The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Silke Haverkamp - One of the best experts on this subject based on the ideXlab platform.
-
morphology and connectivity of the small bistratified a8 Amacrine Cell in the mouse retina
The Journal of Comparative Neurology, 2015Co-Authors: Arndt Meyer, Karin Dedek, Timm Schubert, Laura Huser, Silke HaverkampAbstract:Amacrine Cells comprise ~30 morphological types in the mammalian retina. The synaptic connectivity and function of a few GABAergic wide-field Amacrine Cells have recently been studied, however, with the exception of the rod pathway-specific AII Amacrine Cell the connectivity of glycinergic small-field Amacrine Cells has not been investigated in the mouse retina. Here, we studied the morphology and connectivity pattern of the small-field A8 Amacrine Cell. A8 Cells in mouse retina are bistratified with lobular processes in the ON sublamina and arboreal dendrites in the OFF sublamina of the inner plexiform layer. The distinct bistratified morphology was first visible at postnatal day 8, reaching the adult shape at P13, around eye opening. The connectivity of A8 Cells to bipolar Cells and ganglion Cells was studied by double and triple immunolabeling experiments using various Cell markers combined with synaptic markers. Our data suggest that A8 Amacrine Cells receive glutamatergic input from both OFF and ON cone bipolar Cells. Furthermore, A8 Cells are coupled to ON cone bipolar Cells by gap junctions, and provide inhibitory input via glycine receptor (GlyR) subunit α1 to OFF cone bipolar Cells and to ON A-type ganglion Cells. Measurements of spontaneous glycinergic postsynaptic currents and GlyR immunolabeling revealed that A8 Cells express GlyRs containing the α2 subunit. Taken together, the bistratified A8 Cell makes very similar synaptic contacts with cone bipolar Cells as the rod pathway-specific AII Amacrine Cell. However, unlike AII Cells, A8 Amacrine Cells provide glycinergic input to ON A-type ganglion Cells.
-
Morphology and connectivity of the small bistratified A8 Amacrine Cell in the mouse retina
The Journal of comparative neurology, 2015Co-Authors: Sammy C.s. Lee, Karin Dedek, Arndt Meyer, Timm Schubert, Laura Huser, Silke HaverkampAbstract:Amacrine Cells comprise ∼ 30 morphological types in the mammalian retina. The synaptic connectivity and function of a few γ-aminobutyric acid (GABA)ergic wide-field Amacrine Cells have recently been studied; however, with the exception of the rod pathway-specific AII Amacrine Cell, the connectivity of glycinergic small-field Amacrine Cells has not been investigated in the mouse retina. Here, we studied the morphology and connectivity pattern of the small-field A8 Amacrine Cell. A8 Cells in mouse retina are bistratified with lobular processes in the ON sublamina and arboreal dendrites in the OFF sublamina of the inner plexiform layer. The distinct bistratified morphology was first visible at postnatal day 8, reaching the adult shape at P13, around eye opening. The connectivity of A8 Cells to bipolar Cells and ganglion Cells was studied by double and triple immunolabeling experiments by using various Cell markers combined with synaptic markers. Our data suggest that A8 Amacrine Cells receive glutamatergic input from both OFF and ON cone bipolar Cells. Furthermore, A8 Cells are coupled to ON cone bipolar Cells by gap junctions, and provide inhibitory input via glycine receptor (GlyR) subunit α1 to OFF cone bipolar Cells and to ON A-type ganglion Cells. Measurements of spontaneous glycinergic postsynaptic currents and GlyR immunolabeling revealed that A8 Cells express GlyRs containing the α2 subunit. The results show that the bistratified A8 Cell makes very similar synaptic contacts with cone bipolar Cells as the rod pathway-specific AII Amacrine Cell. However, unlike AII Cells, A8 Amacrine Cells provide glycinergic input to ON A-type ganglion Cells.
-
characterization of an Amacrine Cell type of the mammalian retina immunoreactive for vesicular glutamate transporter 3
The Journal of Comparative Neurology, 2004Co-Authors: Silke Haverkamp, Heinz WassleAbstract:Immunocytochemical staining of vertical sections through rat, mouse, and macaque monkey retinae with antibodies against the vesicular glutamate transporter vesicular glutamate transporter 3 (vGluT3) showed a sparse population of Amacrine Cells. The labeled Cells had similar appearances in the three species and probably represent homologous types. They were studied in detail in the rat retina. The thin varicose dendrites of vGluT3 Amacrine Cells formed a convoluted dendritic tree of approximately 100 μm in diameter that was bistratified in the center of the inner plexiform layer. The dendrites of vGluT3 Cells were squeezed between the two strata of cholinergic dendrites. The density of vGluT3 Cells was measured in retinal wholemounts and increased from 200/mm2 in peripheral retina to 400/mm2 in central retina, accounting for about 1% of all Amacrine Cells in the rat retina. The vGluT3 Cells had a two- to threefold dendritic overlap, and their Cell bodies formed a regular mosaic, suggesting they represent a single type of Amacrine Cell. The vGluT3 Amacrine Cells expressed glycine and glycine transporter 1 (GlyT1) but not the vesicular glycine transporter (vesicular inhibitory amino acid transporter). They also expressed glutamate; hence, there is the possibility that, comparable to cholinergic Amacrine Cells, they are “dual transmitter” Amacrine Cells. The synaptic input of vGluT3 Cells was studied by electron microscopy. They received input from bipolar Cells at ribbon synapses and from other Amacrine Cells at conventional synapses. The types of bipolar Cells possibly involved with vGluT3 Cells were demonstrated by double labeling sections for vGluT3 and the calcium-binding protein CaB5. The axon terminals of type 3 and 5 bipolar Cells costratified with vGluT3 dendrites, and it is possible that vGluT3 Cells have ON and OFF light responses. J. Comp. Neurol. 468:251–263, 2004. © 2003 Wiley-Liss, Inc.
Ramon F Dacheux - One of the best experts on this subject based on the ideXlab platform.
-
synaptic connections of the narrow field bistratified rod Amacrine Cell aii in the rabbit retina
The Journal of Comparative Neurology, 1992Co-Authors: Enrica Strettoi, Elio Raviola, Ramon F DacheuxAbstract:The synaptic connections of the narrow-field, bistratified rod Amacrine Cell (AII) in the inner plexiform layer (IPL) of the rabbit retina were reconstructed from electron micrographs of continuous series of thin sections. The AII Amacrine Cell receives a large synaptic input from the axonal endings of rod bipolar Cells in the most vitreal region of the IPL (sublamina b, S5) and a smaller input from axonal endings of cone bipolar Cells in the scleral region of the IPL (sublamina a, S1-S2). Amacrine input, localized at multiple levels in the IPL, equals the total number of synapses received from bipolar Cells. The axonal endings of cone bipolar Cells represent the major target for the chemical output of the AII Amacrine Cell: these synapses are established by the lobular appendages in sublamina a (S1-S2). Ganglion Cell dendrites represent only 4% of the output of the AII Amacrine and most of them are also postsynaptic to the cone bipolars which receive AII input. The AII Amacrine is not presynaptic to other Amacrine Cells. Finally, the AII Amacrine makes gap junctions with the axonal arborizations of cone bipolars that stratify in sublamina b (S3-S4) as well as with other AII Amacrine Cells in S5. Therefore, in the rabbit retina 1) the rod pathway consists of five neurons arranged in series: rod-->rod bipolar-->AII Amacrine-->cone bipolar-->ganglion Cell; 2) it seems unlikely that a class of ganglion Cells exists that is exclusively devoted to scotopic functions. In ventral, midperipheral retina, about nine rod bipolar Cells converge onto a single AII Amacrine, but one of them establishes a much higher proportion of synaptic contacts than the rest. Conversely, each rod bipolar Cell diverges onto four AII Amacrine Cells, but one of them receives the largest fraction of synapses. Thus, within the pattern of convergence and divergence suggested by population studies, preferential synaptic pathways are established.
-
synaptic connections of the narrow field bistratified rod Amacrine Cell aii in the rabbit retina
The Journal of Comparative Neurology, 1992Co-Authors: Enrica Strettoi, Elio Raviola, Ramon F DacheuxAbstract:The synaptic connections of the narrow-field, bistratified rod Amacrine Cell (All) in the inner plexiform layer (IPL) of the rabbit retina were reconstructed from electron micrographs of continuous series of thin sections. The All Amacrine Cell receives a large synaptic input from the axonal endings of rod bipolar Cells in the most vitreal region of the IPL (sublamina b, S5) and a smaller input from axonal endings of cone bipolar Cells in the scleral region of the IPL (sublamina a, S1–S2). Amacrine input, localized at multiple levels in the IPL, equals the total number of synapses received from bipolar Cells. The axonal endings of cone bipolar Cells represent the major target for the chemical output of the All Amacrine Cell: these synapses are established by the lobular appendages in sublamina a (S1–S2). Ganglion Cell dendrites represent only 4% of the output of the All Amacrine and most of them are also postsynaptic to the cone bipolars which receive All input. The All Amacrine is not presynaptic to other Amacrine Cells. Finally, the AII Amacrine makes gap junctions with the axonal arborizations of cone bipolars that stratify in sublamina b (S3–S4) as well as with other All Amacrine Cells in S5. Therefore, in the rabbit retina 1) the rod pathway consists of five neurons arranged in series: rod → rod bipolar → AII Amacrine → cone bipolar → ganglion Cell; 2) it seems unlikely that a class of ganglion Cells exists that is exclusively devoted to scotopic functions. In ventral, midperipheral retina, about nine rod bipolar Cells converge onto a single All Amacrine, but one of them establishes a much higher proportion of synaptic contacts than the rest. Conversely, each rod bipolar Cell diverges onto four All Amacrine Cells, but one of them receives the largest fraction of synapses. Thus, within the pattern of convergence and divergence suggested by population studies, preferential synaptic pathways are established. © 1992 Wiley-Liss, Inc.
Ian L. Gibbins - One of the best experts on this subject based on the ideXlab platform.
-
Synaptic inputs to retrogradely labeled ganglion Cells in the retina of the cane toad, Bufo marinus
Visual neuroscience, 1997Co-Authors: Bao Song Zhu, Ian L. GibbinsAbstract:The entire population of ganglion Cells in the retina of the toad Bufo marinus was labeled by retrograde transport of a lysine-fixable biotinylated dextran amine of 3000 molecular weight. Synaptic connections between bipolar, Amacrine, and ganglion Cells in the inner plexiform layer were quantitatively analyzed, with emphasis on synaptic inputs to labeled ganglion Cell dendrites. Synapses onto ganglion Cell dendrites comprised 47% of a total of 1234 identified synapses in the inner plexiform layer. Approximately half of the bipolar or Amacrine Cell synapses were directed onto ganglion Cell dendrites, while the rest were made mainly onto Amacrine Cell dendrites. Most of the synaptic inputs to ganglion Cell dendrites derived from Amacrine Cell dendrites (84%), with the rest from bipolar Cell terminals. Synaptic inputs to ganglion Cell dendrites were distributed relatively uniformly throughout all sublaminae of the inner plexiform layer. The present study provides unambiguous identification of ganglion Cell dendrites including very fine processes, enabling a detailed analysis of the types and distribution of synaptic inputs from the bipolar and Amacrine Cell to the ganglion Cells. The retrograde tracing technique used in the present study will prove to be a useful tool for identifying synaptic inputs to ganglion Cell dendrites from neurochemically identified bipolar and Amacrine Cell types in the retina.
-
Synaptic circuitry of neuropeptide-containing Amacrine Cells in the retina of the cane toad, Bufo marinus.
Visual neuroscience, 1995Co-Authors: Bao Song Zhu, Ian L. GibbinsAbstract:Synaptic connections of Amacrine Cells with substance P-like or neuropeptide Y-like immunoreactivity (SP-LI or NPY-LI) in the retina of the cane toad, Bufo marinus, were investigated using ultrastructural immunocytochemistry. The perikarya of SP-LI or NPY-LI Amacrine Cells were located in the innermost row of the inner nuclear layer. The synapses associated with SP-LI Amacrine Cells were distributed mainly in sublaminae 3 and 4 with about 10% in sublamina 1 of the inner plexiform layer. The synapses formed by NPY-LI Amacrine Cells were found in sublaminae 1, 2, and 4 with approximately equal frequency. Of a total of 175 SP-LI profiles, 56% were in presynaptic positions and 44% in postsynaptic positions. The synaptic inputs to SP-LI profiles predominantly derived from other unlabeled Amacrine Cell dendrites, and to a lesser extent, from bipolar Cell terminals. The majority of synaptic outputs from SP-LI Amacrine Cell dendrites were directed onto unlabeled Amacrine Cell processes. The SP-LI profiles also made synapses onto bipolar Cell terminals and formed synapses onto presumed ganglion Cell dendrites. Of a total of 200 NPY-LI profiles, 48% were in presynaptic positions and 52% in postsynaptic positions. The profiles of NPY-LI Amacrine Cells mainly received their synaptic inputs from other unlabeled Amacrine Cell processes, and to a lesser extent, from bipolar Cell terminals. The majority of NPY-LI Amacrine Cell profiles gave their synaptic outputs onto unlabeled Amacrine Cell dendrites, and others formed synapses onto presumed ganglion Cell processes. These results suggest that these two populations of neuropeptide-containing Amacrine Cells in the Bufo retina are involved in different synaptic circuits.
Karin Dedek - One of the best experts on this subject based on the ideXlab platform.
-
morphology and connectivity of the small bistratified a8 Amacrine Cell in the mouse retina
The Journal of Comparative Neurology, 2015Co-Authors: Arndt Meyer, Karin Dedek, Timm Schubert, Laura Huser, Silke HaverkampAbstract:Amacrine Cells comprise ~30 morphological types in the mammalian retina. The synaptic connectivity and function of a few GABAergic wide-field Amacrine Cells have recently been studied, however, with the exception of the rod pathway-specific AII Amacrine Cell the connectivity of glycinergic small-field Amacrine Cells has not been investigated in the mouse retina. Here, we studied the morphology and connectivity pattern of the small-field A8 Amacrine Cell. A8 Cells in mouse retina are bistratified with lobular processes in the ON sublamina and arboreal dendrites in the OFF sublamina of the inner plexiform layer. The distinct bistratified morphology was first visible at postnatal day 8, reaching the adult shape at P13, around eye opening. The connectivity of A8 Cells to bipolar Cells and ganglion Cells was studied by double and triple immunolabeling experiments using various Cell markers combined with synaptic markers. Our data suggest that A8 Amacrine Cells receive glutamatergic input from both OFF and ON cone bipolar Cells. Furthermore, A8 Cells are coupled to ON cone bipolar Cells by gap junctions, and provide inhibitory input via glycine receptor (GlyR) subunit α1 to OFF cone bipolar Cells and to ON A-type ganglion Cells. Measurements of spontaneous glycinergic postsynaptic currents and GlyR immunolabeling revealed that A8 Cells express GlyRs containing the α2 subunit. Taken together, the bistratified A8 Cell makes very similar synaptic contacts with cone bipolar Cells as the rod pathway-specific AII Amacrine Cell. However, unlike AII Cells, A8 Amacrine Cells provide glycinergic input to ON A-type ganglion Cells.
-
Morphology and connectivity of the small bistratified A8 Amacrine Cell in the mouse retina
The Journal of comparative neurology, 2015Co-Authors: Sammy C.s. Lee, Karin Dedek, Arndt Meyer, Timm Schubert, Laura Huser, Silke HaverkampAbstract:Amacrine Cells comprise ∼ 30 morphological types in the mammalian retina. The synaptic connectivity and function of a few γ-aminobutyric acid (GABA)ergic wide-field Amacrine Cells have recently been studied; however, with the exception of the rod pathway-specific AII Amacrine Cell, the connectivity of glycinergic small-field Amacrine Cells has not been investigated in the mouse retina. Here, we studied the morphology and connectivity pattern of the small-field A8 Amacrine Cell. A8 Cells in mouse retina are bistratified with lobular processes in the ON sublamina and arboreal dendrites in the OFF sublamina of the inner plexiform layer. The distinct bistratified morphology was first visible at postnatal day 8, reaching the adult shape at P13, around eye opening. The connectivity of A8 Cells to bipolar Cells and ganglion Cells was studied by double and triple immunolabeling experiments by using various Cell markers combined with synaptic markers. Our data suggest that A8 Amacrine Cells receive glutamatergic input from both OFF and ON cone bipolar Cells. Furthermore, A8 Cells are coupled to ON cone bipolar Cells by gap junctions, and provide inhibitory input via glycine receptor (GlyR) subunit α1 to OFF cone bipolar Cells and to ON A-type ganglion Cells. Measurements of spontaneous glycinergic postsynaptic currents and GlyR immunolabeling revealed that A8 Cells express GlyRs containing the α2 subunit. The results show that the bistratified A8 Cell makes very similar synaptic contacts with cone bipolar Cells as the rod pathway-specific AII Amacrine Cell. However, unlike AII Cells, A8 Amacrine Cells provide glycinergic input to ON A-type ganglion Cells.
-
a novel type of interplexiform Amacrine Cell in the mouse retina
European Journal of Neuroscience, 2009Co-Authors: Karin Dedek, Tobias Breuninger, Luis Perez De Sevilla Muller, Stephan Maxeiner, Konrad Schultz, Ulrike Janssenbienhold, Klaus Willecke, Thomas Euler, Reto WeilerAbstract:Mammalian retinas comprise an enormous variety of Amacrine Cells with distinct properties and functions. The present paper describes a new interplexiform Amacrine Cell type in the mouse retina. A transgenic mouse mutant was used that expressed the gene for the enhanced green fluorescent protein (EGFP) instead of the coding DNA of connexin45 in several retinal Cell classes, among which a single Amacrine Cell population was most prominently labelled. Staining for EGFP and different marker proteins showed that these Amacrine Cells are interplexiform: they stratify in stratum S4 ⁄ 5 of the inner plexiform layer and send processes to the outer plexiform layer. These Cells were termed IPA-S4 ⁄ 5 Cells. They belong to the group of medium-field Amacrine Cells and are coupled homologously and heterologously to other Amacrine Cells by connexin45. Immunostaining revealed that IPA-S4 ⁄ 5 Cells are GABAergic and express GAT-1, a plasma-membrane-bound GABA transporter possibly involved in non-vesicular GABA release. To characterize the light responses of IPA-S4 ⁄ 5 Cells, patch-clamp recordings in retinal slices were made. Consistent with their stratification in the ON sublamina of the inner plexiform layer, Cells depolarized in response to light ON stimuli and transiently hyperpolarized in response to light OFF. Responses of Cells to green (578 nm) and blue (400 nm) light suggest that they receive input from cone bipolar Cells contacting both M- and S-cones, possibly with reduced S-cone input. A new type of interplexiform ON Amacrine Cell is described, which is strongly coupled and uses GABA but not dopamine as its neurotransmitter.
Jonathan B. Demb - One of the best experts on this subject based on the ideXlab platform.
-
selective synaptic connections in the retinal pathway for night vision
The Journal of Comparative Neurology, 2019Co-Authors: Deborah Langrill Beaudoin, Mania Kupershtok, Jonathan B. DembAbstract:The mammalian retina encodes visual information in dim light using rod photoreceptors and a specialized circuit: rods→rod bipolar Cells→AII Amacrine Cell. The AII Amacrine Cell uses sign-conserving electrical synapses to modulate ON cone bipolar Cell terminals and sign-inverting chemical (glycinergic) synapses to modulate OFF cone Cell bipolar terminals; these ON and OFF cone bipolar terminals then drive the output neurons, retinal ganglion Cells (RGCs), following light increments and decrements, respectively. The AII Amacrine Cell also makes direct glycinergic synapses with certain RGCs, but it is not well established how many types receive this direct AII input. Here, we investigated functional AII Amacrine→RGC synaptic connections in the retina of the guinea pig (Cavia porCellus) by recording inhibitory currents from RGCs in the presence of ionotropic glutamate receptor (iGluR) antagonists. This condition isolates a specific pathway through the AII Amacrine Cell that does not require iGluRs: cone→ON cone bipolar Cell→AII Amacrine Cell→RGC. These recordings show that AII Amacrine Cells make direct synapses with OFF Alpha, OFF Delta and a smaller OFF transient RGC type that co-stratifies with OFF Alpha Cells. However, AII Amacrine Cells avoid making synapses with numerous RGC types that co-stratify with the connected RGCs. Selective AII connections ensure that a privileged minority of RGC types receives direct input from the night-vision pathway, independent from OFF bipolar Cell activity. Furthermore, these results illustrate the specificity of retinal connections, which cannot be predicted solely by co-stratification of dendrites and axons within the inner plexiform layer.
-
Intrinsic properties and functional circuitry of the AII Amacrine Cell
Visual neuroscience, 2012Co-Authors: Jonathan B. Demb, Joshua H. SingerAbstract:Amacrine Cells represent the most diverse class of retinal neuron, comprising dozens of distinct Cell types. Each type exhibits a unique morphology and generates specific visual computations through its synapses with a subset of excitatory interneurons (bipolar Cells), other Amacrine Cells, and output neurons (ganglion Cells). Here, we review the intrinsic and network properties that underlie the function of the most common Amacrine Cell in the mammalian retina, the AII Amacrine Cell. The AII connects rod and cone photoreceptor pathways, forming an essential link in the circuit for rod-mediated (scotopic) vision. As such, the AII has become known as the rod-Amacrine Cell. We, however, now understand that AII function extends to cone-mediated (photopic) vision, and AII function in scotopic and photopic conditions utilizes the same underlying circuit: AIIs are electrically coupled to each other and to the terminals of some types of ON cone bipolar Cells. The direction of signal flow, however, varies with illumination. Under photopic conditions, the AII network constitutes a crossover inhibition pathway that allows ON signals to inhibit OFF ganglion Cells and contributes to motion sensitivity in certain ganglion Cell types. We discuss how the AII's combination of intrinsic and network properties accounts for its unique role in visual processing.