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Ogut E, Kaya P, Karakas O, Yildiz E, Sozge I. Investigations into the anatomical location, physiological function, clinical implications, and significance of the nucleus of Perlia. Acta Neurol Belg 2024:10.1007/s13760-024-02533-w. [PMID: 38583111 DOI: 10.1007/s13760-024-02533-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 03/13/2024] [Indexed: 04/08/2024]
Abstract
BACKGROUND The article discusses the investigations into the nucleus of Perlia (NP), a spindle-shaped nucleus located in the dorsal aspect of the oculomotor complex. However, there is still debate over its exact location and function, with conflicting findings in nonhuman primates. Therefore, the current study aimed the describe the location, function, clinical and surgical implications of NP. METHODS A systematic review was conducted to identify studies related to the following MeSH terms: "perlia nucleus" OR "nucleus of "perlia" OR "convergence nucleus" OR "nucleus of convergence" OR "Perlia's nucleus". The search was conducted until September 2022. RESULTS The location of the NP has been consistently reported in various studies, with most describing it as situated ventral to the Edinger-Westphal nucleus (EW) and dorsomedial to the oculomotor complex. The incidence of the NP in humans has been reported to range from 9 to 40%. In primates, it was observed to be absent in 77% of midbrains, while well developed in 9%. It is also noted that the NP is not a single nucleus, but rather a group of nuclei that are interconnected and involved in the coordination of eye movements that contain parasympathetic neurons. CONCLUSIONS The study of the NP holds clinical implications for understanding the neural mechanisms underlying the irregularities in the pupillary light reflex, such as anisocoria or abnormal responses to light, diagnosis, and treatment of neurological disorders like Horner's syndrome, and management of eye movement disorders including one-and-a-half syndrome, vertical gaze palsy, skew deviation and ptosis. The current study also highlighted the limitations of previous studies, including variations in the reported prevalence of the NP, limitations of the histological techniques, and inconsistent findings across human and animal studies.
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Affiliation(s)
- Eren Ogut
- Faculty of Medicine, Department of Anatomy, Istanbul Medeniyet University, 34700, Istanbul, Türkiye.
| | - Pamirhan Kaya
- Faculty of Medicine, Medical Faculty Student, Bahçeşehir University, 34734, Istanbul, Türkiye
| | - Ozge Karakas
- Faculty of Medicine, Medical Faculty Student, Bahçeşehir University, 34734, Istanbul, Türkiye
| | - Edanur Yildiz
- Faculty of Medicine, Medical Faculty Student, Bahçeşehir University, 34734, Istanbul, Türkiye
| | - Ilgin Sozge
- Faculty of Medicine, Medical Faculty Student, Bahçeşehir University, 34734, Istanbul, Türkiye
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Novello M, Bosman LWJ, De Zeeuw CI. A Systematic Review of Direct Outputs from the Cerebellum to the Brainstem and Diencephalon in Mammals. CEREBELLUM (LONDON, ENGLAND) 2024; 23:210-239. [PMID: 36575348 PMCID: PMC10864519 DOI: 10.1007/s12311-022-01499-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/22/2022] [Indexed: 05/13/2023]
Abstract
The cerebellum is involved in many motor, autonomic and cognitive functions, and new tasks that have a cerebellar contribution are discovered on a regular basis. Simultaneously, our insight into the functional compartmentalization of the cerebellum has markedly improved. Additionally, studies on cerebellar output pathways have seen a renaissance due to the development of viral tracing techniques. To create an overview of the current state of our understanding of cerebellar efferents, we undertook a systematic review of all studies on monosynaptic projections from the cerebellum to the brainstem and the diencephalon in mammals. This revealed that important projections from the cerebellum, to the motor nuclei, cerebral cortex, and basal ganglia, are predominantly di- or polysynaptic, rather than monosynaptic. Strikingly, most target areas receive cerebellar input from all three cerebellar nuclei, showing a convergence of cerebellar information at the output level. Overall, there appeared to be a large level of agreement between studies on different species as well as on the use of different types of neural tracers, making the emerging picture of the cerebellar output areas a solid one. Finally, we discuss how this cerebellar output network is affected by a range of diseases and syndromes, with also non-cerebellar diseases having impact on cerebellar output areas.
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Affiliation(s)
- Manuele Novello
- Department of Neuroscience, Erasmus MC, Rotterdam, the Netherlands
| | | | - Chris I De Zeeuw
- Department of Neuroscience, Erasmus MC, Rotterdam, the Netherlands.
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences (KNAW), Amsterdam, the Netherlands.
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Takahashi M, Veale R. Pathways for Naturalistic Looking Behavior in Primate I: Behavioral Characteristics and Brainstem Circuits. Neuroscience 2023; 532:133-163. [PMID: 37776945 DOI: 10.1016/j.neuroscience.2023.09.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 09/09/2023] [Accepted: 09/18/2023] [Indexed: 10/02/2023]
Abstract
Organisms control their visual worlds by moving their eyes, heads, and bodies. This control of "gaze" or "looking" is key to survival and intelligence, but our investigation of the underlying neural mechanisms in natural conditions is hindered by technical limitations. Recent advances have enabled measurement of both brain and behavior in freely moving animals in complex environments, expanding on historical head-fixed laboratory investigations. We juxtapose looking behavior as traditionally measured in the laboratory against looking behavior in naturalistic conditions, finding that behavior changes when animals are free to move or when stimuli have depth or sound. We specifically focus on the brainstem circuits driving gaze shifts and gaze stabilization. The overarching goal of this review is to reconcile historical understanding of the differential neural circuits for different "classes" of gaze shift with two inconvenient truths. (1) "classes" of gaze behavior are artificial. (2) The neural circuits historically identified to control each "class" of behavior do not operate in isolation during natural behavior. Instead, multiple pathways combine adaptively and non-linearly depending on individual experience. While the neural circuits for reflexive and voluntary gaze behaviors traverse somewhat independent brainstem and spinal cord circuits, both can be modulated by feedback, meaning that most gaze behaviors are learned rather than hardcoded. Despite this flexibility, there are broadly enumerable neural pathways commonly adopted among primate gaze systems. Parallel pathways which carry simultaneous evolutionary and homeostatic drives converge in superior colliculus, a layered midbrain structure which integrates and relays these volitional signals to brainstem gaze-control circuits.
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Affiliation(s)
- Mayu Takahashi
- Department of Systems Neurophysiology, Graduate School of Medical and Dental, Sciences, Tokyo Medical and Dental University, Japan.
| | - Richard Veale
- Department of Neurobiology, Graduate School of Medicine, Kyoto University, Japan
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Chen ZL, Zhu SG, Liu RP, Ma LL, Cui J, Zeng GL, Zhang X, Wang JY, Huang SS. Isolated unilateral oculomotor palsy caused by pure midbrain infarction: a case report. Int J Neurosci 2023:1-4. [PMID: 37756126 DOI: 10.1080/00207454.2023.2264479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Accepted: 09/24/2023] [Indexed: 09/29/2023]
Abstract
Purpose: Multiple etiologies may cause oculomotor nerve palsies. Identification of different etiologies is very important for subsequent treatment. Midbrain infarction is a rare cause of oculomotor nerve palsy. Materials and methods: We herein present a case of isolated unilateral oculomotor paresis caused by pure midbrain infarction. Results: Her pupillary sphincter and inferior rectus muscles were selectively spared. The symptoms were completely relieved after two months of antiplatelet therapy. We proposed that fibers from Edinger-Westphal nucleus and inferior rectus nucleus do not course through the paramedian area of the midbrain. Conclusions: Our report adds to the understanding of fascicles arrangement in the midbrain.
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Affiliation(s)
- Zhu-Ling Chen
- Department of Neurology, Institute of Geriatric Neurology, the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Shi-Guo Zhu
- Department of Neurology, Institute of Geriatric Neurology, the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Rong-Pei Liu
- Department of Neurology, Institute of Geriatric Neurology, the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Lu-Lu Ma
- Department of Neurology, Institute of Geriatric Neurology, the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Jian Cui
- Department of Neurology, Institute of Geriatric Neurology, the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Guo-Ling Zeng
- Department of Neurology, Institute of Geriatric Neurology, the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Xiong Zhang
- Department of Neurology, Institute of Geriatric Neurology, the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Jian-Yong Wang
- Department of Neurology, Institute of Geriatric Neurology, the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Shi-Shi Huang
- Department of Neurology, Institute of Geriatric Neurology, the Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
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Superior colliculus projections to target populations in the supraoculomotor area of the macaque monkey. Vis Neurosci 2021; 38. [DOI: 10.1017/s095252382100016x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
A projection by the superior colliculus to the supraoculomotor area (SOA) located dorsal to the oculomotor complex was first described in 1978. This projection’s targets have yet to be identified, although the initial study suggested that vertical gaze motoneuron dendrites might receive this input. Defining the tectal targets is complicated by the fact the SOA contains a number of different cell populations. In the present study, we used anterograde tracers to characterize collicular axonal arbors and retrograde tracers to label prospective SOA target populations in macaque monkeys. Close associations were not found with either superior or medial rectus motoneurons whose axons supply singly innervated muscle fibers. S-group motoneurons, which supply superior rectus multiply innervated muscle fibers, appeared to receive a very minor input, but C-group motoneurons, which supply medial rectus multiply innervated muscle fibers, received no input. A number of labeled boutons were observed in close association with SOA neurons projecting to the spinal cord, or the reticular formation in the pons and medulla. These descending output neurons are presumed to be peptidergic cells within the centrally projecting Edinger–Westphal population. It is possible the collicular input provides a signaling function for neurons in this population that serve roles in either stress responses, or in eating and drinking behavior. Finally, a number of close associations were observed between tectal terminals and levator palpebrae superioris motoneurons, suggesting the possibility that the superior colliculus provides a modest direct input for raising the eyelids during upward saccades.
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Abstract
Eye movements are indispensable for visual image stabilization during self-generated and passive head and body motion and for visual orientation. Eye muscles and neuronal control elements are evolutionarily conserved, with novel behavioral repertoires emerging during the evolution of frontal eyes and foveae. The precise execution of eye movements with different dynamics is ensured by morphologically diverse yet complementary sets of extraocular muscle fibers and associated motoneurons. Singly and multiply innervated muscle fibers are controlled by motoneuronal subpopulations with largely selective premotor inputs from task-specific ocular motor control centers. The morphological duality of the neuromuscular interface is matched by complementary biochemical and molecular features that collectively assign different physiological properties to the motor entities. In contrast, the functionality represents a continuum where most motor elements contribute to any type of eye movement, although within preferential dynamic ranges, suggesting that signal transmission and muscle contractions occur within bands of frequency-selective pathways.
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Affiliation(s)
- Anja K E Horn
- Institute of Anatomy and Cell Biology I, Ludwig-Maximilians-University Munich, 80336 Munich, Germany;
| | - Hans Straka
- Department Biology II, Ludwig-Maximilians-University Munich, 82152 Planegg, Germany
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Warren S, May PJ. Macaque monkey trigeminal blink reflex circuits targeting levator palpebrae superioris motoneurons. J Comp Neurol 2021; 529:3389-3409. [PMID: 34101199 DOI: 10.1002/cne.25198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/21/2021] [Accepted: 05/31/2021] [Indexed: 12/18/2022]
Abstract
For normal viewing, the eyes are held open by the tonic actions of the levator palpebrae superioris (levator) muscle raising the upper eyelid. This activity is interrupted during blinks, when the eyelid sweeps down to spread the tear film or protect the cornea. We examined the circuit connecting the principal trigeminal nucleus to the levator motoneurons by use of both anterograde and retrograde tracers in macaque monkeys. Injections of anterograde tracer were made into the principal trigeminal nucleus using either a stereotaxic approach or localization following physiological characterization of trigeminal second order neurons. Anterogradely labeled axonal arbors were located both within the caudal central subdivision, which contains levator motoneurons, and in the adjacent supraoculomotor area. Labeled boutons made synaptic contacts on retrogradely labeled levator motoneurons indicating a monosynaptic connection. As the eye is also retracted through the actions of the rectus muscles during a blink, we examined whether these trigeminal injections labeled boutons contacting rectus motoneurons within the oculomotor nucleus. These were not found when the injection sites were confined to the principal trigeminal nucleus region. To identify the source of the projection to the levator motoneurons, we injected retrograde tracer into the oculomotor complex. Retrogradely labeled cells were confined to a narrow, dorsoventrally oriented cell population that lined the rostral edge of the principal trigeminal nucleus. Presumably these cells inhibit levator motoneurons, while other parts of the trigeminal sensory complex are activating orbicularis oculi motoneurons, when a blink is initiated by sensory stimuli contacting the face.
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Affiliation(s)
- Susan Warren
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi, USA
| | - Paul J May
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi, USA
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Histochemical Characterization of the Vestibular Y-Group in Monkey. THE CEREBELLUM 2020; 20:701-716. [PMID: 33083961 PMCID: PMC8629908 DOI: 10.1007/s12311-020-01200-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Accepted: 10/04/2020] [Indexed: 12/18/2022]
Abstract
The Y-group plays an important role in the generation of upward smooth pursuit eye movements and contributes to the adaptive properties of the vertical vestibulo-ocular reflex. Malfunction of this circuitry may cause eye movement disorders, such as downbeat nystagmus. To characterize the neuron populations in the Y-group, we performed immunostainings for cellular proteins related to firing characteristics and transmitters (calretinin, GABA-related proteins and ion channels) in brainstem sections of macaque monkeys that had received tracer injections into the oculomotor nucleus. Two histochemically different populations of premotor neurons were identified: The calretinin-positive population represents the excitatory projection to contralateral upgaze motoneurons, whereas the GABAergic population represents the inhibitory projection to ipsilateral downgaze motoneurons. Both populations receive a strong supply by GABAergic nerve endings most likely originating from floccular Purkinje cells. All premotor neurons express nonphosphorylated neurofilaments and are ensheathed by strong perineuronal nets. In addition, they contain the voltage-gated potassium channels Kv1.1 and Kv3.1b which suggests biophysical similarities to high-activity premotor neurons of vestibular and oculomotor systems. The premotor neurons of Y-group form a homogenous population with histochemical characteristics compatible with fast-firing projection neurons that can also undergo plasticity and contribute to motor learning as found for the adaptation of the vestibulo-ocular reflex in response to visual-vestibular mismatch stimulation. The histochemical characterization of premotor neurons in the Y-group allows the identification of the homologue cell groups in human, including their transmitter inputs and will serve as basis for correlated anatomical-neuropathological studies of clinical cases with downbeat nystagmus.
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Lienbacher K, Sänger K, Strassburger S, Ehrt O, Rudolph G, Barnerssoi M, Horn AKE. Extraocular muscles involved in convergence are innervated by an additional set of palisade endings that may differ in their excitability: A human study. PROGRESS IN BRAIN RESEARCH 2019; 248:127-137. [PMID: 31239126 DOI: 10.1016/bs.pbr.2019.04.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Palisade endings are located at the myotendinous junction of extraocular muscles in most mammals. Irrespective of their unclarified function as motor or sensory nerve endings, a specialized role in convergence is proposed, based on their high number in the medial rectus muscle (MR). Further support comes from a study in monkey demonstrating that only the MR and inferior rectus muscle (IR) contain an additional population of palisade endings that express the calcium-binding protein calretinin (CR) in addition to choline acetyltransferase (ChAT). Here we studied, whether CR-positive palisade endings are present in human as well and confined to extraocular muscles most active during convergence. The systematic analysis of all eye muscles of 17 human specimen revealed that only the MR and IR contain an additional population of CR-positive palisade endings and multiple en-grappe endings, which target non-twitch muscle fibers along their whole length. Approximately 80% of all palisade endings in the MR expressed CR. Furthermore, the intrafusal muscle fibers of some muscle spindles in the MR were innervated by CR-positive annulospiral nerve endings that transmit the signals of muscle length changes to the brain. All extraocular muscles contained few thin CR-positive, but ChAT-negative nerve fibers, possibly representing free sensory or autonomic endings arising from the trigeminal ganglion. As in monkey, in the medial periphery of the human oculomotor nucleus ChAT-positive neurons were found to co-express CR. Therefore these neurons most likely represent the cell bodies of CR-positive palisade endings in the MR. Unlike in monkey, these neurons do not lie within a compact cell group, but are more scattered. In conclusion, the MR and IR in human contain two histochemically different populations of palisade and multiple endings that may contribute to ocular alignment and convergence in a different way.
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Affiliation(s)
- Karoline Lienbacher
- Faculty of Medicine, Institute of Anatomy and Cell Biology I, Ludwig-Maximilians-University, Munich, Germany; Center for Vertigo and Balance Disorders DSGZ, Ludwig-Maximilians-University, Munich, Germany
| | - Kathrin Sänger
- Faculty of Medicine, Institute of Anatomy and Cell Biology I, Ludwig-Maximilians-University, Munich, Germany
| | - Sebastian Strassburger
- Faculty of Medicine, Institute of Anatomy and Cell Biology I, Ludwig-Maximilians-University, Munich, Germany
| | - Oliver Ehrt
- Department of Ophthalmology, University Hospital, Ludwig-Maximilians-University, Munich, Germany
| | - Günther Rudolph
- Department of Ophthalmology, University Hospital, Ludwig-Maximilians-University, Munich, Germany
| | - Miriam Barnerssoi
- Faculty of Medicine, Institute of Anatomy and Cell Biology I, Ludwig-Maximilians-University, Munich, Germany
| | - Anja K E Horn
- Faculty of Medicine, Institute of Anatomy and Cell Biology I, Ludwig-Maximilians-University, Munich, Germany; Center for Vertigo and Balance Disorders DSGZ, Ludwig-Maximilians-University, Munich, Germany.
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Bohlen MO, Bui K, Stahl JS, May PJ, Warren S. Mouse Extraocular Muscles and the Musculotopic Organization of Their Innervation. Anat Rec (Hoboken) 2019; 302:1865-1885. [PMID: 30993879 DOI: 10.1002/ar.24141] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 09/18/2018] [Accepted: 11/25/2018] [Indexed: 12/24/2022]
Abstract
The organization of extraocular muscles (EOMs) and their motor nuclei was investigated in the mouse due to the increased importance of this model for oculomotor research. Mice showed a standard EOM organization pattern, although their eyes are set at the side of the head. They do have more prominent oblique muscles, whose insertion points differ from those of frontal-eyed species. Retrograde tracers revealed that the motoneuron layout aligns with the general vertebrate plan with respect to nuclei and laterality. The mouse departed in some significant respects from previously studied species. First, more overlap between the distributions of muscle-specific motoneuronal pools was present in the oculomotor nucleus (III). Furthermore, motoneuron dendrites for each pool filled the entire III and extended beyond the edge of the abducens nucleus (VI). This suggests mouse extraocular motoneuron afferents must target specific pools based on features other than dendritic distribution and nuclear borders. Second, abducens internuclear neurons are located outside the VI. We concluded this because no unlabeled abducens internuclear neurons were observed following lateral rectus muscle injections and because retrograde tracer injections into the III labeled cells immediately ventral and ventrolateral to the VI, not within it. This may provide an anatomical substrate for differential input to motoneurons and internuclear neurons that allows rodents to move their eyes more independently. Finally, while soma size measurements suggested motoneuron subpopulations supplying multiply and singly innervated muscle fibers are present, markers for neurofilaments and perineuronal nets indicated overlap in the size distributions of the two populations. Anat Rec, 302:1865-1885, 2019. © 2019 American Association for Anatomy.
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Affiliation(s)
- Martin O Bohlen
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Kevin Bui
- Department of Neurobiology & Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi
| | - John S Stahl
- Neurology Service, Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio.,Department of Neurology, Case Western Reserve University, Cleveland, Ohio
| | - Paul J May
- Department of Neurobiology & Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi.,Department of Ophthalmology, University of Mississippi Medical Center, Jackson, Mississippi.,Department of Neurology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Susan Warren
- Department of Neurobiology & Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi
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Horn AKE, Horng A, Buresch N, Messoudi A, Härtig W. Identification of Functional Cell Groups in the Abducens Nucleus of Monkey and Human by Perineuronal Nets and Choline Acetyltransferase Immunolabeling. Front Neuroanat 2018; 12:45. [PMID: 29970992 PMCID: PMC6018528 DOI: 10.3389/fnana.2018.00045] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 05/14/2018] [Indexed: 11/23/2022] Open
Abstract
The abducens nucleus (nVI) contains several functional cell groups: motoneurons of the singly-innervated twitch muscle fibers (SIF) and those of the multiply-innervated muscle fibers (MIF) of the lateral rectus muscle (LR), internuclear neurons (INTs) projecting to the contralateral oculomotor nucleus (nIII) and paramedian tract-neurons (PMT) that receive input from premotor neurons of the oculomotor system and project to the floccular region. In monkey, these cell populations can be delineated by their chemical signature. For correlative clinico-pathological studies the identification of the homologous cell groups in the human nVI are required. In this study, we plotted the distribution of these populations in monkey nVI by combined tract-tracing and immunohistochemical staining facilitating the identification of homologous cell groups in man. Paraffin sections of two Rhesus monkeys fixed with 4% paraformaldhehyde and immunostained with antibodies directed against choline acetyltransferase (ChAT) as marker enzyme for cholinergic neurons and chondroitin sulfate proteoglycan (CSPG) to detect perineuronal nets (PNs) revealed four neuron populations in nVI with different chemical signatures: ChAT-positive and CSPG-positive SIF motoneurons, ChAT-positive, but CSPG-negative MIF motoneurons, and ChAT-negative neurons with prominent PNs that were considered as INTs. This was confirmed by combined immunofluorescence labeling of cholera toxin subunit B (CTB) or wheat germ agglutinin (WGA) and ChAT or CSPG in nVI sections from cases with tracer injections into nIII. In the rostral part of nVI and at its medial border, populations of ChAT-negative groups with weak CSPG-staining, but with strong acetylcholinesterase (AChE) activity, were identified as PMT cell groups by correlating them with the location of anterograde tracer labeling from INTs in nIII. Applying ChAT- and CSPG-immunostaining as well as AChE staining to human brainstem sections four neuron groups with the same chemical signature as those in monkey could be identified in and around the nVI in human. In conclusion, the distribution of nVI neuron populations was identified in human based on findings in monkey utilizing their markers for cholinergic neurons and their different ensheathment by PNs of the extracellular matrix.
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Affiliation(s)
- Anja K. E. Horn
- Anatomisches Institut, Ludwig-Maximilians Universität, München, Germany
- Deutsches Schwindel- und Gleichgewichtszentrum, Ludwig-Maximilians Universität, München, Germany
| | - Annie Horng
- RZM—Radiologisches Zentrum München-Pasing, München, Germany
| | - Norbert Buresch
- Institut für Neuropathologie, Ludwig-Maximilians Universität, München, Germany
| | - Ahmed Messoudi
- Anatomisches Institut, Ludwig-Maximilians Universität, München, Germany
| | - Wolfgang Härtig
- Paul-Flechsig-Institut für Hirnforschung, Universität Leipzig, Leipzig, Germany
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Company V, Moreno-Bravo JA, Perez-Balaguer A, Puelles E. The Amniote Oculomotor Complex. Anat Rec (Hoboken) 2018; 302:446-451. [DOI: 10.1002/ar.23827] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 10/10/2017] [Accepted: 10/11/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Verónica Company
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC; Sant Joan d'Alacant, Alicante 03550 Spain
| | - Juan Antonio Moreno-Bravo
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC; Sant Joan d'Alacant, Alicante 03550 Spain
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Institut de la Vision; 17 Rue Moreau, Paris 75012 France
| | - Ariadna Perez-Balaguer
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC; Sant Joan d'Alacant, Alicante 03550 Spain
| | - Eduardo Puelles
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC; Sant Joan d'Alacant, Alicante 03550 Spain
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Bremova-Ertl T, Schiffmann R, Patterson MC, Belmatoug N, Billette de Villemeur T, Bardins S, Frenzel C, Malinová V, Naumann S, Arndt J, Mengel E, Reinke J, Strobl R, Strupp M. Oculomotor and Vestibular Findings in Gaucher Disease Type 3 and Their Correlation with Neurological Findings. Front Neurol 2018; 8:711. [PMID: 29379464 PMCID: PMC5775219 DOI: 10.3389/fneur.2017.00711] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 12/11/2017] [Indexed: 01/26/2023] Open
Abstract
Objectives To evaluate the function of the oculomotor and vestibular systems and to correlate these findings with the clinical status of patients with Gaucher disease type 3 (GD3). The goal of this cross-sectional and longitudinal study was to find oculomotor biomarkers for future clinical trials. Methods Twenty-six patients with GD3 were assessed for eligibility and 21 were able to perform at least one task. Horizontal and vertical reflexive saccades, smooth pursuit, gaze-holding, optokinetic nystagmus, and horizontal vestibulo-ocular reflex (VOR) were examined by video-oculography/video-head impulse test and compared concurrently with 33 healthy controls. The Scale for the Assessment and Rating of Ataxia (SARA), the modified Severity Scoring Tool (mSST), and Grooved Pegboard Test (GPT) were administered to assess overall neurological function. Eleven patients were also re-assessed after 1 year. Results Nine out of 17 patients exhibited gaze-holding deficits. One patient had upbeat nystagmus. Three patients presented with bilateral abducens palsy in combination with central oculomotor disorders, suggesting a bilateral involvement of the abducens nucleus. Horizontal angular VOR gain was reduced in all patients (0.66 ± 0.37) compared with controls (1.1 ± 0.11, p < 0.001). Most strongly correlated with clinical rating scales were peak velocity of downward saccades (SARA: ρ = −0.752, p < 0.0005; mSST: ρ = −0.611, p = 0.003; GPT: ρ = −0.649, p = 0.005) and duration of vertical saccades (SARA: ρ = 0.806, p < 0.001; mSST: ρ = 0.700, p < 0.0005; GPT: ρ = 0.558, p = 0.02) together with the VOR gain (SARA: ρ = −0.63, p = 0.016; mSST: ρ = −0.725, p = 0.003; GPT: ρ = −0.666, p = 0.004). Vertical smooth pursuit gain decreased significantly at follow-up. Interpretation This study shows neuronal degeneration of the brainstem and cerebellum with combined involvement of both supranuclear and nuclear oculomotor structures and the vestibular system in GD3. We also identified oculomotor parameters that correlate with the neurological status and can be used as biomarkers in future clinical trials.
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Affiliation(s)
- Tatiana Bremova-Ertl
- German Center for Vertigo and Balance Disorders, University Hospital Munich, Munich, Germany.,Graduate School of Systemic Neurosciences, Ludwig-Maximilians University of Munich, Munich, Germany
| | - Raphael Schiffmann
- Institute of Metabolic Disease, Baylor Scott & White Research Institute, Dallas, TX, United States
| | - Marc C Patterson
- Department of Neurology, Mayo Clinic Children's Center, Rochester, MN, United States.,Department of Pediatrics, Mayo Clinic Children's Center, Rochester, MN, United States.,Department of Clinical Genomics, Mayo Clinic Children's Center, Rochester, MN, United States
| | - Nadia Belmatoug
- Referral Center for Lysosomal Diseases, Department of Internal Medicine, University Hospital Paris Nord Val-de-Seine, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Thierry Billette de Villemeur
- Sorbonne Universités, UPMC, GRC ConCer-LD and AP-HP, Hôpital Trousseau, Service de Neuropédiatrie - Pathologie du développement, Centre de référence des malformations et maladies congénitales du cervelet, Paris, France
| | - Stanislavs Bardins
- German Center for Vertigo and Balance Disorders, University Hospital Munich, Munich, Germany
| | - Claudia Frenzel
- German Center for Vertigo and Balance Disorders, University Hospital Munich, Munich, Germany.,Department of Neurology, University Hospital Munich, Munich, Germany
| | - Věra Malinová
- First Faculty of Medicine, Department of Pediatrics and Adolescence Medicine, Charles University, General University Hospital Prague, Prague, Czechia
| | - Silvia Naumann
- Villa Metabolica, Center for Paediatric and Adolescent Medicine, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Juliane Arndt
- Villa Metabolica, Center for Paediatric and Adolescent Medicine, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Eugen Mengel
- Villa Metabolica, Center for Paediatric and Adolescent Medicine, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Jörg Reinke
- Villa Metabolica, Center for Paediatric and Adolescent Medicine, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Ralf Strobl
- German Center for Vertigo and Balance Disorders, University Hospital Munich, Munich, Germany.,Institute for Medical Information Processing, Biometrics and Epidemiology, Ludwig-Maximilians University of Munich, Munich, Germany
| | - Michael Strupp
- German Center for Vertigo and Balance Disorders, University Hospital Munich, Munich, Germany.,Department of Neurology, University Hospital Munich, Munich, Germany
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14
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Identification of secondary vestibulo-ocular neurons in human based on their histochemical characteristics found in monkey. J Neurol 2017; 264:583-585. [PMID: 28116496 DOI: 10.1007/s00415-017-8397-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 01/16/2017] [Indexed: 01/05/2023]
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15
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Vestibular function in patients with Niemann-Pick type C disease. J Neurol 2016; 263:2260-2270. [DOI: 10.1007/s00415-016-8247-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 06/30/2016] [Accepted: 07/27/2016] [Indexed: 10/21/2022]
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16
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Adamczyk C, Strupp M, Jahn K, Horn AKE. Calretinin as a Marker for Premotor Neurons Involved in Upgaze in Human Brainstem. Front Neuroanat 2015; 9:153. [PMID: 26696837 PMCID: PMC4677283 DOI: 10.3389/fnana.2015.00153] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 11/16/2015] [Indexed: 01/19/2023] Open
Abstract
Eye movements are generated by different premotor pathways. Damage to them can cause specific deficits of eye movements, such as saccades. For correlative clinico-anatomical post-mortem studies of cases with eye movement disorders it is essential to identify the functional cell groups of the oculomotor system in the human brain by marker proteins. Based on monkey studies, the premotor neurons of the saccadic system can be identified by the histochemical markers parvalbumin (PAV) and perineuronal nets in humans. These areas involve the interstitial nucleus of Cajal (INC) and the rostral interstitial nucleus of the medial longitudinal fascicle (RIMLF), which both contain premotor neurons for upgaze and downgaze. Recent monkey and human studies revealed a selective excitatory calretinin (CR)-positive input to the motoneurons mediating upgaze, but not to those for downgaze. Three premotor regions were identified as sources of CR input in monkey: y-group, INC and RIMLF. These findings suggest that the expression pattern of parvalbumin and CR may help to identify premotor neurons involved in up- or downgaze. In a post-mortem study of five human cases without neurological diseases we investigated the y-group, INC and RIMLF for the presence of parvalbumin and CR positive neurons including their co-expression. Adjacent thin paraffin sections were stained for the aggrecan (ACAN) component of perineuronal nets, parvalbumin or CR and glutamate decarboxylase. The comparative analysis of scanned thin sections of INC and RIMLF revealed medium-sized parvalbumin positive neurons with and without CR coexpression, which were intermingled. The parvalbumin/CR positive neurons in both nuclei are considered as excitatory premotor upgaze neurons. Accordingly, the parvalbumin-positive neurons lacking CR are considered as premotor downgaze neurons in RIMLF, but may in addition include inhibitory premotor upgaze neurons in the INC as indicated by co-expression of glutamate decarboxylase in a subpopulation. CR-positive neurons ensheathed by perineuronal nets in the human y-group are considered as the homolog premotor neurons described in monkey, projecting to superior rectus (SR) and inferior oblique (IO) motoneurons. In conclusion, combined immunostaining for parvalbumin, perineuronal nets and CR may well be suited for the specific identification and subsequent analysis of premotor upgaze pathways in clinical cases of isolated up- or downgaze deficits.
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Affiliation(s)
- Christopher Adamczyk
- Department of Neurology, Klinikum Großhadern, Ludwig-Maximilians University Munich, Germany
| | - Michael Strupp
- Department of Neurology, Klinikum Großhadern, Ludwig-Maximilians University Munich, Germany ; German Center for Vertigo and Balance Disorders, Klinikum Großhadern, Ludwig-Maximilians University Munich, Germany
| | - Klaus Jahn
- German Center for Vertigo and Balance Disorders, Klinikum Großhadern, Ludwig-Maximilians University Munich, Germany ; Department of Neurology, Schön Klinik, Bad Aibling Germany
| | - Anja K E Horn
- German Center for Vertigo and Balance Disorders, Klinikum Großhadern, Ludwig-Maximilians University Munich, Germany ; Institute of Anatomy and Cell Biology, Dept. I, Ludwig-Maximilians University Munich, Germany
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17
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Clark RA, Demer JL. Functional morphometry demonstrates extraocular muscle compartmental contraction during vertical gaze changes. J Neurophysiol 2015; 115:370-8. [PMID: 26538608 DOI: 10.1152/jn.00825.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 11/02/2015] [Indexed: 01/08/2023] Open
Abstract
Anatomical studies demonstrate selective compartmental innervation of most human extraocular muscles (EOMs), suggesting the potential for differential compartmental control. This was supported by magnetic resonance imaging (MRI) demonstrating differential lateral rectus (LR) compartmental contraction during ocular counterrolling, differential medial rectus (MR) compartmental contraction during asymmetric convergence, and differential LR, inferior rectus (IR), and superior oblique (SO) compartmental contraction during vertical vergence. To ascertain possible differential compartmental EOM contraction during vertical ductions, surface coil MRI was performed over a range of target-controlled vertical gaze positions in 25 orbits of 13 normal volunteers. Cross-sectional areas and partial volumes of EOMs were analyzed in contiguous, quasi-coronal 2-mm image planes spanning origins to globe equator to determine morphometric features correlating best with contractility. Confirming and extending prior findings for horizontal EOMs during horizontal ductions, the percent change in posterior partial volume (PPV) of vertical EOMs from 8 to 14 mm posterior to the globe correlated best with vertical duction. EOMs were then divided into equal transverse compartments to evaluate the effect of vertical gaze on changes in PPV. Differential contractile changes were detected in the two compartments of the same EOM during infraduction for the IR medial vs. lateral (+4.4%, P = 0.03), LR inferior vs. superior (+4.0%, P = 0.0002), MR superior vs. inferior (-6.0%, P = 0.001), and SO lateral vs. medial (+9.7%, P = 0.007) compartments, with no differential contractile changes in the superior rectus. These findings suggest that differential compartmental activity occurs during normal vertical ductions. Thus all EOMs may contribute to cyclovertical actions.
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Affiliation(s)
- Robert A Clark
- Stein Eye Institute and Department of Ophthalmology, David Geffen Medical School, University of California, Los Angeles, California; and
| | - Joseph L Demer
- Stein Eye Institute and Department of Ophthalmology, David Geffen Medical School, University of California, Los Angeles, California; and Department of Neurology, David Geffen Medical School, University of California, Los Angeles, California
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18
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Zeeh C, Mustari MJ, Hess BJM, Horn AKE. Transmitter inputs to different motoneuron subgroups in the oculomotor and trochlear nucleus in monkey. Front Neuroanat 2015; 9:95. [PMID: 26257611 PMCID: PMC4513436 DOI: 10.3389/fnana.2015.00095] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 07/06/2015] [Indexed: 11/13/2022] Open
Abstract
In all vertebrates the eyes are moved by six pairs of extraocular muscles enabling horizontal, vertical and rotatory movements. Recent work showed that each extraocular muscle is controlled by two motoneuronal groups: (1) Motoneurons of singly-innervated muscle fibers (SIF) that lie within the boundaries of motonuclei mediating a fast muscle contraction; and (2) motoneurons of multiply-innervated muscle fibers (MIF) in the periphery of motonuclei mediating a tonic muscle contraction. Currently only limited data about the transmitter inputs to the SIF and MIF motoneurons are available. Here we performed a quantitative study on the transmitter inputs to SIF and MIF motoneurons of individual muscles in the oculomotor and trochlear nucleus in monkey. Pre-labeled motoneurons were immunostained for GABA, glutamate decarboxylase, GABA-A receptor, glycine transporter 2, glycine receptor 1, and vesicular glutamate transporters 1 and 2. The main findings were: (1) the inhibitory control of SIF motoneurons for horizontal and vertical eye movements differs. Unlike in previous primate studies a considerable GABAergic input was found to all SIF motoneuronal groups, whereas a glycinergic input was confined to motoneurons of the medial rectus (MR) muscle mediating horizontal eye movements and to those of the levator palpebrae (LP) muscle elevating the upper eyelid. Whereas SIF and MIF motoneurons of individual eye muscles do not differ numerically in their GABAergic, glycinergic and vGlut2 input, vGlut1 containing terminals densely covered the supraoculomotor area (SOA) targeting MR MIF motoneurons. It is reasonable to assume that the vGlut1 input affects the near response system in the SOA, which houses the preganglionic neurons mediating pupillary constriction and accommodation and the MR MIF motoneurones involved in vergence.
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Affiliation(s)
- Christina Zeeh
- Institute of Anatomy and Cell Biology, Department I, Ludwig-Maximilians UniversityMunich, Germany
| | - Michael J. Mustari
- Washington National Primate Research Center and Department of Ophthalmology, University of WashingtonSeattle, WA, USA
| | - Bernhard J. M. Hess
- Vestibulo-Oculomotor Laboratory Zürich, Department of Neurology, University HospitalZürich, Switzerland
| | - Anja K. E. Horn
- Institute of Anatomy and Cell Biology, Department I, Ludwig-Maximilians UniversityMunich, Germany
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Saccadic Palsy following Cardiac Surgery: Possible Role of Perineuronal Nets. PLoS One 2015; 10:e0132075. [PMID: 26135580 PMCID: PMC4489868 DOI: 10.1371/journal.pone.0132075] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 06/09/2015] [Indexed: 12/29/2022] Open
Abstract
Objective Perineuronal nets (PN) form a specialized extracellular matrix around certain highly active neurons within the central nervous system and may help to stabilize synaptic contacts, promote local ion homeostasis, or play a protective role. Within the ocular motor system, excitatory burst neurons and omnipause neurons are highly active cells that generate rapid eye movements – saccades; both groups of neurons contain the calcium-binding protein parvalbumin and are ensheathed by PN. Experimental lesions of excitatory burst neurons and omnipause neurons cause slowing or complete loss of saccades. Selective palsy of saccades in humans is reported following cardiac surgery, but such cases have shown normal brainstem neuroimaging, with only one clinicopathological study that demonstrated paramedian pontine infarction. Our objective was to test the hypothesis that lesions of PN surrounding these brainstem saccade-related neurons may cause saccadic palsy. Methods Together with four controls we studied the brain of a patient who had developed a permanent selective saccadic palsy following cardiac surgery and died several years later. Sections of formalin-fixed paraffin-embedded brainstem blocks were applied to double-immunoperoxidase staining of parvalbumin and three different components of PN. Triple immunofluorescence labeling for all PN components served as internal controls. Combined immunostaining of parvalbumin and synaptophysin revealed the presence of synapses. Results Excitatory burst neurons and omnipause neurons were preserved and still received synaptic input, but their surrounding PN showed severe loss or fragmentation. Interpretation Our findings support current models and experimental studies of the brainstem saccade-generating neurons and indicate that damage to PN may permanently impair the function of these neurons that the PN ensheathe. How a postulated hypoxic mechanism could selectively damage the PN remains unclear. We propose that the well-studied saccadic eye movement system provides an accessible model to evaluate the role of PN in health and disease.
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20
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Development of the human oculomotor nuclear complex: Somatic nuclei. Ann Anat 2014; 196:394-401. [DOI: 10.1016/j.aanat.2014.07.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 07/01/2014] [Accepted: 07/26/2014] [Indexed: 11/22/2022]
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Torres-Torrelo J, Torres B, Carrascal L. Modulation of the input-output function by GABAA receptor-mediated currents in rat oculomotor nucleus motoneurons. J Physiol 2014; 592:5047-64. [PMID: 25194049 PMCID: PMC4259542 DOI: 10.1113/jphysiol.2014.276576] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The neuronal input-output function depends on recruitment threshold and gain of the firing frequency-current (f-I) relationship. These two parameters are positively correlated in ocular motoneurons (MNs) recorded in alert preparation and inhibitory inputs could contribute to this correlation. Phasic inhibition mediated by γ-amino butyric acid (GABA) occurs when a high concentration of GABA at the synaptic cleft activates postsynaptic GABAA receptors, allowing neuronal information transfer. In some neuronal populations, low concentrations of GABA activate non-synaptic GABAA receptors and generate a tonic inhibition, which modulates cell excitability. This study determined how ambient GABA concentrations modulate the input-output relationship of rat oculomotor nucleus MNs. Superfusion of brain slices with GABA (100 μm) produced a GABAA receptor-mediated current that reduced the input resistance, increased the recruitment threshold and shifted the f-I relationship rightward without any change in gain. These modifications did not depend on MN size. In absence of exogenous GABA, gabazine (20 μm; antagonist of GABAA receptors) abolished spontaneous inhibitory postsynaptic currents and revealed a tonic current in MNs. Gabazine increased input resistance and decreased recruitment threshold mainly in larger MNs. The f-I relationship shifted to the left, without any change in gain. Gabazine effects were chiefly due to MN tonic inhibition because tonic current amplitude was five-fold greater than phasic. This study demonstrates a tonic inhibition in ocular MNs that modulates cell excitability depending on cell size. We suggest that GABAA tonic inhibition acting concurrently with glutamate receptors activation could reproduce the positive covariation between threshold and gain reported in alert preparation.
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Affiliation(s)
| | - Blas Torres
- Department of Physiology, University of Seville, Seville, Spain
| | - Livia Carrascal
- Department of Physiology, University of Seville, Seville, Spain
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Khandker N, Schmerler D, Mahajan S, Strbian D, Serra A. Value of eye movement examination in aiding precise localization in stroke. Stroke 2014; 45:e157-9. [PMID: 24938847 DOI: 10.1161/strokeaha.114.005754] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Namir Khandker
- From the Department of Neurology, University Hospitals Case Medical Center, Cleveland, OH (N.K., D. Schmerler, S.M., A.S.); Department of Neurology and Stroke Unit, Helsinki University Central Hospital, Helsinki, Finland (D. Strbian); and Louis Stokes VA Medical Center, Cleveland, OH (A.S.)
| | - David Schmerler
- From the Department of Neurology, University Hospitals Case Medical Center, Cleveland, OH (N.K., D. Schmerler, S.M., A.S.); Department of Neurology and Stroke Unit, Helsinki University Central Hospital, Helsinki, Finland (D. Strbian); and Louis Stokes VA Medical Center, Cleveland, OH (A.S.)
| | - Supriya Mahajan
- From the Department of Neurology, University Hospitals Case Medical Center, Cleveland, OH (N.K., D. Schmerler, S.M., A.S.); Department of Neurology and Stroke Unit, Helsinki University Central Hospital, Helsinki, Finland (D. Strbian); and Louis Stokes VA Medical Center, Cleveland, OH (A.S.)
| | - Daniel Strbian
- From the Department of Neurology, University Hospitals Case Medical Center, Cleveland, OH (N.K., D. Schmerler, S.M., A.S.); Department of Neurology and Stroke Unit, Helsinki University Central Hospital, Helsinki, Finland (D. Strbian); and Louis Stokes VA Medical Center, Cleveland, OH (A.S.)
| | - Alessandro Serra
- From the Department of Neurology, University Hospitals Case Medical Center, Cleveland, OH (N.K., D. Schmerler, S.M., A.S.); Department of Neurology and Stroke Unit, Helsinki University Central Hospital, Helsinki, Finland (D. Strbian); and Louis Stokes VA Medical Center, Cleveland, OH (A.S.).
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