Factors Influencing the Regeneration of Axons in the Central Nervous System
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Neural Control of Movement: Motor Neuron Subtypes, Proprioception and Recurrent Inhibition
List of Papers This thesis is based on the following papers, which are referred to in the text by their Roman numerals. I Enjin A, Rabe N, Nakanishi ST, Vallstedt A, Gezelius H, Mem- ic F, Lind M, Hjalt T, Tourtellotte WG, Bruder C, Eichele G, Whelan PJ, Kullander K (2010) Identification of novel spinal cholinergic genetic subtypes disclose Chodl and Pitx2 as mark- ers for fast motor neurons and partition cells. J Comp Neurol 518:2284-2304. II Wootz H, Enjin A, Wallen-Mackenzie Å, Lindholm D, Kul- lander K (2010) Reduced VGLUT2 expression increases motor neuron viability in Sod1G93A mice. Neurobiol Dis 37:58-66 III Enjin A, Leao KE, Mikulovic S, Le Merre P, Tourtellotte WG, Kullander K. 5-ht1d marks gamma motor neurons and regulates development of sensorimotor connections Manuscript IV Enjin A, Leao KE, Eriksson A, Larhammar M, Gezelius H, Lamotte d’Incamps B, Nagaraja C, Kullander K. Development of spinal motor circuits in the absence of VIAAT-mediated Renshaw cell signaling Manuscript Reprints were made with permission from the respective publishers. Cover illustration Carousel by Sasha Svensson Contents Introduction.....................................................................................................9 Background...................................................................................................11 Neural control of movement.....................................................................11 The motor neuron.....................................................................................12 Organization -
Oligodendrocytes in Development, Myelin Generation and Beyond
cells Review Oligodendrocytes in Development, Myelin Generation and Beyond Sarah Kuhn y, Laura Gritti y, Daniel Crooks and Yvonne Dombrowski * Wellcome-Wolfson Institute for Experimental Medicine, Queen’s University Belfast, Belfast BT9 7BL, UK; [email protected] (S.K.); [email protected] (L.G.); [email protected] (D.C.) * Correspondence: [email protected]; Tel.: +0044-28-9097-6127 These authors contributed equally. y Received: 15 October 2019; Accepted: 7 November 2019; Published: 12 November 2019 Abstract: Oligodendrocytes are the myelinating cells of the central nervous system (CNS) that are generated from oligodendrocyte progenitor cells (OPC). OPC are distributed throughout the CNS and represent a pool of migratory and proliferative adult progenitor cells that can differentiate into oligodendrocytes. The central function of oligodendrocytes is to generate myelin, which is an extended membrane from the cell that wraps tightly around axons. Due to this energy consuming process and the associated high metabolic turnover oligodendrocytes are vulnerable to cytotoxic and excitotoxic factors. Oligodendrocyte pathology is therefore evident in a range of disorders including multiple sclerosis, schizophrenia and Alzheimer’s disease. Deceased oligodendrocytes can be replenished from the adult OPC pool and lost myelin can be regenerated during remyelination, which can prevent axonal degeneration and can restore function. Cell population studies have recently identified novel immunomodulatory functions of oligodendrocytes, the implications of which, e.g., for diseases with primary oligodendrocyte pathology, are not yet clear. Here, we review the journey of oligodendrocytes from the embryonic stage to their role in homeostasis and their fate in disease. We will also discuss the most common models used to study oligodendrocytes and describe newly discovered functions of oligodendrocytes. -
Student Academic Learning Services Nervous System Quiz
Student Academic Learning Services Page 1 of 8 Nervous System Quiz 1. The term central nervous system refers to the: A) autonomic and peripheral nervous systems B) brain, spinal cord, and cranial nerves C) brain and cranial nerves D) spinal cord and spinal nerves E) brain and spinal cord 2. The peripheral nervous system consists of: A) spinal nerves only B) the brain only C) cranial nerves only D) the brain and spinal cord E) the spinal and cranial nerves 3. Which of these cells are not a type of neuroglia found in the CNS: A) astrocytes B) microglia C) Schwann cells D) ependymal cells E) oligodendrocytes 4. The Schwann cells form a myelin sheath around the: A) dendrites B) cell body C) nucleus D) axon E) nodes of Ranvier 5. The neuron processes that normally receives incoming stimuli are called: A) axons B) dendrites C) neurolemmas D) Schwann cells E) satellite cells www.durhamcollege.ca/sals Student Services Building (SSB), Room 204 905.721.2000 ext. 2491 This document last updated: 7/29/2011 Student Academic Learning Services Page 2 of 8 6. Collections of nerve cell bodies inside the PNS are called: A) ganglia B) tracts C) nerves D) nuclei E) tracts or ganglia 7. Which of the following best describes the waxy-appearing material called myelin: A) an outermembrane on a neuroglial cell B) a lipid-protein (lipoprotein) cell membrane on the outside of axons C) a mass of white lipid material that surrounds the cell body of a neuron D) a mass of white lipid material that insulates the axon of a neuron E) a mass of white lipid material that surrounds the dendrites of a neuron 8. -
Chapter 8 Nervous System
Chapter 8 Nervous System I. Functions A. Sensory Input – stimuli interpreted as touch, taste, temperature, smell, sound, blood pressure, and body position. B. Integration – CNS processes sensory input and initiates responses categorizing into immediate response, memory, or ignore C. Homeostasis – maintains through sensory input and integration by stimulating or inhibiting other systems D. Mental Activity – consciousness, memory, thinking E. Control of Muscles & Glands – controls skeletal muscle and helps control/regulate smooth muscle, cardiac muscle, and glands II. Divisions of the Nervous system – 2 anatomical/main divisions A. CNS (Central Nervous System) – consists of the brain and spinal cord B. PNS (Peripheral Nervous System) – consists of ganglia and nerves outside the brain and spinal cord – has 2 subdivisions 1. Sensory Division (Afferent) – conducts action potentials from PNS toward the CNS (by way of the sensory neurons) for evaluation 2. Motor Division (Efferent) – conducts action potentials from CNS toward the PNS (by way of the motor neurons) creating a response from an effector organ – has 2 subdivisions a. Somatic Motor System – controls skeletal muscle only b. Autonomic System – controls/effects smooth muscle, cardiac muscle, and glands – 2 branches • Sympathetic – accelerator “fight or flight” • Parasympathetic – brake “resting and digesting” * 4 Types of Effector Organs: skeletal muscle, smooth muscle, cardiac muscle, and glands. III. Cells of the Nervous System A. Neurons – receive stimuli and transmit action potentials -
A Brief Introduction Into the Peripheral Nervous System
A Brief Introduction into the Peripheral Nervous System Bianca Flores, PhD Candidate, Neuroscience Tuesday, October 15th, 2019 Brief overview: • What are you hoping to learn? • Subdivisions of the peripheral nervous system (PNS) • Physiology • Diseases associated with PNS • Special topics (current research at Vanderbilt) Brief question- • Is there a location in our body that does not have neurons (signals being sent to move or sense)? The body’s nervous system is made up of two parts: The Peripheral Nervous System (PNS) is divided into two parts PNS: Sensory components: • Nociception • Proprioception • Mechanoreception • Thermoception Parasympathetic vs Sympathetic PNS • Includes everything outside of the brain and spinal cord • Is divided into motor and sensory subsets • Controls the “rest and relax” and “flight or fight” responses PNS: Physiology & Anatomy Dorsal Root ganglion are sensory body of the PNS Anatomy of the PNS- Dorsal Root Ganglion How the PNS sends signals to the CNS Nerve impulses carry electrical signals Myelin sheath on surrounds to the nerve to contribute to signal propagation Myelin sheath on surrounds to the nerve to contribute to signal propagation Nerve impulses carry electrical signals PNS Physiology and Anatomy • Dorsal root ganglion are the sensory bodies of the PNS • The Ventral root is responsible for motor movement • Myelin Sheath is imperative to proper nerve function Diseases associated with the PNS: Peripheral Neuropathy What is peripheral neuropathy? Peripheral Neuropathy: -Damage to peripheral nerves -
The Peripheral Nervous System
The Peripheral Nervous System Dr. Ali Ebneshahidi Peripheral Nervous System (PNS) – Consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves. – Serves as a critical link between the body and the central nervous system. – peripheral nerves contain an outermost layer of fibrous connective tissue called epineurium which surrounds a thinner layer of fibrous connective tissue called perineurium (surrounds the bundles of nerve or fascicles). Individual nerve fibers within the nerve are surrounded by loose connective tissue called endoneurium. Cranial Nerves Cranial nerves are direct extensions of the brain. Only Nerve I (olfactory) originates from the cerebrum, the remaining 11 pairs originate from the brain stem. Nerve I (Olfactory)- for the sense of smell (sensory). Nerve II (Optic)- for the sense of vision (sensory). Nerve III (Oculomotor)- for controlling muscles and accessory structures of the eyes ( primarily motor). Nerve IV (Trochlear)- for controlling muscles of the eyes (primarily motor). Nerve V (Trigeminal)- for controlling muscles of the eyes, upper and lower jaws and tear glands (mixed). Nerve VI (Abducens)- for controlling muscles that move the eye (primarily motor). Nerve VII (Facial) – for the sense of taste and controlling facial muscles, tear glands and salivary glands (mixed). Nerve VIII (Vestibulocochlear)- for the senses of hearing and equilibrium (sensory). Nerve IX (Glossopharyngeal)- for controlling muscles in the pharynx and to control salivary glands (mixed). Nerve X (Vagus)- for controlling muscles used in speech, swallowing, and the digestive tract, and controls cardiac and smooth muscles (mixed). Nerve XI (Accessory)- for controlling muscles of soft palate, pharynx and larynx (primarily motor). Nerve XII (Hypoglossal) for controlling muscles that move the tongue ( primarily motor). -
Neuron Morphology Influences Axon Initial Segment Plasticity1,2,3
New Research Neuronal Excitability Neuron Morphology Influences Axon Initial Segment Plasticity1,2,3 Allan T. Gulledge1 and Jaime J. Bravo2 DOI:http://dx.doi.org/10.1523/ENEURO.0085-15.2016 1Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756, and 2Thayer School of Engineering at Dartmouth, Hanover, New Hampshire 03755 Visual Abstract In most vertebrate neurons, action potentials are initiated in the axon initial segment (AIS), a specialized region of the axon containing a high density of voltage-gated sodium and potassium channels. It has recently been proposed that neurons use plasticity of AIS length and/or location to regulate their intrinsic excitability. Here we quantify the impact of neuron morphology on AIS plasticity using computational models of simplified and realistic somatodendritic morphologies. In small neurons (e.g., den- tate granule neurons), excitability was highest when the AIS was of intermediate length and located adjacent to the soma. Conversely, neu- rons having larger dendritic trees (e.g., pyramidal neurons) were most excitable when the AIS was longer and/or located away from the soma. For any given somatodendritic morphology, increasing dendritic mem- brane capacitance and/or conductance favored a longer and more distally located AIS. Overall, changes to AIS length, with corresponding changes in total sodium conductance, were far more effective in regulating neuron excitability than were changes in AIS location, while dendritic capacitance had a larger impact on AIS performance than did dendritic conductance. The somatodendritic influence on AIS performance reflects modest soma- to-AIS voltage attenuation combined with neuron size-dependent changes in AIS input resistance, effective membrane time constant, and isolation from somatodendritic capacitance. -
Are Astrocytes Executive Cells Within the Central Nervous System? ¿Son Los Astrocitos Células Ejecutivas Dentro Del Sistema Nervioso Central? Roberto E
DOI: 10.1590/0004-282X20160101 VIEW AND REVIEW Are astrocytes executive cells within the central nervous system? ¿Son los astrocitos células ejecutivas dentro del Sistema Nervioso Central? Roberto E. Sica1, Roberto Caccuri1, Cecilia Quarracino1, Francisco Capani1 ABSTRACT Experimental evidence suggests that astrocytes play a crucial role in the physiology of the central nervous system (CNS) by modulating synaptic activity and plasticity. Based on what is currently known we postulate that astrocytes are fundamental, along with neurons, for the information processing that takes place within the CNS. On the other hand, experimental findings and human observations signal that some of the primary degenerative diseases of the CNS, like frontotemporal dementia, Parkinson’s disease, Alzheimer’s dementia, Huntington’s dementia, primary cerebellar ataxias and amyotrophic lateral sclerosis, all of which affect the human species exclusively, may be due to astroglial dysfunction. This hypothesis is supported by observations that demonstrated that the killing of neurons by non-neural cells plays a major role in the pathogenesis of those diseases, at both their onset and their progression. Furthermore, recent findings suggest that astrocytes might be involved in the pathogenesis of some psychiatric disorders as well. Keywords: astrocytes; physiology; central nervous system; neurodegenerative diseases. RESUMEN Evidencias experimentales sugieren que los astrocitos desempeñan un rol crucial en la fisiología del sistema nervioso central (SNC) modulando la actividad y plasticidad sináptica. En base a lo actualmente conocido creemos que los astrocitos participan, en pie de igualdad con las neuronas, en los procesos de información del SNC. Además, observaciones experimentales y humanas encontraron que algunas de las enfermedades degenerativas primarias del SNC: la demencia fronto-temporal; las enfermedades de Parkinson, de Alzheimer, y de Huntington, las ataxias cerebelosas primarias y la esclerosis lateral amiotrófica, que afectan solo a los humanos, pueden deberse a astroglíopatía. -
How Does an Axon Grow?
Downloaded from genesdev.cshlp.org on October 2, 2021 - Published by Cold Spring Harbor Laboratory Press REVIEW How does an axon grow? Jeffrey L. Goldberg1 Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305, USA How do axons grow during development, and why do cisions to advance, retract, pause, or turn (Fig. 1). All of they fail to regrow when injured? In the complicated these are potential regulatory sites that could control a mesh of our nervous system, the axon is the information neuron’s ability to elongate or regenerate its axon. superhighway, carrying all of the data we use to sense our environment and carry out behaviors. To wire up our Production of the building blocks, nervous system properly, neurons must elongate their both membrane and cytoplasmic axons during development to reach their targets. This is no simple task, however. The complex morphology of Rapid axon growth requires rapid manufacture and sup- axons and dendrites puts neurons among the most intri- ply of cytoplasm and membrane. Where are the lipid and cate and beautiful cells in the body. Knowledge of how protein building blocks made? It was known from classic neurons extend axons and dendrites, elongate at a par- experiments that axons cut off from the cell bodies of ticular rate, and stop growing at the proper time is criti- adult sensory neurons continue to elongate in culture cal to understanding the development of our nervous (Shaw and Bray 1977), but evidence for local production system, yet the regulation of these processes is poorly of membrane and cytoplasmic elements went lacking for understood. -
Appendix A: Glossary for Section 2.1 (PDF)
APPENDIX A GLOSSARY FOR SECTION 2.1 Sources: The Concise Columbia Encyclopedia. 1995. Columbia University Press; Solomon et al. 1993. Biology, Third Edition. Harcourt Brace Publishing astrocyte - a star-shaped cell, especially a neuroglial cell of nervous tissue. axon - the long, tubular extension of the neuron that conducts nerve impulses away from the cell body. blood-brain barrier - system of capillaries that regulates the movement of chemical substances, ions, and fluids in and out of the brain. central nervous system - the portion of the vertebrate nervous system consisting of the brain and spinal cord. cerebellum - the trilobed structure of the brain, lying posterior to the pons and medulla oblongata and inferior to the occipital lobes of the cerebral hemispheres, that is responsible for the regulation and coordination of complex voluntary muscular movement as well as the maintenance of posture and balance. cerebral cortex - the extensive outer layer of gray matter of the cerebral hemispheres, largely responsible for higher brain functions, including sensation, voluntary muscle movement, thought, reasoning, and memory. cerebrum - the large, rounded structure of the brain occupying most of the cranial cavity, divided into two cerebral hemispheres that are joined at the bottom by the corpus callosum. It controls and integrates motor, sensory, and higher mental functions, such as thought, reason, emotion, and memory. cognitive development - various mental tasks and processes (e.g. receiving, processing, storing, and retrieving information) that mediate between stimulus and response and determine problem-solving ability. demyelination - to destroy or remove the myelin sheath of (a nerve fiber), as through disease. dendrite - a branched protoplasmic extension of a nerve cell that conducts impulses from adjacent cells inward toward the cell body. -
Regulation of Myelin Structure and Conduction Velocity by Perinodal Astrocytes
Correction NEUROSCIENCE Correction for “Regulation of myelin structure and conduc- tion velocity by perinodal astrocytes,” by Dipankar J. Dutta, Dong Ho Woo, Philip R. Lee, Sinisa Pajevic, Olena Bukalo, William C. Huffman, Hiroaki Wake, Peter J. Basser, Shahriar SheikhBahaei, Vanja Lazarevic, Jeffrey C. Smith, and R. Douglas Fields, which was first published October 29, 2018; 10.1073/ pnas.1811013115 (Proc. Natl. Acad. Sci. U.S.A. 115,11832–11837). The authors note that the following statement should be added to the Acknowledgments: “We acknowledge Dr. Hae Ung Lee for preliminary experiments that informed the ultimate experimental approach.” Published under the PNAS license. Published online June 10, 2019. www.pnas.org/cgi/doi/10.1073/pnas.1908361116 12574 | PNAS | June 18, 2019 | vol. 116 | no. 25 www.pnas.org Downloaded by guest on October 2, 2021 Regulation of myelin structure and conduction velocity by perinodal astrocytes Dipankar J. Duttaa,b, Dong Ho Wooa, Philip R. Leea, Sinisa Pajevicc, Olena Bukaloa, William C. Huffmana, Hiroaki Wakea, Peter J. Basserd, Shahriar SheikhBahaeie, Vanja Lazarevicf, Jeffrey C. Smithe, and R. Douglas Fieldsa,1 aSection on Nervous System Development and Plasticity, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892; bThe Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD 20817; cMathematical and Statistical Computing Laboratory, Office of Intramural Research, Center for Information -
NEURAL CONNECTIONS: Some You Use, Some You Lose
NEURAL CONNECTIONS: Some You Use, Some You Lose by JOHN T. BRUER SOURCE: Phi Delta Kappan 81 no4 264-77 D 1999 . The magazine publisher is the copyright holder of this article and it is reproduced with permission. Further reproduction of this article in violation of the copyright is prohibited JOHN T. BRUER is president of the James S. McDonnell Foundation, St. Louis. This article is adapted from his new book, The Myth of the First Three Years (Free Press, 1999), and is reprinted by arrangement with The Free Press, a division of Simon Schuster Inc. ©1999, John T. Bruer . OVER 20 YEARS AGO, neuroscientists discovered that humans and other animals experience a rapid increase in brain connectivity -- an exuberant burst of synapse formation -- early in development. They have studied this process most carefully in the brain's outer layer, or cortex, which is essentially our gray matter. In these studies, neuroscientists have documented that over our life spans the number of synapses per unit area or unit volume of cortical tissue changes, as does the number of synapses per neuron. Neuroscientists refer to the number of synapses per unit of cortical tissue as the brain's synaptic density. Over our lifetimes, our brain's synaptic density changes in an interesting, patterned way. This pattern of synaptic change and what it might mean is the first neurobiological strand of the Myth of the First Three Years. (The second strand of the Myth deals with the notion of critical periods, and the third takes up the matter of enriched, or complex, environments.) Popular discussions of the new brain science trade heavily on what happens to synapses during infancy and childhood.