentration, thus adjusting its resonant frequency to approximately match that of the stimulus. The model reproduces ganglion cell outputs, which sum the ON and OFF bipolar pathways, and it responds to omitted flashes with approximately constant latencies, as observed experimentally.
Collapse
Affiliation(s)
- Juan Gao
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA.
| | | | | | | |
Collapse
|
41
|
Petit-Jacques J, Bloomfield SA. Synaptic regulation of the light-dependent oscillatory currents in starburst amacrine cells of the mouse retina. J Neurophysiol 2008; 100:993-1006. [PMID: 18497354 DOI: 10.1152/jn.01399.2007] [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
Responses of on-center starburst amacrine cells to steady light stimuli were recorded in the dark-adapted mouse retina. The response to spots of dim white light appear to show two components, an initial peak that correspond to the onset of the light stimulus and a series of oscillations that ride on top of the initial peak relaxation. The frequency of oscillations during light stimulation was three time higher than the frequency of spontaneous oscillations recorded in the dark. The light-evoked responses in starburst cells were exclusively dependent on the release of glutamate likely from presynaptic bipolar axon terminals and the binding of glutamate to AMPA/kainate receptors because they were blocked by 6-cyano-7-nitroquinoxalene-2,3-dione. The synaptic pathway responsible for the light responses was blocked by AP4, an agonist of metabotropic glutamate receptors that hyperpolarize on-center bipolar cells on activation. Light responses were inhibited by the calcium channel blockers cadmium ions and nifedipine, suggesting that the release of glutamate was calcium dependent. The oscillatory component of the response was specifically inhibited by blocking the glutamate transporter with d-threo-beta-benzyloxyaspartic acid, suggesting that glutamate reuptake is necessary for the oscillatory release. GABAergic antagonists bicuculline, SR 95531, and picrotoxin increased the amplitude of the initial peak while they inhibit the frequency of oscillations. TTX had a similar effect. Strychnine, the blocker of glycine receptors did not affect the initial peak but strongly decreased the oscillations frequency. These inhibitory inputs onto the bipolar axon terminals shape and synchronize the oscillatory component.
Collapse
Affiliation(s)
- Jerome Petit-Jacques
- Department of Physiology and Neuroscience, New York University School of Medicine, 550 First Ave., New York, NY 10016, USA.
| | | |
Collapse
|
42
|
Schwartz G, Berry MJ. Sophisticated temporal pattern recognition in retinal ganglion cells. J Neurophysiol 2008; 99:1787-98. [PMID: 18272878 DOI: 10.1152/jn.01025.2007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pattern recognition is one of the most important tasks of the visual system, and uncovering the neural mechanisms underlying recognition phenomena has been a focus of researchers for decades. Surprisingly, at the earliest stages of vision, the retina is capable of highly sophisticated temporal pattern recognition. We stimulated the retina of tiger salamander (Ambystoma tigrinum) with periodic dark flash sequences and found that retinal ganglion cells had a wide variety of different responses to a periodic flash sequence with many firing when a flash was omitted. The timing of the omitted stimulus response (OSR) depended on the period, with individual cells tracking the stimulus period down to increments of 5 ms. When flashes occurred earlier than expected, cells updated their expectation of the next flash time by as much as 50 ms. When flashes occurred later than expected, cells fired an OSR and reset their temporal expectation to the average time interval between flashes. Using pharmacology to investigate the retinal circuitry involved, we found that inhibitory transmission from amacrine cells was not required, but on bipolar cells were required. The results suggest a mechanism in which the intrinsic resonance of on bipolars leads to the OSR in ganglion cells. We discuss the implications of retinal pattern recognition on the neural code of the retina and visual processing in general.
Collapse
Affiliation(s)
- Greg Schwartz
- Princeton University, Department of Molecular Biology, Washington Road, Princeton, NJ 08544-1014, USA.
| | | |
Collapse
|
43
|
Coggins MR, Grabner CP, Almers W, Zenisek D. Stimulated exocytosis of endosomes in goldfish retinal bipolar neurons. J Physiol 2007; 584:853-65. [PMID: 17823206 PMCID: PMC2276998 DOI: 10.1113/jphysiol.2007.140848] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
After exocytosis, synaptic vesicle components are selectively retrieved by clathrin-mediated endocytosis and then re-used in future rounds of transmitter release. Under some conditions, synaptic terminals in addition perform bulk endocytosis of large membranous sacs. Bulk endocytosis is less selective than clathrin-mediated endocytosis and probably internalizes components normally targeted to the plasma membrane. Nonetheless, this process plays a major role in some tonic ribbon-type synapses, which release neurotransmitter for prolonged periods of time. We show here, that large endosomes formed after strong and prolonged stimulation undergo stimulated exocytosis in retinal bipolar neurons. The result suggests how cells might return erroneously internalized components to the plasma membrane, and also demonstrates that synaptic vesicles are not the only neuronal organelle that stains with styryl dyes and undergoes stimulated exocytosis.
Collapse
Affiliation(s)
- Michael R Coggins
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | | | | | | |
Collapse
|
44
|
Evans GJO, Cousin MA. Simultaneous monitoring of three key neuronal functions in primary neuronal cultures. J Neurosci Methods 2006; 160:197-205. [PMID: 17049620 PMCID: PMC2225589 DOI: 10.1016/j.jneumeth.2006.09.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Revised: 08/25/2006] [Accepted: 09/02/2006] [Indexed: 11/22/2022]
Abstract
The coupling of Ca2+ influx to synaptic vesicle (SV) recycling in nerve terminals is essential for neurotransmitter release and thus neuronal communication. Both of these parameters have been monitored using fluorescent reporter dyes such as fura-2 and FM1-43 in single central nerve terminals. However, their simultaneous monitoring has been hampered by the proximity of their fluorescence spectra, resulting in significant contamination of their signals by bleedthrough. We have developed an assay that simultaneously monitors both SV recycling and changes in intracellular free Ca2+ ([Ca2+]i) in cultured neurons using the reporter dyes FM4-64 and fura-2AM. By monitoring both fura-2 and FM4-64 emission in the far red range, we were able to visualize functionally independent readouts of both SV recycling and [Ca2+]i independent of fluorescence bleedthrough. We were also able to incorporate an assay of cell viability without any fluorescence bleedthrough from either fura-2 or FM4-64 signals, using the dye SYTOX Green. We propose that this assay of three key neuronal functions could be simply translated into a high content screening format for studies investigating small molecule inhibitors of these processes.
Collapse
|
45
|
Palmer MJ. Modulation of Ca(2+)-activated K+ currents and Ca(2+)-dependent action potentials by exocytosis in goldfish bipolar cell terminals. J Physiol 2006; 572:747-62. [PMID: 16497710 PMCID: PMC1780019 DOI: 10.1113/jphysiol.2006.105205] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Retinal bipolar cells convey light-evoked potentials from photoreceptors to ganglion cells and mediate the initial stages of visual signal processing. They do not fire Na(+)-dependent action potentials (APs) but the Mb1 class of goldfish bipolar cell exhibits Ca(2+)-dependent APs and regenerative potentials that originate in the axon terminal. I have examined the properties of Ca(2+)-dependent APs in isolated bipolar-cell terminals in goldfish retinal slices. All recorded terminals fired spontaneous or evoked APs at frequencies of up to 15 Hz. When an AP waveform was used as a voltage stimulus, exocytosis was evoked by single APs, maintained throughout AP trains and modulated by AP frequency. Furthermore, feedback inhibition of the Ca2+ current (I(Ca)) by released vesicular protons reduced depression of exocytosis during AP trains. In the absence of K+ current inhibition, step depolarizations and AP waveforms evoked a rapidly activated outward current that was dependent on Ca2+ influx I(K(Ca). I therefore investigated whether proton-mediated feedback inhibition of I(Ca) affected the activation of I(K(Ca)). A transient inhibition of I(K(Ca)) was observed that was dependent on exocytosis, blocked by high-pH extracellular buffer, of similar magnitude to inhibition of I(Ca) but occurred with a delay of 2.7 ms. In addition, the amplitude of APs evoked under current clamp was inhibited by the action of vesicular protons released by the APs. Protons released via exocytosis may therefore be a significant modulator of Ca(2+)-dependent currents and regenerative potentials in bipolar-cell terminals.
Collapse
Affiliation(s)
- Mary J Palmer
- Neuroscience Group, Institute for Science and Technology in Medicine, Keele University, Keele ST5 5BG, UK.
| |
Collapse
|
46
|
Miller RF, Staff NP, Velte TJ. Form and Function of on-off Amacrine Cells in the Amphibian Retina. J Neurophysiol 2006; 95:3171-90. [PMID: 16481463 DOI: 10.1152/jn.00090.2005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
on-off amacrine cells were studied with whole cell recording techniques and intracellular staining methods using intact retina-eyecup preparations of the tiger salamander ( Ambystoma tigrinum) and the mudpuppy ( Necturus maculosus). Morphological characterization of these cells included three-dimensional reconstruction methods based on serial optical sections obtained with a confocal microscope. Some cells had their detailed morphology digitized with a computer-assisted tracing system and converted to compartmental models for computer simulations. The dendrites of on-off amacrine cells have spines and numerous varicosities. Physiological recordings confirmed that on-off amacrine cells generate both large- and small-amplitude impulses attributed, respectively, to somatic and dendritic generation sites. Using a multichannel model for impulse generation, computer simulations were carried out to evaluate how impulses are likely to propagate throughout these structures. We conclude that the on-off amacrine cell is organized with multifocal dendritic impulse generating sites and that both dendritic and somatic impulse activity contribute to the functional repertoire of these interneurons: locally generated dendritic impulses can provide regional activation, while somatic impulse activity results in rapid activation of the entire dendritic tree.
Collapse
Affiliation(s)
- Robert F Miller
- Department of Neuroscience, University of Minnesota, 6-145 Jackson Hall, 321 Church St. SE, Minneapolis, MN 55455, USA.
| | | | | |
Collapse
|
47
|
Steele EC, Chen X, Iuvone PM, MacLeish PR. Imaging of Ca2+ dynamics within the presynaptic terminals of salamander rod photoreceptors. J Neurophysiol 2005; 94:4544-53. [PMID: 16107525 DOI: 10.1152/jn.01193.2004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although the overall importance of Ca(2+) as a mediator of cell signaling and neurotransmitter release has long been appreciated, the details of Ca(2+) dynamics within the inner segments of vertebrate rod photoreceptors are just beginning to be elucidated. Even less is known regarding Ca(2+) dynamics within the rod presynaptic terminal compartment. Using fura-2 to report changes in intracellular Ca(2+), we imaged the responses of enzymatically dissociated salamander rod photoreceptors retaining intact axons and presynaptic terminals stimulated with a brief depolarizing puff of KCl (30 mM pipette concentration). In the vast majority of cells, the response was a large increase in Ca(2+) levels in the terminal compartment, but not in the soma. In contrast, rods exhibited a substantial elevation in somatic Ca(2+) levels when depolarized with a brief puff of 100 mM KCl (pipette concentration). These data are consistent with previously reported differences in Ca(2+) buffering mechanisms within the somatic and terminal compartments. Additionally, they may reflect the presence of Ca(2+) channels having distinct properties within the membranes of the two compartments. Consistent with this hypothesis, fluorescent immunocytochemistry using an antibody against the L-type Ca(2+) channel Ca(v)1.2 (alpha1C) subunit and semiquantitative confocal microscopy revealed a high concentration of immunoreactivity in the membranes of terminals of intact rods compared with the somata. Further investigations using enzymatically dissociated preparations of intact rod photoreceptors retaining their presynaptic terminals will allow further testing of these and other hypotheses regarding the compartmentalized regulation of Ca(2+) dynamics within rod photoreceptors.
Collapse
Affiliation(s)
- Ernest C Steele
- Department of Anatomy and Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia, USA.
| | | | | | | |
Collapse
|
48
|
Beaumont V, Llobet A, Lagnado L. Expansion of calcium microdomains regulates fast exocytosis at a ribbon synapse. Proc Natl Acad Sci U S A 2005; 102:10700-5. [PMID: 16027365 PMCID: PMC1180766 DOI: 10.1073/pnas.0501961102] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We investigated the Ca2+ signal regulating fast exocytosis at the ribbon synapse of retinal bipolar cells by using total internal reflection fluorescence microscopy to image fluorescent Ca2+ indicators and interference reflection microscopy to monitor exocytosis. Depolarization generated Ca2+ "microdomains" that expanded over the time scale during which the rapidly releasable pool (RRP) of vesicles was released (<40 ms). Replacing mobile Ca2+ buffers in the terminal with 10 mM EGTA prevented expansion of microdomains and decreased the number of rapidly releasable vesicles by a factor of 2. Conversely, decreasing the concentration of EGTA in the terminal to 0.1 mM increased the apparent width of a Ca2+ microdomain from 580 nm to 930 nm and increased the size of the RRP size by a factor of 1.5. The [Ca2+] over the area that the microdomain expanded was estimated to be 2-7 microM. These results indicate that vesicles within the RRP are located hundreds of nanometers from Ca2+ channels, and that fusion of these vesicles can be triggered by low micromolar levels of Ca2+. Variable distances between docked vesicles and Ca2+ channels at the active zone, therefore, provide an explanation for the heterogeneous release probability of vesicles comprising the RRP.
Collapse
Affiliation(s)
- Vahri Beaumont
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom
| | | | | |
Collapse
|
49
|
Ma YP, Cui J, Pan ZH. Heterogeneous expression of voltage-dependent Na+ and
K+ channels in mammalian retinal bipolar cells. Vis Neurosci 2005; 22:119-33. [PMID: 15935105 DOI: 10.1017/s0952523805222010] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Indexed: 11/05/2022]
Abstract
Retinal bipolar cells show heterogeneous expression of
voltage-dependent Na+ and K+ currents. We used
whole-cell patch-clamp recordings to investigate the possible roles of
these currents in the response properties of bipolar cells in rats.
Isolated bipolar cells showed robust spontaneous regenerative activity,
but the regenerative potential of rod bipolar cells reached a more
depolarized level than that of cone bipolar cells. In both isolated cells
and cells in retinal slices, the membrane depolarization evoked by current
injection was apparently capped. The evoked membrane potential was again
more depolarized in rod bipolar cells than in cone bipolar cells.
Application of tetraethylammonium and 4-aminopyridine shifted the
spontaneous regenerative potential as well as the evoked potential to a
more depolarized level. In addition, a subclass of cone bipolar cells
showed a prominent spike in the initial phase of the voltage response when
the cells were depolarized from a relatively negative membrane potential.
The spike was mediated mainly by tetrodotoxin-sensitive Na+
current. The presence of the spike sped up the response kinetics and
enhanced the peak membrane potential. Results of this study raise the
possibility that voltage-dependent K+ currents may play a role
in defining different membrane operating ranges of rod and cone bipolar
cells and that voltage-dependent Na+ currents may enhance the
response kinetics and amplitude of certain cone bipolar cells.
Collapse
Affiliation(s)
- Yu-Ping Ma
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | | | | |
Collapse
|
50
|
Petit-Jacques J, Völgyi B, Rudy B, Bloomfield S. Spontaneous oscillatory activity of starburst amacrine cells in the mouse retina. J Neurophysiol 2005; 94:1770-80. [PMID: 15917322 DOI: 10.1152/jn.00279.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Using patch-clamp techniques, we investigated the characteristics of the spontaneous oscillatory activity displayed by starburst amacrine cells in the mouse retina. At a holding potential of -70 mV, oscillations appeared as spontaneous, rhythmic inward currents with a frequency of approximately 3.5 Hz and an average maximal amplitude of approximately 120 pA. Application of TEA, a potassium channel blocker, increased the amplitude of oscillatory currents by >70% but reduced their frequency by approximately 17%. The TEA effects did not appear to result from direct actions on starburst cells, but rather a modulation of their synaptic inputs. Oscillatory currents were inhibited by 6-cyano-7-nitroquinoxalene-2,3-dione (CNQX), an antagonist of AMPA/kainate receptors, indicating that they were dependent on a periodic glutamatergic input likely from presynaptic bipolar cells. The oscillations were also inhibited by the calcium channel blockers cadmium and nifedipine, suggesting that the glutamate release was calcium dependent. Application of AP4, an agonist of mGluR6 receptors on on-center bipolar cells, blocked the oscillatory currents in starburst cells. However, application of TEA overcame the AP4 blockade, suggesting that the periodic glutamate release from bipolar cells is intrinsic to the inner plexiform layer in that, under experimental conditions, it can occur independent of photoreceptor input. The GABA receptor antagonists picrotoxin and bicuculline enhanced the amplitude of oscillations in starburst cells prestimulated with TEA. Our results suggest that this enhancement was due to a reduction of a GABAergic feedback inhibition from amacrine cells to bipolar cells and the resultant increased glutamate release. Finally, we found that some ganglion cells and other types of amacrine cell also displayed rhythmic activity, suggesting that oscillatory behavior is expressed by a number of inner retinal neurons.
Collapse
Affiliation(s)
- Jerome Petit-Jacques
- Department of Ophthalmology, New York University School of Medicine, 550 First Ave., New York, New York 10016, USA
| | | | | | | |
Collapse
|