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Fritzsch B, Elliott KL. Fish hearing revealed: Do we understand hearing in critical fishes and marine tetrapods. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2023; 154:3019-3026. [PMID: 37955566 PMCID: PMC10769566 DOI: 10.1121/10.0022355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 09/26/2023] [Accepted: 09/27/2023] [Indexed: 11/14/2023]
Abstract
Hearing evolved in lampreys with a frequency range of 50-200 Hz. This hearing range is comparable to that of elasmobranchs, most non-teleosts, and lungfish. Elasmobranchs most likely use the saccule and the papilla neglecta (PN) for hearing. In non-teleosts and teleosts, lungfish, and certain tetrapods the saccule is the likely sensor for sound reception while the lagena and the PN are important for gravistatic sensing. Coelacanth and most tetrapods have a basilar papilla (BP) for hearing. In coelacanth and tetrapods, the hair cells of the BP are in contact with a basilar and a tectorial membrane. These membranes transmit mechanical vibrations. A cochlear aqueduct (CA) provides a connection between the cerebrospinal fluid that has a sodium rich space in coelacanth and tetrapods while the potassium rich endolymph is known in vertebrates. A unique feature is known in basic sarcopterygians, the intracranial joint, that never developed in actinopterygians and has been lost in lungfish and tetrapods. The BP in coelacanths is thought to generate pressure with the intracranial joint that will be transmitted to the CA. Lungs or a swim bladder are not forming in Chondrichthyes, structures that have a major impact on hearing in teleosts and tetrapods.
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Affiliation(s)
- Bernd Fritzsch
- Department of Biology & Department of Otolaryngology, The University of Iowa, Iowa City, Iowa 52242, USA
| | - Karen L Elliott
- Department of Biology & Department of Otolaryngology, The University of Iowa, Iowa City, Iowa 52242, USA
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2
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Cullen KE. Internal models of self-motion: neural computations by the vestibular cerebellum. Trends Neurosci 2023; 46:986-1002. [PMID: 37739815 PMCID: PMC10591839 DOI: 10.1016/j.tins.2023.08.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 07/15/2023] [Accepted: 08/25/2023] [Indexed: 09/24/2023]
Abstract
The vestibular cerebellum plays an essential role in maintaining our balance and ensuring perceptual stability during activities of daily living. Here I examine three key regions of the vestibular cerebellum: the floccular lobe, anterior vermis (lobules I-V), and nodulus and ventral uvula (lobules X-IX of the posterior vermis). These cerebellar regions encode vestibular information and combine it with extravestibular signals to create internal models of eye, head, and body movements, as well as their spatial orientation with respect to gravity. To account for changes in the external environment and/or biomechanics during self-motion, the neural mechanisms underlying these computations are continually updated to ensure accurate motor behavior. To date, studies on the vestibular cerebellum have predominately focused on passive vestibular stimulation, whereas in actuality most stimulation is the result of voluntary movement. Accordingly, I also consider recent research exploring these computations during active self-motion and emerging evidence establishing the cerebellum's role in building predictive models of self-generated movement.
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Affiliation(s)
- Kathleen E Cullen
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Otolaryngology - Head and Neck Surgery, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA; Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD 21205, USA.
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3
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Cullen KE. Vestibular motor control. HANDBOOK OF CLINICAL NEUROLOGY 2023; 195:31-54. [PMID: 37562876 DOI: 10.1016/b978-0-323-98818-6.00022-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
The vestibular system is an essential sensory system that generates motor reflexes that are crucial for our daily activities, including stabilizing the visual axis of gaze and maintaining head and body posture. In addition, the vestibular system provides us with our sense of movement and orientation relative to space and serves a vital role in ensuring accurate voluntary behaviors. Neurophysiological studies have provided fundamental insights into the functional circuitry of vestibular motor pathways. A unique feature of the vestibular system compared to other sensory systems is that the same central neurons that receive direct input from the afferents of the vestibular component of the 8th nerve can also directly project to motor centers that control vital vestibular motor reflexes. In turn, these reflexes ensure stabilize gaze and the maintenance of posture during everyday activities. For instance, a direct three-neuron pathway mediates the vestibulo-ocular reflex (VOR) pathway to provide stable gaze. Furthermore, recent studies have advanced our understanding of the computations performed by the cerebellum and cortex required for motor learning, compensation, and voluntary movement and navigation. Together, these findings have provided new insights into how the brain ensures accurate self-movement during our everyday activities and have also advanced our knowledge of the neurobiological mechanisms underlying disorders of vestibular processing.
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Affiliation(s)
- Kathleen E Cullen
- Departments of Biomedical Engineering, of Otolaryngology-Head and Neck Surgery, and of Neuroscience; Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD, United States.
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4
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Fritzsch B, Elliott KL, Yamoah EN. Neurosensory development of the four brainstem-projecting sensory systems and their integration in the telencephalon. Front Neural Circuits 2022; 16:913480. [PMID: 36213204 PMCID: PMC9539932 DOI: 10.3389/fncir.2022.913480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 08/23/2022] [Indexed: 11/18/2022] Open
Abstract
Somatosensory, taste, vestibular, and auditory information is first processed in the brainstem. From the brainstem, the respective information is relayed to specific regions within the cortex, where these inputs are further processed and integrated with other sensory systems to provide a comprehensive sensory experience. We provide the organization, genetics, and various neuronal connections of four sensory systems: trigeminal, taste, vestibular, and auditory systems. The development of trigeminal fibers is comparable to many sensory systems, for they project mostly contralaterally from the brainstem or spinal cord to the telencephalon. Taste bud information is primarily projected ipsilaterally through the thalamus to reach the insula. The vestibular fibers develop bilateral connections that eventually reach multiple areas of the cortex to provide a complex map. The auditory fibers project in a tonotopic contour to the auditory cortex. The spatial and tonotopic organization of trigeminal and auditory neuron projections are distinct from the taste and vestibular systems. The individual sensory projections within the cortex provide multi-sensory integration in the telencephalon that depends on context-dependent tertiary connections to integrate other cortical sensory systems across the four modalities.
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Affiliation(s)
- Bernd Fritzsch
- Department of Biology, The University of Iowa, Iowa City, IA, United States
- Department of Otolaryngology, The University of Iowa, Iowa City, IA, United States
- *Correspondence: Bernd Fritzsch,
| | - Karen L. Elliott
- Department of Biology, The University of Iowa, Iowa City, IA, United States
| | - Ebenezer N. Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno, NV, United States
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5
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Noseda R. Cerebro-Cerebellar Networks in Migraine Symptoms and Headache. FRONTIERS IN PAIN RESEARCH 2022; 3:940923. [PMID: 35910262 PMCID: PMC9326053 DOI: 10.3389/fpain.2022.940923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 06/13/2022] [Indexed: 11/13/2022] Open
Abstract
The cerebellum is associated with the biology of migraine in a variety of ways. Clinically, symptoms such as fatigue, motor weakness, vertigo, dizziness, difficulty concentrating and finding words, nausea, and visual disturbances are common in different types of migraine. The neural basis of these symptoms is complex, not completely known, and likely involve activation of both specific and shared circuits throughout the brain. Posterior circulation stroke, or neurosurgical removal of posterior fossa tumors, as well as anatomical tract tracing in animals, provided the first insights to theorize about cerebellar functions. Nowadays, with the addition of functional imaging, much progress has been done on cerebellar structure and function in health and disease, and, as a consequence, the theories refined. Accordingly, the cerebellum may be useful but not necessary for the execution of motor, sensory or cognitive tasks, but, rather, would participate as an efficiency facilitator of neurologic functions by improving speed and skill in performance of tasks produced by the cerebral area to which it is reciprocally connected. At the subcortical level, critical regions in these processes are the basal ganglia and thalamic nuclei. Altogether, a modulatory role of the cerebellum over multiple brain regions appears compelling, mainly by considering the complexity of its reciprocal connections to common neural networks involved in motor, vestibular, cognitive, affective, sensory, and autonomic processing—all functions affected at different phases and degrees across the migraine spectrum. Despite the many associations between cerebellum and migraine, it is not known whether this structure contributes to migraine initiation, symptoms generation or headache. Specific cerebellar dysfunction via genetically driven excitatory/inhibitory imbalances, oligemia and/or increased risk to white matter lesions has been proposed as a critical contributor to migraine pathogenesis. Therefore, given that neural projections and functions of many brainstem, midbrain and forebrain areas are shared between the cerebellum and migraine trigeminovascular pathways, this review will provide a synopsis on cerebellar structure and function, its role in trigeminal pain, and an updated overview of relevant clinical and preclinical literature on the potential role of cerebellar networks in migraine pathophysiology.
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Affiliation(s)
- Rodrigo Noseda
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
- *Correspondence: Rodrigo Noseda
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6
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Cabaraux P, Agrawal SK, Cai H, Calabro RS, Casali C, Damm L, Doss S, Habas C, Horn AKE, Ilg W, Louis ED, Mitoma H, Monaco V, Petracca M, Ranavolo A, Rao AK, Ruggieri S, Schirinzi T, Serrao M, Summa S, Strupp M, Surgent O, Synofzik M, Tao S, Terasi H, Torres-Russotto D, Travers B, Roper JA, Manto M. Consensus Paper: Ataxic Gait. CEREBELLUM (LONDON, ENGLAND) 2022; 22:394-430. [PMID: 35414041 DOI: 10.1007/s12311-022-01373-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/20/2022] [Indexed: 12/19/2022]
Abstract
The aim of this consensus paper is to discuss the roles of the cerebellum in human gait, as well as its assessment and therapy. Cerebellar vermis is critical for postural control. The cerebellum ensures the mapping of sensory information into temporally relevant motor commands. Mental imagery of gait involves intrinsically connected fronto-parietal networks comprising the cerebellum. Muscular activities in cerebellar patients show impaired timing of discharges, affecting the patterning of the synergies subserving locomotion. Ataxia of stance/gait is amongst the first cerebellar deficits in cerebellar disorders such as degenerative ataxias and is a disabling symptom with a high risk of falls. Prolonged discharges and increased muscle coactivation may be related to compensatory mechanisms and enhanced body sway, respectively. Essential tremor is frequently associated with mild gait ataxia. There is growing evidence for an important role of the cerebellar cortex in the pathogenesis of essential tremor. In multiple sclerosis, balance and gait are affected due to cerebellar and spinal cord involvement, as a result of disseminated demyelination and neurodegeneration impairing proprioception. In orthostatic tremor, patients often show mild-to-moderate limb and gait ataxia. The tremor generator is likely located in the posterior fossa. Tandem gait is impaired in the early stages of cerebellar disorders and may be particularly useful in the evaluation of pre-ataxic stages of progressive ataxias. Impaired inter-joint coordination and enhanced variability of gait temporal and kinetic parameters can be grasped by wearable devices such as accelerometers. Kinect is a promising low cost technology to obtain reliable measurements and remote assessments of gait. Deep learning methods are being developed in order to help clinicians in the diagnosis and decision-making process. Locomotor adaptation is impaired in cerebellar patients. Coordinative training aims to improve the coordinative strategy and foot placements across strides, cerebellar patients benefiting from intense rehabilitation therapies. Robotic training is a promising approach to complement conventional rehabilitation and neuromodulation of the cerebellum. Wearable dynamic orthoses represent a potential aid to assist gait. The panel of experts agree that the understanding of the cerebellar contribution to gait control will lead to a better management of cerebellar ataxias in general and will likely contribute to use gait parameters as robust biomarkers of future clinical trials.
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Affiliation(s)
- Pierre Cabaraux
- Unité Des Ataxies Cérébelleuses, Department of Neurology, CHU de Charleroi, Charleroi, Belgium.
| | | | - Huaying Cai
- Department of Neurology, Neuroscience Center, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, China
| | | | - Carlo Casali
- Department of Medico-Surgical Sciences and Biotechnologies, University of Rome Sapienza, Latina, Italy
| | - Loic Damm
- EuroMov Digital Health in Motion, Univ Montpellier, IMT Mines Ales, Montpellier, France
| | - Sarah Doss
- Department of Neurological Sciences, University of Nebraska Medical Center, Omaha, USA
| | - Christophe Habas
- Université Versailles Saint-Quentin, Versailles, France.,Service de NeuroImagerie, Centre Hospitalier National des 15-20, Paris, France
| | - Anja K E Horn
- Institute of Anatomy and Cell Biology I, Ludwig Maximilians-University Munich, Munich, Germany
| | - Winfried Ilg
- Section Computational Sensomotorics, Hertie Institute for Clinical Brain Research, University Tübingen, Tübingen, Germany
| | - Elan D Louis
- Department of Neurology, University of Texas Southwestern, Dallas, TX, USA
| | - Hiroshi Mitoma
- Department of Medical Education, Tokyo Medical University, Tokyo, Japan
| | - Vito Monaco
- The BioRobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Maria Petracca
- Department of Human Neurosciences, University of Rome Sapienza, Rome, Italy
| | - Alberto Ranavolo
- Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, INAIL, Monte Porzio Catone, Rome, Italy
| | - Ashwini K Rao
- Department of Rehabilitation & Regenerative Medicine (Programs in Physical Therapy), Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Serena Ruggieri
- Department of Human Neurosciences, University of Rome Sapienza, Rome, Italy.,Neuroimmunology Unit, IRCSS Fondazione Santa Lucia, Rome, Italy
| | - Tommaso Schirinzi
- Department of Systems Medicine, University of Roma Tor Vergata, Rome, Italy
| | - Mariano Serrao
- Department of Medico-Surgical Sciences and Biotechnologies, University of Rome Sapienza, Latina, Italy.,Movement Analysis LAB, Policlinico Italia, Rome, Italy
| | - Susanna Summa
- MARlab, Neuroscience and Neurorehabilitation Department, Bambino Gesù Children's Hospital - IRCCS, Rome, Italy
| | - Michael Strupp
- Department of Neurology and German Center for Vertigo and Balance Disorders, Hospital of the Ludwig Maximilians-University Munich, Munich, Germany
| | - Olivia Surgent
- Neuroscience Training Program and Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Matthis Synofzik
- Department of Neurodegeneration, Hertie Institute for Clinical Brain Research and Centre of Neurology, Tübingen, Germany
| | - Shuai Tao
- Dalian Key Laboratory of Smart Medical and Health, Dalian University, Dalian, 116622, China
| | - Hiroo Terasi
- Department of Neurology, Tokyo Medical University, Tokyo, Japan
| | - Diego Torres-Russotto
- Department of Neurological Sciences, University of Nebraska Medical Center, Omaha, USA
| | - Brittany Travers
- Department of Kinesiology and Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Jaimie A Roper
- School of Kinesiology, Auburn University, Auburn, AL, USA
| | - Mario Manto
- Unité Des Ataxies Cérébelleuses, Department of Neurology, CHU de Charleroi, Charleroi, Belgium.,Service Des Neurosciences, University of Mons, UMons, Mons, Belgium
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7
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Curthoys IS, Smith PF, de Miguel AR. Why Should Constant Stimulation of Saccular Afferents Modify the Posture and Gait of Patients with Bilateral Vestibular Dysfunction? The Saccular Substitution Hypothesis. J Clin Med 2022; 11:jcm11041132. [PMID: 35207405 PMCID: PMC8874433 DOI: 10.3390/jcm11041132] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 02/18/2022] [Accepted: 02/19/2022] [Indexed: 02/01/2023] Open
Abstract
An ongoing EU Horizon 2020 Project called BionicVEST is investigating the effect of constant electrical stimulation (ES) of the inferior vestibular nerve in patients with bilateral vestibular dysfunction (BVD). The evidence is that constant ES results in improved postural stability and gait performance, and so the question of central importance concerns how constant ES of mainly saccular afferents in these BVD patients could cause this improved performance. We suggest that the constant ES substitutes for the absent saccular neural input to the vestibular nuclei and the cerebellum in these BVD patients and indirectly via these structures to other structures, which have been of great recent interest in motor control. One target area, the anterior midline cerebellum (the uvula), has recently been targeted as a location for deep-brain stimulation in human patients to improve postural stability and gait. There are projections from midline cerebellum to basal ganglia, including the striatum, which are structures involved in the initiation of gait. It may be that the effect of this activation of peripheral saccular afferent neurons is analogous to the effect of deep-brain stimulation (DBS) by electrodes in basal ganglia acting to help alleviate the symptoms of patients with Parkinson’s disease.
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Affiliation(s)
- Ian S. Curthoys
- Vestibular Research Laboratory, School of Psychology, The University of Sydney, Sydney, NSW 2006, Australia
- Correspondence:
| | - Paul F. Smith
- Department of Pharmacology and Toxicology, School of Biomedical Sciences, University of Otago, Dunedin 9016, New Zealand;
- The Brain Health Research Centre, University of Otago, Dunedin 9016, New Zealand
| | - Angel Ramos de Miguel
- Department of Otolaryngology, and Head and Neck Surgery, Complejo Hospitalario Universitario Insular Materno Infantil de Gran Canaria, 35016 Las Palmas de Gran Canaria, Spain;
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8
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Elliott KL, Kersigo J, Lee JH, Yamoah EN, Fritzsch B. Sustained Loss of Bdnf Affects Peripheral but Not Central Vestibular Targets. Front Neurol 2021; 12:768456. [PMID: 34975728 PMCID: PMC8716794 DOI: 10.3389/fneur.2021.768456] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/25/2021] [Indexed: 11/13/2022] Open
Abstract
The vestibular system is vital for proper balance perception, and its dysfunction contributes significantly to fall-related injuries, especially in the elderly. Vestibular ganglion neurons innervate vestibular hair cells at the periphery and vestibular nuclei and the uvula and nodule of the cerebellum centrally. During aging, these vestibular ganglion neurons degenerate, impairing vestibular function. A complete understanding of the molecular mechanisms involved in neurosensory cell survival in the vestibular system is unknown. Brain-derived neurotrophic factor (BDNF) is specifically required for the survival of vestibular ganglion neurons, as its loss leads to early neuronal death. Bdnf null mice die within 3 weeks of birth, preventing the study of the long-term effects on target cells. We use Pax2-cre to conditionally knock out Bdnf, allowing mice survival to approximately 6 months of age. We show that a long-term loss of Bdnf leads to a significant reduction in the number of vestibular ganglion neurons and a reduction in the number of vestibular hair cells. There was no significant decrease in the central targets lateral vestibular nucleus (LVN) or the cerebellum at 6 months. This suggests that the connectivity between central target cells and other neurons suffices to prevent their loss despite vestibular hair cell and ganglion neuron loss. Whether the central neurons would undergo eventual degeneration in the absence of Bdnf remains to be determined.
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Affiliation(s)
- Karen L. Elliott
- Department of Biology, University of Iowa, Iowa City, IA, United States
| | - Jennifer Kersigo
- Department of Biology, University of Iowa, Iowa City, IA, United States
| | - Jeong Han Lee
- Department of Physiology, School of Medicine, University of Nevada, Reno, NV, United States
| | - Ebenezer N. Yamoah
- Department of Physiology, School of Medicine, University of Nevada, Reno, NV, United States
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, United States
- Department of Otolaryngology, University of Iowa, Iowa City, IA, United States
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9
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Kharlamova A, Proshchina A, Gulimova V, Krivova Y, Soldatov P, Saveliev S. Cerebellar morphology and behavioural correlations of the vestibular function alterations in weightlessness. Neurosci Biobehav Rev 2021; 126:314-328. [PMID: 33766673 DOI: 10.1016/j.neubiorev.2021.03.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 01/11/2021] [Accepted: 03/10/2021] [Indexed: 11/25/2022]
Abstract
In humans and other vertebrates, the range of disturbances and behavioural changes induced by spaceflight conditions are well known. Sensory organs and the central nervous system (CNS) are forced to adapt to new environmental conditions of weightlessness. In comparison with peripheral vestibular organs and behavioural disturbances in weightlessness conditions, the CNS vestibular centres of vertebrates, including the cerebellum, have been poorly examined in orbital experiments, as well as in experimental micro- and hypergravity. However, the cerebellum serves as a critical control centre for learning and sensory system integration during space-flight. Thus, it is referred to as a principal brain structure for adaptation to gravity and the entire sensorimotor adaptation and learning during weightlessness. This paper is focused on the prolonged spaceflight effects on the vestibular cerebellum evidenced from animal models used in the Bion-M1 project. The changes in the peripheral vestibular apparatus and brainstem primary vestibular centres with appropriate behavioural disorders after altered gravity exposure are briefly reviewed. The cerebellum studies in space missions and altered gravity are discussed.
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Affiliation(s)
- Anastasia Kharlamova
- Research Institute of Human Morphology, 117418, Tsyurupy St., 3, Moscow, Russia.
| | | | - Victoria Gulimova
- Research Institute of Human Morphology, 117418, Tsyurupy St., 3, Moscow, Russia
| | - Yulia Krivova
- Research Institute of Human Morphology, 117418, Tsyurupy St., 3, Moscow, Russia
| | - Pavel Soldatov
- State Scientific Center of Russian Federation Institute of Biomedical Problems of the Russian Academy of Sciences, 123007, Khoroshevskoyoe Shosse, 76A, Moscow, Russia
| | - Sergey Saveliev
- Research Institute of Human Morphology, 117418, Tsyurupy St., 3, Moscow, Russia
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Barmack NH, Pettorossi VE. Adaptive Balance in Posterior Cerebellum. Front Neurol 2021; 12:635259. [PMID: 33767662 PMCID: PMC7985352 DOI: 10.3389/fneur.2021.635259] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/16/2021] [Indexed: 11/26/2022] Open
Abstract
Vestibular and optokinetic space is represented in three-dimensions in vermal lobules IX-X (uvula, nodulus) and hemisphere lobule X (flocculus) of the cerebellum. Vermal lobules IX-X encodes gravity and head movement using the utricular otolith and the two vertical semicircular canals. Hemispheric lobule X encodes self-motion using optokinetic feedback about the three axes of the semicircular canals. Vestibular and visual adaptation of this circuitry is needed to maintain balance during perturbations of self-induced motion. Vestibular and optokinetic (self-motion detection) stimulation is encoded by cerebellar climbing and mossy fibers. These two afferent pathways excite the discharge of Purkinje cells directly. Climbing fibers preferentially decrease the discharge of Purkinje cells by exciting stellate cell inhibitory interneurons. We describe instances adaptive balance at a behavioral level in which prolonged vestibular or optokinetic stimulation evokes reflexive eye movements that persist when the stimulation that initially evoked them stops. Adaptation to prolonged optokinetic stimulation also can be detected at cellular and subcellular levels. The transcription and expression of a neuropeptide, corticotropin releasing factor (CRF), is influenced by optokinetically-evoked olivary discharge and may contribute to optokinetic adaptation. The transcription and expression of microRNAs in floccular Purkinje cells evoked by long-term optokinetic stimulation may provide one of the subcellular mechanisms by which the membrane insertion of the GABAA receptors is regulated. The neurosteroids, estradiol (E2) and dihydrotestosterone (DHT), influence adaptation of vestibular nuclear neurons to electrically-induced potentiation and depression. In each section of this review, we discuss how adaptive changes in the vestibular and optokinetic subsystems of lobule X, inferior olivary nuclei and vestibular nuclei may contribute to the control of balance.
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Affiliation(s)
- Neal H. Barmack
- Department of Physiology & Pharmacology, Oregon Health & Science University, Portland, OR, United States
| | - Vito Enrico Pettorossi
- Section of Human Physiology and Biochemistry, Department of Experimental Medicine, University of Perugia, Perugia, Italy
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11
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Ren P, Li B, Dong S, Lyu B, Qu J, Gong S, Zhang Q, Han P. The real identity and sensory overlap mechanism of special vestibular afferent neurons that sense both rotation and linear force. Life Sci 2020; 259:118144. [PMID: 32755624 DOI: 10.1016/j.lfs.2020.118144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 07/12/2020] [Accepted: 07/21/2020] [Indexed: 10/23/2022]
Abstract
AIMS Although the vestibular system has been widely investigated over the past 50 years, there is still an unsolved mystery. Some special vestibular afferent (SVA) neurons responding to both rotation and linear force were found through neurophysiological techniques, however, the sensory overlap mechanism of SVA neurons is still unclear, which may be closely related to vestibular-related diseases. MATERIALS AND METHODS To address the above-mentioned problem, a cupula buoyancy theory was established in the present study, where SVA neurons were considered semicircular canal afferent (SCCA) neurons. Then labyrinth anatomy and neural response dynamics of vestibular afferent neurons in chinchilla were investigated through vestibular labyrinth reconstruction and single unit recording technique, respectively. KEY FINDINGS We analyzed the deflections of cupulae under multiple conditions with the help of Amira Software and predicted the neural response law of SCCA neurons to linear force based on the cupula buoyancy theory. Data analysis confirmed that the basic response characteristic of SVA neurons had no significant difference to those of SCCA neurons, but were significantly different from those of otolith afferent neurons. Further, the actual responses of SVA neurons to linear force are completely consistent with our predictions. These results strongly suggest that SVA neurons actually are SCCA neurons, and the cupula buoyancy theory is the key to the sensory overlap mechanism of SCCA neurons. SIGNIFICANCE Our study revealed the real identity of SVA neurons and provided a reasonable mechanism for sensory overlap of rotation and linear force, which improved our understanding about the vestibular system.
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Affiliation(s)
- Pengyu Ren
- Department of Neurosurgery, The Second Affiliated Hospital of Xi'an Jiaotong University, 157 West 5th Road, Xi'an, Shaanxi 710004, China; Departments of Otolaryngology-Head & Neck Surgery, Johns Hopkins University School of Medicine, 720 Rutland Ave, Baltimore, MD 21205, USA
| | - Bowen Li
- Division of Health Sciences Informatics, Johns Hopkins University School of Medicine, 2024 E Monument St, Baltimore, MD 21205, USA
| | - Shiyao Dong
- Departments of Otolaryngology-Head & Neck Surgery, Johns Hopkins University School of Medicine, 720 Rutland Ave, Baltimore, MD 21205, USA
| | - Boqiang Lyu
- Department of Neurosurgery, The Second Affiliated Hospital of Xi'an Jiaotong University, 157 West 5th Road, Xi'an, Shaanxi 710004, China
| | - Jianqiang Qu
- Department of Neurosurgery, The Second Affiliated Hospital of Xi'an Jiaotong University, 157 West 5th Road, Xi'an, Shaanxi 710004, China
| | - Shouping Gong
- Department of Neurosurgery, The Second Affiliated Hospital of Xi'an Jiaotong University, 157 West 5th Road, Xi'an, Shaanxi 710004, China
| | - Qing Zhang
- Department of Otolaryngology-Head & Neck Surgery, Xinhua Hospital of Shanghai Jiaotong University, 1665 Kongjiang Rd, Shanghai 200093, China
| | - Peng Han
- Department of Otolaryngology-Head & Neck Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, 227 Yanta West Roud, Xi'an, Shaanxi 710061, China.
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12
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Schmidt H, Fritzsch B. Npr2 null mutants show initial overshooting followed by reduction of spiral ganglion axon projections combined with near-normal cochleotopic projection. Cell Tissue Res 2019; 378:15-32. [PMID: 31201541 PMCID: PMC7243364 DOI: 10.1007/s00441-019-03050-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 05/20/2019] [Indexed: 12/19/2022]
Abstract
Npr2 (natriuretic peptide receptor 2) affects bifurcation of neural crest or placode-derived afferents upon entering the brain stem/spinal cord, leading to a lack of either rostral or caudal branches. Previous work has shown that early embryonic growth of cochlear and vestibular afferents is equally affected in this mutant but later work on postnatal Npr2 point mutations suggested some additional effects on the topology of afferent projections and mild functional defects. Using multicolor lipophilic dye tracing, we show that absence of Npr2 has little to no effect on the initial patterning of inner ear afferents with respect to their dorsoventral cochleotopic-specific projections. However, in contrast to control animals, we found a variable degree of embryonic extension of auditory afferents beyond the boundaries of the anterior cochlear nucleus into the cerebellum that emanates only from apical spiral ganglion neurons. Such expansion has previously only been reported for Hox gene mutants and implies an unclear interaction of Hox codes with Npr2-mediated afferent projection patterning to define boundaries. Some vestibular ganglion neurons expand their projections to reach the cochlear apex and the cochlear nuclei, comparable to previous findings in Neurod1 mutant mice. Before birth, such expansions are reduced or lost leading to truncated projections to the anteroventral cochlear nucleus and expansion of low-frequency fibers of the apex to the posteroventral cochlear nucleus.
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Affiliation(s)
- Hannes Schmidt
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Bernd Fritzsch
- Department of Biology & Department of Otolaryngology, CLAS, University of Iowa, 128 Jefferson Avenue, Iowa City, IA, 52242, USA.
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Duncan JS, Fritzsch B, Houston DW, Ketchum EM, Kersigo J, Deans MR, Elliott KL. Topologically correct central projections of tetrapod inner ear afferents require Fzd3. Sci Rep 2019; 9:10298. [PMID: 31311957 PMCID: PMC6635624 DOI: 10.1038/s41598-019-46553-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 06/29/2019] [Indexed: 12/27/2022] Open
Abstract
Inner ear sensory afferent connections establish sensory maps between the inner ear hair cells and the vestibular and auditory nuclei to allow vestibular and sound information processing. While molecular guidance of sensory afferents to the periphery has been well studied, molecular guidance of central projections from the ear is only beginning to emerge. Disorganized central projections of spiral ganglion neurons in a Wnt/PCP pathway mutant, Prickle1, suggest the Wnt/PCP pathway plays a role in guiding cochlear afferents to the cochlear nuclei in the hindbrain, consistent with known expression of the Wnt receptor, Frizzled3 (Fzd3) in inner ear neurons. We therefore investigated the role of Wnt signaling in central pathfinding in Fzd3 mutant mice and Fzd3 morpholino treated frogs and found aberrant central projections of vestibular afferents in both cases. Ear transplantations from knockdown to control Xenopus showed that it is the Fzd3 expressed within the ear that mediates this guidance. Also, cochlear afferents of Fzd3 mutant mice lack the orderly topological organization observed in controls. Quantification of Fzd3 expression in spiral ganglion neurons show a gradient of expression with Fzd3 being higher in the apex than in the base. Together, these results suggest that a gradient of Fzd3 in inner ear afferents directs projections to the correct dorsoventral column within the hindbrain.
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Affiliation(s)
- Jeremy S Duncan
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, USA
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | | | - Elizabeth M Ketchum
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, USA
| | | | - Michael R Deans
- Department of Surgery, Division of Otolaryngology, and Department of Neurobiology & Anatomy, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Karen L Elliott
- Department of Biology, University of Iowa, Iowa City, IA, USA.
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Balmer TS, Trussell LO. Selective targeting of unipolar brush cell subtypes by cerebellar mossy fibers. eLife 2019; 8:44964. [PMID: 30994458 PMCID: PMC6469928 DOI: 10.7554/elife.44964] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 03/12/2019] [Indexed: 01/26/2023] Open
Abstract
In vestibular cerebellum, primary afferents carry signals from single vestibular end organs, whereas secondary afferents from vestibular nucleus carry integrated signals. Selective targeting of distinct mossy fibers determines how the cerebellum processes vestibular signals. We focused on vestibular projections to ON and OFF classes of unipolar brush cells (UBCs), which transform single mossy fiber signals into long-lasting excitation or inhibition respectively, and impact the activity of ensembles of granule cells. To determine whether these contacts are indeed selective, connectivity was traced back from UBC to specific ganglion cell, hair cell and vestibular organ subtypes in mice. We show that a specialized subset of primary afferents contacts ON UBCs, but not OFF UBCs, while secondary afferents contact both subtypes. Striking anatomical differences were observed between primary and secondary afferents, their synapses, and the UBCs they contact. Thus, each class of UBC functions to transform specific signals through distinct anatomical pathways. While out jogging, you have no trouble keeping your eyes fixed on objects in the distance even though your head and eyes are moving with every step. Humans owe this stability of the visual world partly to a region of the brain called the vestibular cerebellum. From its position underneath the rest of the brain, the vestibular cerebellum detects head motion and then triggers compensatory movements to stabilize the head, body and eyes. The vestibular cerebellum receives sensory input from the body via direct and indirect routes. The direct input comes from five structures within the inner ear, each of which detects movement of the head in one particular direction. The indirect input travels to the cerebellum via the brainstem, which connects the brain with the spinal cord. The indirect input contains information on head movements in multiple directions combined with input from other senses such as vision. By studying the mouse brain, Balmer and Trussell have now mapped the direct and indirect circuits that carry sensory information to the vestibular cerebellum. Both types of input activate cells within the vestibular cerebellum called unipolar brush cells (UBCs). There are two types of UBCs: ON and OFF. Direct sensory input from the inner ear activates only ON UBCs. These cells respond to the arrival of sensory input by increasing their activity. Indirect input from the brainstem activates both ON UBCs and OFF UBCs. The latter respond to the input by decreasing their activity. The vestibular cerebellum thus processes direct and indirect inputs via segregated pathways containing different types of UBCs. The next step in understanding how the cerebellum maintains a stable visual world is to identify the circuitry beyond the UBCs. Understanding these circuits will ultimately provide insights into balance disorders, such as vertigo.
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Affiliation(s)
- Timothy S Balmer
- Vollum Institute and Oregon Hearing Research Center, Oregon Health and Science University, Portland, United States
| | - Laurence O Trussell
- Vollum Institute and Oregon Hearing Research Center, Oregon Health and Science University, Portland, United States
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15
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Powles-Glover N, Maconochie M. Prenatal and postnatal development of the mammalian ear. Birth Defects Res 2017; 110:228-245. [DOI: 10.1002/bdr2.1167] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 10/16/2017] [Accepted: 10/28/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Nicola Powles-Glover
- AstraZeneca, Innovative Medicines and Early Development; Drug Safety and Metabolism; Hertfordshire SG8 6HB United Kingdom
| | - Mark Maconochie
- Queen Mary University of London; London E1 4NS United Kingdom
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16
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17
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Barmack NH, Yakhnitsa V. Climbing fibers mediate vestibular modulation of both "complex" and "simple spikes" in Purkinje cells. THE CEREBELLUM 2016; 14:597-612. [PMID: 26424151 DOI: 10.1007/s12311-015-0725-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Climbing and mossy fibers comprise two distinct afferent paths to the cerebellum. Climbing fibers directly evoke a large multispiked action potential in Purkinje cells termed a "complex spike" (CS). By logical exclusion, the other class of Purkinje cell action potential, termed "simple spike" (SS), has often been attributed to activity conveyed by mossy fibers and relayed to Purkinje cells through granule cells. Here, we investigate the relative importance of climbing and mossy fiber pathways in modulating neuronal activity by recording extracellularly from Purkinje cells, as well as from mossy fiber terminals and interneurons in folia 8-10. Sinusoidal roll-tilt vestibular stimulation vigorously modulates the discharge of climbing and mossy fiber afferents, Purkinje cells, and interneurons in folia 9-10 in anesthetized mice. Roll-tilt onto the side ipsilateral to the recording site increases the discharge of both climbing fibers (CSs) and mossy fibers. However, the discharges of SSs decrease during ipsilateral roll-tilt. Unilateral microlesions of the beta nucleus (β-nucleus) of the inferior olive blocks vestibular modulation of both CSs and SSs in contralateral Purkinje cells. The blockage of SSs occurs even though primary and secondary vestibular mossy fibers remain intact. When mossy fiber afferents are damaged by a unilateral labyrinthectomy (UL), vestibular modulation of SSs in Purkinje cells ipsilateral to the UL remains intact. Two inhibitory interneurons, Golgi and stellate cells, could potentially contribute to climbing fiber-induced modulation of SSs. However, during sinusoidal roll-tilt, only stellate cells discharge appropriately out of phase with the discharge of SSs. Golgi cells discharge in phase with SSs. When the vestibularly modulated discharge is blocked by a microlesion of the inferior olive, the modulated discharge of CSs and SSs is also blocked. When the vestibular mossy fiber pathway is destroyed, vestibular modulation of ipsilateral CSs and SSs persists. We conclude that climbing fibers are primarily responsible for the vestibularly modulated discharge of both CSs and SSs. Modulation of the discharge of SSs is likely caused by climbing fiber-evoked stellate cell inhibition.
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Affiliation(s)
- N H Barmack
- Department of Physiology and Pharmacology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.
| | - V Yakhnitsa
- Department of Physiology and Pharmacology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA
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18
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Bohuslavova R, Dodd N, Macova I, Chumak T, Horak M, Syka J, Fritzsch B, Pavlinkova G. Pax2-Islet1 Transgenic Mice Are Hyperactive and Have Altered Cerebellar Foliation. Mol Neurobiol 2016; 54:1352-1368. [PMID: 26843111 PMCID: PMC5310572 DOI: 10.1007/s12035-016-9716-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 01/12/2016] [Indexed: 12/18/2022]
Abstract
The programming of cell fate by transcription factors requires precise regulation of their time and level of expression. The LIM-homeodomain transcription factor Islet1 (Isl1) is involved in cell-fate specification of motor neurons, and it may play a similar role in the inner ear. In order to study its role in the regulation of vestibulo-motor development, we investigated a transgenic mouse expressing Isl1 under the Pax2 promoter control (Tg+/−). The transgenic mice show altered level, time, and place of expression of Isl1 but are viable. However, Tg+/− mice exhibit hyperactivity, including circling behavior, and progressive age-related decline in hearing, which has been reported previously. Here, we describe the molecular and morphological changes in the cerebellum and vestibular system that may cause the hyperactivity of Tg+/− mice. The transgene altered the formation of folia in the cerebellum, the distribution of calretinin labeled unipolar brush cells, and reduced the size of the cerebellum, inferior colliculus, and saccule. Age-related progressive reduction of calbindin expression was detected in Purkinje cells in the transgenic cerebella. The hyperactivity of Tg+/− mice is reduced upon the administration of picrotoxin, a non-competitive channel blocker for the γ-aminobutyric acid (GABA) receptor chloride channels. This suggests that the overexpression of Isl1 significantly affects the functions of GABAergic neurons. We demonstrate that the overexpression of Isl1 affects the development and function of the cerebello-vestibular system, resulting in hyperactivity.
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Affiliation(s)
- Romana Bohuslavova
- Institute of Biotechnology CAS, Prumyslova 595, Vestec, Prague-West District, 25242, Czech Republic
| | - Nicole Dodd
- Institute of Biotechnology CAS, Prumyslova 595, Vestec, Prague-West District, 25242, Czech Republic
| | - Iva Macova
- Institute of Biotechnology CAS, Prumyslova 595, Vestec, Prague-West District, 25242, Czech Republic
| | - Tetyana Chumak
- Institute of Experimental Medicine CAS, Prague, Czech Republic
| | - Martin Horak
- Institute of Physiology CAS, Prague, Czech Republic
| | - Josef Syka
- Institute of Experimental Medicine CAS, Prague, Czech Republic
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - Gabriela Pavlinkova
- Institute of Biotechnology CAS, Prumyslova 595, Vestec, Prague-West District, 25242, Czech Republic.
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19
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Fritzsch B, Duncan JS, Kersigo J, Gray B, Elliott KL. Neuroanatomical Tracing Techniques in the Ear: History, State of the Art, and Future Developments. Methods Mol Biol 2016; 1427:243-62. [PMID: 27259931 PMCID: PMC4993453 DOI: 10.1007/978-1-4939-3615-1_14] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The inner ear has long been at the cutting edge of tract tracing techniques that have shaped and reshaped our understanding of the ear's innervation patterns. This review provides a historical framework to understand the importance of these techniques for ear innervation and for development of tracing techniques in general; it is hoped that lessons learned will help to quickly adopt transformative novel techniques and their information and correct past beliefs based on technical limitations. The technical part of the review presents details of our protocol as developed over the last 30 years. We also include arguments as to why these recommendations work best to generate the desired outcome of distinct fiber and cell labeling, and generate reliable data for any investigation. We specifically focus on two tracing techniques, in part developed and/or championed for ear innervation analysis: the low molecular multicolor dextran amine tract tracing technique and the multicolor tract tracing technique with lipophilic dyes.
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Affiliation(s)
- Bernd Fritzsch
- Department of Biology, CLAS, University of Iowa, 356 Medical Research Center, Iowa City, IA, 52242, USA.
| | - Jeremy S Duncan
- Division of Otolaryngology, University of Utah, Salt Lake City, UT, USA
| | - Jennifer Kersigo
- Department of Biology, CLAS, University of Iowa, 356 Medical Research Center, Iowa City, IA, 52242, USA
| | - Brian Gray
- Molecular Targeting Technologies, Inc., West Chester, PA, USA
| | - Karen L Elliott
- Department of Biology, CLAS, University of Iowa, 356 Medical Research Center, Iowa City, IA, 52242, USA
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20
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Beh SC, Frohman TC, Frohman EM. Neuro-ophthalmic Manifestations of Cerebellar Disease. Neurol Clin 2014; 32:1009-80. [DOI: 10.1016/j.ncl.2014.07.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Shin C Beh
- Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Teresa C Frohman
- Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Elliot M Frohman
- Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA; Department of Ophthalmology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.
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21
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Kitama T, Komagata J, Ozawa K, Suzuki Y, Sato Y. Plane-specific Purkinje cell responses to vertical head rotations in the cat cerebellar nodulus and uvula. J Neurophysiol 2014; 112:644-59. [DOI: 10.1152/jn.00029.2014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We recorded simple spike (SS) and complex spike (CS) firing of Purkinje cell in the cerebellar nodulus and uvula of awake, head-restrained cats during sinusoidal vertical rotation of the head in four stimulus planes (pitch, roll, and two vertical canal planes). Two SS response types (position- and velocity-types) with response phases close to those of head position and velocity, respectively, were recognized. Optimal response planes and directions for SS and CS of each cell were estimated from the response amplitudes in the four stimulus planes by fitting with a sinusoidal function. The principal findings are as follows: 1) two rostrocaudally oriented functional zones of Purkinje cells can be distinguished; 2) the medially located parasagittal band is active during rotation in the pitch plane; 3) the laterally located band is active during rotation in the roll plane. These two zones are the same as previously reported zones in the cerebellar flocculus active during head rotation in the canal planes in the point that both cerebellar sagittal zones are plane-specific functional zones, suggesting that the anatomical sagittal zones serve as functional plane-specific zones at least in the vestibulocerebellum.
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Affiliation(s)
- Toshihiro Kitama
- Center for Life Science Research, University of Yamanashi, Yamanashi, Japan
| | - Junya Komagata
- Center for Life Science Research, University of Yamanashi, Yamanashi, Japan
| | - Kenichi Ozawa
- Department of Occupational Therapy, Health Science University, Yamanashi, Japan
| | - Yutaka Suzuki
- Center for Life Science Research, University of Yamanashi, Yamanashi, Japan
| | - Yu Sato
- Department of Physiology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan; and
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22
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Yang T, Bassuk AG, Stricker S, Fritzsch B. Prickle1 is necessary for the caudal migration of murine facial branchiomotor neurons. Cell Tissue Res 2014; 357:549-61. [PMID: 24927917 DOI: 10.1007/s00441-014-1925-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Accepted: 05/15/2014] [Indexed: 12/20/2022]
Abstract
Facial branchiomotor neurons (FBMs) of vertebrates typically develop in rhombomere 4 (r4), and in mammals and several other vertebrate taxa, migrate caudally into r6 and subsequently laterally and ventrally to the pial surface. How similar or dissimilar these migratory processes between species are at a molecular level remains unclear. In zebrafish and mouse, mutations in certain PCP genes disrupt normal caudal migration of FBMs. Zebrafish prickle1a (prickle-like 1a) and prickle1b, two orthologs of Prickle1, act non-cell-autonomously and cell-autonomously, respectively, to regulate FBM migration. Here, we show that, in Prickle1 (C251X/C251X) mice which have reduced Prickle1 expression, the caudal migration of FBMs is affected. Most FBM neurons do not migrate caudally along the floor plate. However, some neurons perform limited caudal migration such that the neurons eventually lie near the pial surface from r4 to anterior r6. FBMs in Prickle1 (C251X/C251X) mice survive until P0 and form an ectopic nucleus dorsal to the olivo-cochlear efferents of r4. Ror2, which modifies the PCP pathway in other systems, is expressed by the migrating mouse FBMs, but is not required for FBM caudal migration. Our results suggest that, in mice, Prickle1 is part of a molecular mechanism that regulates FBM caudal migration and separates the FBM and the olivo-cochlear efferents. This defective caudal migration of FBMs in Prickle1C251X mutants resembles Vangl2 mutant defects. In contrast to other developing systems that show similar defects in Prickle1, Wnt5a and Ror2, the latter two only have limited or no effect on FBM caudal migration.
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Affiliation(s)
- Tian Yang
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA
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23
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Straka H, Fritzsch B, Glover JC. Connecting ears to eye muscles: evolution of a 'simple' reflex arc. BRAIN, BEHAVIOR AND EVOLUTION 2014; 83:162-75. [PMID: 24776996 DOI: 10.1159/000357833] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 12/05/2013] [Indexed: 11/19/2022]
Abstract
Developmental and evolutionary data from vertebrates are beginning to elucidate the origin of the sensorimotor pathway that links gravity and motion detection to image-stabilizing eye movements--the vestibulo-ocular reflex (VOR). Conserved transcription factors coordinate the development of the vertebrate ear into three functional sensory compartments (graviception/translational linear acceleration, angular acceleration and sound perception). These sensory components connect to specific populations of vestibular and auditory projection neurons in the dorsal hindbrain through undetermined molecular mechanisms. In contrast, a molecular basis for the patterning of the vestibular projection neurons is beginning to emerge. These are organized through the actions of rostrocaudally and dorsoventrally restricted transcription factors into a 'hodological mosaic' within which coherent and largely segregated subgroups are specified to project to different targets in the spinal cord and brain stem. A specific set of these regionally diverse vestibular projection neurons functions as the central element that transforms vestibular sensory signals generated by active and passive head and body movements into motor output through the extraocular muscles. The large dynamic range of motion-related sensory signals requires an organization of VOR pathways as parallel, frequency-tuned, hierarchical connections from the sensory periphery to the motor output. We suggest that eyes, ears and functional connections subserving the VOR are vertebrate novelties that evolved into a functionally coherent motor control system in an almost stereotypic organization across vertebrate taxa.
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Affiliation(s)
- Hans Straka
- Department of Biology II, Ludwig Maximilians University Munich, Planegg, Germany
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Mahmoud A, Reed C, Maklad A. Central projections of lagenar primary neurons in the chick. J Comp Neurol 2014; 521:3524-40. [PMID: 23749554 DOI: 10.1002/cne.23369] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 05/06/2013] [Accepted: 05/23/2013] [Indexed: 12/19/2022]
Abstract
Perception of linear acceleration and head position is the function of the utricle and saccule in mammals. Nonmammalian vertebrates possess a third otolith endorgan, the macula lagena. Different functions have been ascribed to the lagena in arboreal birds, including hearing, equilibrium, homing behavior, and magnetoreception. However, no conclusive evidence on the function of the lagena in birds is currently available. The present study is aimed at providing a neuroanatomical substrate for the function of the lagena in the chicken as an example of terrestrial birds. The afferents from the lagena of chick embryos (E19) to the brainstem and cerebellum were investigated by the sensitive lipophilic tracer Neuro Vue Red in postfixed ears. The results revealed that all the main vestibular nuclei, including the tangential nucleus, received lagenar projections. No lagenar terminals were found in auditory centers, including the cochlear nuclei. In the cerebellum, the labeled terminals were found variably in all of the cerebellar nuclei. In the cerebellar cortex, the labeled fibers were found mostly in the uvula, with fewer afferents in the flocculus and paraflocculus. None was seen in the nodulus. The absence of lagenar afferent projections in auditory nuclei and the presence of a projection pattern in the vestibular nuclei and cerebellum similar to that of the utricle and saccule suggest that the primary role of the lagena in the chick lies in the processing of vestibular information related to linear acceleration and static head position.
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Affiliation(s)
- Amany Mahmoud
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi, 39216
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25
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Jamon M. The development of vestibular system and related functions in mammals: impact of gravity. Front Integr Neurosci 2014; 8:11. [PMID: 24570658 PMCID: PMC3916785 DOI: 10.3389/fnint.2014.00011] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 01/20/2014] [Indexed: 12/12/2022] Open
Abstract
This chapter reviews the knowledge about the adaptation to Earth gravity during the development of mammals. The impact of early exposure to altered gravity is evaluated at the level of the functions related to the vestibular system, including postural control, homeostatic regulation, and spatial memory. The hypothesis of critical periods in the adaptation to gravity is discussed. Demonstrating a critical period requires removing the gravity stimulus during delimited time windows, what is impossible to do on Earth surface. The surgical destruction of the vestibular apparatus, and the use of mice strains with defective graviceptors have provided useful information on the consequences of missing gravity perception, and the possible compensatory mechanisms, but transitory suppression of the stimulus can only be operated during spatial flight. The rare studies on rat pups housed on board of space shuttle significantly contributed to this problem, but the use of hypergravity environment, produced by means of chronic centrifugation, is the only available tool when repeated experiments must be carried out on Earth. Even though hypergravity is sometimes considered as a mirror situation to microgravity, the two situations cannot be confused because a gravitational force is still present. The theoretical considerations that validate the paradigm of hypergravity to evaluate critical periods are discussed. The question of adaption of graviceptor is questioned from an evolutionary point of view. It is possible that graviception is hardwired, because life on Earth has evolved under the constant pressure of gravity. The rapid acquisition of motor programming by precocial mammals in minutes after birth is consistent with this hypothesis, but the slow development of motor skills in altricial species and the plasticity of vestibular perception in adults suggest that gravity experience is required for the tuning of graviceptors. The possible reasons for this dichotomy are discussed.
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Affiliation(s)
- Marc Jamon
- Faculté de Médecine de la Timone, Institut National de la Santé et de la Recherche Médicale U 1106, Aix-Marseille University Marseille, France
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26
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Spatiotemporal properties of optic flow and vestibular tuning in the cerebellar nodulus and uvula. J Neurosci 2013; 33:15145-60. [PMID: 24048845 DOI: 10.1523/jneurosci.2118-13.2013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Convergence of visual motion and vestibular information is essential for accurate spatial navigation. Such multisensory integration has been shown in cortex, e.g., the dorsal medial superior temporal (MSTd) and ventral intraparietal (VIP) areas, but not in the parieto-insular vestibular cortex (PIVC). Whether similar convergence occurs subcortically remains unknown. Many Purkinje cells in vermal lobules 10 (nodulus) and 9 (uvula) of the macaque cerebellum are tuned to vestibular translation stimuli, yet little is known about their visual motion responsiveness. Here we show the existence of translational optic flow-tuned Purkinje cells, found exclusively in the anterior part of the nodulus and ventral uvula, near the midline. Vestibular responses of Purkinje cells showed a remarkable similarity to those in MSTd (but not PIVC or VIP) neurons, in terms of both response latency and relative contributions of velocity, acceleration, and position components. In contrast, the spatiotemporal properties of optic flow responses differed from those in MSTd, and matched the vestibular properties of these neurons. Compared with MSTd, optic flow responses of Purkinje cells showed smaller velocity contributions and larger visual motion acceleration responses. The remarkable similarity between the nodulus/uvula and MSTd vestibular translation responsiveness suggests a functional coupling between the two areas for vestibular processing of self-motion information.
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27
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Meng H, Blázquez PM, Dickman JD, Angelaki DE. Diversity of vestibular nuclei neurons targeted by cerebellar nodulus inhibition. J Physiol 2013; 592:171-88. [PMID: 24127616 DOI: 10.1113/jphysiol.2013.259614] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
A functional role of the cerebellar nodulus and ventral uvula (lobules X and IXc,d of the vermis) for vestibular processing has been strongly suggested by direct reciprocal connections with the vestibular nuclei, as well as direct vestibular afferent inputs as mossy fibres. Here we have explored the types of neurons in the macaque vestibular nuclei targeted by nodulus/ventral uvula inhibition using orthodromic identification from the caudal vermis. We found that all nodulus-target neurons are tuned to vestibular stimuli, and most are insensitive to eye movements. Such non-eye-movement neurons are thought to project to vestibulo-spinal and/or thalamo-cortical pathways. Less than 20% of nodulus-target neurons were sensitive to eye movements, suggesting that the caudal vermis can also directly influence vestibulo-ocular pathways. In general, response properties of nodulus-target neurons were diverse, spanning the whole continuum previously described in the vestibular nuclei. Most nodulus-target cells responded to both rotation and translation stimuli and only a few were selectively tuned to translation motion only. Other neurons were sensitive to net linear acceleration, similar to otolith afferents. These results demonstrate that, unlike the flocculus and ventral paraflocculus which target a particular cell group, nodulus/ventral uvula inhibition targets a large diversity of cell types in the vestibular nuclei, consistent with a broad functional significance contributing to vestibulo-ocular, vestibulo-thalamic and vestibulo-spinal pathways.
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Affiliation(s)
- Hui Meng
- D. Angelaki: Department of Neuroscience, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
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Laurens J, Meng H, Angelaki DE. Computation of linear acceleration through an internal model in the macaque cerebellum. Nat Neurosci 2013; 16:1701-8. [PMID: 24077562 PMCID: PMC3818145 DOI: 10.1038/nn.3530] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 09/04/2013] [Indexed: 11/18/2022]
Abstract
A combination of theory and behavioral findings has supported a role for internal models in the resolution of sensory ambiguities and sensorimotor processing. Although the cerebellum has been proposed as a candidate for implementation of internal models, concrete evidence from neural responses is lacking. Here we exploit un-natural motion stimuli, which induce incorrect self-motion perception and eye movements, to explore the neural correlates of an internal model proposed to compensate for Einstein’s equivalence principle and generate neural estimates of linear acceleration and gravity. We show that caudal cerebellar vermis Purkinje cells and cerebellar nuclei neurons selective for actual linear acceleration also encode erroneous linear acceleration, as expected from the internal model hypothesis, even when no actual linear acceleration occurs. These findings provide strong evidence that the cerebellum might be involved in the implementation of internal models that mimic physical principles to interpret sensory signals, as previously hypothesized by theorists.
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Affiliation(s)
- Jean Laurens
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri, USA
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Barmack NH, Yakhnitsa V. Modulated discharge of Purkinje and stellate cells persists after unilateral loss of vestibular primary afferent mossy fibers in mice. J Neurophysiol 2013; 110:2257-74. [PMID: 23966673 DOI: 10.1152/jn.00352.2013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cerebellar Purkinje cells are excited by two afferent pathways: climbing and mossy fibers. Climbing fibers evoke large "complex spikes" (CSs) that discharge at low frequencies. Mossy fibers synapse on granule cells whose parallel fibers excite Purkinje cells and may contribute to the genesis of "simple spikes" (SSs). Both afferent systems convey vestibular information to folia 9c-10. After making a unilateral labyrinthectomy (UL) in mice, we tested how the discharge of CSs and SSs was changed by the loss of primary vestibular afferent mossy fibers during sinusoidal roll tilt. We recorded from cells identified by juxtacellular neurobiotin labeling. The UL preferentially reduced vestibular modulation of CSs and SSs in folia 8-10 contralateral to the UL. The effects of a UL on Purkinje cell discharge were similar in folia 9c-10, to which vestibular primary afferents project, and in folia 8-9a, to which they do not project, suggesting that vestibular primary afferent mossy fibers were not responsible for the UL-induced alteration of SS discharge. UL also induced reduced vestibular modulation of stellate cell discharge contralateral to the UL. We attribute the decreased modulation to reduced vestibular modulation of climbing fibers. In summary, climbing fibers modulate CSs directly and SSs indirectly through activation of stellate cells. Whereas vestibular primary afferent mossy fibers cannot account for the modulated discharge of SSs or stellate cells, the nonspecific excitation of Purkinje cells by parallel fibers may set an operating point about which the discharges of SSs are sculpted by climbing fibers.
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Affiliation(s)
- N H Barmack
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon
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Fritzsch B, Pan N, Jahan I, Duncan JS, Kopecky BJ, Elliott KL, Kersigo J, Yang T. Evolution and development of the tetrapod auditory system: an organ of Corti-centric perspective. Evol Dev 2013; 15:63-79. [PMID: 23331918 DOI: 10.1111/ede.12015] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The tetrapod auditory system transmits sound through the outer and middle ear to the organ of Corti or other sound pressure receivers of the inner ear where specialized hair cells translate vibrations of the basilar membrane into electrical potential changes that are conducted by the spiral ganglion neurons to the auditory nuclei. In other systems, notably the vertebrate limb, a detailed connection between the evolutionary variations in adaptive morphology and the underlying alterations in the genetic basis of development has been partially elucidated. In this review, we attempt to correlate evolutionary and partially characterized molecular data into a cohesive perspective of the evolution of the mammalian organ of Corti out of the tetrapod basilar papilla. We propose a stepwise, molecularly partially characterized transformation of the ancestral, vestibular developmental program of the vertebrate ear. This review provides a framework to decipher both discrete steps in development and the evolution of unique functional adaptations of the auditory system. The combined analysis of evolution and development establishes a powerful cross-correlation where conclusions derived from either approach become more meaningful in a larger context which is not possible through exclusively evolution or development centered perspectives. Selection may explain the survival of the fittest auditory system, but only developmental genetics can explain the arrival of the fittest auditory system. [Modified after (Wagner 2011)].
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Affiliation(s)
- Bernd Fritzsch
- Department of Biology, University of Iowa, CLAS, 143 BB, Iowa City, IA, 52242, USA. bernd‐
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Reeber SL, White JJ, George-Jones NA, Sillitoe RV. Architecture and development of olivocerebellar circuit topography. Front Neural Circuits 2013; 6:115. [PMID: 23293588 PMCID: PMC3534185 DOI: 10.3389/fncir.2012.00115] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 12/12/2012] [Indexed: 11/21/2022] Open
Abstract
The cerebellum has a simple tri-laminar structure that is comprised of relatively few cell types. Yet, its internal micro-circuitry is anatomically, biochemically, and functionally complex. The most striking feature of cerebellar circuit complexity is its compartmentalized topography. Each cell type within the cerebellar cortex is organized into an exquisite map; molecular expression patterns, dendrite projections, and axon terminal fields divide the medial-lateral axis of the cerebellum into topographic sagittal zones. Here, we discuss the mechanisms that establish zones and highlight how gene expression and neural activity contribute to cerebellar pattern formation. We focus on the olivocerebellar system because its developmental mechanisms are becoming clear, its topographic termination patterns are very precise, and its contribution to zonal function is debated. This review deconstructs the architecture and development of the olivocerebellar pathway to provide an update on how brain circuit maps form and function.
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Affiliation(s)
- Stacey L Reeber
- Department of Pathology and Immunology, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital Houston, TX, USA ; Department of Neuroscience, Baylor College of Medicine, Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital Houston, TX, USA
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Voogd J, Schraa-Tam CKL, van der Geest JN, De Zeeuw CI. Visuomotor cerebellum in human and nonhuman primates. CEREBELLUM (LONDON, ENGLAND) 2012; 11:392-410. [PMID: 20809106 PMCID: PMC3359447 DOI: 10.1007/s12311-010-0204-7] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In this paper, we will review the anatomical components of the visuomotor cerebellum in human and, where possible, in non-human primates and discuss their function in relation to those of extracerebellar visuomotor regions with which they are connected. The floccular lobe, the dorsal paraflocculus, the oculomotor vermis, the uvula-nodulus, and the ansiform lobule are more or less independent components of the visuomotor cerebellum that are involved in different corticocerebellar and/or brain stem olivocerebellar loops. The floccular lobe and the oculomotor vermis share different mossy fiber inputs from the brain stem; the dorsal paraflocculus and the ansiform lobule receive corticopontine mossy fibers from postrolandic visual areas and the frontal eye fields, respectively. Of the visuomotor functions of the cerebellum, the vestibulo-ocular reflex is controlled by the floccular lobe; saccadic eye movements are controlled by the oculomotor vermis and ansiform lobule, while control of smooth pursuit involves all these cerebellar visuomotor regions. Functional imaging studies in humans further emphasize cerebellar involvement in visual reflexive eye movements and are discussed.
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Affiliation(s)
- Jan Voogd
- Department of Neuroscience, Erasmus MC, Rotterdam, the Netherlands.
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Oberdick J, Sillitoe RV. Cerebellar zones: history, development, and function. THE CEREBELLUM 2012; 10:301-6. [PMID: 21822545 DOI: 10.1007/s12311-011-0306-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The longitudinal and transverse zonal arrangement of axonal projections to and from the cerebellum, even more than the well-known laminar cytoarchitecture, is the hallmark of cerebellar anatomy. No model of cerebellar function, whether in motor control, cognition, or emotion, will be complete without understanding the development and function of zones. To this end, a special issue of this journal is dedicated to zones, and the purpose of this article is to summarize the research and review articles that are contained within. The special issue begins by considering some of the very first studies in the 1960s and 1970s that led to our modern understanding of this unique and defining anatomical substructure. Then, it considers the molecular analogs of longitudinal zones in the form of stripes in the cerebellar cortex and related sub-areas in the deep cerebellar nuclei, and it includes studies on the genetic underpinnings of stripes and zones. Several articles address the evolution of both embryonic clusters and adult zones across vertebrate species, and others discuss the functional and clinical relevance of zones. While we do not yet fully understand the role of zones with respect to motor behavior in all of its complexities, cerebellar function is clearly modular, and combinatorial models of complex motor movements based on multi-purpose modules are beginning to emerge. This special issue, by refocusing attention on this fundamental organization of the cerebellum, sets the stage for future studies that will more fully reveal the cellular, developmental, behavioral, and clinical relevance of zones.
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Affiliation(s)
- John Oberdick
- Department of Neuroscience, The Ohio State University, Columbus, OH 43210, USA.
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Microlesions of the inferior olive reduce vestibular modulation of Purkinje cell complex and simple spikes in mouse cerebellum. J Neurosci 2011; 31:9824-35. [PMID: 21734274 DOI: 10.1523/jneurosci.1738-11.2011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cerebellar Purkinje cells have two distinct action potentials: complex spikes (CSs) are evoked by single climbing fibers that originate from the contralateral inferior olive. Simple spikes (SSs) are often ascribed to mossy fiber-granule cell-parallel fiber inputs to Purkinje cells. Although generally accepted, this view lacks experimental support. Vestibular stimulation independently activates primary afferent mossy fibers and tertiary afferent climbing fibers that project to the uvula-nodulus (folia 8-10). CSs and SSs normally discharge antiphasically during sinusoidal roll-tilt. When CSs increase, SSs decrease. We tested the relative independence of these pathways in mice by making electrolytic microlesions of the two inferior olivary nuclei from which vestibular climbing fibers originate; the β-nucleus and dorsomedial cell column. This reduced vestibular climbing fiber signaling to the contralateral folia 8-10, while leaving intact vestibular primary and secondary afferent mossy fibers. We recorded from Purkinje cells and interneurons in folia 8-10, identified by juxtacellular labeling with Neurobiotin. Microlesions of the inferior olive increased the spontaneous discharge of SSs in contralateral folia 8-10, but blocked their modulation during vestibular stimulation. The vestibularly evoked discharge of excitatory cerebellar interneurons (granule cells and unipolar brush cells) was not modified by olivary microlesions. The modulated discharge of stellate cells, but not Golgi cells, was reduced by olivary microlesions. We conclude that vestibular modulation of CSs and SSs depends on intact climbing fibers. The absence of vestibularly modulated SSs following olivary microlesions reflects the loss of climbing fiber-evoked stellate cell discharge.
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Barmack NH, Yakhnitsa V. Topsy turvy: functions of climbing and mossy fibers in the vestibulo-cerebellum. Neuroscientist 2011; 17:221-36. [PMID: 21362689 DOI: 10.1177/1073858410380251] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The cerebellum's role in sensory-motor control and adaptation is undisputed. However, a key hypothesis pertaining to the function of cerebellar circuitry lacks experimental support. It is universally assumed that the discharge of mossy fibers accounts for modulation of Purkinje cell "simple spikes" (SSs). This assumption acts as a prism through which all other functions of cerebellar circuitry are viewed. The vestibulo-cerebellum (nodulus and uvula) receives a large, unilateral, vestibular primary afferent mossy fiber projection. We can test its role in modulating Purkinje cell SSs by recording the modulated activity of both mossy fiber terminals and Purkinje cell SSs evoked by identical natural vestibular stimulation. Sinusoidal rotation about the longitudinal axis (roll) modulates the activity of vestibular primary afferent mossy and climbing fibers as well as Purkinje cell SSs and complex spikes (CSs). Remarkably, vestibular primary afferent mossy fibers discharge 180 degrees out of phase with SSs. This indicates that mossy fibers cannot account for SS modulation unless an inhibitory synapse is interposed between mossy fibers or vestibular climbing fibers and Purkinje cells. The authors review several experiments that address the relative contributions of mossy and climbing fiber afferents to the modulation of SSs. They conclude that climbing fibers, not mossy fibers, are primarily responsible for the modulation of SSs as well as CSs and they propose revised functions for these two afferent systems.
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Affiliation(s)
- Neal H Barmack
- Department of Physiology & Pharmacology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
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Mugnaini E, Sekerková G, Martina M. The unipolar brush cell: a remarkable neuron finally receiving deserved attention. BRAIN RESEARCH REVIEWS 2011; 66:220-45. [PMID: 20937306 PMCID: PMC3030675 DOI: 10.1016/j.brainresrev.2010.10.001] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 10/05/2010] [Accepted: 10/05/2010] [Indexed: 12/17/2022]
Abstract
Unipolar brush cells (UBC) are small, glutamatergic neurons residing in the granular layer of the cerebellar cortex and the granule cell domain of the cochlear nuclear complex. Recent studies indicate that this neuronal class consists of three or more subsets characterized by distinct chemical phenotypes, as well as by intrinsic properties that may shape their synaptic responses and firing patterns. Yet, all UBCs have a unique morphology, as both the dendritic brush and the large endings of the axonal branches participate in the formation of glomeruli. Although UBCs and granule cells may share the same excitatory and inhibitory inputs, the two cell types are distinctively differentiated. Typically, whereas the granule cell has 4-5 dendrites that are innervated by different mossy fibers, and an axon that divides only once to form parallel fibers after ascending to the molecular layer, the UBC has but one short dendrite whose brush engages in synaptic contact with a single mossy fiber terminal, and an axon that branches locally in the granular layer; branches of UBC axons form a non-canonical, cortex-intrinsic category of mossy fibers synapsing with granule cells and other UBCs. This is thought to generate a feed-forward amplification of single mossy fiber afferent signals that would reach the overlying Purkinje cells via ascending granule cell axons and their parallel fibers. In sharp contrast to other classes of cerebellar neurons, UBCs are not distributed homogeneously across cerebellar lobules, and subsets of UBCs also show different, albeit overlapping, distributions. UBCs are conspicuously rare in the expansive lateral cerebellar areas targeted by the cortico-ponto-cerebellar pathway, while they are a constant component of the vermis and the flocculonodular lobe. The presence of UBCs in cerebellar regions involved in the sensorimotor processes that regulate body, head and eye position, as well as in regions of the cochlear nucleus that process sensorimotor information suggests a key role in these critical functions; it also invites further efforts to clarify the cellular biology of the UBCs and their specific functions in the neuronal microcircuits in which they are embedded. High density of UBCs in specific regions of the cerebellar cortex is a feature largely conserved across mammals and suggests an involvement of these neurons in fundamental aspects of the input/output organization as well as in clinical manifestation of focal cerebellar disease.
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Affiliation(s)
- Enrico Mugnaini
- Department of Cellular and Molecular Biology, The Feinberg School of Medicine of Northwestern University, Chicago, IL, USA.
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Abstract
Accurate diagnosis of abnormal eye movements depends upon knowledge of the purpose, properties, and neural substrate of distinct functional classes of eye movement. Here, we summarize current concepts of the anatomy of eye movement control. Our approach is bottom-up, starting with the extraocular muscles and their innervation by the cranial nerves. Second, we summarize the neural circuits in the pons underlying horizontal gaze control, and the midbrain connections that coordinate vertical and torsional movements. Third, the role of the cerebellum in governing and optimizing eye movements is presented. Fourth, each area of cerebral cortex contributing to eye movements is discussed. Last, descending projections from cerebral cortex, including basal ganglionic circuits that govern different components of gaze, and the superior colliculus, are summarized. At each stage of this review, the anatomical scheme is used to predict the effects of lesions on the control of eye movements, providing clinical-anatomical correlation.
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Ethanol and Vestibular Stimulation Reveal Simple and Complex Aspects of Cerebellar Heterogeneity. THE CEREBELLUM 2010; 10:475-83. [DOI: 10.1007/s12311-010-0238-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Walker MF, Tian J, Shan X, Tamargo RJ, Ying H, Zee DS. The cerebellar nodulus/uvula integrates otolith signals for the translational vestibulo-ocular reflex. PLoS One 2010; 5:e13981. [PMID: 21085587 PMCID: PMC2981566 DOI: 10.1371/journal.pone.0013981] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Accepted: 10/09/2010] [Indexed: 11/19/2022] Open
Abstract
Background The otolith-driven translational vestibulo-ocular reflex (tVOR) generates compensatory eye movements to linear head accelerations. Studies in humans indicate that the cerebellum plays a critical role in the neural control of the tVOR, but little is known about mechanisms of this control or the functions of specific cerebellar structures. Here, we chose to investigate the contribution of the nodulus and uvula, which have been shown by prior studies to be involved in the processing of otolith signals in other contexts. Methodology/Principal Findings We recorded eye movements in two rhesus monkeys during steps of linear motion along the interaural axis before and after surgical lesions of the cerebellar uvula and nodulus. The lesions strikingly reduced eye velocity during constant-velocity motion but had only a small effect on the response to initial head acceleration. We fit eye velocity to a linear combination of head acceleration and velocity and to a dynamic mathematical model of the tVOR that incorporated a specific integrator of head acceleration. Based on parameter optimization, the lesion decreased the gain of the pathway containing this new integrator by 62%. The component of eye velocity that depended directly on head acceleration changed little (gain decrease of 13%). In a final set of simulations, we compared our data to the predictions of previous models of the tVOR, none of which could account for our experimental findings. Conclusions/ Significance Our results provide new and important information regarding the neural control of the tVOR. Specifically, they point to a key role for the cerebellar nodulus and uvula in the mathematical integration of afferent linear head acceleration signals. This function is likely to be critical not only for the tVOR but also for the otolith-mediated reflexes that control posture and balance.
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Affiliation(s)
- Mark F Walker
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
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Sciarretta C, Fritzsch B, Beisel K, Rocha-Sanchez SM, Buniello A, Horn JM, Minichiello L. PLCγ-activated signalling is essential for TrkB mediated sensory neuron structural plasticity. BMC DEVELOPMENTAL BIOLOGY 2010; 10:103. [PMID: 20932311 PMCID: PMC2964534 DOI: 10.1186/1471-213x-10-103] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 10/08/2010] [Indexed: 11/10/2022]
Abstract
Background The vestibular system provides the primary input of our sense of balance and spatial orientation. Dysfunction of the vestibular system can severely affect a person's quality of life. Therefore, understanding the molecular basis of vestibular neuron survival, maintenance, and innervation of the target sensory epithelia is fundamental. Results Here we report that a point mutation at the phospholipase Cγ (PLCγ) docking site in the mouse neurotrophin tyrosine kinase receptor TrkB (Ntrk2) specifically impairs fiber guidance inside the vestibular sensory epithelia, but has limited effects on the survival of vestibular sensory neurons and growth of afferent processes toward the sensory epithelia. We also show that expression of the TRPC3 cation calcium channel, whose activity is known to be required for nerve-growth cone guidance induced by brain-derived neurotrophic factor (BDNF), is altered in these animals. In addition, we find that absence of the PLCγ mediated TrkB signalling interferes with the transformation of bouton type afferent terminals of vestibular dendrites into calyces (the largest synaptic contact of dendrites known in the mammalian nervous system) on type I vestibular hair cells; the latter are normally distributed in these mutants as revealed by an unaltered expression pattern of the potassium channel KCNQ4 in these cells. Conclusions These results demonstrate a crucial involvement of the TrkB/PLCγ-mediated intracellular signalling in structural aspects of sensory neuron plasticity.
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Affiliation(s)
- Carla Sciarretta
- European Molecular Biology Laboratory, Mouse Biology Unit, Via Ramornie 32, 00015 Monterotondo, Rome, Italy
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Angelaki DE, Yakusheva TA, Green AM, Dickman JD, Blazquez PM. Computation of egomotion in the macaque cerebellar vermis. THE CEREBELLUM 2010; 9:174-82. [PMID: 20012388 DOI: 10.1007/s12311-009-0147-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The nodulus and uvula (lobules X and IX of the vermis) receive mossy fibers from both vestibular afferents and vestibular nuclei neurons and are thought to play a role in spatial orientation. Their properties relate to a sensory ambiguity of the vestibular periphery: otolith afferents respond identically to translational (inertial) accelerations and changes in orientation relative to gravity. Based on theoretical and behavioral evidence, this sensory ambiguity is resolved using rotational cues from the semicircular canals. Recordings from the cerebellar cortex have identified a neural correlate of the brain's ability to resolve this ambiguity in the simple spike activities of nodulus/uvula Purkinje cells. This computation, which likely involves the cerebellar circuitry and its reciprocal connections with the vestibular nuclei, results from a remarkable convergence of spatially- and temporally-aligned otolith-driven and semicircular canal-driven signals. Such convergence requires a spatio-temporal transformation of head-centered canal-driven signals into an estimate of head reorientation relative to gravity. This signal must then be subtracted from the otolith-driven estimate of net acceleration to compute inertial motion. At present, Purkinje cells in the nodulus/uvula appear to encode the output of this computation. However, how the required spatio-temporal matching takes place within the cerebellar circuitry and what role complex spikes play in spatial orientation and disorientation remains unknown. In addition, the role of visual cues in driving and/or modifying simple and complex spike activity, a process potentially critical for long-term adaptation, constitutes another important direction for future studies.
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Affiliation(s)
- Dora E Angelaki
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Relationship between complex and simple spike activity in macaque caudal vermis during three-dimensional vestibular stimulation. J Neurosci 2010; 30:8111-26. [PMID: 20554862 DOI: 10.1523/jneurosci.5779-09.2010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Lobules 10 and 9 in the caudal posterior vermis [also known as nodulus and uvula (NU)] are thought important for spatial orientation and balance. Here, we characterize complex spike (CS) and simple spike (SS) activity in response to three-dimensional vestibular stimulation. The strongest modulation was seen during translation (CS: 12.8 +/- 1.5, SS: 287.0 +/- 23.2 spikes/s/G, 0.5 Hz). Preferred directions tended to cluster along the cardinal axes (lateral, fore-aft, vertical) for CSs and along the semicircular canal axes for SSs. Most notably, the preferred directions for CS/SS pairs arising from the same Purkinje cells were rarely aligned. During 0.5 Hz pitch/roll tilt, only about a third of CSs had significant modulation. Thus, most CSs correlated best with inertial rather than net linear acceleration. By comparison, all SSs were selective for translation and ignored changes in spatial orientation relative to gravity. Like SSs, tilt modulation of CSs increased at lower frequencies. CSs and SSs had similar response dynamics, responding to linear velocity during translation and angular position during tilt. The most salient finding is that CSs did not always modulate out-of-phase with SSs. The CS/SS phase difference varied broadly among Purkinje cells, yet for each cell it was precisely matched for the otolith-driven and canal-driven components of the response. These findings illustrate a spatiotemporal mismatch between CS/SS pairs and provide the first comprehensive description of the macaque NU, an important step toward understanding how CSs and SSs interact during complex movements and spatial disorientation.
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Maklad A, Kamel S, Wong E, Fritzsch B. Development and organization of polarity-specific segregation of primary vestibular afferent fibers in mice. Cell Tissue Res 2010; 340:303-21. [PMID: 20424840 PMCID: PMC2953634 DOI: 10.1007/s00441-010-0944-1] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 02/04/2010] [Indexed: 12/19/2022]
Abstract
A striking feature of vestibular hair cells is the polarized arrangement of their stereocilia as the basis for their directional sensitivity. In mammals, each of the vestibular end organs is characterized by a distinct distribution of these polarized cells. We utilized the technique of post-fixation transganglionic neuronal tracing with fluorescent lipid soluble dyes in embryonic and postnatal mice to investigate whether these polarity characteristics correlate with the pattern of connections between the endorgans and their central targets; the vestibular nuclei and cerebellum. We found that the cerebellar and brainstem projections develop independently from each other and have a non-overlapping distribution of neurons and afferents from E11.5 on. In addition, we show that the vestibular fibers projecting to the cerebellum originate preferentially from the lateral half of the utricular macula and the medial half of the saccular macula. In contrast, the brainstem vestibular afferents originate primarily from the medial half of the utricular macula and the lateral half of the saccular macula. This indicates that the line of hair cell polarity reversal within the striola region segregates almost mutually exclusive central projections. A possible interpretation of this feature is that this macular organization provides an inhibitory side-loop through the cerebellum to produce synergistic tuning effects in the vestibular nuclei. The canal cristae project to the brainstem vestibular nuclei and cerebellum, but the projection to the vestibulocerebellum originates preferentially from the superior half of each of the cristae. The reason for this pattern is not clear, but it may compensate for unequal activation of crista hair cells or may be an evolutionary atavism reflecting a different polarity organization in ancestral vertebrate ears.
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Affiliation(s)
- Adel Maklad
- Department of Anatomy, University of Mississippi Medical Center, Jackson, MS 39216, USA.
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Katayama KI, Zine A, Ota M, Matsumoto Y, Inoue T, Fritzsch B, Aruga J. Disorganized innervation and neuronal loss in the inner ear of Slitrk6-deficient mice. PLoS One 2009; 4:e7786. [PMID: 19936227 PMCID: PMC2777407 DOI: 10.1371/journal.pone.0007786] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Accepted: 10/14/2009] [Indexed: 12/24/2022] Open
Abstract
Slitrks are type I transmembrane proteins that share conserved leucine-rich repeat domains similar to those in the secreted axonal guidance molecule Slit. They also show similarities to Ntrk neurotrophin receptors in their carboxy-termini, sharing a conserved tyrosine residue. Among 6 Slitrk family genes in mammals, Slitrk6 has a unique expression pattern, with strong expression in the sensory epithelia of the inner ear. We generated Slitrk6-knockout mice and investigated the development of their auditory and vestibular sensory organs. Slitrk6-deficient mice showed pronounced reduction in the cochlear innervation. In the vestibule, the innervation to the posterior crista was often lost, reduced, or sometimes misguided. These defects were accompanied by the loss of neurons in the spiral and vestibular ganglia. Cochlear sensory epithelia from Slitrk6-knockout mice have reduced ability in promoting neurite outgrowth of spiral ganglion neurons. Indeed the Slitrk6-deficient inner ear showed a mild but significant decrease in the expression of Bdnf and Ntf3, both of which are essential for the innervation and survival of sensory neurons. In addition, the expression of Ntrk receptors, including their phosphorylated forms was decreased in Slitrk6-knockout cochlea. These results suggest that Slitrk6 promotes innervation and survival of inner ear sensory neurons by regulating the expression of trophic and/or tropic factors including neurotrophins from sensory epithelia.
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Affiliation(s)
- Kei-ichi Katayama
- Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute (BSI), Wako-shi, Saitama, Japan
| | - Azel Zine
- University of Montpellier I, Institute of Neurosciences, INSERM U583, Montpellier, France
| | - Maya Ota
- Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute (BSI), Wako-shi, Saitama, Japan
| | - Yoshifumi Matsumoto
- Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute (BSI), Wako-shi, Saitama, Japan
| | - Takashi Inoue
- Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute (BSI), Wako-shi, Saitama, Japan
| | - Bernd Fritzsch
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, Iowa, United States of America
| | - Jun Aruga
- Laboratory for Behavioral and Developmental Disorders, RIKEN Brain Science Institute (BSI), Wako-shi, Saitama, Japan
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Pan N, Jahan I, Lee JE, Fritzsch B. Defects in the cerebella of conditional Neurod1 null mice correlate with effective Tg(Atoh1-cre) recombination and granule cell requirements for Neurod1 for differentiation. Cell Tissue Res 2009; 337:407-28. [PMID: 19609565 DOI: 10.1007/s00441-009-0826-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Accepted: 06/12/2009] [Indexed: 01/19/2023]
Abstract
Neurod1 is a crucial basic helix-loop-helix gene for most cerebellar granule cells and mediates the differentiation of these cells downstream of Atoh1-mediated proliferation of the precursors. In Neurod1 null mice, granule cells die throughout the posterior two thirds of the cerebellar cortex during development. However, Neurod1 is also necessary for pancreatic beta-cell development, and therefore Neurod1 null mice are diabetic, which potentially influences cerebellar defects. Here, we report a new Neurod1 conditional knock-out mouse model created by using a Tg(Atoh1-cre) line to eliminate Neurod1 in the cerebellar granule cell precursors. Our data confirm and extend previous work on systemic Neurod1 null mice and show that, in the central lobules, granule cells can be eradicated in the absence of Neurod1. Granule cells in the anterior lobules are partially viable and depend on as yet unknown genes, but the Purkinje cells show defects not previously recognized. Interestingly, delayed and incomplete Tg(Atoh1-cre) upregulation occurs in the most posterior lobules; this leads to near normal expression of Neurod1 with a concomitant normal differentiation of granule cells, Purkinje cells, and unipolar brush cells in lobules IX and X. Our analysis suggests that Neurod1 negatively regulates Atoh1 to ensure a rapid transition from proliferative precursors to differentiating neurons. Our data have implications for research on medulloblastoma, one of the most frequent brain tumors of children, as the results suggest that targeted overexpression of Neurod1 under Atoh1 promoter control may initiate the differentiation of these tumors.
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Affiliation(s)
- Ning Pan
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, IA 52242, USA
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Frequency-selective coding of translation and tilt in macaque cerebellar nodulus and uvula. J Neurosci 2008; 28:9997-10009. [PMID: 18829957 DOI: 10.1523/jneurosci.2232-08.2008] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Spatial orientation depends critically on the brain's ability to segregate linear acceleration signals arising from otolith afferents into estimates of self-motion and orientation relative to gravity. In the absence of visual information, this ability is known to deteriorate at low frequencies. The cerebellar nodulus/uvula (NU) has been shown to participate in this computation, although its exact role remains unclear. Here, we show that NU simple spike (SS) responses also exhibit a frequency dependent selectivity to self-motion (translation) and spatial orientation (tilt). At 0.5 Hz, Purkinje cells encode three-dimensional translation and only weakly modulate during pitch and roll tilt (0.4 +/- 0.05 spikes/s/degrees/s). But this ability to selectively signal translation over tilt is compromised at lower frequencies, such that at 0.05 Hz tilt response gains average 2.0 +/- 0.3 spikes/s/degrees/s. We show that such frequency-dependent properties are attributable to an incomplete cancellation of otolith-driven SS responses during tilt by a canal-driven signal coding angular position with a sensitivity of 3.9 +/- 0.3 spikes/s/degrees. This incomplete cancellation is brought about because otolith-driven SS responses are also partially integrated, thus encoding combinations of linear velocity and acceleration. These results are consistent with the notion that NU SS modulation represents an internal neural representation of similar frequency dependencies seen in behavior.
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Gubbels SP, Woessner DW, Mitchell JC, Ricci AJ, Brigande JV. Functional auditory hair cells produced in the mammalian cochlea by in utero gene transfer. Nature 2008; 455:537-41. [PMID: 18754012 DOI: 10.1038/nature07265] [Citation(s) in RCA: 199] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Accepted: 07/17/2008] [Indexed: 02/07/2023]
Abstract
Sensory hair cells in the mammalian cochlea convert mechanical stimuli into electrical impulses that subserve audition. Loss of hair cells and their innervating neurons is the most frequent cause of hearing impairment. Atonal homologue 1 (encoded by Atoh1, also known as Math1) is a basic helix-loop-helix transcription factor required for hair-cell development, and its misexpression in vitro and in vivo generates hair-cell-like cells. Atoh1-based gene therapy to ameliorate auditory and vestibular dysfunction has been proposed. However, the biophysical properties of putative hair cells induced by Atoh1 misexpression have not been characterized. Here we show that in utero gene transfer of Atoh1 produces functional supernumerary hair cells in the mouse cochlea. The induced hair cells display stereociliary bundles, attract neuronal processes and express the ribbon synapse marker carboxy-terminal binding protein 2 (refs 12,13). Moreover, the hair cells are capable of mechanoelectrical transduction and show basolateral conductances with age-appropriate specializations. Our results demonstrate that manipulation of cell fate by transcription factor misexpression produces functional sensory cells in the postnatal mammalian cochlea. We expect that our in utero gene transfer paradigm will enable the design and validation of gene therapies to ameliorate hearing loss in mouse models of human deafness.
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Affiliation(s)
- Samuel P Gubbels
- Department of Otolaryngology, Oregon Hearing Research Center, Portland, Oregon 97239, USA
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Distribution of granule cells projecting to focal Purkinje cells in mouse uvula-nodulus. Neuroscience 2008; 156:216-21. [PMID: 18706489 DOI: 10.1016/j.neuroscience.2008.07.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 06/16/2008] [Accepted: 07/10/2008] [Indexed: 11/22/2022]
Abstract
Mossy and climbing fibers convey a broad array of signals from vestibular end organs to Purkinje cells in the vestibulo-cerebellum. We have shown previously that Purkinje cell simple spikes (SSs) and climbing fiber-evoked complex spikes (CSs) in the mouse uvula-nodulus are arrayed in 400 microm wide sagittal climbing fiber zones corresponding to the rotational axes of the vertical semicircular canals. It is often assumed that mossy fibers modulate a higher frequency of SSs through the intermediary action of granule cells whose parallel fibers course through the Purkinje cell dendritic tree. This assumption is complicated by the diffuse topography of vestibular primary afferent mossy fiber projections to the uvula-nodulus and the dispersion of mossy fiber signals along folial axes by parallel fibers. Here we measure this parallel fiber dispersion. We made microinjections of neurobiotin into the molecular layers of different folia within the mouse vestibulo-cerebellum and measured the distribution of granule cells retrogradely labeled by the injected neurobiotin. Sixty-two percent of labeled granule cells were located outside a 400 microm sagittal zone flanking the injection site. The dispersion of labeled granule cells was approximately 2.5 mm along folial axes that were 2.7-2.9 mm wide. Our data suggest that topographic specificity of SSs could not be attributed to the topography of vestibular primary afferent mossy fiber-granule cell projections. Rather the response specificity of SSs must be attributed to other mechanisms related to climbing fiber-evoked Purkinje cell and interneuronal activity.
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Jensen-Smith H, Gray B, Muirhead K, Ohlsson-Wilhelm B, Fritzsch B. Long-distance three-color neuronal tracing in fixed tissue using NeuroVue dyes. Immunol Invest 2008; 36:763-89. [PMID: 18161528 PMCID: PMC2430174 DOI: 10.1080/08820130701706711] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Dissecting development of neuronal connections is critical for understanding neuronal function in both normal and diseased states. Charting the development of the multitude of connections is a monumental task, since a given neuron typically receives hundreds of convergent inputs from other neurons and provides divergent outputs for hundreds of other neurons. Although progress is being made utilizing various mutants and/or genetic constructs expressing fluorescent proteins like GFP, substantial work remains before a database documenting the development and final location of the neuronal pathways in an adult animal is completed. The vast majority of developing neurons cannot be specifically labeled with antibodies and making specific GFP-expressing constructs to tag each of them is an overwhelming task. Fortunately, fluorescent lipophilic dyes have emerged as very useful tools to systematically compare changes in neuronal networks between wild-type and mutant mice. These dyes diffuse laterally along nerve cell membranes in fixed preparations, allowing tracing of the position of a given neuron within the neuronal network in murine mutants fixed at various stages of development. Until recently, however, most evaluations have been limited to one, or at most, two color analyses. We have previously reported three color neuronal profiling using the novel lipophilic dyes NeuroVue (NV) Green, Red and Maroon (Fritzsch et al., Brain. Res. Bull. 66: 249-258, 2005). Unfortunately such three color experiments have been limited by the fact that NV Green and its brighter successor, NV Emerald, both exhibit substantially decreased signal intensities when times greater than 48 hours at 37 degrees C are required to achieve neuronal profile filling (unpublished observations). Here we describe a standardized test system developed to allow comparison of candidate dyes and its use to evaluate a series of 488 nm-excited green-emitting lipophilic dyes. The best of these, NV Jade, has spectral properties well matched to NV Red and NV Maroon, better solubility in DMF than DiO or DiA, improved thermostability compared with NV Emerald, and the ability to fill neuronal profiles at rates of 1 mm per day for periods of at least 5 days. Use of NV Jade in combination with NV Red and NV Maroon substantially improves the efficiency of connectional analysis in complex mutants and transgenic models where limited numbers of specimens are available.
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Abstract
The output signal of Purkinje cells is conveyed by the modulated discharge of simple spikes (SSs) often ascribed to mossy fiber-granule cell-parallel fiber inputs to Purkinje cell dendrites. Although generally accepted, this view lacks experimental support. We can address this view by controlling afferent signals that reach the cerebellum over climbing and mossy fiber pathways. Vestibular primary afferents constitute the largest mossy fiber projection to the uvula-nodulus. The discharge of vestibular primary afferent mossy fibers increases during ipsilateral roll tilt. The discharge of SSs decreases during ipsilateral roll tilt. Climbing fiber discharge [complex spikes (CSs)] increases during ipsilateral roll tilt. These observations suggest that the modulation of SSs during vestibular stimulation cannot be attributed directly to vestibular mossy fiber afferents. Rather we suggest that interneurons driven by vestibular climbing fibers may determine SS modulation. We recorded from cerebellar interneurons (granule, unipolar brush, Golgi, stellate, basket, and Lugaro cells) and Purkinje cells in the uvula-nodulus of anesthetized mice during vestibular stimulation. We identified all neuronal types by juxtacellular labeling with neurobiotin. Granule, unipolar brush, stellate, and basket cells discharge in phase with ipsilateral roll tilt and in phase with CSs. Golgi cells discharge out of phase with ipsilateral roll tilt and out of phase with CSs. The phases of stellate and basket cell discharge suggests that their activity could account for the antiphasic behavior of CSs and SSs. Because Golgi cells discharge in phase with SSs, Golgi cell activity cannot account for SS modulation. The sagittal array of Golgi cell axon terminals suggests that they contribute to the organization of discrete parasagittal vestibular zones.
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