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Quitt PR, Reese S, Fischer A, Bertram S, Tauber C, Matiasek L. Assessment of menace response in neurologically and ophthalmologically healthy cats. J Feline Med Surg 2018; 21:537-543. [DOI: 10.1177/1098612x18788890] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Objectives Assessment and interpretation of menace response (MeR) in cats can be challenging. The prevalence of abnormal MeR in healthy cats is unknown. The aim of this study was to prospectively evaluate MeR in visually healthy cats. Methods Fifty cats without history or clinical evidence of neurological or ophthalmological disease were assessed by two examiners: standing behind the cat (mode A), in front of the cat (mode B), and in front of the cat, covering the contralateral eye (mode C). MeR was scored from 1–5 (absent, weak, moderate, strong, complete). Examination modes were compared concerning presence and score (descriptive statistic, 95% confidence interval, χ2 test). This was compared to a three-level scoring system (negative, reduced, positive). Score reproducibility between the two examiners was assessed (Cohen’s kappa [κ] test). Video footage allowed self-re-evaluation and evaluation of the second examiner (κ analysis). Learning/tiring effect (McNemar test), influence of age, body weight (Spearman’s rho test), skull type (χ2 test) and being an indoor or outdoor cat (Mann–Whitney U-test) were evaluated. Results MeR was always elicited with at least one technique. Comparable results were obtained with the five- and three-level scoring systems. Mode A achieved strong/complete (positive) MeR in 84.5%, mode B in 82% and mode C in 60%. Exact score reproducibility between the two examiners was slight to fair (κ = 0.208–0.281). Intrarater agreement for video self-assessment (κ = 0.544–0.639), as well as inter-rater agreement (extrinsic video assessment), was moderate to substantial (κ = 0.584–0.645). No learning/tiring effect ( P = 0.530) or association with body weight ( P = 0.897), age ( P = 0.724), skull type ( P >0.05) and being an indoor/outdoor cat ( P = 0.511) were evident. Conclusions and relevance The majority of visually healthy cats revealed a strong/complete MeR when the contralateral eye remained uncovered, but 40% failed when the contralateral eye was covered. The most reliable examination mode was achieved standing behind the cat.
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Affiliation(s)
- Pia R Quitt
- Centre for Clinical Veterinary Medicine, Faculty of Veterinary Medicine, LMU Munich, Munich, Germany
| | - Sven Reese
- Centre for Clinical Veterinary Medicine, Faculty of Veterinary Medicine, LMU Munich, Munich, Germany
| | - Andrea Fischer
- Centre for Clinical Veterinary Medicine, Faculty of Veterinary Medicine, LMU Munich, Munich, Germany
| | - Simon Bertram
- Centre for Clinical Veterinary Medicine, Faculty of Veterinary Medicine, LMU Munich, Munich, Germany
- Department of Clinical Science and Services, Veterinary Neurology and Neurosurgery, Royal Veterinary College, London, UK
| | - Clara Tauber
- Centre for Clinical Veterinary Medicine, Faculty of Veterinary Medicine, LMU Munich, Munich, Germany
| | - Lara Matiasek
- Centre for Clinical Veterinary Medicine, Faculty of Veterinary Medicine, LMU Munich, Munich, Germany
- Anicura Kleintierklinik Babenhausen GmbH, Babenhausen, Germany
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2
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Kwan WC, Mundinano IC, de Souza MJ, Lee SCS, Martin PR, Grünert U, Bourne JA. Unravelling the subcortical and retinal circuitry of the primate inferior pulvinar. J Comp Neurol 2018; 527:558-576. [PMID: 29292493 DOI: 10.1002/cne.24387] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 12/14/2017] [Accepted: 12/21/2017] [Indexed: 12/21/2022]
Abstract
The primate visual brain possesses a myriad of pathways, whereby visual information originating at the retina is transmitted to multiple subcortical areas in parallel, before being relayed onto the visual cortex. The dominant retinogeniculostriate pathway has been an area of extensive study, and Vivien Casagrande's work in examining the once overlooked koniocellular pathway of the lateral geniculate nucleus has generated interest in how alternate subcortical pathways can contribute to visual perception. Another subcortical visual relay center is the inferior pulvinar (PI), which has four subdivisions and numerous connections with other subcortical and cortical areas and is directly recipient of retinal afferents. The complexity of subcortical connections associated with the PI subdivisions has led to differing results from various groups. A particular challenge in determining the exact connectivity pattern has been in accurately targeting the subdivisions of the PI with neural tracers. Therefore, in the present study, we used a magnetic resonance imaging (MRI)-guided stereotaxic injection system to inject bidirectional tracers in the separate subdivisions of the PI, the superior layers of the superior colliculus, the retina, and the lateral geniculate nucleus. Our results have determined for the first time that the medial inferior pulvinar (PIm) is innervated by widefield retinal ganglion cells (RGCs), and this pathway is not a collateral branch of the geniculate and collicular projecting RGCs. Furthermore, our tracing data shows no evidence of collicular terminations in the PIm, which are confined to the centromedial and posterior PI.
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Affiliation(s)
- William C Kwan
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria, Australia
| | - Inaki-Carril Mundinano
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria, Australia
| | - Mitchell J de Souza
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria, Australia
| | - Sammy C S Lee
- Save Sight Institute and Department of Clinical Ophthalmology, The University of Sydney, Sydney, New South Wales, Australia.,Australian Research Council Centre of Excellence for Integrative Brain Function, Sydney Node, The University of Sydney, Sydney, New South Wales, Australia
| | - Paul R Martin
- Save Sight Institute and Department of Clinical Ophthalmology, The University of Sydney, Sydney, New South Wales, Australia.,Australian Research Council Centre of Excellence for Integrative Brain Function, Sydney Node, The University of Sydney, Sydney, New South Wales, Australia.,School of Medical Sciences, The University of Sydney, Sydney, New South Wales, Australia
| | - Ulrike Grünert
- Save Sight Institute and Department of Clinical Ophthalmology, The University of Sydney, Sydney, New South Wales, Australia.,Australian Research Council Centre of Excellence for Integrative Brain Function, Sydney Node, The University of Sydney, Sydney, New South Wales, Australia.,School of Medical Sciences, The University of Sydney, Sydney, New South Wales, Australia
| | - James A Bourne
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria, Australia
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Pickard GE, So KF, Pu M. Dorsal raphe nucleus projecting retinal ganglion cells: Why Y cells? Neurosci Biobehav Rev 2015; 57:118-31. [PMID: 26363667 PMCID: PMC4646079 DOI: 10.1016/j.neubiorev.2015.08.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 06/30/2015] [Accepted: 08/01/2015] [Indexed: 10/23/2022]
Abstract
Retinal ganglion Y (alpha) cells are found in retinas ranging from frogs to mice to primates. The highly conserved nature of the large, fast conducting retinal Y cell is a testament to its fundamental task, although precisely what this task is remained ill-defined. The recent discovery that Y-alpha retinal ganglion cells send axon collaterals to the serotonergic dorsal raphe nucleus (DRN) in addition to the lateral geniculate nucleus (LGN), medial interlaminar nucleus (MIN), pretectum and the superior colliculus (SC) has offered new insights into the important survival tasks performed by these cells with highly branched axons. We propose that in addition to its role in visual perception, the Y-alpha retinal ganglion cell provides concurrent signals via axon collaterals to the DRN, the major source of serotonergic afferents to the forebrain, to dramatically inhibit 5-HT activity during orientation or alerting/escape responses, which dis-facilitates ongoing tonic motor activity while dis-inhibiting sensory information processing throughout the visual system. The new data provide a fresh view of these evolutionarily old retinal ganglion cells.
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Affiliation(s)
- Gary E Pickard
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE, 68583, United States; Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE, 68198, United States; GHM Institute of CNS Regeneration, Jinan University, Guangzhou, China
| | - Kwok-Fai So
- Department of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China; Department of Ophthalmology, The University of Hong Kong, Hong Kong, China; GHM Institute of CNS Regeneration, Jinan University, Guangzhou, China; State Key Laboratory for Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, China.
| | - Mingliang Pu
- Department of Anatomy and Embryology, School of Basic Medical Sciences, Peking University, Beijing, China; Key Laboratory on Machine Perception (Ministry of Education), Peking University, Beijing, China; Key Laboratory for Visual Impairment and Restoration (Ministry of Education), Peking University, Beijing, China.
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4
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Hayashi T, Shimazawa M, Watabe H, Ose T, Inokuchi Y, Ito Y, Yamanaka H, Urayama SI, Watanabe Y, Hara H, Onoe H. Kinetics of neurodegeneration based on a risk-related biomarker in animal model of glaucoma. Mol Neurodegener 2013; 8:4. [PMID: 23331478 PMCID: PMC3599096 DOI: 10.1186/1750-1326-8-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 01/04/2013] [Indexed: 01/12/2023] Open
Abstract
Background Neurodegenerative diseases including Parkinson’s and Alzheimer’s diseases progress slowly and steadily over years or decades. They show significant between-subject variation in progress and clinical symptoms, which makes it difficult to predict the course of long-term disease progression with or without treatments. Recent technical advances in biomarkers have facilitated earlier, preclinical diagnoses of neurodegeneration by measuring or imaging molecules linked to pathogenesis. However, there is no established “biomarker model” by which one can quantitatively predict the progress of neurodegeneration. Here, we show predictability of a model with risk-based kinetics of neurodegeneration, whereby neurodegeneration proceeds as probabilistic events depending on the risk. Results We used five experimental glaucomatous animals, known for causality between the increased intraocular pressure (IOP) and neurodegeneration of visual pathways, and repeatedly measured IOP as well as white matter integrity by diffusion tensor imaging (DTI) as a biomarker of axonal degeneration. The IOP in the glaucomatous eye was significantly increased than in normal and was varied across time and animals; thus we tested whether this measurement is useful to predict kinetics of the integrity. Among four kinds of models of neurodegeneration, constant-rate, constant-risk, variable-risk and heterogeneity models, goodness of fit of the model and F-test for model selection showed that the time course of optic nerve integrity was best explained by the variable-risk model, wherein neurodegeneration kinetics is expressed in an exponential function across cumulative risk based on measured IOP. The heterogeneity model with stretched exponential decay function also fit well to the data, but without statistical superiority to the variable-risk model. The variable-risk model also predicted the number of viable axons in the optic nerve, as assessed by immunohistochemistry, which was also confirmed to be correlated with the pre-mortem integrity of the optic nerve. In addition, the variable-risk model identified the disintegrity in the higher-order visual pathways, known to underlie the transsynaptic degeneration in this disease. Conclusions These findings indicate that the variable-risk model, using a risk-related biomarker, could predict the spatiotemporal progression of neurodegeneration. This model, virtually equivalent to survival analysis, may allow us to estimate possible effect of neuroprotection in delaying progress of neurodegeneration.
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Affiliation(s)
- Takuya Hayashi
- Functional Probe Research Laboratory, RIKEN Center for Molecular Imaging Science, Kobe, Hyogo, 650-0047, Japan.
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Cao J, Naito J, Chen Y. Retrograde Tracing with Fluorescent Microspheres Reveals Bifurcating Projections from Central Retina to Tectum and Thalamus in Chicks. Anat Histol Embryol 2012; 41:306-10. [DOI: 10.1111/j.1439-0264.2011.01131.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 12/01/2011] [Indexed: 11/27/2022]
Affiliation(s)
- J. Cao
- Laboratory of Anatomy of Domestic Animal, College of Animal Medicine; China Agricultural University; Haidian; Beijing; 100193; China
| | - J. Naito
- Department of Animal Sciences, Faculty of Life and Environment Sciences; Teikyo University of Science and Technology; Uenohara; Yamanashi; 409-0193; Japan
| | - Y. Chen
- Laboratory of Anatomy of Domestic Animal, College of Animal Medicine; China Agricultural University; Haidian; Beijing; 100193; China
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Jordan TR, Fuggetta G, Paterson KB, Kurtev S, Xu M. An ERP assessment of hemispheric projections in foveal and extrafoveal word recognition. PLoS One 2011; 6:e23957. [PMID: 21935368 PMCID: PMC3174137 DOI: 10.1371/journal.pone.0023957] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 08/02/2011] [Indexed: 11/19/2022] Open
Abstract
Background The existence and function of unilateral hemispheric projections within foveal vision may substantially affect foveal word recognition. The purpose of this research was to reveal these projections and determine their functionality. Methodology Single words (and pseudowords) were presented to the left or right of fixation, entirely within either foveal or extrafoveal vision. To maximize the likelihood of unilateral projections for foveal displays, stimuli in foveal vision were presented away from the midline. The processing of stimuli in each location was assessed by combining behavioural measures (reaction times, accuracy) with on-line monitoring of hemispheric activity using event-related potentials recorded over each hemisphere, and carefully-controlled presentation procedures using an eye-tracker linked to a fixation-contingent display. Principal Findings Event-related potentials 100–150 ms and 150–200 ms after stimulus onset indicated that stimuli in extrafoveal and foveal locations were projected unilaterally to the hemisphere contralateral to the presentation hemifield with no concurrent projection to the ipsilateral hemisphere. These effects were similar for words and pseudowords, suggesting this early division occurred before word recognition. Indeed, event-related potentials revealed differences between words and pseudowords 300–350 ms after stimulus onset, for foveal and extrafoveal locations, indicating that word recognition had now occurred. However, these later event-related potentials also revealed that the hemispheric division observed previously was no longer present for foveal locations but remained for extrafoveal locations. These findings closely matched the behavioural finding that foveal locations produced similar performance each side of fixation but extrafoveal locations produced left-right asymmetries. Conclusions These findings indicate that an initial division in unilateral hemispheric projections occurs in foveal vision away from the midline but is not apparent, or functional, when foveal word recognition actually occurs. In contrast, the division in unilateral hemispheric projections that occurs in extrafoveal locations is still apparent, and is functional, when extrafoveal word recognition takes place.
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Affiliation(s)
- Timothy R Jordan
- Faculty of Medicine and Biological Sciences, University of Leicester, Leicester, United Kingdom.
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May PJ. The mammalian superior colliculus: laminar structure and connections. PROGRESS IN BRAIN RESEARCH 2006; 151:321-78. [PMID: 16221594 DOI: 10.1016/s0079-6123(05)51011-2] [Citation(s) in RCA: 443] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The superior colliculus is a laminated midbrain structure that acts as one of the centers organizing gaze movements. This review will concentrate on sensory and motor inputs to the superior colliculus, on its internal circuitry, and on its connections with other brainstem gaze centers, as well as its extensive outputs to those structures with which it is reciprocally connected. This will be done in the context of its laminar arrangement. Specifically, the superficial layers receive direct retinal input, and are primarily visual sensory in nature. They project upon the visual thalamus and pretectum to influence visual perception. These visual layers also project upon the deeper layers, which are both multimodal, and premotor in nature. Thus, the deep layers receive input from both somatosensory and auditory sources, as well as from the basal ganglia and cerebellum. Sensory, association, and motor areas of cerebral cortex provide another major source of collicular input, particularly in more encephalized species. For example, visual sensory cortex terminates superficially, while the eye fields target the deeper layers. The deeper layers are themselves the source of a major projection by way of the predorsal bundle which contributes collicular target information to the brainstem structures containing gaze-related burst neurons, and the spinal cord and medullary reticular formation regions that produce head turning.
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Affiliation(s)
- Paul J May
- Department of Anatomy, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA.
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8
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Kenigfest N, Rio JP, Belekhova M, Repérant J, Vesselkin N, Ward R. Pretectal and tectal afferents to the dorsal lateral geniculate nucleus of the turtle: An electron microscopic axon tracing and γ-aminobutyric acid immunocytochemical study. J Comp Neurol 2004; 475:107-27. [PMID: 15176088 DOI: 10.1002/cne.20159] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The pretectal and tectal projections to the dorsal lateral geniculate nucleus (GLd) of two species of turtle (Emys orbicularis and Testudo horsfieldi) were examined under the electron microscope by using axonal tracing techniques (horseradish peroxidase or biotinylated dextran amine) and postembedding gamma-aminobutyric acid (GABA) immunocytochemistry. After injection of tracer into the pretectum, two types of axon terminals were identified as those of pretectogeniculate pathways. Both contained pleomorphic synaptic vesicles and were more numerous in the inner part of the nucleus. They could be distinguished on the bases of size and shape of their synaptic vesicles, type of synaptic contact, and level of GABA immunoreactivity. One type had a higher density of immunolabeling and established symmetric synaptic contacts, whereas the other, less densely immunolabeled, made asymmetric synaptic contacts. In both cases, synaptic contacts were mainly with relay cells and occasionally with interneurons. We suggest that these two types of pretectogeniculate terminals originate in two separate pretectal nuclei. After injection of tracer into the optic tectum, a single population of GABA-immunonegative tracer-labeled terminals was identified as belonging to the tectogeniculate pathway. These were small, had smooth contours, contained very small round synaptic vesicles, and established asymmetric synaptic contacts with long active zones, predominantly with relay cells and less frequently with interneurons, in the inner part of the nucleus. In addition, a population of GABA-negative and occasionally GABA-positive terminals, labeled by tracer injected into either the pretectum or the tectum, was identified as retinal terminals; these were presumably labeled by the retrograde transport of tracer in collateral branches of visual fibers innervating both the GLd and the pretectum or tectum. Comparison of the present ultrastructural findings in turtles with those previously reported in mammals shows that the cytological features, synaptic morphology, and immunochemical properties of the pretectogeniculate and tectogeniculate terminals of both groups share many similarities. Nevertheless, the postsynaptic targets of these two categories of terminals display some pronounced differences between the two groups, which are discussed in terms of their possible functional significance.
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Affiliation(s)
- Natalia Kenigfest
- Muséum National d'Histoire Naturelle USM-0501, Bâtiment d'Anatomie Comparée, 55 Rue Buffon, 75005 Paris, France.
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Fite KV, Birkett MA, Smith A, Janusonis S, McLaughlin S. Retinal ganglion cells projecting to the dorsal raphe and lateral geniculate complex in Mongolian gerbils. Brain Res 2003; 973:146-50. [PMID: 12729964 DOI: 10.1016/s0006-8993(03)02549-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Injections of rhodamine-B into the dorsal raphe nucleus (DRN) and Fluoro-Gold into the lateral geniculate nucleus (LGN) revealed double-labeled retinal ganglion cells (DL RGCs) projecting to both nuclei. The soma-size distribution of DL RGCs was compared with three other distributions: DRN-projecting RGCs, LGN-projecting RGCs, and a large sample of RGCs labeled via the optic nerve with DiI. DL RGC soma diameters fell primarily within the mid-to-upper size range of all three distributions. DL RGCs may provide information to both nuclei concerning comparable aspects of light and visual stimulation via collateralized axons.
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Affiliation(s)
- Katherine V Fite
- Neuroscience and Behavior Program, Tobin Hall, University of Massachusetts, Amherst, MA 01003, USA.
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Abstract
The optic nerve is divided in four regions: intraocular, intraorbital, intracanalicular, and intracranial. The vertebrate retinal ganglion cells are classified by morphology, physiology and soma size. Species differences and similarities occur with retinal ganglion cells. Alpha retinal ganglion cells have large somata, large dendritic fields, large-diameter axons, and are most dense in the peripheral retina. Beta retinal ganglion cells have smaller diameter somata, smaller dendritic fields, small diameter axons, and predominate in the central retina. Gamma retinal ganglion cells are a heterogenous class of cells and have small diameter axons, and slow axon conduction velocities. The spatial distribution and organization of the retinal ganglion cells extends retinotopically through the nerve fiber layer, optic nerve, optic chiasm, optic tract, lateral geniculate nucleus, and visual cortex. The retinal nerve fiber layer thickness decreases from the optic disk toward the periphery of the retina. The retrobulbar optic nerve axon counts and axon density vary by species, with larger nerves having higher axon counts. Decussation of the optic nerve axons at the optic chiasm varies with 100% decussation in most birds and fish, 65% in cats, 75% in dogs, 80-90% in large animals, and 50% in primates. Centrifugal axons also occur in the optic nerve and may represent a method by which the brain can influence retinal activity.
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Affiliation(s)
- D.E. Brooks
- University of Florida, PO Box 100126, Gainesville, FL 32610, USA
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Tassinari G, Bentivoglio M, Chen S, Campara D. Overlapping ipsilateral and contralateral retinal projections to the lateral geniculate nucleus and superior colliculus in the cat: a retrograde triple labelling study. Brain Res Bull 1997; 43:127-39. [PMID: 9222525 DOI: 10.1016/s0361-9230(96)00215-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
To analyze the relative proportion and distribution of retinal ganglion cells projecting ipsilaterally and contralaterally in the cat, large injections of the fluorescent tracers Fluoro Gold, Fast Blue, and Diamidino Yellow were made in the main layers of the lateral geniculate nucleus (LGN) and superior colliculus (SC). One tracer was injected in both the LGN and SC on one side, and the other two tracers were injected contralaterally, in the LGN and SC, respectively; labelled ganglion cells were charted on retinal whole mounts. Ganglion cells labelled from the LGN and SC were highly intermingled in both the ipsilateral and contralateral retinae. The adopted combinations of tracers allowed the detection of cells double labelled from the SC and LGN, supporting the occurrence of branched retino-thalamic axons to the SC. About one-fourth of the ganglion cells labelled from the LGN and SC was located in the eye ipsilateral to the injection. Retrograde labelling from the ipsilateral side was almost entirely confined to the temporal hemiretina. In the contralateral eye, labelled cells were mainly concentrated in the nasal hemiretina, but more than 10% were also detected in the temporal half of the retina. In the latter area, cells displaying the entire range of sizes of the retinal ganglion cells, labelled from the contralateral LGN and SC, were found throughout the entire hemiretina. However, more than 50% of such "wrong" projecting cells were grouped in a strip of 2 mm closest to the nasotemporal division. Control experiments, in which the tracers injections were restricted to the rostral and dorsal portions of the LGN to avoid optic tract contamination, consistently confirmed the occurrence and distribution of the "wrong" projecting cells in the temporal hemiretina. Thus, these latter cells are not grouped in a central strip, where ganglion cells would have the same chance of projecting to the same or to the opposite side, and sparsely distributed in the temporal periphery, as previously believed. Instead, the present findings indicate that the retinal ganglion cells of origin of contralateral projections are distributed more in a continuum, with a naso-temporal gradient of density, across the temporal hemiretina.
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Affiliation(s)
- G Tassinari
- Dipartimento di Scienze Neurologiche e della Visione, Sezione di Fisiologia Umana, Verona, Italy
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Dong K, Qu T, Ahmed FA, Zhang L, Yamada K, Guison NG, Miller M, Yamadori T. Fluoro-Green and Fluoro-Red: two new fluorescent retrograde tracers with a number of unique properties. Brain Res 1996; 736:61-7. [PMID: 8930309 DOI: 10.1016/0006-8993(96)00654-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
As a means of improving nerve tract-tracing in the peripheral and central nervous systems we experimented with two (retrograde) fluorescent emulsions, which we have tentatively named Fluoro-Green (FGr) and Fluoro-Red (FRe), and which we believe possess the following seven advantages: (1) they show little diffusion beyond the injection site; (2) their excitation/emission characteristics allow their use in double-tracing experiments; (3) they do not 'leak' from labeled cells; (4) their fluorescence is presented as large granules in the cytoplasm and its processes; (5) the fluorescence lasts for a sufficiently long time to permit repeated observation; (6) they may be used in combination with a wide variety of other neuroanatomical tracing methods; (7) they are economical, non-toxic and easy to utilize.
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Affiliation(s)
- K Dong
- First Department of Anatomy, Kobe University School of Medicine, Japan
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Dong K, Qu T, Ahmed AK, Setsu T, Sugioka K, Yamadori T. Bifurcated projections of retinal ganglion cells bilaterally innervate the lateral geniculate nuclei in the cat. Brain Res 1995; 703:231-6. [PMID: 8719639 DOI: 10.1016/0006-8993(95)01190-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Cats were injected with the fluorescent retrograde tracers, Fluoro-Gold (FG) and Evans Blue (EB), into the left and right lateral geniculate nuclei (LGN), respectively. About 4.56% of the ganglion cells in the temporal retina were double-labeled by these dyes. 4.7% of these cells were of the large type, 30.3% were of the medium type, and 65% were classified as cells of the small type. These results indicate that members of all three ganglion cell size classes, mainly those of small type, bilaterally innervate the LGN via axonal bifurcation.
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Affiliation(s)
- K Dong
- First Department of Anatomy, Kobe University School of Medicine, Japan
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