Properties of synaptic transmission from photoreceptors to bipolar cells in the mudpuppy retina

1993 ◽  
Vol 69 (2) ◽  
pp. 352-360 ◽  
Author(s):  
H. G. Kim ◽  
R. F. Miller
Keyword(s):  
Kynurenic Acid ◽  
Response Times ◽  
Plexiform Layer ◽  
Bipolar Cells ◽  
Slice Preparation ◽  
Peak Response ◽  
Rods And Cones ◽  
Significant Difference ◽  
Pharmacological Studies ◽  
Whole Cell Recordings

1. Simultaneous, whole-cell recordings were obtained from synaptically coupled photoreceptor/bipolar cell pairs, by the use of direct visualization in a superfused, mudpuppy retinal slice preparation. 2. OFF-bipolar cells (BPs) generated sign-conserving responses when extrinsic current was injected into rods and cones, whereas ON-BPs generated a sign-reversing response. OFF-BPs (n = 24) responded faster than ON-BPs (n = 12), in terms of response latency (27.8 vs. 80.6 ms) and peak response times (50.5 vs. 159.8 ms) when current was injected into photoreceptors. We did not detect any significant difference between rod- versus cone-mediated latency or peak response times in the ON- and OFF-BP subtypes. 3. Rod and cone inputs to OFF-BPs were blocked by kynurenic acid (Kyn), but the doses required were significantly higher for rod inputs: the IC50 (the concentration at which an antagonist blocks 50% of the responses) for Kyn was 0.3 mM for cone inputs and 1 mM for rod inputs. 4. Rod inputs to OFF-BPs showed the same Kyn sensitivity as rod inputs to horizontal cells (HCs). However, cone inputs to HCs (IC50 < 200 microM) were more sensitive to Kyn than those to OFF-BPs. 5. The pharmacological studies presented here, together with previous studies, suggest that the sign-conserving pathway in the outer plexiform layer of the mudpuppy retina involves at least three subtypes of glutamate receptors: 1) cone-activated receptors of HCs; 2) cone-activated receptors of OFF-BPs; and 3) rod-activated receptors found in HCs and BPs.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Histological Studies on the Retina of the Falcon "S Eye Ball (Circus Cyaneus C.) Under Light and Electron Microscopy

2012 ◽  
Vol 36 (2) ◽  
pp. 83-92
Author(s):  
Samawal Jassim Mohamed Al-Robaae
Keyword(s):  
Histological Study ◽  
Light And Electron Microscopy ◽  
Plexiform Layer ◽  
Internal Limiting Membrane ◽  
Bipolar Cells ◽  
Horizontal Cells ◽  
Histological Studies ◽  
Rods And Cones ◽  
Pigmented Epithelium ◽  
Circus Cyaneus

The histological study showed that the retina of falcon"s eyeball was thin at the peripheryand ranges between 0.6-0.8 μ but it was thick at center 1.68-2.64 μ. The retina consists fromten layers: pigmented epithelium, rods and cons layer, external nuclear layer, externalplexiform layer, internal nuclear layer, internal plexiform layer, Gangilionic cells layer,neurofibres layer and internal limiting membrane layer. The ultra-structural study stated thatthe rods and cons layers contained single rods with single and double cons. The retinacharacterized by lacking of the oil droplets in the internal segments of rods with narrowexternal plexiform layer in order to form network connecting rods and cones, horizontal cells,bipolar cells and Muller's cells.

Roles of aspartate and glutamate in synaptic transmission in rabbit retina. I. Outer plexiform layer

1985 ◽  
Vol 53 (3) ◽  
pp. 699-713 ◽  
Author(s):  
S. A. Bloomfield ◽  
J. E. Dowling
Keyword(s):  
Plexiform Layer ◽  
Second Order ◽  
Bipolar Cells ◽  
Outer Plexiform Layer ◽  
Horizontal Cells ◽  
Diethyl Ester ◽  
Rabbit Retina ◽  
Lower Vertebrate ◽  
Rods And Cones ◽  
Low Concentrations

Intracellular recordings were obtained from horizontal and bipolar cells of the superfused, isolated retina-eyecup of the rabbit. The putative neurotransmitters aspartate, glutamate, and several analogues were added to the superfusate while the membrane potential and light-responsiveness of the retinal neurons were monitored. Both L-aspartate and L-glutamate mimicked the actions of the endogenous photoreceptor transmitter on horizontal cells, on-bipolar cells, and off-bipolar cells. At applied concentrations of 2.5-20 mM, the actions of L-aspartate and L-glutamate were indistinguishable. D-aspartate potentiated the effects of both L-aspartate and L-glutamate on horizontal cells. This suggests that active uptake systems for these amino acids exist in the outer plexiform layer (OPL) of the rabbit retina. The glutamate analogue kainate produced effects similar to those of aspartate and glutamate on second-order neurons, but at concentrations lower by over two orders of magnitude. The glutamate analogue quisqualate had effects similar to kainate but with much less potency. The aspartate analogue n-methyl DL-aspartate (NMDLA) antagonized the effects of the photoreceptor transmitter on horizontal and off-bipolar cells. This action of NMDLA was only observed at low concentrations (50 microM). In addition, NMDLA could block the effects of exogenously applied kainate. The NMDLA had no clear effects on on-bipolar cells. The glutamate analogue 2-amino-4-phosphonobutyrate reversibly blocked the responses of on-bipolar cells but had no effect on either horizontal or off-bipolar cell responses. This suggests that on-bipolar cells possess a unique synaptic receptor. The aspartate analogue 2-amino-3-phosphonoproprionate did not show this selectivity, suggesting that this unique receptor is a glutamate-preferring receptor. The antagonists alpha-methyl glutamate, alpha-amino adipate, and glutamate diethyl ester all showed only a weak ability to antagonize the actions of the photoreceptor transmitter on second-order neurons. The results of this study indicate that glutamate or a glutamate-like substance is the likely transmitter of rods and cones in the rabbit retina. A comparison of the present findings with those previously obtained in lower vertebrate retinas suggests that the basic pharmacological design of the OPL of all vertebrate retinas is very similar.

Patch-Clamp Investigations and Compartmental Modeling of Rod Bipolar Axon Terminals in an In Vitro Thin-Slice Preparation of the Mammalian Retina

2007 ◽  
Vol 97 (2) ◽  
pp. 1171-1187 ◽  
Author(s):  
Leif Oltedal ◽  
Svein Harald Mørkve ◽  
Margaret Lin Veruki ◽  
Espen Hartveit
Keyword(s):  
Synaptic Transmission ◽  
Computer Simulations ◽  
Bipolar Cells ◽  
Slice Preparation ◽  
Whole Cell ◽  
Axon Terminals ◽  
Postsynaptic Currents ◽  
Whole Cell Recordings ◽  
Rod Bipolar Cells

To extend the usefulness of rod bipolar cells for studies of chemical synaptic transmission, we have performed electrophysiological recordings from rod bipolar axon terminals in an in vitro slice preparation of the rat retina. Whole cell recordings from axon terminals and cell bodies were used to investigate the passive membrane properties of rod bipolar cells and analyzed with a two-compartment equivalent electrical circuit model developed by Mennerick et al. For both terminal- and soma-end recordings, capacitive current decays were well fitted by biexponential functions. Computer simulations of simplified models of rod bipolar cells demonstrated that estimates of the capacitance of the axon terminal compartment can depend critically on the recording location, with terminal-end recordings giving the best estimates. Computer simulations and whole cell recordings demonstrated that terminal-end recordings can yield more accurate estimates of the peak amplitude and kinetic properties of postsynaptic currents generated at the axon terminals due to increased electrotonic filtering of these currents when recorded at the soma. Finally, we present whole cell and outside-out patch recordings from axon terminals with responses evoked by GABA and glycine, spontaneous inhibitory postsynaptic currents, voltage-gated Ca2+ currents, and depolarization-evoked reciprocal synaptic responses, verifying that the recorded axon terminals are involved in normal pre- and postsynaptic relationships. These results demonstrate that axon terminals of rod bipolar cells are directly accessible to whole cell and outside-out patch recordings, extending the usefulness of this preparation for detailed studies of pre- and postsynaptic mechanisms of synaptic transmission in the CNS.

GABA responses of rod bipolar cells in rabbit retinal slices

2000 ◽  
Vol 17 (3) ◽  
pp. 381-389 ◽  
Author(s):  
GREGORY S. McGILLEM ◽  
THOMAS C. ROTOLO ◽  
RAMON F. DACHEUX
Keyword(s):  
Bipolar Cell ◽  
Axon Terminal ◽  
Bipolar Cells ◽  
Slice Preparation ◽  
Pharmacological Agents ◽  
Axon Terminals ◽  
Receptor Input ◽  
Sr 95531 ◽  
Whole Cell Recordings ◽  
Rod Bipolar Cells

GABAergic responses of rabbit rod bipolar cells were reexamined by using whole-cell recordings in the superfused slice preparation to determine if there is GABAC receptor input to their axon terminal and to characterize the contribution that GABAA and GABAC receptors make to the total GABA current on the axon terminals of these cells. Pharmacological agents specifically blocking GABAA and GABAC receptor currents demonstrated that 37% of the GABA-activated current was blocked by either the GABAA antagonists bicuculline or SR-95531, whereas the remaining 63% of the GABA current was blocked by a mixture of bicuculline and the GABAC antagonist TPMPA. This indicated that GABAC receptors were present on the axon terminal of the rabbit rod bipolar cell and that they were responsible for mediating the bicuculline insensitive GABA current.

scholarly journals Retinal microvascular signs in COVID-19

2021 ◽  
pp. bjophthalmol-2020-318236
Author(s):  
Ralene Sim ◽  
Gemmy Cheung ◽  
Daniel Ting ◽  
Edmund Wong ◽  
Tien Yin Wong ◽  
...  
Keyword(s):  
Medical History ◽  
Vital Signs ◽  
Plexiform Layer ◽  
Nasopharyngeal Swab ◽  
Inner Plexiform Layer ◽  
Cross Sectional ◽  
Imaging Device ◽  
Asymptomatic Patients ◽  
Significant Difference ◽  
Retinal Microvascular Signs

Background/aimsTo explore if retinal findings are associated with COVID-19 infection.MethodsIn this prospective cross-sectional study, we recruited participants positive for COVID-19 by nasopharyngeal swab, with no medical history. Subjects underwent retinal imaging with an automated imaging device (3D OCT-1 Maestro, Topcon, Tokyo, Japan) to obtain colour fundus photographs (CFP) and optical coherence tomographic (OCT) scans of the macula. Data on personal biodata, medical history and vital signs were collected from electronic medical records.Results108 patients were recruited. Mean age was 36.0±5.4 years. 41 (38.0%) had symptoms of acute respiratory infection (ARI) at presentation. Of 216 eyes, 25 (11.6%) had retinal signs—eight (3.7%) with microhaemorrhages, six (2.8%) with retinal vascular tortuosity and two (0.93%) with cotton wool spots (CWS). 11 eyes (5.1%) had hyper-reflective plaques in the ganglion cell-inner plexiform layer layer on OCT, of which two also had retinal signs visible on CFP (CWS and microhaemorrhage, respectively). There was no significant difference in the prevalence of retinal signs in symptomatic versus asymptomatic patients (12 (15.0%) vs 13 (9.6%), p=0.227). Patients with retinal signs were significantly more likely to have transiently elevated blood pressure than those without (p=0.03).ConclusionOne in nine had retinal microvascular signs on ocular imaging. These signs were observed even in asymptomatic patients with normal vital signs. These retinal microvascular signs may be related to underlying cardiovascular and thrombotic alternations associated with COVID-19 infection.

Lateralization of lexical processing in monolinguals and bilinguals

2021 ◽  
pp. 136700692110188
Author(s):  
Filiz Mergen ◽  
Gulmira Kuruoglu
Keyword(s):  
Lexical Processing ◽  
Response Times ◽  
Visual Fields ◽  
Decision Task ◽  
Bilingual Speakers ◽  
Visual Hemifield ◽  
Significant Difference ◽  
Brain Correlates ◽  
Orthographic Neighbors

Aims and objectives: This study aims to investigate how lexical processing (LP) is organized in early Turkish–English bilinguals and Turkish monolinguals. Methodology: We used a visual hemifield paradigm where bilingual ( n = 48) and monolingual ( n = 53) participants performed a lexical decision task. Bilingual participants performed the task in both their languages. Data and analysis: We recorded response times (RTs) and the accuracy rates (ARs) of the participants. An analysis of variance and t-test were run to analyze the bilingual and monolingual data, respectively. Findings: The results obtained from the analysis of the RTs and ARs for the Turkish and English words showed a balanced hemispheric organization in LP in bilingual speakers. The RTs for Turkish words in the monolingual group provided supportive evidence for the predominant role of the left hemisphere in LP. However, no significant difference was found in the accuracy of their answers, suggesting that the monolingual participants’ performance was not influenced by visual field of presentation of the words. Finally, the comparison of the two groups revealed that bilingual participants’ performance was inferior to monolinguals’ in speed and accuracy of processing of words presented in both visual fields. This result gives further support for the differential representation of LP in monolinguals and bilinguals. Originality: The psycholinguistic literature abounds with studies of LP in bilinguals and monolinguals from a variety of language backgrounds; however, there is much less data regarding the brain correlates of LP in Turkish–English bilinguals and Turkish monolinguals. Implications: Since Turkish–English bilinguals and Turkish monolinguals are underrepresented in the literature as compared to the population who speak other languages with alphabetic writing, this study provides preliminary data for future studies. Limitations: We did not control for gender or lexical factors such as orthographic neighbors when designing the word sets used as stimuli.

Membrane currents evoked by ionotropic glutamate receptor agonists in rod bipolar cells in the rat retinal slice preparation

1996 ◽  
Vol 76 (1) ◽  
pp. 401-422 ◽  
Author(s):  
E. Hartveit
Keyword(s):  
Nmda Receptor ◽  
Plexiform Layer ◽  
Amacrine Cells ◽  
Bipolar Cells ◽  
Inner Plexiform Layer ◽  
Receptor Agonists ◽  
Long Latency ◽  
Glutamate Receptor Agonists ◽  
Conductance Increase ◽  
Rod Bipolar Cells

1. With the use of the whole cell voltage-clamp technique, I have recorded the current responses to ionotropic glutamate receptor agonists of rod bipolar cells in vertical slices of rat retina. Rod bipolar cells constitute a single population of cells and were visualized by infrared differential interference contrast video microscopy. They were targeted by the position of their cell bodies in the inner nuclear layer and, after recording, were visualized in their entirety by labeling with the fluorescent dye Lucifer yellow, which was included in the recording pipette. To study current-voltage relationships of evoked currents, voltage-gated potassium currents were blocked by including Cs+ and tetraethylammonium+ in the recording pipette. 2. Pressure application of the non-N-methyl-D-aspartate (non-NMDA) receptor agonists kainate and (S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) from puffer pipettes evoked a long-latency conductance increase selective for chloride ions. When the intracellular chloride concentration was increased, the reversal potential changed, corresponding to the change in equilibrium potential for chloride. The response was evoked in the presence of 5 mM Co2+ and nominally O mM Ca2+ in the extracellular solution, presumably blocking all external Ca2(+)-dependent release of neurotransmitter. 3. The long latency of kainate-evoked currents in bipolar cells contrasted with the short-latency currents evoked by gamma-aminobutyric acid (GABA) and glycine in rod bipolar cells and by kainate in amacrine cells. 4. Application of NMDA evoked no response in rod bipolar cells. 5. Coapplication of AMPA with cyclothiazide, a blocker of agonist-evoked desensitization of AMPA receptors, enhanced the conductance increase compared with application of AMPA alone. Coapplication of the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione blocked the response to kainate and AMPA, indicating that the response was mediated by conventional ionotropic glutamate receptors. 6. The conductance increase evoked by non-NMDA receptor agonists could not be blocked by a combination of 100 microM picrotoxin and 10 microM strychnine. Application of the GABAC receptor antagonist 3-aminopropyl (methyl)phosphinic acid (3-APMPA) strongly reduced the response, and coapplication of 500 microM 3-APMPA and 100 microM picrotoxin completely blocked the response. These results suggested that the conductance increase evoked by non-NMDA receptor agonists was mediated by release of GABA and activation of GABAC receptors, and most likely also GABAA receptors, on rod bipolar cells. 7. Kainate responses like those described above could not be evoked in bipolar cells in which the axon had been cut somewhere along its passage to the inner plexiform layer during the slicing procedure. This suggests that the response was dependent on the integrity of the axon terminal in the inner plexiform layer, known to receive GABAergic synaptic input from amacrine cells. 8. The results indicate that ionotropic glutamate receptors are not involved in mediating synaptic input from photoreceptors to rod bipolar cells and that an unconventional mechanism of GABA release from amacrine cells might operate in the inner plexiform layer.

scholarly journals Morphology of Inner Retina in Rhesus Monkeys of Various Ages: A Comparative Study

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Jingfei Chen ◽  
Qihui Luo ◽  
Chao Huang ◽  
Wen Zeng ◽  
Ping Chen ◽  
...  
Keyword(s):  
Rhesus Monkeys ◽  
Morphological Structure ◽  
Plexiform Layer ◽  
Bipolar Cells ◽  
Growth Stages ◽  
Retinal Layer ◽  
Inner Plexiform Layer ◽  
Fiber Layer ◽  
Inner Retina ◽  
Biological Studies

Purpose. To investigate the changes of thickness in each layer, the morphology and density of inner neurons in rhesus monkeys’ retina at various growth stages, thus contribute useful data for further biological studies. Methods. The thickness of nerve fiber layer (NFL), the whole retina, inner plexiform layer (IPL), and outer plexiform layer (OPL) of rhesus monkeys at different ages were observed with hematoxylin and eosin (H&E) staining. The morphology and the density of inner neurons of rhesus monkey retina were detected by immunofluorescence. Results. The retina showed the well-known ten layers, the thickness of each retinal layer in rhesus monkeys at various ages increased rapidly after infant, and the retina was the thickest in adulthood, but the retinal thickness stop growing in senescent. Quantitative analysis showed that the maximum density of inner neurons was reached in adolescent, and then, the density of inner neurons decreased in adults and senescent retinas. And some changes in the morphology of rod bipolar cells have occurred in senescent. Conclusions. The structure of retina in rhesus monkeys is relatively immature at infant, and the inner retina of rhesus monkeys is mature in adolescent, while the thickness of each retinal layer was the most developed in the adult group. There was no significant change in senescence for the thickness of each retinal layer, but the number of the neurons in our study has a decreasing trend and the morphological structure has changed.

Accuracy and Speed of Orthographic Processing in Persons with Developmental Dyslexia

2005 ◽  
Vol 101 (1) ◽  
pp. 95-107 ◽  
Author(s):  
Wayne M. King ◽  
Linda L. Lombardino ◽  
Sarah Ahmed
Keyword(s):  
Developmental Dyslexia ◽  
Word Reading ◽  
Response Times ◽  
Age Groups ◽  
Group Differences ◽  
Control Group ◽  
Age Difference ◽  
Significant Difference ◽  
Typically Achieving ◽  
Reading Disabled

A group of 39 persons (20 male and 19 female, 11.0 to 32.5 yr.) with developmental dyslexia and 42 controls (21 male and 21 female, 11.2 to 32.3 years) were compared on computerized tests of sight word reading, nonword decoding, and spelling recognition. The subjects with developmental dyslexia performed significantly slower and less accurately than controls on all tasks. Further, the effect size of the group differences was larger for the older group. Within-group analyses showed a significant difference by age group on accuracy. Only the control group showed a significant age difference between groups on response time. Mean accuracy and response times for the reading-disabled subjects resembled shifted versions of the control group means. These results agree with previous reports that phonological deficits persist for reading-disabled adults and suggest a test of whether the discrepancy between reading-disabled and typically achieving readers may actually increase across age groups.

scholarly journals Thicknesses of Macular Inner Retinal Layers in Children with Anisometropic Amblyopia

2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Zheren Xia ◽  
Hao Chen ◽  
Suilian Zheng
Keyword(s):  
Structural Changes ◽  
Plexiform Layer ◽  
Inner Plexiform Layer ◽  
Macular Area ◽  
Anisometropic Amblyopia ◽  
Retinal Layers ◽  
Significant Difference ◽  
The Right ◽  
Fellow Eyes ◽  
Sd Oct

Objective. To investigate the thicknesses of macular inner retinal layers in children with anisometropic amblyopia using spectral domain optical coherence tomography (SD-OCT). Methods. Thirty-seven children with anisometropic amblyopia and fifty-seven children with normal vision were recruited in the study. Both eyes of children with anisometropic amblyopia and the right eyes of normal controls underwent scanning with the Spectralis OCT. The segmentation of retinal layers was performed automatically to measure individual inner retinal layers in the five sectors of the macular. An independent sample t -test was applied to compare the mean layer thicknesses of anisometropic eyes and fellow eyes with those of control eyes. Results. There was no significant difference in the total macular thickness between amblyopic and control eyes. However, in the peripheral macular area, three of the four quadrants of both the ganglion cell layer (GCL) and the inner plexiform layer (IPL) thicknesses were significantly reduced in amblyopic eyes compared to control eyes. Moreover, two of the four quadrants of the GCL thickness and three of the four quadrants of the IPL thickness in the peripheral macular area were significantly reduced in fellow eyes than in control eyes. Conclusion. The SD-OCT data revealed differences in the thicknesses of some macular inner retinal layers in both eyes of children with anisometropic amblyopia compared with those with emmetropia, indicating that structural changes might exist in the retina of children with amblyopia.

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