Myelinated Fibers and Saltatory Conduction in the Shrimp : The Fastest Impulse Conduction in the Animal Kingdom

In 1961, neurobiologists found that the conduction velocity of the nerve impulse in the giant nerve fiber of the __Penaeus__ shrimp abdominal nerve cord was over 200 m/s, the highest speed of information transmission ever observed in the animal kingdom. The peculiar myelin sheath with its unique nodal structure and the electrical properties of the nerve fibers of the shrimp have continued to be investigated for a quarter of century and are now fully described in this book. The investigation dispels the commonly held belief that the fastest recorded impulse conduction is about 120 m/s in the thickest vertebrate myelinated nerve fibers. In the shrimp, researchers found a completely novel type of functional node in the giant fiber which they designated as the fenestration node. In portions of the myelinated fiber, the fenestration node furnished the sites of excitation. Also discovered was a new strategy for increasing impulse conduction in the shrimp. The book includes a section on the formation of the fenestration node and the discovery of a strategy that allows the shrimp to escape its predators by an action of the fastest velocity. The data presented in this volume on the myelin sheath of invertebrates present a new direction for this field and a rich source of information for neurobiologists worldwide. Foreword 5 Preface 8 About the Authors 11 Contents 12 Chapter 1: Introduction 16 Chapter 2: The Penaeus Shrimp as an Experimental Marine Animal for Neurobiological Study 22 2.1 Classification of Some Higher Species of Penaeus Shrimp 23 2.2 Morphology of the Nervous System of the Penaeus Shrimp 24 2.3 Myelinated Giant Fiber Preparation 25 2.4 Axon–Axonal Giant Synapse Preparation 28 2.5 Giant Neuron Preparation 31 2.6 Stretch Receptor Preparation 31 2.7 Cardiac Ganglion Preparation 31 2.8 Overall View 32 Chapter 3: Morphological Studies on the Myelin Sheath of Nerve Fibers 33 3.1 Some Significant Events in the Morphological Studies of Nerve Fibers by Light Microscopy 33 3.2 The Myelin Sheath of the Nerve Fibers of Vertebrates Studied by Electron Microscopy 35 3.3 The Myelin-Like Sheath of the Nerve Fibers of Some Invertebrates Studied by Electron Microscopy 39 3.4 The Myelin Sheath Was Concluded to Have Evolved in Vertebrates 42 Chapter 4: Biochemical Studies on Myelin of the Nervous System 44 4.1 Myelin Composition in Vertebrates 44 4.2 Compositions of the Myelin Sheath in Penaeus Shrimp and Myelin-Like Sheath in Some Invertebrates 47 Chapter 5: Myelin Sheath with a New Type of Fine Structure Found in the Nervous System of Penaeus Shrimp, an Invertebrate 48 5.1 Necessary Conditions for Identification of the Myelin Sheath 48 5.2 Specific Morphological Structures of the Myelinated Fibers of the Penaeus Shrimp 49 5.3 Identification of the Location of the Axolemma and the Sheath Component in the Myelinated Fibers of the Penaeus Shrimp 49 5.4 Specific Characteristics of the Fine Structure of the Myelin Sheath of the Penaeus Shrimp 52 5.5 Electrical Properties of the Myelin Sheath Measured in the Giant Fiber Preparation of Penaeus japonicus 56 5.6 Overall View of the Myelin Sheaths of Vertebrate and Invertebrate ( Penaeus Shrimp) Nerve Fibers 57 Chapter 6: Two Unique Structures Discovered in the Myelinated Fibers of the Penaeus Shrimp 59 6.1 Wide Extracellular Gap Space Filled with an Amorphous Gel Substance Under the Myelin Sheath of the Nerve Fibers of the ... 62 6.2 Unique Thin Nucleated Wall Containing Microtubule Bundles and Tightly Enclosing the Axon of the Myelinated Fibers of th... 64 6.3 Overall View of Two Specific Structures of the Myelinated Fibers of the Penaeus Shrimp 65 Chapter 7: Studies on Impulse Conduction of Nerve Fibers 67 7.1 Some Significant Events of Studying the Electrical Impulse of Nerve Fibers 67 7.2 Mechanism of Impulse Conduction in Unmyelinated Nerve Fibers 69 7.3 Experiments for Establishing the Saltatory Conduction Hypothesis with the Myelinated Fiber Preparations of Toad and Frog 70 7.4 Difference in the Distribution of Ion Channels in the Axoplasmic Membranes Between Unmyelinated and Myelinated Fibers o... 74 7.5 Saltatory Conduction Was Concluded to Have Evolved Before Vertebrates 76 Chapter 8: Saltatory Conduction Found in the Nervous System of Two Model Invertebrates, the Shrimp ( Penaeus) and the Earth... 77 8.1 Necessary Conditions for Identifying the Nodal Structure of Myelinated Nerve Fibers 77 8.2 Saltatory Conduction Based on the Functional Nodes Found in the Giant Nerve Fibers of the Penaeus Shrimp 78 8.3 Saltatory Conduction Based on the “Spot Openings” in the Median Giant Fiber of the Earthworm ( Lumbricus terrestris) 80 8.4 Experiments Analyzing the Ion Currents of the Functional Nodal Membrane in the Medial Giant Fiber Preparation of Penaeu... 80 8.5 Saltatory Conduction Based on Fenestration Node, a Novel Node of Common Type in the Myelinated Fibers of the Penaeus Sh... 83 8.6 Ionic Currents of the Nodal Fenestration Membrane in the Myelinated Fiber Preparation of Penaeus japonicus 86 8.7 Overall View of Saltatory Conduction in the Myelinated Nerve Fibers of Vertebrates and Penaeus Shrimp 87 Chapter 9: Experimental Confirmation of the Saltatory Conduction Hypothesis 89 9.1 Inexcitability of the Internodal Axoplasmic Membrane of Myelinated Nerve Fibers 89 9.2 Excitability of Axoplasmic Membrane Confined to the Nodal Region of Myelinated Nerve Fibers 91 9.3 The Local Action Current Is Conducted from Node to Node in Myelinated Nerve Fibers 93 9.4 Overall View of Saltatory Conduction as the Common Principle of Impulse Conduction in Myelinated Nerve Fibers 94 Chapter 10: Three Mechanisms or Strategies for Increasing Conduction Velocity of Nerve Fibers 95 10.1 Some Significant Events of Studying the Mechanism of Impulse Conduction in Nerve Fibers 95 10.2 Conduction Velocity and the Electrical Properties of Nerve Fibers 96 10.3 Mechanisms for Increasing the Conduction Velocity of Nerve Fibers 97 10.4 Two Strategies for Increasing the Conduction Velocity of Nerve Fibers Have Evolved in the Nervous System of Living Org... 98 10.5 New Mechanism or Strategy for Increasing the Conduction Velocity of Nerve Fibers Found in the Myelinated Fibers of the... 99 10.6 Overall View of Three Mechanisms or Strategies for Increasing the Conduction Velocity of Nerve Fibers 102 Chapter 11: Ultrahigh Conduction Velocity Found in the Medial Giant Fibers of Penaeus chinensis and Penaeus japonicus 103 11.1 Conduction Velocities of 80–210 m/s in Giant Fibers of P. chinensis and P. japonicus 103 11.2 Analysis of the Wide Dispersion in Conduction Velocity of the Medial Giant Fiber of P. chinensis and P. japonicus 104 11.3 Factors Determining the Ultrahigh Conduction Velocity of the Medial Giant Fibers of P. chinensis and P. japonicus 106 11.4 Overall View of the Factors Contributing to the Highest Conduction Velocity of Nerve Fibers 107 Chapter 12: Remarks on the Evolution of Myelin Sheath, Glial Cells, Nodal Structure, and Conduction Function of Nerve Fibers 109 12.1 Evolution of the Myelin Sheath 109 12.2 Evolution of Glial Cells in Nerve Fibers 109 12.3 Evolution of Nodal Structures 110 12.4 Evolution of the Conduction Function of Nerve Fibers 111 References 113 Index 118 Front Matter....Pages i-xviii Introduction....Pages 1-6 The Penaeus Shrimp as an Experimental Marine Animal for Neurobiological Study....Pages 7-17 Morphological Studies on the Myelin Sheath of Nerve Fibers....Pages 19-29 Biochemical Studies on Myelin of the Nervous System....Pages 31-34 Myelin Sheath with a New Type of Fine Structure Found in the Nervous System of Penaeus Shrimp, an Invertebrate....Pages 35-45 Two Unique Structures Discovered in the Myelinated Fibers of the Penaeus Shrimp....Pages 47-54 Studies on Impulse Conduction of Nerve Fibers....Pages 55-64 Saltatory Conduction Found in the Nervous System of Two Model Invertebrates, the Shrimp ( Penaeus ) and the Earthworm ( Lumbricus terrestris )....Pages 65-76 Experimental Confirmation of the Saltatory Conduction Hypothesis....Pages 77-82 Three Mechanisms or Strategies for Increasing Conduction Velocity of Nerve Fibers....Pages 83-90 Ultrahigh Conduction Velocity Found in the Medial Giant Fibers of Penaeus chinensis and Penaeus japonicus ....Pages 91-96 Remarks on the Evolution of Myelin Sheath, Glial Cells, Nodal Structure, and Conduction Function of Nerve Fibers....Pages 97-100 Back Matter....Pages 101-110 1. Introduction -- 2. The Penaeus Shrimp As An Experimental Marine Animal For Neurobiological Study -- 3. Morphological Studies On The Myelin Sheath Of Nerve Fibers -- 4. Biochemical Studies On Myelin Of The Nervous System -- 5. Myelin Sheath With A New Type Of Fine Structure Found In The Nervous System Of Penaeus Shrimp, An Invertebrate -- 6. Two Unique Structures Discovered In The Myelinated Fibers Of The Penaeus Shrimp -- 7. Studies On Impulse Conduction Of Nerve Fibers -- 8. Saltatory Conduction Found In The Nervous System Of Two Model Invertebrates, The Shrimp (penaeus) And The Earthworm (lumbricus Terrestris) -- 9. Experimental Confirmation Of The Saltatory Conduction Hypothesis -- 10. Three Mechanisms Or Strategies For Increasing Conduction Velocity Of Nerve Fibers -- 11. Ultrahigh Conduction Velocity Found In The Medial Giant Fibers Of Penaeus Chinensis And Penaeus Japonicus -- 12. Remarks On The Evolution Of Myelin Sheath, Glial Cells, Nodal Structure, And Conduction Function Of Nerve Fibers. Ke Xu, Susumu Terakawa. Includes Bibliographical References (pages 101-105) And Index. Mode Of Access: World Wide Web.