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Adámek P, Grygarová D, Jajcay L, Bakštein E, Fürstová P, Juríčková V, Jonáš J, Langová V, Neskoroďana I, Kesner L, Horáček J. The Gaze of Schizophrenia Patients Captured by Bottom-up Saliency. SCHIZOPHRENIA (HEIDELBERG, GERMANY) 2024; 10:21. [PMID: 38378724 PMCID: PMC10879495 DOI: 10.1038/s41537-024-00438-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 01/19/2024] [Indexed: 02/22/2024]
Abstract
Schizophrenia (SCHZ) notably impacts various human perceptual modalities, including vision. Prior research has identified marked abnormalities in perceptual organization in SCHZ, predominantly attributed to deficits in bottom-up processing. Our study introduces a novel paradigm to differentiate the roles of top-down and bottom-up processes in visual perception in SCHZ. We analysed eye-tracking fixation ground truth maps from 28 SCHZ patients and 25 healthy controls (HC), comparing these with two mathematical models of visual saliency: one bottom-up, based on the physical attributes of images, and the other top-down, incorporating machine learning. While the bottom-up (GBVS) model revealed no significant overall differences between groups (beta = 0.01, p = 0.281, with a marginal increase in SCHZ patients), it did show enhanced performance by SCHZ patients with highly salient images. Conversely, the top-down (EML-Net) model indicated no general group difference (beta = -0.03, p = 0.206, lower in SCHZ patients) but highlighted significantly reduced performance in SCHZ patients for images depicting social interactions (beta = -0.06, p < 0.001). Over time, the disparity between the groups diminished for both models. The previously reported bottom-up bias in SCHZ patients was apparent only during the initial stages of visual exploration and corresponded with progressively shorter fixation durations in this group. Our research proposes an innovative approach to understanding early visual information processing in SCHZ patients, shedding light on the interplay between bottom-up perception and top-down cognition.
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Affiliation(s)
- Petr Adámek
- Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic.
- Third Faculty of Medicine, Charles University, Prague, Czech Republic.
| | - Dominika Grygarová
- Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic
- Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Lucia Jajcay
- Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic
- Institute of Computer Science of the Czech Academy of Sciences, Prague, Czech Republic
- Faculty of Electrical Engineering, Czech Technical University in Prague, Prague, Czech Republic
| | - Eduard Bakštein
- Early Episodes of SMI Research Center, National Institute of Mental Health, Klecany, Czech Republic
- Department of Cybernetics, Faculty of Electrical Engineering, Czech Technical University, Prague, Czech Republic
| | - Petra Fürstová
- Early Episodes of SMI Research Center, National Institute of Mental Health, Klecany, Czech Republic
| | - Veronika Juríčková
- Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic
- First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Juraj Jonáš
- Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic
- Faculty of Humanities, Charles University, Prague, Czech Republic
| | - Veronika Langová
- Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic
- Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Iryna Neskoroďana
- Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic
| | - Ladislav Kesner
- Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic
- Department of Art History, Masaryk University, Brno, Czech Republic
| | - Jiří Horáček
- Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic
- Third Faculty of Medicine, Charles University, Prague, Czech Republic
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2
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Adámek P, Langová V, Horáček J. Early-stage visual perception impairment in schizophrenia, bottom-up and back again. SCHIZOPHRENIA (HEIDELBERG, GERMANY) 2022; 8:27. [PMID: 35314712 PMCID: PMC8938488 DOI: 10.1038/s41537-022-00237-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 02/17/2022] [Indexed: 01/01/2023]
Abstract
Visual perception is one of the basic tools for exploring the world. However, in schizophrenia, this modality is disrupted. So far, there has been no clear answer as to whether the disruption occurs primarily within the brain or in the precortical areas of visual perception (the retina, visual pathways, and lateral geniculate nucleus [LGN]). A web-based comprehensive search of peer-reviewed journals was conducted based on various keyword combinations including schizophrenia, saliency, visual cognition, visual pathways, retina, and LGN. Articles were chosen with respect to topic relevance. Searched databases included Google Scholar, PubMed, and Web of Science. This review describes the precortical circuit and the key changes in biochemistry and pathophysiology that affect the creation and characteristics of the retinal signal as well as its subsequent modulation and processing in other parts of this circuit. Changes in the characteristics of the signal and the misinterpretation of visual stimuli associated with them may, as a result, contribute to the development of schizophrenic disease.
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Affiliation(s)
- Petr Adámek
- Third Faculty of Medicine, Charles University, Prague, Czech Republic. .,Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic.
| | - Veronika Langová
- Third Faculty of Medicine, Charles University, Prague, Czech Republic.,Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic
| | - Jiří Horáček
- Third Faculty of Medicine, Charles University, Prague, Czech Republic.,Center for Advanced Studies of Brain and Consciousness, National Institute of Mental Health, Klecany, Czech Republic
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3
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Ye J, Sinha P, Hou F, He X, Shen M, Lu F, Shao Y. Impact of Temporal Visual Flicker on Spatial Contrast Sensitivity in Myopia. Front Neurosci 2021; 15:710344. [PMID: 34421527 PMCID: PMC8374145 DOI: 10.3389/fnins.2021.710344] [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: 05/16/2021] [Accepted: 07/19/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose To investigate whether short-term exposure to high temporal frequency full-field flicker has an impact on spatial visual acuity in individuals with varying degrees of myopia. Methods Thirty subjects (evenly divided between control and experimental groups) underwent a 5-min exposure to full-field flicker. The flicker rate was lower than critical flicker frequency (CFF) for the experimental group (12.5 Hz) and significantly higher than CFF for the controls (60 Hz). Spatial contrast sensitivity function (CSF) was measured before and immediately after flicker exposure. We examined whether the post flicker CSF parameters were different from the pre-exposure CSF values in either of the subject groups. Additionally, we examined the relationship between the amount of CSF change from pre to post timepoints and the degree of subjects’ myopia. The CSF parameters included peak frequency, peak sensitivity, bandwidth, truncation, and area under log CSF (AULCSF). Results There was no significant difference of all five pre-exposure CSF parameters between the two groups at baseline (P = 0.333 ∼ 0.424). Experimental group subjects exhibited significant (P < 0.005) increases in peak sensitivity and AULCSF, when comparing post-exposure results to pre-exposure ones. Controls showed no such enhancements. Furthermore, the extent of these changes in the experimental group was correlated significantly with the participants’ refractive error (P = 0.005 and 0.018, respectively). Conclusion Our data suggest that exposure to perceivable high-frequency flicker (but, not to supra-CFF frequencies) enhances important aspects of spatial contrast sensitivity, and these enhancements are correlated to the degree of myopia. This finding has implications for potential interventions for cases of modest myopia.
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Affiliation(s)
- Jie Ye
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Pawan Sinha
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Fang Hou
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Xianghang He
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China.,Fuzhou Aier Eye Hospital, Fuzhou, China
| | - Meixiao Shen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Fan Lu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Yilei Shao
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
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4
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The effects of reduced ambient lighting on lens compensation in infant rhesus monkeys. Vision Res 2021; 187:14-26. [PMID: 34144362 DOI: 10.1016/j.visres.2021.05.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 05/21/2021] [Accepted: 05/31/2021] [Indexed: 11/22/2022]
Abstract
Although reduced ambient lighting (~50 lx) does not increase the degree of form-deprivation myopia (FDM) in chickens or infant monkeys, it does reduce the probability that monkeys will recover from FDM and that the normal age-dependent reduction in hyperopia will occur in monkeys reared with unrestricted vision. These findings suggest that low ambient lighting levels affect the regulatory mechanism responsible for emmetropization. To study this issue, infant rhesus monkeys (age ~ 24 days) were reared under dim light (55 ± 9 lx) with monocular -3D (dim-light lens-induced myopia, DL-LIM, n = 8) or +3D spectacle lenses (dim-light lens-induced hyperopia, DL-LIH, n = 7) until approximately 150 days of age. Refractive errors, ocular parameters and sub-foveal choroidal thickness were measured periodically and compared with normal-light-reared, lens-control monkeys (NL-LIM, n = 16; NL-LIH, n = 7). Dim light rearing significantly attenuated the degree of compensatory anisometropias in both the DL-LIM (-0.63 ± 0.77D vs. -2.11 ± 1.10D in NL-LIM) and DL-LIH treatment groups (-0.18 ± 1.93D vs. +1.71 ± 0.39D in NL-LIH). These effects came about because the treated and fellow control eyes had a lower probability of responding appropriately to the eye's effective refractive state. Vision-induced interocular differences in choroidal thickness were only observed in monkeys that exhibited compensating refractive changes, suggesting that failures in detecting the relative magnitude of optical errors underlay the abnormal refractive responses. Our findings suggest that low ambient lighting levels reduce the efficacy of the vision-dependent mechanisms that regulate refractive development.
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De-Miguel FF, Leon-Pinzon C, Torres-Platas SG, Del-Pozo V, Hernández-Mendoza GA, Aguirre-Olivas D, Méndez B, Moore S, Sánchez-Sugía C, García-Aguilera MA, Martínez-Valencia A, Ramírez-Santiago G, Rubí JM. Extrasynaptic Communication. Front Mol Neurosci 2021; 14:638858. [PMID: 33994942 PMCID: PMC8119753 DOI: 10.3389/fnmol.2021.638858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 04/01/2021] [Indexed: 12/18/2022] Open
Abstract
Streams of action potentials or long depolarizations evoke a massive exocytosis of transmitters and peptides from the surface of dendrites, axons and cell bodies of different neuron types. Such mode of exocytosis is known as extrasynaptic for occurring without utilization of synaptic structures. Most transmitters and all peptides can be released extrasynaptically. Neurons may discharge their contents with relative independence from the axon, soma and dendrites. Extrasynaptic exocytosis takes fractions of a second in varicosities or minutes in the soma or dendrites, but its effects last from seconds to hours. Unlike synaptic exocytosis, which is well localized, extrasynaptic exocytosis is diffuse and affects neuronal circuits, glia and blood vessels. Molecules that are liberated may reach extrasynaptic receptors microns away. The coupling between excitation and exocytosis follows a multistep mechanism, different from that at synapses, but similar to that for the release of hormones. The steps from excitation to exocytosis have been studied step by step for the vital transmitter serotonin in leech Retzius neurons. The events leading to serotonin exocytosis occur similarly for the release of other transmitters and peptides in central and peripheral neurons. Extrasynaptic exocytosis occurs commonly onto glial cells, which react by releasing the same or other transmitters. In the last section, we discuss how illumination of the retina evokes extrasynaptic release of dopamine and ATP. Dopamine contributes to light-adaptation; ATP activates glia, which mediates an increase in blood flow and oxygenation. A proper understanding of the workings of the nervous system requires the understanding of extrasynaptic communication.
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Affiliation(s)
- Francisco F De-Miguel
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, México City, Mexico.,Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, México City, Mexico
| | - Carolina Leon-Pinzon
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, México City, Mexico
| | - Susana G Torres-Platas
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, México City, Mexico
| | - Vanessa Del-Pozo
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, México City, Mexico
| | | | - Dilia Aguirre-Olivas
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, México City, Mexico
| | - Bruno Méndez
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, México City, Mexico
| | - Sharlen Moore
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, México City, Mexico
| | - Celeste Sánchez-Sugía
- Instituto de Fisiología Celular-Neurociencias, Universidad Nacional Autónoma de México, México City, Mexico
| | | | | | | | - J Miguel Rubí
- Facultat de Fisica, Universitat de Barcelona, Barcelona, Spain
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Muralidharan AR, Lança C, Biswas S, Barathi VA, Wan Yu Shermaine L, Seang-Mei S, Milea D, Najjar RP. Light and myopia: from epidemiological studies to neurobiological mechanisms. Ther Adv Ophthalmol 2021; 13:25158414211059246. [PMID: 34988370 PMCID: PMC8721425 DOI: 10.1177/25158414211059246] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 10/25/2021] [Indexed: 12/22/2022] Open
Abstract
Myopia is far beyond its inconvenience and represents a true, highly prevalent, sight-threatening ocular condition, especially in Asia. Without adequate interventions, the current epidemic of myopia is projected to affect 50% of the world population by 2050, becoming the leading cause of irreversible blindness. Although blurred vision, the predominant symptom of myopia, can be improved by contact lenses, glasses or refractive surgery, corrected myopia, particularly high myopia, still carries the risk of secondary blinding complications such as glaucoma, myopic maculopathy and retinal detachment, prompting the need for prevention. Epidemiological studies have reported an association between outdoor time and myopia prevention in children. The protective effect of time spent outdoors could be due to the unique characteristics (intensity, spectral distribution, temporal pattern, etc.) of sunlight that are lacking in artificial lighting. Concomitantly, studies in animal models have highlighted the efficacy of light and its components in delaying or even stopping the development of myopia and endeavoured to elucidate possible mechanisms involved in this process. In this narrative review, we (1) summarize the current knowledge concerning light modulation of ocular growth and refractive error development based on studies in human and animal models, (2) summarize potential neurobiological mechanisms involved in the effects of light on ocular growth and emmetropization and (3) highlight a potential pathway for the translational development of noninvasive light-therapy strategies for myopia prevention in children.
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Affiliation(s)
| | | | | | | | | | | | - Dan Milea
- Singapore Eye Research Institute, Singapore
| | - Raymond P Najjar
- Visual Neurosciences Group, Singapore Eye Research Institute, The Academia, 20 College Road, Discovery Tower Level 6, Singapore 169856
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7
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Korshunov KS, Blakemore LJ, Trombley PQ. Illuminating and Sniffing Out the Neuromodulatory Roles of Dopamine in the Retina and Olfactory Bulb. Front Cell Neurosci 2020; 14:275. [PMID: 33110404 PMCID: PMC7488387 DOI: 10.3389/fncel.2020.00275] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 08/04/2020] [Indexed: 01/28/2023] Open
Abstract
In the central nervous system, dopamine is well-known as the neuromodulator that is involved with regulating reward, addiction, motivation, and fine motor control. Yet, decades of findings are revealing another crucial function of dopamine: modulating sensory systems. Dopamine is endogenous to subsets of neurons in the retina and olfactory bulb (OB), where it sharpens sensory processing of visual and olfactory information. For example, dopamine modulation allows the neural circuity in the retina to transition from processing dim light to daylight and the neural circuity in the OB to regulate odor discrimination and detection. Dopamine accomplishes these tasks through numerous, complex mechanisms in both neural structures. In this review, we provide an overview of the established and emerging research on these mechanisms and describe similarities and differences in dopamine expression and modulation of synaptic transmission in the retinas and OBs of various vertebrate organisms. This includes discussion of dopamine neurons’ morphologies, potential identities, and biophysical properties along with their contributions to circadian rhythms and stimulus-driven synthesis, activation, and release of dopamine. As dysregulation of some of these mechanisms may occur in patients with Parkinson’s disease, these symptoms are also discussed. The exploration and comparison of these two separate dopamine populations shows just how remarkably similar the retina and OB are, even though they are functionally distinct. It also shows that the modulatory properties of dopamine neurons are just as important to vision and olfaction as they are to motor coordination and neuropsychiatric/neurodegenerative conditions, thus, we hope this review encourages further research to elucidate these mechanisms.
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Affiliation(s)
- Kirill S Korshunov
- Department of Biological Science, Florida State University, Tallahassee, FL, United States.,Program in Neuroscience, Florida State University, Tallahassee, FL, United States
| | - Laura J Blakemore
- Department of Biological Science, Florida State University, Tallahassee, FL, United States.,Program in Neuroscience, Florida State University, Tallahassee, FL, United States
| | - Paul Q Trombley
- Department of Biological Science, Florida State University, Tallahassee, FL, United States.,Program in Neuroscience, Florida State University, Tallahassee, FL, United States
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8
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Hellmer CB, Bohl JM, Hall LM, Koehler CC, Ichinose T. Dopaminergic Modulation of Signal Processing in a Subset of Retinal Bipolar Cells. Front Cell Neurosci 2020; 14:253. [PMID: 32922266 PMCID: PMC7456991 DOI: 10.3389/fncel.2020.00253] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 07/23/2020] [Indexed: 11/13/2022] Open
Abstract
The retina and the olfactory bulb are the gateways to the visual and olfactory systems, respectively, similarly using neural networks to initiate sensory signal processing. Sensory receptors receive signals that are transmitted to neural networks before projecting to primary cortices. These networks filter sensory signals based on their unique features and adjust their sensitivities by gain control systems. Interestingly, dopamine modulates sensory signal transduction in both systems. In the retina, dopamine adjusts the retinal network for daylight conditions (“light adaptation”). In the olfactory system, dopamine mediates lateral inhibition between the glomeruli, resulting in odorant signal decorrelation and discrimination. While dopamine is essential for signal discrimination in the olfactory system, it is not understood whether dopamine has similar roles in visual signal processing in the retina. To elucidate dopaminergic effects on visual processing, we conducted patch-clamp recording from second-order retinal bipolar cells, which exhibit multiple types that can convey different temporal features of light. We recorded excitatory postsynaptic potentials (EPSPs) evoked by various frequencies of sinusoidal light in the absence and presence of a dopamine receptor 1 (D1R) agonist or antagonist. Application of a D1R agonist, SKF-38393, shifted the peak temporal responses toward higher frequencies in a subset of bipolar cells. In contrast, a D1R antagonist, SCH-23390, reversed the effects of SKF on these types of bipolar cells. To examine the mechanism of dopaminergic modulation, we recorded voltage-gated currents, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, and low-voltage activated (LVA) Ca2+ channels. SKF modulated HCN and LVA currents, suggesting that these channels are the target of D1R signaling to modulate visual signaling in these bipolar cells. Taken together, we found that dopamine modulates the temporal tuning of a subset of retinal bipolar cells. Consequently, we determined that dopamine plays a role in visual signal processing, which is similar to its role in signal decorrelation in the olfactory bulb.
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Affiliation(s)
- Chase B Hellmer
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Jeremy M Bohl
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Leo M Hall
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Christina C Koehler
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
| | - Tomomi Ichinose
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI, United States
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9
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Cameron MA, Morley JW, Pérez-Fernández V. Seeing the light: different photoreceptor classes work together to drive adaptation in the mammalian retina. CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2020.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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10
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Altered spatial summation optimizes visual function in axial myopia. Sci Rep 2020; 10:12179. [PMID: 32699286 PMCID: PMC7376210 DOI: 10.1038/s41598-020-67893-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 02/28/2020] [Indexed: 12/27/2022] Open
Abstract
This study demonstrates significant differences between the area of complete spatial summation (Ricco's area, RA) in eyes with and without non-pathological, axial myopia. Contrast thresholds were measured for six stimuli (0.01-2.07 deg2) presented at 10º eccentricity in 24 myopic subjects and 20 age-similar non-myopic controls, with RA estimated using iterative two-phase regression analysis. To explore the effects of axial length-induced variations in retinal image size (RIS) on the measurement of RA, refractive error was separately corrected with (i) trial lenses at the anterior focal point (near constant inter-participant RIS in mm), and (ii) contact lenses (RIS changed with axial length). For spectacle corrected measurements, RA was significantly larger in the myopic group, with a significant positive correlation also being observed between RA and measures of co-localised peripheral ocular length. With contact lens correction, there was no significant difference in RA between the groups and no relationship with peripheral ocular length. The results suggest RA changes with axial elongation in myopia to compensate for reduced retinal ganglion cell density. Furthermore, as these changes are only observed when axial length induced variations in RIS are accounted for, they may reflect a functional adaptation of the axially-myopic visual system to an enlarged RIS.
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11
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Thoreson WB, Dacey DM. Diverse Cell Types, Circuits, and Mechanisms for Color Vision in the Vertebrate Retina. Physiol Rev 2019; 99:1527-1573. [PMID: 31140374 PMCID: PMC6689740 DOI: 10.1152/physrev.00027.2018] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 03/27/2019] [Accepted: 04/02/2019] [Indexed: 01/13/2023] Open
Abstract
Synaptic interactions to extract information about wavelength, and thus color, begin in the vertebrate retina with three classes of light-sensitive cells: rod photoreceptors at low light levels, multiple types of cone photoreceptors that vary in spectral sensitivity, and intrinsically photosensitive ganglion cells that contain the photopigment melanopsin. When isolated from its neighbors, a photoreceptor confounds photon flux with wavelength and so by itself provides no information about color. The retina has evolved elaborate color opponent circuitry for extracting wavelength information by comparing the activities of different photoreceptor types broadly tuned to different parts of the visible spectrum. We review studies concerning the circuit mechanisms mediating opponent interactions in a range of species, from tetrachromatic fish with diverse color opponent cell types to common dichromatic mammals where cone opponency is restricted to a subset of specialized circuits. Distinct among mammals, primates have reinvented trichromatic color vision using novel strategies to incorporate evolution of an additional photopigment gene into the foveal structure and circuitry that supports high-resolution vision. Color vision is absent at scotopic light levels when only rods are active, but rods interact with cone signals to influence color perception at mesopic light levels. Recent evidence suggests melanopsin-mediated signals, which have been identified as a substrate for setting circadian rhythms, may also influence color perception. We consider circuits that may mediate these interactions. While cone opponency is a relatively simple neural computation, it has been implemented in vertebrates by diverse neural mechanisms that are not yet fully understood.
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Affiliation(s)
- Wallace B Thoreson
- Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center , Omaha, Nebraska ; and Department of Biological Structure, Washington National Primate Research Center, University of Washington , Seattle, Washington
| | - Dennis M Dacey
- Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center , Omaha, Nebraska ; and Department of Biological Structure, Washington National Primate Research Center, University of Washington , Seattle, Washington
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12
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Roy S, Field GD. Dopaminergic modulation of retinal processing from starlight to sunlight. J Pharmacol Sci 2019; 140:86-93. [PMID: 31109761 DOI: 10.1016/j.jphs.2019.03.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/13/2019] [Accepted: 03/29/2019] [Indexed: 12/17/2022] Open
Abstract
Neuromodulators such as dopamine, enable context-dependent plasticity of neural circuit function throughout the central nervous system. For example, in the retina, dopamine tunes visual processing for daylight and nightlight conditions. Specifically, high levels of dopamine release in the retina tune vision for daylight (photopic) conditions, while low levels tune it for nightlight (scotopic) conditions. This review covers the cellular and circuit-level mechanisms within the retina that are altered by dopamine. These mechanisms include changes in gap junction coupling and ionic conductances, both of which are altered by the activation of diverse types of dopamine receptors across diverse types of retinal neurons. We contextualize the modulatory actions of dopamine in terms of alterations and optimizations to visual processing under photopic and scotopic conditions, with particular attention to how they differentially impact distinct cell types. Finally, we discuss how transgenic mice and disease models have shaped our understanding of dopaminergic signaling and its role in visual processing. Cumulatively, this review illustrates some of the diverse and potent mechanisms through which neuromodulation can shape brain function.
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Affiliation(s)
- Suva Roy
- Department of Neurobiology, Duke University School of Medicine, Durham, NC, USA
| | - Greg D Field
- Department of Neurobiology, Duke University School of Medicine, Durham, NC, USA.
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13
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An Alternative Splice Variant of Zebrafish Cx52.6 is Expressed in Retinal Horizontal Cells. Neuroscience 2018; 388:191-202. [PMID: 30048782 DOI: 10.1016/j.neuroscience.2018.07.024] [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: 04/06/2018] [Revised: 06/27/2018] [Accepted: 07/16/2018] [Indexed: 11/22/2022]
Abstract
Retinal horizontal cells (HCs) are inhibitory neurons, which modulate the transmission of light-elicited signals from photoreceptors to bipolar cells in the outer retina. HCs of the same physiological type are extensively coupled via gap junctions. In the zebrafish retina, the population of HCs comprises up to four morphologically distinct subtypes. Four different connexins (Cx52.6, Cx52.7, Cx52.9 and Cx55.5) were detected in these cells with overlapping expression patterns. In this study, we show that Cx52.6 is alternatively spliced in the retina, resulting in an additional isoform, designated as Cx53.4, which differs from the originally described Cx52.6 only by the final C-terminal peptide (12 vs. 4 aa). Further protein sequence alignments revealed that Cx53.4 represents the counterpart of alternatively spliced mouse Cx57 and human Cx62. RT-PCR analyses of mRNA expression in different adult zebrafish tissues showed that Cx53.4 is expressed exclusively in the retina. The localization of Cx53.4 protein within the retina was analyzed using a specific antibody. Immunofluorescence analyses demonstrated that the expression of Cx53.4 is restricted to HCs of all four subtypes. Further, immunoelectron microscopy confirmed the presence of Cx53.4 in gap junctions between HC dendrites and between their axon terminals.
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Fernandes TMP, de Andrade MJO, Santana JB, Nogueira RMTBL, dos Santos NA. Tobacco Use Decreases Visual Sensitivity in Schizophrenia. Front Psychol 2018; 9:288. [PMID: 29559947 PMCID: PMC5845747 DOI: 10.3389/fpsyg.2018.00288] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 02/20/2018] [Indexed: 12/27/2022] Open
Abstract
Smoking prevalence in patients who are diagnosed with schizophrenia (SCZ) is higher than in the general population. Chronic tobacco use in SCZ patients may reduce the side effects of antipsychotic drugs, thus serving as a self-medication for such side effects. Understanding the ways in which chronic tobacco use influences visual sensitivity has clinical implications, which may serve as a tool for non-invasively diagnosing early-stage visual processing deficits. The present study evaluated the effects of chronic tobacco use on visual sensitivity in SCZ patients. Our purpose was to provide new directions for future research, mainly psychophysical and electrophysiological studies. In the present study, 40 smoker controls (SC), 20 SCZ tobacco users, and 20 SCZ tobacco nonusers were recruited from the Psychosocial Care Center. Visual sensitivity was compared between both SCZ groups and the SC group. Patients with SCZ who were chronic tobacco users presented lower visual sensitivity for chromatic (p < 0.001) and achromatic (p < 0.001) stimuli compared with the other groups. Our findings highlight the need to evaluate possible addictive behavior in patients with SCZ, which may contribute to public policies that seek to improve the quality of life of SCZ patients and their families.
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Affiliation(s)
- Thiago M. P. Fernandes
- Department of Psychology, Federal University of Paraiba, João Pessoa, Brazil
- Perception, Neuroscience and Behavior Laboratory, Federal University of Paraiba, João Pessoa, Brazil
| | - Michael J. Oliveira de Andrade
- Department of Psychology, Federal University of Paraiba, João Pessoa, Brazil
- Perception, Neuroscience and Behavior Laboratory, Federal University of Paraiba, João Pessoa, Brazil
| | - Jessica B. Santana
- Department of Psychology, Federal University of Paraiba, João Pessoa, Brazil
- Perception, Neuroscience and Behavior Laboratory, Federal University of Paraiba, João Pessoa, Brazil
| | | | - Natanael A. dos Santos
- Department of Psychology, Federal University of Paraiba, João Pessoa, Brazil
- Perception, Neuroscience and Behavior Laboratory, Federal University of Paraiba, João Pessoa, Brazil
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15
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Spatiochromatic Interactions between Individual Cone Photoreceptors in the Human Retina. J Neurosci 2017; 37:9498-9509. [PMID: 28871030 DOI: 10.1523/jneurosci.0529-17.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 07/19/2017] [Accepted: 08/17/2017] [Indexed: 11/21/2022] Open
Abstract
A remarkable feature of human vision is that the retina and brain have evolved circuitry to extract useful spatial and spectral information from signals originating in a photoreceptor mosaic with trichromatic constituents that vary widely in their relative numbers and local spatial configurations. A critical early transformation applied to cone signals is horizontal-cell-mediated lateral inhibition, which imparts a spatially antagonistic surround to individual cone receptive fields, a signature inherited by downstream neurons and implicated in color signaling. In the peripheral retina, the functional connectivity of cone inputs to the circuitry that mediates lateral inhibition is not cone-type specific, but whether these wiring schemes are maintained closer to the fovea remains unsettled, in part because central retinal anatomy is not easily amenable to direct physiological assessment. Here, we demonstrate how the precise topography of the long (L)-, middle (M)-, and short (S)-wavelength-sensitive cones in the human parafovea (1.5° eccentricity) shapes perceptual sensitivity. We used adaptive optics microstimulation to measure psychophysical detection thresholds from individual cones with spectral types that had been classified independently by absorptance imaging. Measured against chromatic adapting backgrounds, the sensitivities of L and M cones were, on average, receptor-type specific, but individual cone thresholds varied systematically with the number of preferentially activated cones in the immediate neighborhood. The spatial and spectral patterns of these interactions suggest that interneurons mediating lateral inhibition in the central retina, likely horizontal cells, establish functional connections with L and M cones indiscriminately, implying that the cone-selective circuitry supporting red-green color vision emerges after the first retinal synapse.SIGNIFICANCE STATEMENT We present evidence for spatially antagonistic interactions between individual, spectrally typed cones in the central retina of human observers using adaptive optics. Using chromatic adapting fields to modulate the relative steady-state activity of long (L)- and middle (M)-wavelength-sensitive cones, we found that single-cone detection thresholds varied predictably with the spectral demographics of the surrounding cones. The spatial scale and spectral pattern of these photoreceptor interactions were consistent with lateral inhibition mediated by retinal horizontal cells that receive nonselective input from L and M cones. These results demonstrate a clear link between the neural architecture of the visual system inputs-cone photoreceptors-and visual perception and have implications for the neural locus of the cone-specific circuitry supporting color vision.
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Zhou X, Pardue MT, Iuvone PM, Qu J. Dopamine signaling and myopia development: What are the key challenges. Prog Retin Eye Res 2017; 61:60-71. [PMID: 28602573 DOI: 10.1016/j.preteyeres.2017.06.003] [Citation(s) in RCA: 182] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 05/23/2017] [Accepted: 06/05/2017] [Indexed: 01/11/2023]
Abstract
In the face of an "epidemic" increase in myopia over the last decades and myopia prevalence predicted to reach 2.5 billion people by the end of this decade, there is an urgent need to develop effective and safe therapeutic interventions to slow down this "myopia booming" and prevent myopia-related complications and vision loss. Dopamine (DA) is an important neurotransmitter in the retina and mediates diverse functions including retina development, visual signaling, and refractive development. Inspired by the convergence of epidemiological and animal studies in support of the inverse relationship between outdoor activity and risk of developing myopia and by the close biological relationship between light exposure and dopamine release/signaling, we felt it is timely and important to critically review the role of DA in myopia development. This review will revisit several key points of evidence for and against DA mediating light control of myopia: 1) the causal role of extracellular retinal DA levels, 2) the mechanism and action of dopamine D1 and D2 receptors and 3) the roles of cellular/circuit retinal pathways. We examine the experiments that show causation by altering DA, DA receptors and visual pathways using pharmacological, transgenic, or visual environment approaches. Furthermore, we critically evaluate the safety issues of a DA-based treatment strategy and some approaches to address these issues. The review identifies the key questions and challenges in translating basic knowledge on DA signaling and myopia from animal studies into effective pharmacological treatments for myopia in children.
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Affiliation(s)
- Xiangtian Zhou
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, 270 Xueyuan Road, Wenzhou, Zhejiang 325003, China; State Key Laboratory of Ophthalmology, Optometry and Vision Science. 270 Xueyuan Road, Wenzhou, Zhejiang, 325003, China
| | - Machelle T Pardue
- Department of Biomedical Engineering, Georgia Institute of Technology, 313 Ferst Dr, Atlanta, GA 30332, United States; Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, 1670 Clairmont Rd, Decatur, GA 30033, United States
| | - P Michael Iuvone
- Department of Ophthalmology, Emory University School of Medicine, 1365B Clifton Rd NE, Atlanta, GA 30322, United States; Department of Pharmacology, Emory University School of Medicine, 1365B Clifton Rd NE, Atlanta, GA 30322, United States
| | - Jia Qu
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, 270 Xueyuan Road, Wenzhou, Zhejiang 325003, China; State Key Laboratory of Ophthalmology, Optometry and Vision Science. 270 Xueyuan Road, Wenzhou, Zhejiang, 325003, China.
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17
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Liu X, Grove JCR, Hirano AA, Brecha NC, Barnes S. Dopamine D1 receptor modulation of calcium channel currents in horizontal cells of mouse retina. J Neurophysiol 2016; 116:686-97. [PMID: 27193322 DOI: 10.1152/jn.00990.2015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 05/12/2016] [Indexed: 12/22/2022] Open
Abstract
Horizontal cells form the first laterally interacting network of inhibitory interneurons in the retina. Dopamine released onto horizontal cells under photic and circadian control modulates horizontal cell function. Using isolated, identified horizontal cells from a connexin-57-iCre × ROSA26-tdTomato transgenic mouse line, we investigated dopaminergic modulation of calcium channel currents (ICa) with whole cell patch-clamp techniques. Dopamine (10 μM) blocked 27% of steady-state ICa, an action blunted to 9% in the presence of the L-type Ca channel blocker verapamil (50 μM). The dopamine type 1 receptor (D1R) agonist SKF38393 (20 μM) inhibited ICa by 24%. The D1R antagonist SCH23390 (20 μM) reduced dopamine and SKF38393 inhibition. Dopamine slowed ICa activation, blocking ICa by 38% early in a voltage step. Enhanced early inhibition of ICa was eliminated by applying voltage prepulses to +120 mV for 100 ms, increasing ICa by 31% and 11% for early and steady-state currents, respectively. Voltage-dependent facilitation of ICa and block of dopamine inhibition after preincubation with a Gβγ-blocking peptide suggested involvement of Gβγ proteins in the D1R-mediated modulation. When the G protein activator guanosine 5'-O-(3-thiotriphosphate) (GTPγS) was added intracellularly, ICa was smaller and showed the same slowed kinetics seen during D1R activation. With GTPγS in the pipette, additional block of ICa by dopamine was only 6%. Strong depolarizing voltage prepulses restored the GTPγS-reduced early ICa amplitude by 36% and steady-state ICa amplitude by 3%. These results suggest that dopaminergic inhibition of ICa via D1Rs is primarily mediated through the action of Gβγ proteins in horizontal cells.
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Affiliation(s)
- Xue Liu
- Biomaterials and Live Cell Imaging Institute, Chongqing University of Science and Technology, Chongqing, People's Republic of China; Department of Neurobiology and Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, California
| | - James C R Grove
- Department of Neurobiology and Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Arlene A Hirano
- Department of Neurobiology and Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, California; Department of Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; and
| | - Nicholas C Brecha
- Department of Neurobiology and Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, California; Department of Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; and
| | - Steven Barnes
- Department of Neurobiology and Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, California; Department of Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; and Department of Physiology and Biophysics and Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada
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18
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Qiao M, Sanes JR. Genetic Method for Labeling Electrically Coupled Cells: Application to Retina. Front Mol Neurosci 2016; 8:81. [PMID: 26778956 PMCID: PMC4703850 DOI: 10.3389/fnmol.2015.00081] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 12/11/2015] [Indexed: 01/08/2023] Open
Abstract
Understanding how the nervous system functions requires mapping synaptic connections between neurons. Several methods are available for imaging neurons connected by chemical synapses, but few enable marking neurons connected by electrical synapses. Here, we demonstrate that a peptide transporter, Pept2, can be used for this purpose. Pept2 transports a gap junction-permeable fluorophore-coupled dipeptide, beta-alanine-lysine-N-7-amino-4-methyl coumarin-3-acid (βALA). Cre-dependent expression of pept2 in specific neurons followed by incubation in βALA labeled electrically coupled synaptic partners. Using this method, we analyze light-dependent modulation of electrical connectivity among retinal horizontal cells.
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Affiliation(s)
- Mu Qiao
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge MA, USA
| | - Joshua R Sanes
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge MA, USA
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19
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Ho T, Jobling AI, Greferath U, Chuang T, Ramesh A, Fletcher EL, Vessey KA. Vesicular expression and release of ATP from dopaminergic neurons of the mouse retina and midbrain. Front Cell Neurosci 2015; 9:389. [PMID: 26500494 PMCID: PMC4593860 DOI: 10.3389/fncel.2015.00389] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 09/17/2015] [Indexed: 12/20/2022] Open
Abstract
Vesicular nucleotide transporter (VNUT) is required for active accumulation of adenosine tri-phosphate (ATP) into vesicles for purinergic neurotransmission, however, the cell types that express VNUT in the central nervous system remain unknown. This study characterized VNUT expression within the mammalian retina and brain and assessed a possible functional role in purinergic signaling. Two native isoforms of VNUT were detected in mouse retina and brain based on RNA transcript and protein analysis. Using immunohistochemistry, VNUT was found to co-localize with tyrosine hydroxylase (TH) positive, dopaminergic (DA) neurons of the substantia nigra and ventral tegmental area, however, VNUT expression in extranigral non-DA neurons was also observed. In the retina, VNUT labeling was found to co-localize solely with TH-positive DA-cells. In the outer retina, VNUT-positive interplexiform cell processes were in close contact with horizontal cells and cone photoreceptor terminals, which are known to express P2 purinergic-receptors. In order to assess function, dissociated retinal neurons were loaded with fluorescent ATP markers (Quinacrine or Mant-ATP) and the DA marker FFN102, co-labeled with a VNUT antibody and imaged in real time. Fluorescent ATP markers and FFN102 puncta were found to co-localize in VNUT positive neurons and upon stimulation with high potassium, ATP marker fluorescence at the cell membrane was reduced. This response was blocked in the presence of cadmium. These data suggest DA neurons co-release ATP via calcium dependent exocytosis and in the retina this may modulate the visual response by activating purine receptors on closely associated neurons.
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Affiliation(s)
- Tracy Ho
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne Parkville, VIC, Australia
| | - Andrew I Jobling
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne Parkville, VIC, Australia
| | - Ursula Greferath
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne Parkville, VIC, Australia
| | - Trinette Chuang
- Polyclonal Antibody Development, R&D Antibody Development, EMD Millipore Temecula, CA, USA
| | - Archana Ramesh
- Polyclonal Antibody Development, R&D Antibody Development, EMD Millipore Temecula, CA, USA
| | - Erica L Fletcher
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne Parkville, VIC, Australia
| | - Kirstan A Vessey
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne Parkville, VIC, Australia
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20
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Nagaya M, Ueno S, Kominami T, Nakanishi A, Koyasu T, Kondo M, Furukawa T, Terasaki H. Pikachurin Protein Required for Increase of Cone Electroretinogram B-Wave during Light Adaptation. PLoS One 2015; 10:e0128921. [PMID: 26091521 PMCID: PMC4475018 DOI: 10.1371/journal.pone.0128921] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 05/01/2015] [Indexed: 11/18/2022] Open
Abstract
In normal eyes, the amplitude of the b-wave of the photopic ERGs increases during light adaptation, but the mechanism causing this increase has not been fully determined. The purpose of this study was to evaluate the contribution of receptoral and post-receptoral components of the retina to this phenomenon. To accomplish this, we examined the ERGs during light adaptation in Pikachurin null-mutant (Pika -/-) mice, which have a misalignment of the bipolar cell dendritic tips to the photoreceptor ribbon synapses. After dark-adaptation, photopic ERGs were recorded from Pika -/- and wild type (WT) mice during the first 9 minutes of light adaptation. In some of the mice, post-receptoral components were blocked pharmacologically. The photopic b-waves of WT mice increased by 50% during the 9 min of light adaptation as previously reported. On the other hand, the b-waves of the Pika -/- mice decreased by 20% during the same time period. After blocking post-receptoral components, the b-waves were abolished from the WT mice, and the ERGs resembled those of the Pika -/- mice. The extracted post-receptoral component increased during light adaptation in the WT mice, but decreased for the first 3 minutes to a plateau in Pika -/- mice. We conclude that the normal synaptic connection between photoreceptor and retinal ON bipolar cells, which is controlled by pikachurin, is required for the ERGs to increase during light-adaptation. The contributions of post-receptoral components are essential for the photopic b-wave increase during the light adaptation.
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Affiliation(s)
- Masatoshi Nagaya
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
| | - Shinji Ueno
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
- * E-mail:
| | - Taro Kominami
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
| | - Ayami Nakanishi
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
| | - Toshiyuki Koyasu
- Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Mie, Japan
| | - Mineo Kondo
- Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Mie, Japan
| | - Takahisa Furukawa
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Suita, Osaka, Japan
- JST, CREST, Suita, Osaka, Japan
| | - Hiroko Terasaki
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
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21
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Elevated intraocular pressure decreases response sensitivity of inner retinal neurons in experimental glaucoma mice. Proc Natl Acad Sci U S A 2015; 112:2593-8. [PMID: 25675503 DOI: 10.1073/pnas.1419921112] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Glaucoma is the second leading cause of blindness in the United States and the world, characterized by progressive degeneration of the optic nerve and retinal ganglion cells (RGCs). Glaucoma patients exhibit an early diffuse loss of retinal sensitivity followed by focal loss of RGCs in sectored patterns. Recent evidence has suggested that this early sensitivity loss may be associated with dysfunctions in the inner retina, but detailed cellular and synaptic mechanisms underlying such sensitivity changes are largely unknown. In this study, we use whole-cell voltage-clamp techniques to analyze light responses of individual bipolar cells (BCs), AII amacrine cells (AIIACs), and ON and sustained OFF alpha-ganglion cells (ONαGCs and sOFFαGCs) in dark-adapted mouse retinas with elevated intraocular pressure (IOP). We present evidence showing that elevated IOP suppresses the rod ON BC inputs to AIIACs, resulting in less sensitive AIIACs, which alter AIIAC inputs to ONαGCs via the AIIAC→cone ON BC→ONαGC pathway, resulting in lower ONαGC sensitivity. The altered AIIAC response also reduces sOFFαGC sensitivity via the AIIAC→sOFFαGC chemical synapses. These sensitivity decreases in αGCs and AIIACs were found in mice with elevated IOP for 3-7 wk, a stage when little RGC or optic nerve degeneration was observed. Our finding that elevated IOP alters neuronal function in the inner retina before irreversible structural damage occurs provides useful information for developing new diagnostic tools and treatments for glaucoma in human patients.
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22
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Jastrow H, Yarwood A, Majorovits E, Harris JR. Tomographic reconstruction reveals the morphology of a unique cellular organelle, the aggregated macrotubules (Macrotubuli aggregati) of human retinal horizontal cells. Tissue Cell 2015; 47:186-97. [PMID: 25660563 DOI: 10.1016/j.tice.2014.12.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 12/19/2014] [Accepted: 12/19/2014] [Indexed: 12/24/2022]
Abstract
Horizontal cells of the human retina contain unique tubular organelles that have a diameter which is about 10 times larger than that of microtubules (~230 nm). These macrotubuli in most cases form regular aggregates. Therefore we propose to introduce them as Macrotubuli aggregati in the Terminologia histologica. Tomographic investigation of the structures revealed that the walls of the tubules most probably consist of intermediate filaments running nearly parallel to each other and show somewhat regularly attached ribosomes on their inner and also outer surface. About 2% of the organelles exhibit double- to multiple layered walls and less than 1% resemble large scrolls. The tubules may extend 10 to over 20 μm in the cytoplasm and are also encountered in soma-near processes extending into the outer plexiform layer. It remains unclear why these structures are only present in humans and few other species and why almost only in horizontal cells. Speculations on possible functions are discussed.
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Affiliation(s)
- Holger Jastrow
- IMCES Electron Microscopy Unit, University Hospital, University Duisburg-Essen, Germany.
| | | | | | - J Robin Harris
- Institute of Cell and Molecular Biosciences, Newcastle University, Newcastle-upon-Tyne NE2 4HH, United Kingdom; Institute of Zoology, University of Mainz, Becherweg 12, 55099 Mainz, Germany.
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23
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Tian N, Xu HP, Wang P. Dopamine D2 receptors preferentially regulate the development of light responses of the inner retina. Eur J Neurosci 2014; 41:17-30. [PMID: 25393815 DOI: 10.1111/ejn.12783] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 09/25/2014] [Accepted: 10/13/2014] [Indexed: 01/14/2023]
Abstract
Retinal light responsiveness measured via electroretinography undergoes developmental modulation, and is thought to be critically regulated by both visual experience and dopamine. The primary goal of this study was to determine whether dopamine D2 receptors regulate the visual experience-dependent functional development of the retina. Accordingly, we recorded electroretinograms from wild-type mice and mice with a genetic deletion of the gene that encodes the D2 receptor raised under normal cyclic light conditions and constant darkness. Our results demonstrate that D2 receptor mutation preferentially increases the amplitude of the inner retinal light responses evoked by high-intensity light measured as oscillatory potentials in adult mice. During postnatal development, all three major components of electroretinograms, i.e. a-waves, b-waves, and oscillatory potentials, increase with age. Comparatively, D2 receptor mutation preferentially reduces the age-dependent increase in b-waves evoked by low-intensity light. Light deprivation from birth reduces b-wave amplitudes and completely abolishes the increased amplitude of oscillatory potentials of D2 receptor mutants. Taken together, these results demonstrate that D2 receptors play an important role in the activity-dependent functional development of the mouse retina.
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Affiliation(s)
- Ning Tian
- Department of Ophthalmology and Visual Science, University of Utah School of Medicine, Salt Lake City, UT, 84132, USA
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24
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Popova E. Role of dopamine in distal retina. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2014; 200:333-58. [PMID: 24728309 DOI: 10.1007/s00359-014-0906-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 03/24/2014] [Accepted: 03/25/2014] [Indexed: 01/11/2023]
Abstract
Dopamine is the most abundant catecholamine in the vertebrate retina. Despite the description of retinal dopaminergic cells three decades ago, many aspects of their function in the retina remain unclear. There is no consensus among the authors about the stimulus conditions for dopamine release (darkness, steady or flickering light) as well as about its action upon the various types of retinal cells. Many contradictory results exist concerning the dopamine effect on the gross electrical activity of the retina [reflected in electroretinogram (ERG)] and the receptors involved in its action. This review summarized current knowledge about the types of the dopaminergic neurons and receptors in the retina as well as the effects of dopamine receptor agonists and antagonists on the light responses of photoreceptors, horizontal and bipolar cells in both nonmammalian and mammalian retina. Special focus of interest concerns their effects upon the diffuse ERG as a useful tool for assessment of the overall function of the distal retina. An attempt is made to reveal some differences between the dopamine actions upon the activity of the ON versus OFF channel in the distal retina. The author has included her own results demonstrating such differences.
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Affiliation(s)
- E Popova
- Department of Physiology, Medical Faculty, Medical University, 1431, Sofia, Bulgaria,
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25
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Márquez BT, Krahe R, Chacron MJ. Neuromodulation of early electrosensory processing in gymnotiform weakly electric fish. ACTA ACUST UNITED AC 2014; 216:2442-50. [PMID: 23761469 DOI: 10.1242/jeb.082370] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Sensory neurons continually adapt their processing properties in response to changes in the sensory environment or the brain's internal state. Neuromodulators are thought to mediate such adaptation through a variety of receptors and their action has been implicated in processes such as attention, learning and memory, aggression, reproductive behaviour and state-dependent mechanisms. Here, we review recent work on neuromodulation of electrosensory processing by acetylcholine and serotonin in the weakly electric fish Apteronotus leptorhynchus. Specifically, our review focuses on how experimental application of these neuromodulators alters excitability and responses to sensory input of pyramidal cells within the hindbrain electrosensory lateral line lobe. We then discuss current hypotheses on the functional roles of these two neuromodulatory pathways in regulating electrosensory processing at the organismal level and the need for identifying the natural behavioural conditions that activate these pathways.
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Affiliation(s)
- Brenda Toscano Márquez
- Department of Biology, McGill University, 1205 Docteur Penfield, Montreal, QC, Canada, H3A 1B1
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26
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He Q, Xu HP, Wang P, Tian N. Dopamine D1 receptors regulate the light dependent development of retinal synaptic responses. PLoS One 2013; 8:e79625. [PMID: 24260267 PMCID: PMC3834122 DOI: 10.1371/journal.pone.0079625] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 10/02/2013] [Indexed: 12/30/2022] Open
Abstract
Retinal synaptic connections and function are developmentally regulated. Retinal synaptic activity plays critical roles in the development of retinal synaptic circuitry. Dopamine receptors have been thought to play important roles in the activity-dependent synaptic plasticity in central nervous system. The primary goal of this study is to determine whether dopamine D1 receptor regulates the activity-dependent development of retinal light responsiveness. Accordingly, we recorded electroretinogram from wild type mice and mice with genetic deletion of D1 dopamine receptor (D1-/- mice) raised under cyclic light conditions and constant darkness. Our results demonstrated that D1-/- mice have reduced amplitudes of all three major components of electroretinogram in adulthood. When the relative strength of the responses is considered, the D1-/- mice have selective reduction of the amplitudes of a-wave and oscillatory potentials evoked by low-intermediate intensities of lights. During postnatal development, D1-/- mice have increased amplitude of b-wave at the time of eye-opening but reduced developmental increase of the amplitude of b-wave after eye opening. Light deprivation from birth significantly reduced the amplitudes of b-wave and oscillatory potentials, increased the outer retinal light response gain and altered the light response kinetics of both a- and b-waves of wild type mice. In D1-/- mice, the effect of dark rearing on the amplitude of oscillatory potentials was diminished and dark rearing induced effects on the response gain of outer retina and the kinetics of a-wave were reversed. These results demonstrated roles of dopamine D1 receptor in the activity-dependent functional development of mouse retina.
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Affiliation(s)
- Quanhua He
- College of Pharmacy, The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio, United States of America
| | - Hong-ping Xu
- Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Ping Wang
- Department of Ophthalmology and Visual Science, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Ning Tian
- Department of Ophthalmology and Visual Science, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
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Fleming RL, Silveira MS, Santos LE, Henze IP, Gardino PF, de Mello MCF, de Mello FG. Pituitary adenylyl cyclase-activating polypeptide receptor re-sensitization induces plastic changes in the dopaminergic phenotype in the mature avian retina. J Neurochem 2012; 124:621-31. [DOI: 10.1111/jnc.12121] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 12/04/2012] [Accepted: 12/04/2012] [Indexed: 01/08/2023]
Affiliation(s)
- Renata L. Fleming
- Laboratório de Neuroquímica; Instituto de Biofísica Carlos Chagas Filho; Universidade Federal do Rio de Janeiro; RJ Brazil
| | - Mariana S. Silveira
- Laboratório de Neurogênese; Instituto de Biofísica Carlos Chagas Filho; Universidade Federal do Rio de Janeiro; RJ Brazil
| | - Luís E. Santos
- Laboratório de Neuroquímica; Instituto de Biofísica Carlos Chagas Filho; Universidade Federal do Rio de Janeiro; RJ Brazil
| | - Isabela P. Henze
- Laboratório de Neuroquímica; Instituto de Biofísica Carlos Chagas Filho; Universidade Federal do Rio de Janeiro; RJ Brazil
| | - Patrícia F. Gardino
- Laboratório de Neurobiologia da Retina; Instituto de Biofísica Carlos Chagas Filho; Universidade Federal do Rio de Janeiro; RJ Brazil
| | - Maria Christina F. de Mello
- Laboratório de Neuroquímica; Instituto de Biofísica Carlos Chagas Filho; Universidade Federal do Rio de Janeiro; RJ Brazil
| | - Fernando G. de Mello
- Laboratório de Neuroquímica; Instituto de Biofísica Carlos Chagas Filho; Universidade Federal do Rio de Janeiro; RJ Brazil
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28
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Buldyrev I, Taylor WR. Inhibitory mechanisms that generate centre and surround properties in ON and OFF brisk-sustained ganglion cells in the rabbit retina. J Physiol 2012; 591:303-25. [PMID: 23045347 DOI: 10.1113/jphysiol.2012.243113] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Lateral inhibition produces the centre-surround organization of retinal receptive fields, in which inhibition driven by the mean luminance enhances the sensitivity of ganglion cells to spatial and temporal contrast. Surround inhibition is generated in both synaptic layers; however, the synaptic mechanisms within the inner plexiform layer are not well characterized within specific classes of retinal ganglion cell. Here, we compared the synaptic circuits generating concentric centre-surround receptive fields in ON and OFF brisk-sustained ganglion cells (BSGCs) in the rabbit retina. We first characterized the synaptic inputs to the centre of ON BSGCs, for comparison with previous results from OFF BSGCs. Similar to wide-field ganglion cells, the spatial extent of the excitatory centre and inhibitory surround was larger for the ON than the OFF BSGCs. The results indicate that the surrounds of ON and OFF BSGCs are generated in both the outer and the inner plexiform layers. The inner plexiform layer surround inhibition comprised GABAergic suppression of excitatory inputs from bipolar cells. However, ON and OFF BSGCs displayed notable differences. Surround suppression of excitatory inputs was weaker in ON than OFF BSGCs, and was mediated largely by GABA(C) receptors in ON BSGCs, and by both GABA(A) and GABA(C) receptors in OFF BSGCs. Large ON pathway-mediated glycinergic inputs to ON and OFF BSGCs also showed surround suppression, while much smaller GABAergic inputs showed weak, if any, spatial tuning. Unlike OFF BSGCs, which receive strong glycinergic crossover inhibition from the ON pathway, the ON BSGCs do not receive crossover inhibition from the OFF pathway. We compare and discuss possible roles for glycinergic inhibition in the two cell types.
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Affiliation(s)
- Ilya Buldyrev
- Casey Eye Institute, Department of Ophthalmology, School of Medicine, Oregon Health and Science University, Portland, OR 97239, USA
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29
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Thoreson WB, Mangel SC. Lateral interactions in the outer retina. Prog Retin Eye Res 2012; 31:407-41. [PMID: 22580106 PMCID: PMC3401171 DOI: 10.1016/j.preteyeres.2012.04.003] [Citation(s) in RCA: 136] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 03/05/2012] [Accepted: 03/09/2012] [Indexed: 10/28/2022]
Abstract
Lateral interactions in the outer retina, particularly negative feedback from horizontal cells to cones and direct feed-forward input from horizontal cells to bipolar cells, play a number of important roles in early visual processing, such as generating center-surround receptive fields that enhance spatial discrimination. These circuits may also contribute to post-receptoral light adaptation and the generation of color opponency. In this review, we examine the contributions of horizontal cell feedback and feed-forward pathways to early visual processing. We begin by reviewing the properties of bipolar cell receptive fields, especially with respect to modulation of the bipolar receptive field surround by the ambient light level and to the contribution of horizontal cells to the surround. We then review evidence for and against three proposed mechanisms for negative feedback from horizontal cells to cones: 1) GABA release by horizontal cells, 2) ephaptic modulation of the cone pedicle membrane potential generated by currents flowing through hemigap junctions in horizontal cell dendrites, and 3) modulation of cone calcium currents (I(Ca)) by changes in synaptic cleft proton levels. We also consider evidence for the presence of direct horizontal cell feed-forward input to bipolar cells and discuss a possible role for GABA at this synapse. We summarize proposed functions of horizontal cell feedback and feed-forward pathways. Finally, we examine the mechanisms and functions of two other forms of lateral interaction in the outer retina: negative feedback from horizontal cells to rods and positive feedback from horizontal cells to cones.
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Affiliation(s)
- Wallace B. Thoreson
- Departments of Ophthalmology & Visual Sciences and Pharmacology & Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198 USA
| | - Stuart C. Mangel
- Department of Neuroscience, The Ohio State University College of Medicine, Columbus, OH 43210 USA
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30
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Jackson CR, Ruan GX, Aseem F, Abey J, Gamble K, Stanwood G, Palmiter RD, Iuvone PM, McMahon DG. Retinal dopamine mediates multiple dimensions of light-adapted vision. J Neurosci 2012; 32:9359-68. [PMID: 22764243 PMCID: PMC3400466 DOI: 10.1523/jneurosci.0711-12.2012] [Citation(s) in RCA: 184] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 05/14/2012] [Accepted: 05/19/2012] [Indexed: 11/21/2022] Open
Abstract
Dopamine is a key neuromodulator in the retina and brain that supports motor, cognitive, and visual function. Here, we developed a mouse model on a C57 background in which expression of the rate-limiting enzyme for dopamine synthesis, tyrosine hydroxylase, is specifically disrupted in the retina. This model enabled assessment of the overall role of retinal dopamine in vision using electrophysiological (electroretinogram), psychophysical (optokinetic tracking), and pharmacological techniques. Significant disruptions were observed in high-resolution, light-adapted vision caused by specific deficits in light responses, contrast sensitivity, acuity, and circadian rhythms in this retinal dopamine-depleted mouse model. These global effects of retinal dopamine on vision are driven by the differential actions of dopamine D1 and D4 receptors on specific retinal functions and appear to be due to the ongoing bioavailability of dopamine rather than developmental effects. Together, our data indicate that dopamine is necessary for the circadian nature of light-adapted vision as well as optimal contrast detection and acuity.
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Affiliation(s)
- Chad R. Jackson
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
| | - Guo-Xiang Ruan
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
| | - Fazila Aseem
- Departments of Ophthalmology and Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Jane Abey
- Departments of Ophthalmology and Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Karen Gamble
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama-Birmingham, Birmingham, Alabama 35294-0017
| | - Greg Stanwood
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, and
| | - Richard D. Palmiter
- Howard Hughes Medical Institute and Department of Biochemistry, University of Washington, Seattle, Washington 98195
| | - P. Michael Iuvone
- Departments of Ophthalmology and Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Douglas G. McMahon
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235
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31
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Li H, Liu WZ, Liang PJ. Adaptation-dependent synchronous activity contributes to receptive field size change of bullfrog retinal ganglion cell. PLoS One 2012; 7:e34336. [PMID: 22479604 PMCID: PMC3313981 DOI: 10.1371/journal.pone.0034336] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 03/01/2012] [Indexed: 11/18/2022] Open
Abstract
Nearby retinal ganglion cells of similar functional subtype have a tendency to discharge spikes in synchrony. The synchronized activity is involved in encoding some aspects of visual input. On the other hand, neurons always continuously adjust their activities in adaptation to some features of visual stimulation, including mean ambient light, contrast level, etc. Previous studies on adaptation were primarily focused on single neuronal activity, however, it is also intriguing to investigate the adaptation process in population neuronal activities. In the present study, by using multi-electrode recording system, we simultaneously recorded spike discharges from a group of dimming detectors (OFF-sustained type ganglion cells) in bullfrog retina. The changes in receptive field properties and synchronization strength during contrast adaptation were analyzed. It was found that, when perfused using normal Ringer's solution, single neuronal receptive field size was reduced during contrast adaptation, which was accompanied by weakening in synchronization strength between adjacent neurons' activities. When dopamine (1 µM) was applied, the adaptation-related receptive field area shrinkage and synchronization weakening were both eliminated. The activation of D1 receptor was involved in the adaptation-related modulation of synchronization and receptive field. Our results thus suggest that the size of single neuron's receptive field is positively related to the strength of its synchronized activity with its neighboring neurons, and the dopaminergic pathway is responsible for the modulation of receptive field property and synchronous activity of the ganglion cells during the adaptation process.
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Affiliation(s)
| | | | - Pei-Ji Liang
- Department of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
- * E-mail:
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32
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Fox DA, Hamilton WR, Johnson JE, Xiao W, Chaney S, Mukherjee S, Miller DB, O'Callaghan JP. Gestational lead exposure selectively decreases retinal dopamine amacrine cells and dopamine content in adult mice. Toxicol Appl Pharmacol 2011; 256:258-67. [PMID: 21703292 DOI: 10.1016/j.taap.2011.05.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Revised: 05/30/2011] [Accepted: 05/31/2011] [Indexed: 10/18/2022]
Abstract
Gestational lead exposure (GLE) produces supernormal scotopic electroretinograms (ERG) in children, monkeys and rats, and a novel retinal phenotype characterized by an increased number of rod photoreceptors and bipolar cells in adult mice and rats. Since the loss of dopaminergic amacrine cells (DA ACs) in GLE monkeys and rats contributes to supernormal ERGs, the retinal DA system was analyzed in mice following GLE. C57BL/6 female mice were exposed to low (27 ppm), moderate (55 ppm) or high (109 ppm) lead throughout gestation and until postnatal day 10 (PN10). Blood [Pb] in control, low-, moderate- and high-dose GLE was ≤ 1, ≤ 10, ~25 and ~40 μg/dL, respectively, on PN10 and by PN30 all were ≤ 1 μg/dL. At PN60, confocal-stereology studies used vertical sections and wholemounts to characterize tyrosine hydroxylase (TH) expression and the number of DA and other ACs. GLE dose-dependently and selectively decreased the number of TH-immunoreactive (IR) DA ACs and their synaptic plexus without affecting GABAergic, glycinergic or cholinergic ACs. Immunoblots and confocal revealed dose-dependent decreases in retinal TH protein expression and content, although monoamine oxidase-A protein and gene expression were unchanged. High-pressure liquid chromatography showed that GLE dose-dependently decreased retinal DA content, its metabolites and DA utilization/release. The mechanism of DA selective vulnerability is unknown. However, a GLE-induced loss/dysfunction of DA ACs during development could increase the number of rods and bipolar cells since DA helps regulate neuronal proliferation, whereas during adulthood it could produce ERG supernormality as well as altered circadian rhythms, dark/light adaptation and spatial contrast sensitivity.
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Affiliation(s)
- Donald A Fox
- College of Optometry, University of Houston, Houston, TX 77204-2020, USA.
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