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Tworig JM, Coate C, Feller MB. Excitatory neurotransmission activates compartmentalized calcium transients in Müller glia without affecting lateral process motility. eLife 2021; 10:73202. [PMID: 34913435 PMCID: PMC8806189 DOI: 10.7554/elife.73202] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 12/15/2021] [Indexed: 11/13/2022] Open
Abstract
Neural activity has been implicated in the motility and outgrowth of glial cell processes throughout the central nervous system. Here, we explore this phenomenon in Müller glia, which are specialized radial astroglia that are the predominant glial type of the vertebrate retina. Müller glia extend fine filopodia-like processes into retinal synaptic layers, in similar fashion to brain astrocytes and radial glia that exhibit perisynaptic processes. Using two-photon volumetric imaging, we found that during the second postnatal week, Müller glial processes were highly dynamic, with rapid extensions and retractions that were mediated by cytoskeletal rearrangements. During this same stage of development, retinal waves led to increases in cytosolic calcium within Müller glial lateral processes and stalks. These regions comprised distinct calcium compartments, distinguished by variable participation in waves, timing, and sensitivity to an M1 muscarinic acetylcholine receptor antagonist. However, we found that motility of lateral processes was unaffected by the presence of pharmacological agents that enhanced or blocked wave-associated calcium transients. Finally, we found that mice lacking normal cholinergic waves in the first postnatal week also exhibited normal Müller glial process morphology. Hence, outgrowth of Müller glial lateral processes into synaptic layers is determined by factors that are independent of neuronal activity. When it comes to studying the nervous system, neurons often steal the limelight; yet, they can only work properly thanks to an ensemble cast of cell types whose roles are only just emerging. For example, ‘glial cells’ – their name derives from the Greek word for glue – were once thought to play only a passive, supporting function in nervous tissues. Now, growing evidence shows that they are, in fact, integrated into neural circuits: their activity is influenced by neurons, and, in turn, they help neurons to function properly. The role of glial cells is becoming clear in the retina, the thin, light-sensitive layer that lines the back of the eye and relays visual information to the brain. There, beautifully intricate Müller glial cells display fine protrusions (or ‘processes') that intermingle with synapses, the busy space between neurons where chemical messengers are exchanged. These messengers can act on Müller cells, triggering cascades of molecular events that may influence the structure and function of glia. This is of particular interest during development: as Müller cells mature, they are exposed to chemicals released by more fully formed retinal neurons. Tworig et al. explored how neuronal messengers can influence the way Müller cells grow their processes. To do so, they tracked mouse retinal glial cells ‘live’ during development, showing that they were growing fine, highly dynamic processes in a region rich in synapses just as neurons and glia increased their communication. However, using drugs to disrupt this messaging for a short period did not seem to impact how the processes grew. Extending the blockade over a longer timeframe also did not change the way Müller cells developed, with the cells still acquiring their characteristic elaborate process networks. Taken together, these results suggest that the structural maturation of Müller glial cells is not impacted by neuronal signaling, giving a more refined understanding of how glia form in the retina and potentially in the brain.
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Affiliation(s)
- Joshua M Tworig
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Chandler Coate
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Marla B Feller
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
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52
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Hellmer CB, Hall LM, Bohl JM, Sharpe ZJ, Smith RG, Ichinose T. Cholinergic feedback to bipolar cells contributes to motion detection in the mouse retina. Cell Rep 2021; 37:110106. [PMID: 34910920 PMCID: PMC8793255 DOI: 10.1016/j.celrep.2021.110106] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 08/11/2021] [Accepted: 11/16/2021] [Indexed: 11/25/2022] Open
Abstract
Retinal bipolar cells are second-order neurons that transmit basic features of the visual scene to postsynaptic partners. However, their contribution to motion detection has not been fully appreciated. Here, we demonstrate that cholinergic feedback from starburst amacrine cells (SACs) to certain presynaptic bipolar cells via alpha-7 nicotinic acetylcholine receptors (α7-nAChRs) promotes direction-selective signaling. Patch clamp recordings reveal that distinct bipolar cell types making synapses at proximal SAC dendrites also express α7-nAChRs, producing directionally skewed excitatory inputs. Asymmetric SAC excitation contributes to motion detection in On-Off direction-selective ganglion cells (On-Off DSGCs), predicted by computational modeling of SAC dendrites and supported by patch clamp recordings from On-Off DSGCs when bipolar cell α7-nAChRs is eliminated pharmacologically or by conditional knockout. Altogether, these results show that cholinergic feedback to bipolar cells enhances direction-selective signaling in postsynaptic SACs and DSGCs, illustrating how bipolar cells provide a scaffold for postsynaptic microcircuits to cooperatively enhance retinal motion detection.
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Affiliation(s)
- Chase B Hellmer
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA; Present address: Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40202, USA
| | - Leo M Hall
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA; Present address: Department of Internal Medicine, St. Mary Mercy Livonia Hospital, Livonia, MI 48154, USA
| | - Jeremy M Bohl
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Zachary J Sharpe
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Robert G Smith
- Department of Neuroscience, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Tomomi Ichinose
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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53
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Ezra-Tsur E, Amsalem O, Ankri L, Patil P, Segev I, Rivlin-Etzion M. Realistic retinal modeling unravels the differential role of excitation and inhibition to starburst amacrine cells in direction selectivity. PLoS Comput Biol 2021; 17:e1009754. [PMID: 34968385 PMCID: PMC8754344 DOI: 10.1371/journal.pcbi.1009754] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 01/12/2022] [Accepted: 12/14/2021] [Indexed: 11/19/2022] Open
Abstract
Retinal direction-selectivity originates in starburst amacrine cells (SACs), which display a centrifugal preference, responding with greater depolarization to a stimulus expanding from soma to dendrites than to a collapsing stimulus. Various mechanisms were hypothesized to underlie SAC centrifugal preference, but dissociating them is experimentally challenging and the mechanisms remain debatable. To address this issue, we developed the Retinal Stimulation Modeling Environment (RSME), a multifaceted data-driven retinal model that encompasses detailed neuronal morphology and biophysical properties, retina-tailored connectivity scheme and visual input. Using a genetic algorithm, we demonstrated that spatiotemporally diverse excitatory inputs-sustained in the proximal and transient in the distal processes-are sufficient to generate experimentally validated centrifugal preference in a single SAC. Reversing these input kinetics did not produce any centrifugal-preferring SAC. We then explored the contribution of SAC-SAC inhibitory connections in establishing the centrifugal preference. SAC inhibitory network enhanced the centrifugal preference, but failed to generate it in its absence. Embedding a direction selective ganglion cell (DSGC) in a SAC network showed that the known SAC-DSGC asymmetric connectivity by itself produces direction selectivity. Still, this selectivity is sharpened in a centrifugal-preferring SAC network. Finally, we use RSME to demonstrate the contribution of SAC-SAC inhibitory connections in mediating direction selectivity and recapitulate recent experimental findings. Thus, using RSME, we obtained a mechanistic understanding of SACs' centrifugal preference and its contribution to direction selectivity.
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Affiliation(s)
- Elishai Ezra-Tsur
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
- Department of Mathematics and Computer Science, The Open University of Israel, Ra’anana, Israel
| | - Oren Amsalem
- Department of Neurobiology, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Lea Ankri
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Pritish Patil
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Idan Segev
- Department of Neurobiology, Hebrew University of Jerusalem, Jerusalem, Israel
- Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
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54
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Otgondemberel Y, Roh H, Fried SI, Im M. Spiking Characteristics of Network-Mediated Responses Arising in Direction-Selective Ganglion Cells of Rabbit and Mouse Retinas to Electric Stimulation for Retinal Prostheses. IEEE Trans Neural Syst Rehabil Eng 2021; 29:2445-2455. [PMID: 34784280 PMCID: PMC8654582 DOI: 10.1109/tnsre.2021.3128878] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To restore the sight of individuals blinded by outer retinal degeneration, numerous retinal prostheses have been developed. However, the performance of those implants is still hampered by some factors including the lack of comprehensive understanding of the electrically-evoked responses arising in various retinal ganglion cell (RGC) types. In this study, we characterized the electrically-evoked network-mediated responses (hereafter referred to as electric responses) of ON-OFF direction-selective (DS) RGCs in rabbit and mouse retinas for the first time. Interestingly, both species in common demonstrated strong negative correlations between spike counts of electric responses and direction selective indices (DSIs), suggesting electric stimulation activates inhibitory presynaptic neurons that suppress null direction responses for high direction tuning in their light responses. The DS cells of the two species showed several differences including different numbers of bursts. Also, spiking patterns were more heterogeneous across DS RGCs of rabbits than those of mice. The electric response magnitudes of rabbit DS cells showed positive and negative correlations with ON and OFF light response magnitudes to preferred direction motion, respectively. But the mouse DS cells showed positive correlations in both comparisons. Our Fano Factor (FF) and spike time tiling coefficient (STTC) analyses revealed that spiking consistencies across repeats were reduced in late electric responses in both species. Moreover, the response consistencies of DS RGCs were lower than those of non-DS RGCs. Our results indicate the species-dependent retinal circuits may result in different electric response features and therefore suggest a proper animal model may be crucial in prosthetic researches.
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55
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Matsumoto A, Agbariah W, Nolte SS, Andrawos R, Levi H, Sabbah S, Yonehara K. Direction selectivity in retinal bipolar cell axon terminals. Neuron 2021; 109:2928-2942.e8. [PMID: 34390651 PMCID: PMC8478419 DOI: 10.1016/j.neuron.2021.07.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 06/18/2021] [Accepted: 07/09/2021] [Indexed: 12/20/2022]
Abstract
The ability to encode the direction of image motion is fundamental to our sense of vision. Direction selectivity along the four cardinal directions is thought to originate in direction-selective ganglion cells (DSGCs) because of directionally tuned GABAergic suppression by starburst cells. Here, by utilizing two-photon glutamate imaging to measure synaptic release, we reveal that direction selectivity along all four directions arises earlier than expected at bipolar cell outputs. Individual bipolar cells contained four distinct populations of axon terminal boutons with different preferred directions. We further show that this bouton-specific tuning relies on cholinergic excitation from starburst cells and GABAergic inhibition from wide-field amacrine cells. DSGCs received both tuned directionally aligned inputs and untuned inputs from among heterogeneously tuned glutamatergic bouton populations. Thus, directional tuning in the excitatory visual pathway is incrementally refined at the bipolar cell axon terminals and their recipient DSGC dendrites by two different neurotransmitters co-released from starburst cells.
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Affiliation(s)
- Akihiro Matsumoto
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Department of Biomedicine, Aarhus University, Ole Worms Allé 8, 8000 Aarhus C, Denmark
| | - Weaam Agbariah
- Department of Medical Neurobiology, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 9112102, Israel
| | - Stella Solveig Nolte
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Department of Biomedicine, Aarhus University, Ole Worms Allé 8, 8000 Aarhus C, Denmark
| | - Rawan Andrawos
- Department of Medical Neurobiology, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 9112102, Israel
| | - Hadara Levi
- Department of Medical Neurobiology, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 9112102, Israel
| | - Shai Sabbah
- Department of Medical Neurobiology, Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem 9112102, Israel.
| | - Keisuke Yonehara
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Department of Biomedicine, Aarhus University, Ole Worms Allé 8, 8000 Aarhus C, Denmark.
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56
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Pottackal J, Singer JH, Demb JB. Computational and Molecular Properties of Starburst Amacrine Cell Synapses Differ With Postsynaptic Cell Type. Front Cell Neurosci 2021; 15:660773. [PMID: 34381333 PMCID: PMC8351878 DOI: 10.3389/fncel.2021.660773] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 06/08/2021] [Indexed: 11/22/2022] Open
Abstract
A presynaptic neuron can increase its computational capacity by transmitting functionally distinct signals to each of its postsynaptic cell types. To determine whether such computational specialization occurs over fine spatial scales within a neurite arbor, we investigated computation at output synapses of the starburst amacrine cell (SAC), a critical component of the classical direction-selective (DS) circuit in the retina. The SAC is a non-spiking interneuron that co-releases GABA and acetylcholine and forms closely spaced (<5 μm) inhibitory synapses onto two postsynaptic cell types: DS ganglion cells (DSGCs) and neighboring SACs. During dynamic optogenetic stimulation of SACs in mouse retina, whole-cell recordings of inhibitory postsynaptic currents revealed that GABAergic synapses onto DSGCs exhibit stronger low-pass filtering than those onto neighboring SACs. Computational analyses suggest that this filtering difference can be explained primarily by presynaptic properties, rather than those of the postsynaptic cells per se. Consistent with functionally diverse SAC presynapses, blockade of N-type voltage-gated calcium channels abolished GABAergic currents in SACs but only moderately reduced GABAergic and cholinergic currents in DSGCs. These results jointly demonstrate how specialization of synaptic outputs could enhance parallel processing in a compact interneuron over fine spatial scales. Moreover, the distinct transmission kinetics of GABAergic SAC synapses are poised to support the functional diversity of inhibition within DS circuitry.
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Affiliation(s)
- Joseph Pottackal
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT, United States.,Department of Biology, University of Maryland, College Park, College Park, MD, United States
| | - Joshua H Singer
- Department of Biology, University of Maryland, College Park, College Park, MD, United States
| | - Jonathan B Demb
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT, United States.,Department of Ophthalmology and Visual Science, Yale University, New Haven, CT, United States.,Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, United States.,Department of Neuroscience, Yale University, New Haven, CT, United States
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57
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Grimes WN, Aytürk DG, Hoon M, Yoshimatsu T, Gamlin C, Carrera D, Nath A, Nadal-Nicolás FM, Ahlquist RM, Sabnis A, Berson DM, Diamond JS, Wong RO, Cepko C, Rieke F. A High-Density Narrow-Field Inhibitory Retinal Interneuron with Direct Coupling to Müller Glia. J Neurosci 2021; 41:6018-6037. [PMID: 34083252 PMCID: PMC8276741 DOI: 10.1523/jneurosci.0199-20.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 05/16/2021] [Accepted: 05/17/2021] [Indexed: 11/21/2022] Open
Abstract
Amacrine cells are interneurons composing the most diverse cell class in the mammalian retina. They help encode visual features, such as edges or directed motion, by mediating excitatory and inhibitory interactions between input (i.e., bipolar) and output (i.e., ganglion) neurons in the inner plexiform layer (IPL). Like other brain regions, the retina also contains glial cells that contribute to neurotransmitter uptake, metabolic regulation, and neurovascular control. Here, we report that, in mouse retina (of either sex), an abundant, though previously unstudied inhibitory amacrine cell is coupled directly to Müller glia. Electron microscopic reconstructions of this amacrine type revealed chemical synapses with known retinal cell types and extensive associations with Müller glia, the processes of which often completely ensheathe the neurites of this amacrine cell. Microinjecting small tracer molecules into the somas of these amacrine cells led to selective labeling of nearby Müller glia, leading us to suggest the name "Müller glia-coupled amacrine cell," or MAC. Our data also indicate that MACs release glycine at conventional chemical synapses, and viral retrograde transsynaptic tracing from the dorsal lateral geniculate nucleus showed selective connections between MACs and a subpopulation of retinal ganglion cell types. Visually evoked responses revealed a strong preference for light increments; these "ON" responses were primarily mediated by excitatory chemical synaptic input and direct electrical coupling with other cells. This initial characterization of the MAC provides the first evidence for neuron-glia coupling in the mammalian retina and identifies the MAC as a potential link between inhibitory processing and glial function.SIGNIFICANCE STATEMENT Gap junctions between pairs of neurons or glial cells are commonly found throughout the nervous system and play multiple roles, including electrical coupling and metabolic exchange. In contrast, gap junctions between neurons and glia cells have rarely been reported and are poorly understood. Here we report the first evidence for neuron-glia coupling in the mammalian retina, specifically between an abundant (but previously unstudied) inhibitory interneuron and Müller glia. Moreover, viral tracing, optogenetics, and serial electron microscopy provide new information about the neuron's synaptic partners and physiological responses.
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Affiliation(s)
- William N Grimes
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195
- National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland 20892
| | - Didem Göz Aytürk
- Harvard Medical School, Blavatnik Institute, Howard Hughes Medical Institute, Boston, Massachusetts 02115
| | - Mrinalini Hoon
- Department of Biological Structure, University of Washington, Seattle, Washington 98195
| | - Takeshi Yoshimatsu
- Department of Biological Structure, University of Washington, Seattle, Washington 98195
| | - Clare Gamlin
- Department of Biological Structure, University of Washington, Seattle, Washington 98195
| | - Daniel Carrera
- National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland 20892
| | - Amurta Nath
- National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland 20892
| | - Francisco M Nadal-Nicolás
- Retinal Neurophysiology Section, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Richard M Ahlquist
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195
| | - Adit Sabnis
- National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland 20892
| | - David M Berson
- Department of Neuroscience, Brown University, Providence, Rhode Island 02912
| | - Jeffrey S Diamond
- National Institute of Neurological Disease and Stroke, National Institutes of Health, Bethesda, Maryland 20892
| | - Rachel O Wong
- Department of Biological Structure, University of Washington, Seattle, Washington 98195
| | - Connie Cepko
- Harvard Medical School, Blavatnik Institute, Howard Hughes Medical Institute, Boston, Massachusetts 02115
| | - Fred Rieke
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195
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58
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Ding J, Chen A, Chung J, Acaron Ledesma H, Wu M, Berson DM, Palmer SE, Wei W. Spatially displaced excitation contributes to the encoding of interrupted motion by a retinal direction-selective circuit. eLife 2021; 10:e68181. [PMID: 34096504 PMCID: PMC8211448 DOI: 10.7554/elife.68181] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/06/2021] [Indexed: 12/19/2022] Open
Abstract
Spatially distributed excitation and inhibition collectively shape a visual neuron's receptive field (RF) properties. In the direction-selective circuit of the mammalian retina, the role of strong null-direction inhibition of On-Off direction-selective ganglion cells (On-Off DSGCs) on their direction selectivity is well-studied. However, how excitatory inputs influence the On-Off DSGC's visual response is underexplored. Here, we report that On-Off DSGCs have a spatially displaced glutamatergic receptive field along their horizontal preferred-null motion axes. This displaced receptive field contributes to DSGC null-direction spiking during interrupted motion trajectories. Theoretical analyses indicate that population responses during interrupted motion may help populations of On-Off DSGCs signal the spatial location of moving objects in complex, naturalistic visual environments. Our study highlights that the direction-selective circuit exploits separate sets of mechanisms under different stimulus conditions, and these mechanisms may help encode multiple visual features.
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Affiliation(s)
- Jennifer Ding
- Committee on Neurobiology Graduate Program, The University of ChicagoChicagoUnited States
- Department of Neurobiology, The University of ChicagoChicagoUnited States
| | - Albert Chen
- Department of Organismal Biology, The University of ChicagoChicagoUnited States
| | - Janet Chung
- Department of Neurobiology, The University of ChicagoChicagoUnited States
| | - Hector Acaron Ledesma
- Graduate Program in Biophysical Sciences, The University of ChicagoChicagoUnited States
| | - Mofei Wu
- Department of Neurobiology, The University of ChicagoChicagoUnited States
| | - David M Berson
- Department of Neuroscience and Carney Institute for Brain Science, Brown UniversityProvidenceUnited States
| | - Stephanie E Palmer
- Committee on Neurobiology Graduate Program, The University of ChicagoChicagoUnited States
- Department of Organismal Biology, The University of ChicagoChicagoUnited States
- Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of ChicagoChicagoUnited States
| | - Wei Wei
- Committee on Neurobiology Graduate Program, The University of ChicagoChicagoUnited States
- Department of Neurobiology, The University of ChicagoChicagoUnited States
- Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of ChicagoChicagoUnited States
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59
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Antagonistic Center-Surround Mechanisms for Direction Selectivity in the Retina. Cell Rep 2021; 31:107608. [PMID: 32375036 PMCID: PMC7221349 DOI: 10.1016/j.celrep.2020.107608] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 01/22/2020] [Accepted: 04/13/2020] [Indexed: 12/29/2022] Open
Abstract
An antagonistic center-surround receptive field is a key feature in sensory processing, but how it contributes to specific computations such as direction selectivity is often unknown. Retinal On-starburst amacrine cells (SACs), which mediate direction selectivity in direction-selective ganglion cells (DSGCs), exhibit antagonistic receptive field organization: depolarizing to light increments and decrements in their center and surround, respectively. We find that a repetitive stimulation exhausts SAC center and enhances its surround and use it to study how center-surround responses contribute to direction selectivity. Center, but not surround, activation induces direction-selective responses in SACs. Nevertheless, both SAC center and surround elicited direction-selective responses in DSGCs, but to opposite directions. Physiological and modeling data suggest that the opposing direction selectivity can result from inverted temporal balance between excitation and inhibition in DSGCs, implying that SAC's response timing dictates direction selectivity. Our findings reveal antagonistic center-surround mechanisms for direction selectivity and demonstrate how context-dependent receptive field reorganization enables flexible computations.
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60
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Kim TY, Shin S, Choi H, Jeong SH, Myung D, Hahn SK. Smart Contact Lenses with a Transparent Silver Nanowire Strain Sensor for Continuous Intraocular Pressure Monitoring. ACS APPLIED BIO MATERIALS 2021; 4:4532-4541. [PMID: 35006789 PMCID: PMC10867858 DOI: 10.1021/acsabm.1c00267] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Continuous intraocular pressure (IOP) monitoring can provide a paradigm shift in the management of patients with glaucoma as a facile alternative to conventional diagnostic methods. However, the low sensitivity and functional instability of current IOP sensors have limited their clinical utility in the management of glaucoma. Here, we have developed a smart contact lens integrated with a transparent silver nanowire IOP strain sensor and wireless circuits for noninvasive, continuous IOP monitoring. After confirming the robust stability of the IOP sensor within the smart contact lens in the presence of tears and repeated eyelid blink model cycles, we were able to monitor IOP changes on polydimethylsiloxane model eyes in vitro. In vivo tests demonstrated that our fully integrated wireless smart contact lens could successfully monitor the change in IOP in living rabbit eyes, which was clearly validated by the conventional invasive tonometer IOP test. Taken together, we could confirm the feasibility of our smart contact lens as a noninvasive platform for continuous IOP monitoring of glaucoma patients.
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Affiliation(s)
- Tae Yeon Kim
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Korea
| | - Sangbaie Shin
- PHI BIOMED Co., 168 Yeoksam-ro, Gangnam-gu, Seoul 06248, South Korea
| | - Hyunsik Choi
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Korea
| | - Sang Hoon Jeong
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Korea
| | - David Myung
- Department of Ophthalmology and Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, California 94305, United States
| | - Sei Kwang Hahn
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Korea
- PHI BIOMED Co., 168 Yeoksam-ro, Gangnam-gu, Seoul 06248, South Korea
- Department of Ophthalmology and Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, California 94305, United States
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61
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El-Quessny M, Maanum K, Feller MB. Visual Experience Influences Dendritic Orientation but Is Not Required for Asymmetric Wiring of the Retinal Direction Selective Circuit. Cell Rep 2021; 31:107844. [PMID: 32610144 DOI: 10.1016/j.celrep.2020.107844] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 05/22/2020] [Accepted: 06/10/2020] [Indexed: 01/02/2023] Open
Abstract
Changes in dendritic morphology in response to activity have long been thought to be a critical component of how neural circuits develop to properly encode sensory information. Ventral-preferring direction-selective ganglion cells (vDSGCs) have asymmetric dendrites oriented along their preferred direction, and this has been hypothesized to play a critical role in their tuning. Here we report the surprising result that visual experience is critical for the alignment of vDSGC dendrites to their preferred direction. Interestingly, vDSGCs in dark-reared mice lose their inhibition-independent dendritic contribution to direction-selective tuning while maintaining asymmetric inhibitory input. These data indicate that different mechanisms of a cell's computational abilities can be constructed over development through divergent mechanisms.
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Affiliation(s)
- Malak El-Quessny
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Kayla Maanum
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Marla B Feller
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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62
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Friedrich RW, Wanner AA. Dense Circuit Reconstruction to Understand Neuronal Computation: Focus on Zebrafish. Annu Rev Neurosci 2021; 44:275-293. [PMID: 33730512 DOI: 10.1146/annurev-neuro-110220-013050] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The dense reconstruction of neuronal wiring diagrams from volumetric electron microscopy data has the potential to generate fundamentally new insights into mechanisms of information processing and storage in neuronal circuits. Zebrafish provide unique opportunities for dynamical connectomics approaches that combine reconstructions of wiring diagrams with measurements of neuronal population activity and behavior. Such approaches have the power to reveal higher-order structure in wiring diagrams that cannot be detected by sparse sampling of connectivity and that is essential for neuronal computations. In the brain stem, recurrently connected neuronal modules were identified that can account for slow, low-dimensional dynamics in an integrator circuit. In the spinal cord, connectivity specifies functional differences between premotor interneurons. In the olfactory bulb, tuning-dependent connectivity implements a whitening transformation that is based on the selective suppression of responses to overrepresented stimulus features. These findings illustrate the potential of dynamical connectomics in zebrafish to analyze the circuit mechanisms underlying higher-order neuronal computations.
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Affiliation(s)
- Rainer W Friedrich
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland; .,Faculty of Natural Sciences, University of Basel, 4003 Basel, Switzerland
| | - Adrian A Wanner
- Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey 08544, USA;
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63
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Sawant A, Ebbinghaus BN, Bleckert A, Gamlin C, Yu WQ, Berson D, Rudolph U, Sinha R, Hoon M. Organization and emergence of a mixed GABA-glycine retinal circuit that provides inhibition to mouse ON-sustained alpha retinal ganglion cells. Cell Rep 2021; 34:108858. [PMID: 33730586 PMCID: PMC8030271 DOI: 10.1016/j.celrep.2021.108858] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 12/07/2020] [Accepted: 02/19/2021] [Indexed: 12/04/2022] Open
Abstract
In the retina, amacrine interneurons inhibit retinal ganglion cell (RGC) dendrites to shape retinal output. Amacrine cells typically use either GABA or glycine to exert synaptic inhibition. Here, we combined transgenic tools with immunohistochemistry, electrophysiology, and 3D electron microscopy to determine the composition and organization of inhibitory synapses across the dendritic arbor of a well-characterized RGC type in the mouse retina: the ON-sustained alpha RGC. We find mixed GABA-glycine receptor synapses across this RGC type, unveiling the existence of "mixed" inhibitory synapses in the retinal circuit. Presynaptic amacrine boutons with dual release sites are apposed to ON-sustained alpha RGC postsynapses. We further reveal the sequence of postsynaptic assembly for these mixed synapses: GABA receptors precede glycine receptors, and a lack of early GABA receptor expression impedes the recruitment of glycine receptors. Together our findings uncover the organization and developmental profile of an additional motif of inhibition in the mammalian retina.
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Affiliation(s)
- Abhilash Sawant
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA; Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, USA
| | - Briana N Ebbinghaus
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA; McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, USA
| | - Adam Bleckert
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Clare Gamlin
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Wan-Qing Yu
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - David Berson
- Department of Neuroscience, Brown University, Providence, RI, USA
| | - Uwe Rudolph
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Champaign, IL, USA; Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| | - Raunak Sinha
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA; Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, USA; McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, USA
| | - Mrinalini Hoon
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA; Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, USA; McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI, USA.
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64
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Sethuramanujam S, Matsumoto A, deRosenroll G, Murphy-Baum B, Grosman C, McIntosh JM, Jing M, Li Y, Berson D, Yonehara K, Awatramani GB. Rapid multi-directed cholinergic transmission in the central nervous system. Nat Commun 2021; 12:1374. [PMID: 33654091 PMCID: PMC7925691 DOI: 10.1038/s41467-021-21680-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 01/27/2021] [Indexed: 01/31/2023] Open
Abstract
In many parts of the central nervous system, including the retina, it is unclear whether cholinergic transmission is mediated by rapid, point-to-point synaptic mechanisms, or slower, broad-scale 'non-synaptic' mechanisms. Here, we characterized the ultrastructural features of cholinergic connections between direction-selective starburst amacrine cells and downstream ganglion cells in an existing serial electron microscopy data set, as well as their functional properties using electrophysiology and two-photon acetylcholine (ACh) imaging. Correlative results demonstrate that a 'tripartite' structure facilitates a 'multi-directed' form of transmission, in which ACh released from a single vesicle rapidly (~1 ms) co-activates receptors expressed in multiple neurons located within ~1 µm of the release site. Cholinergic signals are direction-selective at a local, but not global scale, and facilitate the transfer of information from starburst to ganglion cell dendrites. These results suggest a distinct operational framework for cholinergic signaling that bears the hallmarks of synaptic and non-synaptic forms of transmission.
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Affiliation(s)
| | - Akihiro Matsumoto
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | | | | | - Claudio Grosman
- Department of Molecular and Integrative Physiology, 407 S. Goodwin Ave, Urbana, IL, 61801, USA
| | - J Michael McIntosh
- George E. Whalen Veterans Affairs Medical Center, Department of Psychiatry, School of Biological Sciences, University of Utah, Salt Lake City, UT, USA
- Department of Psychiatry; School of Biological Sciences, University of Utah, Salt Lake City, UT, USA
- School of Biological Sciences, University of Utah, Salt Lake City, UT, USA
| | - Miao Jing
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China
| | - David Berson
- Neuroscience, Brown University, Providence, RI, USA
| | - Keisuke Yonehara
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Department of Biomedicine, Aarhus University, Aarhus C, Denmark.
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65
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Chen Q, Smith RG, Huang X, Wei W. Preserving inhibition with a disinhibitory microcircuit in the retina. eLife 2020; 9:62618. [PMID: 33269700 PMCID: PMC7728437 DOI: 10.7554/elife.62618] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 12/02/2020] [Indexed: 01/13/2023] Open
Abstract
Previously, we found that in the mammalian retina, inhibitory inputs onto starburst amacrine cells (SACs) are required for robust direction selectivity of On-Off direction-selective ganglion cells (On-Off DSGCs) against noisy backgrounds (Chen et al., 2016). However, the source of the inhibitory inputs to SACs and how this inhibition confers noise resilience of DSGCs are unknown. Here, we show that when visual noise is present in the background, the motion-evoked inhibition to an On-Off DSGC is preserved by a disinhibitory motif consisting of a serially connected network of neighboring SACs presynaptic to the DSGC. This preservation of inhibition by a disinhibitory motif arises from the interaction between visually evoked network dynamics and short-term synaptic plasticity at the SAC-DSGC synapse. Although the disinhibitory microcircuit is well studied for its disinhibitory function in brain circuits, our results highlight the algorithmic flexibility of this motif beyond disinhibition due to the mutual influence between network and synaptic plasticity mechanisms.
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Affiliation(s)
- Qiang Chen
- Committee on Computational Neuroscience, University of Chicago, Chicago, United States
| | - Robert G Smith
- Department of Neuroscience, University of Pennsylvania, Philadelphia, United States
| | - Xiaolin Huang
- Committee on Neurobiology, University of Chicago, Chicago, United States
| | - Wei Wei
- Committee on Computational Neuroscience, University of Chicago, Chicago, United States.,Committee on Neurobiology, University of Chicago, Chicago, United States.,Department of Neurobiology, the University of Chicago, Chicago, United States.,Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, University of Chicago, Chicago, United States
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66
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Pottackal J, Singer JH, Demb JB. Receptoral Mechanisms for Fast Cholinergic Transmission in Direction-Selective Retinal Circuitry. Front Cell Neurosci 2020; 14:604163. [PMID: 33324168 PMCID: PMC7726240 DOI: 10.3389/fncel.2020.604163] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 10/22/2020] [Indexed: 01/09/2023] Open
Abstract
Direction selectivity represents an elementary sensory computation that can be related to underlying synaptic mechanisms. In mammalian retina, direction-selective ganglion cells (DSGCs) respond strongly to visual motion in a "preferred" direction and weakly to motion in the opposite, "null" direction. The DS mechanism depends on starburst amacrine cells (SACs), which provide null direction-tuned GABAergic inhibition and untuned cholinergic excitation to DSGCs. GABAergic inhibition depends on conventional synaptic transmission, whereas cholinergic excitation apparently depends on paracrine (i.e., non-synaptic) transmission. Despite its paracrine mode of transmission, cholinergic excitation is more transient than GABAergic inhibition, yielding a temporal difference that contributes essentially to the DS computation. To isolate synaptic mechanisms that generate the distinct temporal properties of cholinergic and GABAergic transmission from SACs to DSGCs, we optogenetically stimulated SACs while recording postsynaptic currents (PSCs) from DSGCs in mouse retina. Direct recordings from channelrhodopsin-2-expressing (ChR2+) SACs during quasi-white noise (WN) (0-30 Hz) photostimulation demonstrated precise, graded optogenetic control of SAC membrane current and potential. Linear systems analysis of ChR2-evoked PSCs recorded in DSGCs revealed cholinergic transmission to be faster than GABAergic transmission. A deconvolution-based analysis showed that distinct postsynaptic receptor kinetics fully account for the temporal difference between cholinergic and GABAergic transmission. Furthermore, GABAA receptor blockade prolonged cholinergic transmission, identifying a new functional role for GABAergic inhibition of SACs. Thus, fast cholinergic transmission from SACs to DSGCs arises from at least two distinct mechanisms, yielding temporal properties consistent with conventional synapses despite its paracrine nature.
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Affiliation(s)
- Joseph Pottackal
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT, United States
| | - Joshua H. Singer
- Department of Biology, University of Maryland, College Park, MD, United States
| | - Jonathan B. Demb
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT, United States
- Department of Ophthalmology and Visual Science, Yale University, New Haven, CT, United States
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, United States
- Department of Neuroscience, Yale University, New Haven, CT, United States
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67
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Rangel Olguin AG, Rochon PL, Krishnaswamy A. New Optical Tools to Study Neural Circuit Assembly in the Retina. Front Neural Circuits 2020; 14:44. [PMID: 32848633 PMCID: PMC7424070 DOI: 10.3389/fncir.2020.00044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 06/23/2020] [Indexed: 12/17/2022] Open
Abstract
During development, neurons navigate a tangled thicket of thousands of axons and dendrites to synapse with just a few specific targets. This phenomenon termed wiring specificity, is critical to the assembly of neural circuits and the way neurons manage this feat is only now becoming clear. Recent studies in the mouse retina are shedding new insight into this process. They show that specific wiring arises through a series of stages that include: directed axonal and dendritic growth, the formation of neuropil layers, positioning of such layers, and matching of co-laminar synaptic partners. Each stage appears to be directed by a distinct family of recognition molecules, suggesting that the combinatorial expression of such family members might act as a blueprint for retinal connectivity. By reviewing the evidence in support of each stage, and by considering their underlying molecular mechanisms, we attempt to synthesize these results into a wiring model which generates testable predictions for future studies. Finally, we conclude by highlighting new optical methods that could be used to address such predictions and gain further insight into this fundamental process.
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68
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Park SJH, Lieberman EE, Ke JB, Rho N, Ghorbani P, Rahmani P, Jun NY, Lee HL, Kim IJ, Briggman KL, Demb JB, Singer JH. Connectomic analysis reveals an interneuron with an integral role in the retinal circuit for night vision. eLife 2020; 9:e56077. [PMID: 32412412 PMCID: PMC7228767 DOI: 10.7554/elife.56077] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Accepted: 04/27/2020] [Indexed: 12/28/2022] Open
Abstract
Night vision in mammals depends fundamentally on rod photoreceptors and the well-studied rod bipolar (RB) cell pathway. The central neuron in this pathway, the AII amacrine cell (AC), exhibits a spatially tuned receptive field, composed of an excitatory center and an inhibitory surround, that propagates to ganglion cells, the retina's projection neurons. The circuitry underlying the surround of the AII, however, remains unresolved. Here, we combined structural, functional and optogenetic analyses of the mouse retina to discover that surround inhibition of the AII depends primarily on a single interneuron type, the NOS-1 AC: a multistratified, axon-bearing GABAergic cell, with dendrites in both ON and OFF synaptic layers, but with a pure ON (depolarizing) response to light. Our study demonstrates generally that novel neural circuits can be identified from targeted connectomic analyses and specifically that the NOS-1 AC mediates long-range inhibition during night vision and is a major element of the RB pathway.
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Affiliation(s)
- Silvia JH Park
- Department of Ophthalmology & Visual Science, Yale UniversityNew HavenUnited States
| | - Evan E Lieberman
- Department of Biology, University of MarylandCollege ParkUnited States
| | - Jiang-Bin Ke
- Department of Biology, University of MarylandCollege ParkUnited States
| | - Nao Rho
- Department of Biology, University of MarylandCollege ParkUnited States
| | - Padideh Ghorbani
- Department of Biology, University of MarylandCollege ParkUnited States
| | - Pouyan Rahmani
- Department of Ophthalmology & Visual Science, Yale UniversityNew HavenUnited States
| | - Na Young Jun
- Department of Ophthalmology & Visual Science, Yale UniversityNew HavenUnited States
| | - Hae-Lim Lee
- Department of Cellular & Molecular Physiology, Yale UniversityNew HavenUnited States
| | - In-Jung Kim
- Department of Ophthalmology & Visual Science, Yale UniversityNew HavenUnited States
| | - Kevin L Briggman
- Circuit Dynamics and Connectivity Unit, National Institute of Neurological Disorders and Stroke, National Institutes of HealthBethesdaUnited States
| | - Jonathan B Demb
- Department of Ophthalmology & Visual Science, Yale UniversityNew HavenUnited States
- Department of Cellular & Molecular Physiology, Yale UniversityNew HavenUnited States
- Department of Neuroscience, Yale UniversityNew HavenUnited States
| | - Joshua H Singer
- Department of Biology, University of MarylandCollege ParkUnited States
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69
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Jain V, Murphy-Baum BL, deRosenroll G, Sethuramanujam S, Delsey M, Delaney KR, Awatramani GB. The functional organization of excitation and inhibition in the dendrites of mouse direction-selective ganglion cells. eLife 2020; 9:52949. [PMID: 32096758 PMCID: PMC7069718 DOI: 10.7554/elife.52949] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 02/24/2020] [Indexed: 12/14/2022] Open
Abstract
Recent studies indicate that the precise timing and location of excitation and inhibition (E/I) within active dendritic trees can significantly impact neuronal function. How synaptic inputs are functionally organized at the subcellular level in intact circuits remains unclear. To address this issue, we took advantage of the retinal direction-selective ganglion cell circuit, where directionally tuned inhibition is known to shape non-directional excitatory signals. We combined two-photon calcium imaging with genetic, pharmacological, and single-cell ablation methods to examine the extent to which inhibition ‘vetoes’ excitation at the level of individual dendrites of direction-selective ganglion cells. We demonstrate that inhibition shapes direction selectivity independently within small dendritic segments (<10µm) with remarkable accuracy. The data suggest that the parallel processing schemes proposed for direction encoding could be more fine-grained than previously envisioned.
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Affiliation(s)
- Varsha Jain
- Department of Biology, University of Victoria, Victoria, Canada
| | | | | | | | - Mike Delsey
- Department of Biology, University of Victoria, Victoria, Canada
| | - Kerry R Delaney
- Department of Biology, University of Victoria, Victoria, Canada
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70
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Baden T, Euler T, Berens P. Understanding the retinal basis of vision across species. Nat Rev Neurosci 2019; 21:5-20. [PMID: 31780820 DOI: 10.1038/s41583-019-0242-1] [Citation(s) in RCA: 146] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/22/2019] [Indexed: 12/12/2022]
Abstract
The vertebrate retina first evolved some 500 million years ago in ancestral marine chordates. Since then, the eyes of different species have been tuned to best support their unique visuoecological lifestyles. Visual specializations in eye designs, large-scale inhomogeneities across the retinal surface and local circuit motifs mean that all species' retinas are unique. Computational theories, such as the efficient coding hypothesis, have come a long way towards an explanation of the basic features of retinal organization and function; however, they cannot explain the full extent of retinal diversity within and across species. To build a truly general understanding of vertebrate vision and the retina's computational purpose, it is therefore important to more quantitatively relate different species' retinal functions to their specific natural environments and behavioural requirements. Ultimately, the goal of such efforts should be to build up to a more general theory of vision.
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Affiliation(s)
- Tom Baden
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, UK. .,Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.
| | - Thomas Euler
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.,Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, Tübingen, Germany
| | - Philipp Berens
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.,Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, Tübingen, Germany.,Institute for Bioinformatics and Medical Informatics, University of Tübingen, Tübingen, Germany.,Bernstein Centre for Computational Neuroscience, University of Tübingen, Tübingen, Germany
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71
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Soto F, Tien NW, Goel A, Zhao L, Ruzycki PA, Kerschensteiner D. AMIGO2 Scales Dendrite Arbors in the Retina. Cell Rep 2019; 29:1568-1578.e4. [PMID: 31693896 PMCID: PMC6871773 DOI: 10.1016/j.celrep.2019.09.085] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 08/21/2019] [Accepted: 09/27/2019] [Indexed: 12/24/2022] Open
Abstract
The size of dendrite arbors shapes their function and differs vastly between neuron types. The signals that control dendritic arbor size remain obscure. Here, we find that in the retina, starburst amacrine cells (SACs) and rod bipolar cells (RBCs) express the homophilic cell-surface protein AMIGO2. In Amigo2 knockout (KO) mice, SAC and RBC dendrites expand while arbors of other retinal neurons remain stable. SAC dendrites are divided into a central input region and a peripheral output region that provides asymmetric inhibition to direction-selective ganglion cells (DSGCs). Input and output compartments scale precisely with increased arbor size in Amigo2 KO mice, and SAC dendrites maintain asymmetric connectivity with DSGCs. Increased coverage of SAC dendrites is accompanied by increased direction selectivity of DSGCs without changes to other ganglion cells. Our results identify AMIGO2 as a cell-type-specific dendritic scaling factor and link dendrite size and coverage to visual feature detection.
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Affiliation(s)
- Florentina Soto
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA.
| | - Nai-Wen Tien
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA; Graduate Program in Neuroscience, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Anurag Goel
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Lei Zhao
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Philip A Ruzycki
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Daniel Kerschensteiner
- John F. Hardesty, MD Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Neuroscience, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Biomedical Engineering, Washington University School of Medicine, Saint Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, Saint Louis, MO 63110, USA.
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72
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Abstract
In animal eyes, the detection of slow global image motion is crucial to preventing blurry vision. A new study reveals how a mammalian global motion detector achieves this through 'space-time wiring' at its dendrites.
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Affiliation(s)
- Anna Vlasits
- Institute of Ophthalmic Research, Otfried-Mueller-Str. 25, University of Tuebingen, 72076 Tuebingen, Germany.
| | - Tom Baden
- Institute of Ophthalmic Research, Otfried-Mueller-Str. 25, University of Tuebingen, 72076 Tuebingen, Germany; School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK.
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73
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Spatiotemporally Asymmetric Excitation Supports Mammalian Retinal Motion Sensitivity. Curr Biol 2019; 29:3277-3288.e5. [PMID: 31564498 PMCID: PMC6865067 DOI: 10.1016/j.cub.2019.08.048] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 08/15/2019] [Accepted: 08/20/2019] [Indexed: 11/20/2022]
Abstract
The detection of visual motion is a fundamental function of the visual system. How motion speed and direction are computed together at the cellular level, however, remains largely unknown. Here, we suggest a circuit mechanism by which excitatory inputs to direction-selective ganglion cells in the mouse retina become sensitive to the motion speed and direction of image motion. Electrophysiological, imaging, and connectomic analyses provide evidence that the dendrites of ON direction-selective cells receive spatially offset and asymmetrically filtered glutamatergic inputs along motion-preference axis from asymmetrically wired bipolar and amacrine cell types with distinct release dynamics. A computational model shows that, with this spatiotemporal structure, the input amplitude becomes sensitive to speed and direction by a preferred direction enhancement mechanism. Our results highlight the role of an excitatory mechanism in retinal motion computation by which feature selectivity emerges from non-selective inputs.
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74
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Hall LM, Hellmer CB, Koehler CC, Ichinose T. Bipolar Cell Type-Specific Expression and Conductance of Alpha-7 Nicotinic Acetylcholine Receptors in the Mouse Retina. Invest Ophthalmol Vis Sci 2019; 60:1353-1361. [PMID: 30934054 PMCID: PMC6738513 DOI: 10.1167/iovs.18-25753] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Purpose Motion detection is performed by a unique neural network in the mouse retina. Starburst amacrine cells (SACs), which release acetylcholine and gamma-aminobutyric acid (GABA) into the network, are key neurons in the motion detection pathway. Although GABA contributions to the network have been extensively studied, the role of acetylcholine is minimally understood. Acetylcholine receptors are present in a subset of bipolar, amacrine, and ganglion cells. We focused on α7-nicotinic acetylcholine receptor (α7-nAChR) expression in bipolar cells, and investigated which types of bipolar cells possess α7-nAChRs. Methods Retinal slice sections were prepared from C57BL/6J and Gus8.4-GFP mice. Specific expression of α7-nAChRs in bipolar cells was examined using α-bungarotoxin (αBgTx)-conjugated Alexa dyes co-labeled with specific bipolar cell markers. Whole-cell recordings were conducted from bipolar cells in retinal slice sections. A selective α7-nAChR agonist, PNU282987, was applied by a puff and responses were recorded. Results αBgTx fluorescence was observed primarily in bipolar cell somas. We found that α7-nAChRs were expressed by the majority of type 1, 2, 4, and 7 bipolar cells. Whole-cell recordings revealed that type 2 and 7 bipolar cells depolarized by PNU application. In contrast, α7-nAChRs were not detected in most of type 3, 5, 6, and rod bipolar cells. Conclusions We found that α7-nAChRs are present in bipolar cells in a type-specific manner. Because these bipolar cells provide synaptic inputs to SACs and direction selective ganglion cells, α7-nAChRs may play a role in direction selectivity by modulating these bipolar cells' outputs.
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Affiliation(s)
- Leo M Hall
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Chase B Hellmer
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Christina C Koehler
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
| | - Tomomi Ichinose
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, Michigan, United States
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75
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Poleg-Polsky A, Ding H, Diamond JS. Functional Compartmentalization within Starburst Amacrine Cell Dendrites in the Retina. Cell Rep 2019. [PMID: 29539419 PMCID: PMC5877421 DOI: 10.1016/j.celrep.2018.02.064] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Dendrites in many neurons actively compute information. In retinal starburst amacrine cells, transformations from synaptic input to output occur within individual dendrites and mediate direction selectivity, but directional signal fidelity at individual synaptic outputs and correlated activity among neighboring outputs on starburst dendrites have not been examined systematically. Here, we record visually evoked calcium signals simultaneously at many individual synaptic outputs within single starburst amacrine cells in mouse retina. We measure visual receptive fields of individual output synapses and show that small groups of outputs are functionally compartmentalized within starburst dendrites, creating distinct computational units. Inhibition enhances compartmentalization and directional tuning of individual outputs but also decreases the signal-to-noise ratio. Simulations suggest, however, that the noise underlying output signal variability is well tolerated by postsynaptic direction-selective ganglion cells, which integrate convergent inputs to acquire reliable directional information.
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Affiliation(s)
- Alon Poleg-Polsky
- Synaptic Physiology Section, National Institute of Neurological Disorders and Stroke, NIH, 35 Convent Drive, Building 35A, Room 3E-621, Bethesda, MD 20892, USA
| | - Huayu Ding
- Synaptic Physiology Section, National Institute of Neurological Disorders and Stroke, NIH, 35 Convent Drive, Building 35A, Room 3E-621, Bethesda, MD 20892, USA
| | - Jeffrey S Diamond
- Synaptic Physiology Section, National Institute of Neurological Disorders and Stroke, NIH, 35 Convent Drive, Building 35A, Room 3E-621, Bethesda, MD 20892, USA.
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Qin B, Humberg TH, Kim A, Kim HS, Short J, Diao F, White BH, Sprecher SG, Yuan Q. Muscarinic acetylcholine receptor signaling generates OFF selectivity in a simple visual circuit. Nat Commun 2019; 10:4093. [PMID: 31501438 PMCID: PMC6733798 DOI: 10.1038/s41467-019-12104-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Accepted: 08/21/2019] [Indexed: 11/30/2022] Open
Abstract
ON and OFF selectivity in visual processing is encoded by parallel pathways that respond to either light increments or decrements. Despite lacking the anatomical features to support split channels, Drosophila larvae effectively perform visually-guided behaviors. To understand principles guiding visual computation in this simple circuit, we focus on investigating the physiological properties and behavioral relevance of larval visual interneurons. We find that the ON vs. OFF discrimination in the larval visual circuit emerges through light-elicited cholinergic signaling that depolarizes a cholinergic interneuron (cha-lOLP) and hyperpolarizes a glutamatergic interneuron (glu-lOLP). Genetic studies further indicate that muscarinic acetylcholine receptor (mAchR)/Gαo signaling produces the sign-inversion required for OFF detection in glu-lOLP, the disruption of which strongly impacts both physiological responses of downstream projection neurons and dark-induced pausing behavior. Together, our studies identify the molecular and circuit mechanisms underlying ON vs. OFF discrimination in the Drosophila larval visual system. Drosophila larvae are able to perform visually-guided behaviours yet the molecular and circuit mechanisms for discriminating changes in light intensity are not known. Here, the authors report that ON versus OFF discrimination results from opposing cholinergic and glutamatergic mechanisms.
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Affiliation(s)
- Bo Qin
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | | | - Anna Kim
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Hyong S Kim
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jacob Short
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Fengqiu Diao
- National Institute of Mental Health, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Benjamin H White
- National Institute of Mental Health, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Simon G Sprecher
- Department of Biology, University of Fribourg, 1700, Fribourg, Switzerland
| | - Quan Yuan
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA.
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77
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Bloss EB, Hunt DL. Revealing the Synaptic Hodology of Mammalian Neural Circuits With Multiscale Neurocartography. Front Neuroinform 2019; 13:52. [PMID: 31427940 PMCID: PMC6690003 DOI: 10.3389/fninf.2019.00052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 07/02/2019] [Indexed: 11/20/2022] Open
Abstract
The functional features of neural circuits are determined by a combination of properties that range in scale from projections systems across the whole brain to molecular interactions at the synapse. The burgeoning field of neurocartography seeks to map these relevant features of brain structure—spanning a volume ∼20 orders of magnitude—to determine how neural circuits perform computations supporting cognitive function and complex behavior. Recent technological breakthroughs in tissue sample preparation, high-throughput electron microscopy imaging, and automated image analyses have produced the first visualizations of all synaptic connections between neurons of invertebrate model systems. However, the sheer size of the central nervous system in mammals implies that reconstruction of the first full brain maps at synaptic scale may not be feasible for decades. In this review, we outline existing and emerging technologies for neurocartography that complement electron microscopy-based strategies and are beginning to derive some basic organizing principles of circuit hodology at the mesoscale, microscale, and nanoscale. Specifically, we discuss how a host of light microscopy techniques including array tomography have been utilized to determine both long-range and subcellular organizing principles of synaptic connectivity. In addition, we discuss how new techniques, such as two-photon serial tomography of the entire mouse brain, have become attractive approaches to dissect the potential connectivity of defined cell types. Ultimately, principles derived from these techniques promise to facilitate a conceptual understanding of how connectomes, and neurocartography in general, can be effectively utilized toward reaching a mechanistic understanding of circuit function.
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Affiliation(s)
- Erik B Bloss
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA, United States
| | - David L Hunt
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA, United States
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78
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Curto C, Morrison K. Relating network connectivity to dynamics: opportunities and challenges for theoretical neuroscience. Curr Opin Neurobiol 2019; 58:11-20. [PMID: 31319287 DOI: 10.1016/j.conb.2019.06.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 06/22/2019] [Indexed: 11/29/2022]
Abstract
We review recent work relating network connectivity to the dynamics of neural activity. While concepts stemming from network science provide a valuable starting point, the interpretation of graph-theoretic structures and measures can be highly dependent on the dynamics associated to the network. Properties that are quite meaningful for linear dynamics, such as random walk and network flow models, may be of limited relevance in the neuroscience setting. Theoretical and computational neuroscience are playing a vital role in understanding the relationship between network connectivity and the nonlinear dynamics associated to neural networks.
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Affiliation(s)
- Carina Curto
- The Pennsylvania State University, PA 16802, United States.
| | - Katherine Morrison
- School of Mathematical Sciences, University of Northern Colorado, Greeley, CO 80639, USA
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79
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Neural mechanisms of contextual modulation in the retinal direction selective circuit. Nat Commun 2019; 10:2431. [PMID: 31160566 PMCID: PMC6547848 DOI: 10.1038/s41467-019-10268-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 04/26/2019] [Indexed: 01/07/2023] Open
Abstract
Contextual modulation of neuronal responses by surrounding environments is a fundamental attribute of sensory processing. In the mammalian retina, responses of On–Off direction selective ganglion cells (DSGCs) are modulated by motion contexts. However, the underlying mechanisms are unknown. Here, we show that posterior-preferring DSGCs (pDSGCs) are sensitive to discontinuities of moving contours owing to contextually modulated cholinergic excitation from starburst amacrine cells (SACs). Using a combination of synapse-specific genetic manipulations, patch clamp electrophysiology and connectomic analysis, we identified distinct circuit motifs upstream of On and Off SACs that are required for the contextual modulation of pDSGC activity for bright and dark contrasts. Furthermore, our results reveal a class of wide-field amacrine cells (WACs) with straight, unbranching dendrites that function as “continuity detectors” of moving contours. Therefore, divergent circuit motifs in the On and Off pathways extend the information encoding of On-Off DSGCs beyond their direction selectivity during complex stimuli. The mechanisms of contextual modulation in direction selective ganglion cells in the retina remain unclear. Here, the authors find that that On-Off direction-selective ganglion cells are differentially sensitive to discontinuities of dark and bright moving edges in the visual environment and, using synapse-specific genetic manipulations with functional measurements, reveal the microcircuits underlying this contextual sensitivity.
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80
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Vlasits AL, Euler T, Franke K. Function first: classifying cell types and circuits of the retina. Curr Opin Neurobiol 2019; 56:8-15. [DOI: 10.1016/j.conb.2018.10.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 10/24/2018] [Indexed: 12/30/2022]
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81
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Hanson L, Sethuramanujam S, deRosenroll G, Jain V, Awatramani GB. Retinal direction selectivity in the absence of asymmetric starburst amacrine cell responses. eLife 2019; 8:42392. [PMID: 30714905 PMCID: PMC6377229 DOI: 10.7554/elife.42392] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 02/01/2019] [Indexed: 01/18/2023] Open
Abstract
In the mammalian retina, direction-selectivity is thought to originate in the dendrites of GABAergic/cholinergic starburst amacrine cells, where it is first observed. However, here we demonstrate that direction selectivity in downstream ganglion cells remains remarkably unaffected when starburst dendrites are rendered non-directional, using a novel strategy combining a conditional GABAA α2 receptor knockout mouse with optogenetics. We show that temporal asymmetries between excitation/inhibition, arising from the differential connectivity patterns of starburst cholinergic and GABAergic synapses to ganglion cells, form the basis for a parallel mechanism generating direction selectivity. We further demonstrate that these distinct mechanisms work in a coordinated way to refine direction selectivity as the stimulus crosses the ganglion cell’s receptive field. Thus, precise spatiotemporal patterns of inhibition and excitation that determine directional responses in ganglion cells are shaped by two ‘core’ mechanisms, both arising from distinct specializations of the starburst network.
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Affiliation(s)
- Laura Hanson
- Department of Biology, University of Victoria, Victoria, Canada
| | | | | | - Varsha Jain
- Department of Biology, University of Victoria, Victoria, Canada
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82
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83
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Cyr A, Thériault F, Ross M, Berberian N, Chartier S. Spiking Neurons Integrating Visual Stimuli Orientation and Direction Selectivity in a Robotic Context. Front Neurorobot 2018; 12:75. [PMID: 30524261 PMCID: PMC6256284 DOI: 10.3389/fnbot.2018.00075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 10/31/2018] [Indexed: 11/13/2022] Open
Abstract
Visual motion detection is essential for the survival of many species. The phenomenon includes several spatial properties, not fully understood at the level of a neural circuit. This paper proposes a computational model of a visual motion detector that integrates direction and orientation selectivity features. A recent experiment in the Drosophila model highlights that stimulus orientation influences the neural response of direction cells. However, this interaction and the significance at the behavioral level are currently unknown. As such, another objective of this article is to study the effect of merging these two visual processes when contextualized in a neuro-robotic model and an operant conditioning procedure. In this work, the learning task was solved using an artificial spiking neural network, acting as the brain controller for virtual and physical robots, showing a behavior modulation from the integration of both visual processes.
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Affiliation(s)
- André Cyr
- Conec Laboratory, School of Psychology, Ottawa University, Ottawa, ON, Canada
| | - Frédéric Thériault
- Department of Computer Science, Cégep du Vieux Montréal, Montreal, QC, Canada
| | - Matthew Ross
- Conec Laboratory, School of Psychology, Ottawa University, Ottawa, ON, Canada
| | - Nareg Berberian
- Conec Laboratory, School of Psychology, Ottawa University, Ottawa, ON, Canada
| | - Sylvain Chartier
- Conec Laboratory, School of Psychology, Ottawa University, Ottawa, ON, Canada
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84
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The Circuit Motif as a Conceptual Tool for Multilevel Neuroscience. Trends Neurosci 2018; 41:128-136. [PMID: 29397990 DOI: 10.1016/j.tins.2018.01.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 11/07/2017] [Accepted: 01/04/2018] [Indexed: 11/24/2022]
Abstract
Modern neuroscientific techniques that specifically manipulate and measure neuronal activity in behaving animals now allow bridging of the gap from the cellular to the behavioral level. However, in doing so, they also pose new challenges. Research using incompletely defined manipulations in a high-dimensional space without clear hypotheses is likely to suffer from multiple well-known conceptual and statistical problems. In this context it is essential to develop hypotheses with testable implications across levels. Here we propose that a focus on circuit motifs can help achieve this goal. Viewing neural structures as an assembly of circuit motif building blocks is not new. However, recent tool advances have made it possible to extensively map, specifically manipulate, and quantitatively investigate circuit motifs and thereby reexamine their relevance to brain function.
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85
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GABA release selectively regulates synapse development at distinct inputs on direction-selective retinal ganglion cells. Proc Natl Acad Sci U S A 2018; 115:E12083-E12090. [PMID: 30509993 DOI: 10.1073/pnas.1803490115] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Synaptic inhibition controls a neuron's output via functionally distinct inputs at two subcellular compartments, the cell body and the dendrites. It is unclear whether the assembly of these distinct inhibitory inputs can be regulated independently by neurotransmission. In the mammalian retina, γ-aminobutyric acid (GABA) release from starburst amacrine cells (SACs) onto the dendrites of on-off direction-selective ganglion cells (ooDSGCs) is essential for directionally selective responses. We found that ooDSGCs also receive GABAergic input on their somata from other amacrine cells (ACs), including ACs containing the vasoactive intestinal peptide (VIP). When net GABAergic transmission is reduced, somatic, but not dendritic, GABAA receptor clusters on the ooDSGC increased in number and size. Correlative fluorescence imaging and serial electron microscopy revealed that these enlarged somatic receptor clusters are localized to synapses. By contrast, selectively blocking vesicular GABA release from either SACs or VIP ACs did not alter dendritic or somatic receptor distributions on the ooDSGCs, showing that neither SAC nor VIP AC GABA release alone is required for the development of inhibitory synapses in ooDSGCs. Furthermore, a reduction in net GABAergic transmission, but not a selective reduction from SACs, increased excitatory drive onto ooDSGCs. This increased excitation may drive a homeostatic increase in ooDSGC somatic GABAA receptors. Differential regulation of GABAA receptors on the ooDSGC's soma and dendrites could facilitate homeostatic control of the ooDSGC's output while enabling the assembly of the GABAergic connectivity underlying direction selectivity to be indifferent to altered transmission.
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86
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Molecular Fingerprinting of On-Off Direction-Selective Retinal Ganglion Cells Across Species and Relevance to Primate Visual Circuits. J Neurosci 2018; 39:78-95. [PMID: 30377226 DOI: 10.1523/jneurosci.1784-18.2018] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 10/08/2018] [Accepted: 10/23/2018] [Indexed: 12/27/2022] Open
Abstract
The ability to detect moving objects is an ethologically salient function. Direction-selective neurons have been identified in the retina, thalamus, and cortex of many species, but their homology has remained unclear. For instance, it is unknown whether direction-selective retinal ganglion cells (DSGCs) exist in primates and, if so, whether they are the equivalent to mouse and rabbit DSGCs. Here, we used a molecular/circuit approach in both sexes to address these issues. In mice, we identify the transcription factor Satb2 (special AT-rich sequence-binding protein 2) as a selective marker for three RGC types: On-Off DSGCs encoding motion in either the anterior or posterior direction, a newly identified type of Off-DSGC, and an Off-sustained RGC type. In rabbits, we find that expression of Satb2 is conserved in On-Off DSGCs; however, it has evolved to include On-Off DSGCs encoding upward and downward motion in addition to anterior and posterior motion. Next, we show that macaque RGCs express Satb2 most likely in a single type. We used rabies virus-based circuit-mapping tools to reveal the identity of macaque Satb2-RGCs and discovered that their dendritic arbors are relatively large and monostratified. Together, these data indicate Satb2-expressing On-Off DSGCs are likely not present in the primate retina. Moreover, if DSGCs are present in the primate retina, it is unlikely that they express Satb2.SIGNIFICANCE STATEMENT The ability to detect object motion is a fundamental feature of almost all visual systems. Here, we identify a novel marker for retinal ganglion cells encoding directional motion that is evolutionarily conserved in mice and rabbits, but not in primates. We show in macaque monkeys that retinal ganglion cells (RGCs) that express this marker comprise a single type and are morphologically distinct from mouse and rabbit direction-selective RGCs. Our findings indicate that On-Off direction-selective retinal neurons may have evolutionarily diverged in primates and more generally provide novel insight into the identity and organization of primate parallel visual pathways.
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87
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Ikeda K, Suzuki N, Bekkers JM. Sodium and potassium conductances in principal neurons of the mouse piriform cortex: a quantitative description. J Physiol 2018; 596:5397-5414. [PMID: 30194865 DOI: 10.1113/jp275824] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 08/21/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The primary olfactory (or piriform) cortex is a promising model system for understanding how the cerebral cortex processes sensory information, although an investigation of the piriform cortex is hindered by a lack of detailed information about the intrinsic electrical properties of its component neurons. In the present study, we quantify the properties of voltage-dependent sodium currents and voltage- and calcium-dependent potassium currents in two important classes of excitatory neurons in the main input layer of the piriform cortex. We identify several classes of these currents and show that their properties are similar to those found in better-studied cortical regions. Our detailed quantitative descriptions of these currents will be valuable to computational neuroscientists who aim to build models that explain how the piriform cortex encodes odours. ABSTRACT The primary olfactory cortex (or piriform cortex, PC) is an anatomically simple palaeocortex that is increasingly used as a model system for investigating cortical sensory processing. However, little information is available on the intrinsic electrical conductances in neurons of the PC, hampering efforts to build realistic computational models of this cortex. In the present study, we used nucleated macropatches and whole-cell recordings to rigorously quantify the biophysical properties of voltage-gated sodium (NaV ), voltage-gated potassium (KV ) and calcium-activated potassium (KCa ) conductances in two major classes of glutamatergic neurons in layer 2 of the PC, semilunar (SL) cells and superficial pyramidal (SP) cells. We found that SL and SP cells both express a fast-inactivating NaV current, two types of KV current (A-type and delayed rectifier-type) and three types of KCa current (fast-, medium- and slow-afterhyperpolarization currents). The kinetic and voltage-dependent properties of the NaV and KV conductances were, with some exceptions, identical in SL and SP cells and similar to those found in neocortical pyramidal neurons. The KCa conductances were also similar across the different types of neurons. Our results are summarized in a series of empirical equations that should prove useful to computational neuroscientists seeking to model the PC. More broadly, our findings indicate that, at the level of single-cell electrical properties, this palaeocortex is not so different from the neocortex, vindicating efforts to use the PC as a model of cortical sensory processing in general.
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Affiliation(s)
- Kaori Ikeda
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | | | - John M Bekkers
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
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88
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Abstract
Visual motion on the retina activates a cohort of retinal ganglion cells (RGCs). This population activity encodes multiple streams of information extracted by parallel retinal circuits. Motion processing in the retina is best studied in the direction-selective circuit. The main focus of this review is the neural basis of direction selectivity, which has been investigated in unprecedented detail using state-of-the-art functional, connectomic, and modeling methods. Mechanisms underlying the encoding of other motion features by broader RGC populations are also discussed. Recent discoveries at both single-cell and population levels highlight the dynamic and stimulus-dependent engagement of multiple mechanisms that collectively implement robust motion detection under diverse visual conditions.
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Affiliation(s)
- Wei Wei
- Department of Neurobiology, The University of Chicago, Chicago, Illinois 60637, USA
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89
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Graydon CW, Lieberman EE, Rho N, Briggman KL, Singer JH, Diamond JS. Synaptic Transfer between Rod and Cone Pathways Mediated by AII Amacrine Cells in the Mouse Retina. Curr Biol 2018; 28:2739-2751.e3. [PMID: 30122532 PMCID: PMC6133723 DOI: 10.1016/j.cub.2018.06.063] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 05/24/2018] [Accepted: 06/22/2018] [Indexed: 02/03/2023]
Abstract
To understand computation in a neural circuit requires a complete synaptic connectivity map and a thorough grasp of the information-processing tasks performed by the circuit. Here, we dissect a microcircuit in the mouse retina in which scotopic visual information (i.e., single photon events, luminance, contrast) is encoded by rod bipolar cells (RBCs) and distributed to parallel ON and OFF cone bipolar cell (CBC) circuits via the AII amacrine cell, an inhibitory interneuron. Serial block-face electron microscopy (SBEM) reconstructions indicate that AIIs preferentially connect to one OFF CBC subtype (CBC2); paired whole-cell patch-clamp recordings demonstrate that, depending on the level of network activation, AIIs transmit distinct components of synaptic input from single RBCs to downstream ON and OFF CBCs. These findings highlight specific synaptic and circuit-level features that allow intermediate neurons (e.g., AIIs) within a microcircuit to filter and propagate information to downstream neurons.
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Affiliation(s)
- Cole W Graydon
- Synaptic Physiology Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, USA
| | - Evan E Lieberman
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Nao Rho
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Kevin L Briggman
- Circuit Dynamics and Connectivity Unit, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, USA
| | - Joshua H Singer
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Jeffrey S Diamond
- Synaptic Physiology Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, USA.
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90
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Stincic TL, Keeley PW, Reese BE, Taylor WR. Bistratified starburst amacrine cells in Sox2 conditional knockout mouse retina display ON and OFF responses. J Neurophysiol 2018; 120:2121-2129. [PMID: 30089022 DOI: 10.1152/jn.00322.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cell-intrinsic factors, in conjunction with environmental signals, guide migration, differentiation, and connectivity during early development of neuronal circuits. Within the retina, inhibitory starburst amacrine cells (SBACs) comprise ON types with somas in the ganglion cell layer (GCL) and dendrites stratifying narrowly in the inner half of the inner plexiform layer (IPL) and OFF types with somas in the inner nuclear layer (INL) and dendrites stratifying narrowly in the outer half of the IPL. The transcription factor Sox2 is crucial to this subtype specification. Without Sox2, many ON-type SBACs destined for the GCL settle in the INL while many that reach the GCL develop bistratified dendritic arbors. This study asked whether ON-type SBACs in Sox2-conditional knockout retinas exhibit selective connectivity only with ON-type bipolar cells or their bistratified morphology allows them to connect to both ON and OFF bipolar cells. Physiological data demonstrate that these cells receive ON and OFF excitatory inputs, indicating that the ectopically stratified dendrites make functional synapses with bipolar cells. The excitatory inputs were smaller and more transient in Sox2-conditional knockout compared with wild type; however, inhibitory inputs appeared largely unchanged. Thus dendritic stratification, rather than cellular identification, may be the major factor that determines ON vs. OFF connectivity. NEW & NOTEWORTHY Conditional knockout of the transcription factor Sox2 during early embryogenesis converts a monostratifying starburst amacrine cell into a bistratifying starburst cell. Here we show that these bistratifying starburst amacrine cells form functional synaptic connections with both ON and OFF bipolar cells. This suggests that normal ON vs. OFF starburst connectivity may not require distinct molecular specification. Proximity alone may be sufficient to allow formation of functional synapses.
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Affiliation(s)
- Todd L Stincic
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University , Portland, Oregon
| | - Patrick W Keeley
- Neuroscience Research Institute, University of California , Santa Barbara, California
| | - Benjamin E Reese
- Neuroscience Research Institute, University of California , Santa Barbara, California.,Department of Psychological and Brain Sciences, University of California , Santa Barbara, California
| | - W Rowland Taylor
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University , Portland, Oregon.,School of Optometry and Helen Wills Neuroscience Institute, University of California , Berkeley, California
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91
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Prigge CL, Kay JN. Dendrite morphogenesis from birth to adulthood. Curr Opin Neurobiol 2018; 53:139-145. [PMID: 30092409 DOI: 10.1016/j.conb.2018.07.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 07/19/2018] [Accepted: 07/30/2018] [Indexed: 01/04/2023]
Abstract
Dendrites are the conduits for receiving (and in some cases transmitting) neural signals; their ability to do these jobs is a direct result of their morphology. Developmental patterning mechanisms are critical to ensuring concordance between dendritic form and function. This article reviews recent studies in vertebrate retina and brain that elucidate key strategies for dendrite functional maturation. Specific cellular and molecular signals control the initiation and elaboration of dendritic arbors, and facilitate integration of young neurons into particular circuits. In some cells, dendrite growth and remodeling continues into adulthood. Once formed, dendrites subdivide into compartments with distinct physiological properties that enable dendritic computations. Understanding these key stages of dendrite patterning will help reveal how circuit functional properties arise during development.
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Affiliation(s)
- Cameron L Prigge
- Department of Neurobiology, Duke University School of Medicine, Durham, NC 27710, USA; Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Jeremy N Kay
- Department of Neurobiology, Duke University School of Medicine, Durham, NC 27710, USA; Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA.
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92
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Zhang Q, Wang W, Dong C. Blood platelet and serum bilirubin in the diagnosis of central serous chorioretinopathy. Exp Ther Med 2018; 16:874-878. [PMID: 30116339 PMCID: PMC6090241 DOI: 10.3892/etm.2018.6267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 05/25/2018] [Indexed: 11/25/2022] Open
Abstract
Diagnostic value of blood platelet (PLT) and serum total bilirubin (TBIL) for central serous chorioretinopathy (CSC) was investigated. A total of 537 patients with CSC and 182 people with normal physical conditions were selected from June 2012 to August 2016. The 537 patients included 294 males and 243 females with an average age of 45.5±17.8 years, and all patients were treated in the Department of Ophthalmology of Yantai Hospital of Traditional Chinese Medicine and the Department of Ophthalmology of Yantai Liuhuangding Hospital. Clinical data of the patients were retrospectively analyzed. The 182 people with normal physical conditions included 103 males and 79 females with an average age of 43.6±15.2 years, and they were set as the control group. PLT and TBIL tests at admission and after treatment were collected and compared between CSC and the control group to analyze the diagnostic values of PLT and TBIL for CSC. PLT level in the CSC group was significantly higher than that in the control group, but TBIL level in the CSC group was significantly lower than that in the control group (p<0.05). Linear correlation analysis showed that PLT was a risk factor for CSC, and TBIL was a protective factor for CSC. The sensitivity of PLT and TBIL in diagnosis of CSC was 75.2 and 72.7%, respectively, and the specificity of PLT and TBIL in diagnosis of CSC was 65.8 and 63.3%, respectively. PLT of CSC patients was significantly higher than that of the control group, and TBIL of CSC patients was significantly lower than that of the control group, but they both gradually reduced to normal levels after treatment, which can be regarded as the index for the clinical diagnosis of CSC in the future.
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Affiliation(s)
- Qiang Zhang
- Department of Ophthalmology, Yantai Hospital of Traditional Chinese Medicine, Yantai, Shandong 264000, P.R. China
| | - Wei Wang
- Department of Ophthalmology, Yantai Yeda Hospital, Yantai, Shandong 264000, P.R. China
| | - Changxia Dong
- Department of Ophthalmology, Yantai Yuhuangding Hospital, Yantai, Shandong 264000, P.R. China
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Zheng Z, Lauritzen JS, Perlman E, Robinson CG, Nichols M, Milkie D, Torrens O, Price J, Fisher CB, Sharifi N, Calle-Schuler SA, Kmecova L, Ali IJ, Karsh B, Trautman ET, Bogovic JA, Hanslovsky P, Jefferis GSXE, Kazhdan M, Khairy K, Saalfeld S, Fetter RD, Bock DD. A Complete Electron Microscopy Volume of the Brain of Adult Drosophila melanogaster. Cell 2018; 174:730-743.e22. [PMID: 30033368 PMCID: PMC6063995 DOI: 10.1016/j.cell.2018.06.019] [Citation(s) in RCA: 457] [Impact Index Per Article: 76.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 02/28/2018] [Accepted: 06/10/2018] [Indexed: 12/16/2022]
Abstract
Drosophila melanogaster has a rich repertoire of innate and learned behaviors. Its 100,000-neuron brain is a large but tractable target for comprehensive neural circuit mapping. Only electron microscopy (EM) enables complete, unbiased mapping of synaptic connectivity; however, the fly brain is too large for conventional EM. We developed a custom high-throughput EM platform and imaged the entire brain of an adult female fly at synaptic resolution. To validate the dataset, we traced brain-spanning circuitry involving the mushroom body (MB), which has been extensively studied for its role in learning. All inputs to Kenyon cells (KCs), the intrinsic neurons of the MB, were mapped, revealing a previously unknown cell type, postsynaptic partners of KC dendrites, and unexpected clustering of olfactory projection neurons. These reconstructions show that this freely available EM volume supports mapping of brain-spanning circuits, which will significantly accelerate Drosophila neuroscience. VIDEO ABSTRACT.
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Affiliation(s)
- Zhihao Zheng
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - J Scott Lauritzen
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Eric Perlman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Camenzind G Robinson
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Matthew Nichols
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | | | - Omar Torrens
- Coleman Technologies, Newtown Square, PA 19073, USA
| | - John Price
- Hudson Price Designs, Hingham, MA 02043, USA
| | - Corey B Fisher
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Nadiya Sharifi
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | | | - Lucia Kmecova
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Iqbal J Ali
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Bill Karsh
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Eric T Trautman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - John A Bogovic
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Philipp Hanslovsky
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Gregory S X E Jefferis
- Division of Neurobiology, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK; Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Michael Kazhdan
- Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Khaled Khairy
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Stephan Saalfeld
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Richard D Fetter
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Davi D Bock
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
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94
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Abstract
Motion in the visual world provides critical information to guide the behavior of sighted animals. Furthermore, as visual motion estimation requires comparisons of signals across inputs and over time, it represents a paradigmatic and generalizable neural computation. Focusing on the Drosophila visual system, where an explosion of technological advances has recently accelerated experimental progress, we review our understanding of how, algorithmically and mechanistically, motion signals are first computed.
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Affiliation(s)
- Helen H Yang
- Department of Neurobiology, Stanford University, Stanford, California 94305, USA; .,Current affiliation: Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA;
| | - Thomas R Clandinin
- Department of Neurobiology, Stanford University, Stanford, California 94305, USA;
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95
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Sethuramanujam S, Awatramani GB, Slaughter MM. Cholinergic excitation complements glutamate in coding visual information in retinal ganglion cells. J Physiol 2018; 596:3709-3724. [PMID: 29758086 DOI: 10.1113/jp275073] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Accepted: 04/25/2018] [Indexed: 01/07/2023] Open
Abstract
KEY POINTS Starburst amacrine cells release GABA and ACh. This study explores the coordinated function of starburst-mediated cholinergic excitation and GABAergic inhibition to bistratified retinal ganglion cells, predominantly direction-selective ganglion cells (DSGCs). In rat retina, under our recording conditions, starbursts were found to provide the major excitatory drive to a sub-population of ganglion cells whose dendrites co-stratify with starburst dendrites (putative DSGCs). In mouse retina, recordings from genetically identified DSGCs at physiological temperatures reveal that ACh inputs dominate the response to small spot-high contrast light stimuli, with preferential addition of bipolar cell input shifting the balance towards glutamate for larger spot stimuli In addition, starbursts also appear to gate glutamatergic excitation to DSGCs by postsynaptic and possibly presynaptic inhibitory processes ABSTRACT: Starburst amacrine cells release both GABA and ACh, allowing them to simultaneously mediate inhibition and excitation. However, the precise pre- and postsynaptic targets for ACh and GABA remain under intense investigation. Most previous studies have focused on starburst-mediated postsynaptic GABAergic inhibition and its role in the formation of directional selectivity in ganglion cells. However, the significance of postsynaptic cholinergic excitation is only beginning to be appreciated. Here, we found that light-evoked responses measured in bi-stratified rat ganglion cells with dendrites that co-fasciculate with ON and OFF starburst dendrites (putative direction-selective ganglion cells, DSGCs) were abolished by the application of nicotinic receptor antagonists, suggesting ACh could act as the primary source of excitation. Recording from genetically labelled DSGCs in mouse retina at physiological temperatures revealed that cholinergic synaptic inputs dominated the excitation for high contrast stimuli only when the size of the stimulus was small. Canonical glutamatergic inputs mediated by bipolar cells were prominent when GABA/glycine receptors were blocked or when larger spot stimuli were utilized. In mouse DSGCs, bipolar cell excitation could also be unmasked through the activation of mGluR2,3 receptors, which we show suppresses starburst output, suggesting that GABA from starbursts serves to inhibit bipolar cell signals in DSGCs. Taken together, these results suggest that starbursts amplify excitatory signals traversing the retina, endowing DSGCs with the ability to encode fine spatial information without compromising their ability to encode direction.
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Affiliation(s)
- Santhosh Sethuramanujam
- Center for Neuroscience and Department of Physiology and Biophysics, University at Buffalo, Buffalo, NY, 14214, USA.,Department of Biology, University of Victoria, Victoria, BC, V8W2Y2, Canada
| | | | - Malcolm M Slaughter
- Center for Neuroscience and Department of Physiology and Biophysics, University at Buffalo, Buffalo, NY, 14214, USA
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96
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Chen Q, Wei W. Stimulus-dependent engagement of neural mechanisms for reliable motion detection in the mouse retina. J Neurophysiol 2018; 120:1153-1161. [PMID: 29897862 DOI: 10.1152/jn.00716.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Direction selectivity is a fundamental computation in the visual system and is first computed by the direction-selective circuit in the mammalian retina. Although landmark discoveries on the neural basis of direction selectivity have been made in the rabbit, many technological advances designed for the mouse have emerged, making this organism a favored model for investigating the direction-selective circuit at the molecular, synaptic, and network levels. Studies using diverse motion stimuli in the mouse retina demonstrate that retinal direction selectivity is implemented by multilayered mechanisms. This review begins with a set of central mechanisms that are engaged under a wide range of visual conditions and then focuses on additional layers of mechanisms that are dynamically recruited under different visual stimulus conditions. Together, recent findings allude to an emerging theme: robust motion detection in the natural environment requires flexible neural mechanisms.
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Affiliation(s)
- Qiang Chen
- Department of Neurobiology, The University of Chicago , Chicago, Illinois.,Committee on Computational Neuroscience, The University of Chicago , Chicago, Illinois
| | - Wei Wei
- Department of Neurobiology, The University of Chicago , Chicago, Illinois.,Committee on Computational Neuroscience, The University of Chicago , Chicago, Illinois
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97
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Meinertzhagen IA. Of what use is connectomics? A personal perspective on the Drosophila connectome. ACTA ACUST UNITED AC 2018; 221:221/10/jeb164954. [PMID: 29784759 DOI: 10.1242/jeb.164954] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The brain is a network of neurons and its biological output is behaviour. This is an exciting age, with a growing acknowledgement that the comprehensive compilation of synaptic circuits densely reconstructed in the brains of model species is now both technologically feasible and a scientifically enabling possibility in neurobiology, much as 30 years ago genomics was in molecular biology and genetics. Implemented by huge advances in electron microscope technology, especially focused ion beam-scanning electron microscope (FIB-SEM) milling (see Glossary), image capture and alignment, and computer-aided reconstruction of neuron morphologies, enormous progress has been made in the last decade in the detailed knowledge of the actual synaptic circuits formed by real neurons, in various brain regions of the fly Drosophila It is useful to distinguish synaptic pathways that are major, with 100 or more presynaptic contacts, from those that are minor, with fewer than about 10; most neurites are both presynaptic and postsynaptic, and all synaptic sites have multiple postsynaptic dendrites. Work on Drosophila has spearheaded these advances because cell numbers are manageable, and neuron classes are morphologically discrete and genetically identifiable, many confirmed by reporters. Recent advances are destined within the next few years to reveal the complete connectome in an adult fly, paralleling advances in the larval brain that offer the same prospect possibly within an even shorter time frame. The final amendment and validation of segmented bodies by human proof-readers remains the most time-consuming step, however. The value of a complete connectome in Drosophila is that, by targeting to specific neurons transgenes that either silence or activate morphologically identified circuits, and then identifying the resulting behavioural outcome, we can determine the causal mechanism for behaviour from its loss or gain. More importantly, the connectome reveals hitherto unsuspected pathways, leading us to seek novel behaviours for these. Circuit information will eventually be required to understand how differences between brains underlie differences in behaviour, and especially to herald yet more advanced connectomic strategies for the vertebrate brain, with an eventual prospect of understanding cognitive disorders having a connectomic basis. Connectomes also help us to identify common synaptic circuits in different species and thus to reveal an evolutionary progression in candidate pathways.
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Affiliation(s)
- Ian A Meinertzhagen
- FlyEM Team, Janelia Research Campus of HHMI, 19700 Helix Drive, Ashburn, VA 20147-2408, USA .,Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS, Canada B3H 4R2.,Department of Biology, Life Sciences Centre, Dalhousie University, Halifax, NS, Canada B3H 4R2
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98
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Morrie RD, Feller MB. A Dense Starburst Plexus Is Critical for Generating Direction Selectivity. Curr Biol 2018; 28:1204-1212.e5. [PMID: 29606419 PMCID: PMC5916530 DOI: 10.1016/j.cub.2018.03.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 02/27/2018] [Accepted: 03/01/2018] [Indexed: 01/02/2023]
Abstract
Starburst amacrine cell (SAC) morphology is considered central to retinal direction selectivity. In Sema6A-/- mice, SAC dendritic arbors are smaller and no longer radially symmetric, leading to a reduction in SAC dendritic plexus density. Sema6A-/- mice also have a dramatic reduction in the directional tuning of retinal direction-selective ganglion cells (DSGCs). Here we show that the loss of DSGC tuning in Sema6A-/- mice is due to reduced null direction inhibition, even though strong asymmetric SAC-DSGC connectivity and SAC dendritic direction selectivity are maintained. Hence, the reduced coverage factor of SAC dendrites leads specifically to a loss of null direction inhibition. Moreover, SAC dendrites are no longer strictly tuned to centrifugal motion, indicating that SAC morphology is critical in coordinating synaptic connectivity and dendritic integration to generate direction selectivity.
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Affiliation(s)
- Ryan D Morrie
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Marla B Feller
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA.
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99
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Ray TA, Roy S, Kozlowski C, Wang J, Cafaro J, Hulbert SW, Wright CV, Field GD, Kay JN. Formation of retinal direction-selective circuitry initiated by starburst amacrine cell homotypic contact. eLife 2018; 7:e34241. [PMID: 29611808 PMCID: PMC5931800 DOI: 10.7554/elife.34241] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 03/29/2018] [Indexed: 12/23/2022] Open
Abstract
A common strategy by which developing neurons locate their synaptic partners is through projections to circuit-specific neuropil sublayers. Once established, sublayers serve as a substrate for selective synapse formation, but how sublayers arise during neurodevelopment remains unknown. Here, we identify the earliest events that initiate formation of the direction-selective circuit in the inner plexiform layer of mouse retina. We demonstrate that radially migrating newborn starburst amacrine cells establish homotypic contacts on arrival at the inner retina. These contacts, mediated by the cell-surface protein MEGF10, trigger neuropil innervation resulting in generation of two sublayers comprising starburst-cell dendrites. This dendritic scaffold then recruits projections from circuit partners. Abolishing MEGF10-mediated contacts profoundly delays and ultimately disrupts sublayer formation, leading to broader direction tuning and weaker direction-selectivity in retinal ganglion cells. Our findings reveal a mechanism by which differentiating neurons transition from migratory to mature morphology, and highlight this mechanism's importance in forming circuit-specific sublayers.
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Affiliation(s)
- Thomas A Ray
- Department of NeurobiologyDuke University School of MedicineDurhamUnited States
- Department of OphthalmologyDuke University School of MedicineDurhamUnited States
| | - Suva Roy
- Department of NeurobiologyDuke University School of MedicineDurhamUnited States
| | - Christopher Kozlowski
- Department of NeurobiologyDuke University School of MedicineDurhamUnited States
- Department of OphthalmologyDuke University School of MedicineDurhamUnited States
| | - Jingjing Wang
- Department of NeurobiologyDuke University School of MedicineDurhamUnited States
- Department of OphthalmologyDuke University School of MedicineDurhamUnited States
| | - Jon Cafaro
- Department of NeurobiologyDuke University School of MedicineDurhamUnited States
| | - Samuel W Hulbert
- Department of NeurobiologyDuke University School of MedicineDurhamUnited States
| | - Christopher V Wright
- Department of Cell and Developmental BiologyVanderbilt University School of MedicineNashvilleUnited States
| | - Greg D Field
- Department of NeurobiologyDuke University School of MedicineDurhamUnited States
| | - Jeremy N Kay
- Department of NeurobiologyDuke University School of MedicineDurhamUnited States
- Department of OphthalmologyDuke University School of MedicineDurhamUnited States
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100
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