Introduction to Neural Engineering for Motor Rehabilitation E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Serie: IEEE Press Series on Biomedical Engineering
• Sprache: Englisch

Seitenzahl: 1016

Veröffentlichungsjahr: 2013

Beschreibung

Neural engineering is a discipline that uses engineering techniques to understand, repair, replace, enhance, or treat diseases of neural systems. Currently, no book other than this one covers this broad range of topics within motor rehabilitation technology. With a focus on cutting edge technology, it describes state-of-the-art methods within this field, from brain-computer interfaces to spinal and cortical plasticity. Touching on electrode design, signal processing, the neurophysiology of movement, robotics, and much more, this innovative volume collects the latest information for a wide range of readers working in biomedical engineering.

Leseprobe

Table of Contents

IEEE Press

Title page

Copyright page

Contributors

Preface

PART I: Injuries of the Nervous System

1: Diseases and Injuries of the Central Nervous System Leading to Sensory–Motor Impairment

Neuron Injury

Cerebrovascular Accident

Spinal Cord Injuries

Multiple Sclerosis and Amyotrophic Lateral Sclerosis

Cerebral Paralysis

Incidence of CNS Disease

2: Peripheral and Spinal Plasticity after Nerve Injuries

Introduction

Nerve Degeneration and Regeneration

Plasticity and Remodeling at the Spinal Cord

Conclusion

3: Motor Control Modules of Human Movement in Health and Disease

Introduction

State of the Art

Current Challenges and Future Directions

Conclusions

PART II: Signal Detection and Conditioning

4: Progress in Peripheral Neural Interfaces

Introduction

State of the Art

Current Challenges and Future Directions

Conclusions

5: Multimodal, Multisite Neuronal Recordings for Brain Research

Introduction

Multisite Microelectrodes for Electrophysiology

Combining Optical and Electrophysiological Probes

Conclusion and Outlook

Acknowledgments

6: Surface Electromyogram Detection

Electrode–Skin Interface

Conditioning of Surface Electromyographic Signals

Detection of sEMG Signals: Electrode Configuration, Distance, Location

Spatial Sampling

7: Methods for Noninvasive Electroencephalogram Detection

Introduction

Electrodes

Amplifiers

Interfacing to Electrodes, the Computer, and Programming Environment

Future Directions

8: Spike Sorting

Introduction

Signal Model

State of the Art

Conclusions

9: Wavelet Denoising and Conditioning of Neural Recordings

Background

Application

Conclusions

10: Instantaneous Cross-Correlation Analysis of Neural Ensembles with High Temporal Resolution

Introduction

Background

Instantaneous Cross-Correlation

Experiments

Discussion

11: Unsupervised Decomposition Methods for Analysis of Multimodal Neural Data

Introduction

Principal Component Analysis

Canonical Correlation Analysis

Convolutive CCA

PART III: Function Replacement (Prostheses and Orthosis)

12: Brain–Computer Interfaces

Introduction

BCI Signals

Voluntary Activity versus Evoked Potentials

Mutual Learning

Context-Aware BCI

BCI-Based Motor Rehabilitation

Future Directions

13: Movement-Related Cortical Potentials and Their Application in Brain–Computer Interfacing

Introduction

Characteristics of Movement-Related Cortical Potentials

Single-Trial Classification of MRCPs

Conclusion and Outlook

14: Introduction to Upper Limb Prosthetics

Introduction

State of the Art

Future Directions

Conclusion

Acknowledgments

15: Myoelectric Prostheses and Targeted Reinnervation

Introduction

State of the Art

Current Challenges and Future Directions

Conclusions

16: Controlling Prostheses Using PNS Invasive Interfaces for Amputees

Introduction

State of the Art

Current Challenges and Future Directions

17: Exoskeletal Robotics for Functional Substitution

Introduction

State of the Art

Current Challenges and Future Directions

Conclusions

PART IV: Function Restoration

18: Methods for Movement Restoration

Introduction

Robot-Based Assistance of Movement

Neural Prostheses to Assist Lost Motor Function

Functional Electrical Stimulation for Restoring Upper and Lower Extremity Functions

Future Directions

19: Advanced User Interfaces for Upper Limb Functional Electrical Stimulation

Introduction

Existing Methods for Functional Electrical Stimulation and Prosthetic Control

Use of Signals Recorded from the Cerebral Cortex

Combinations of Sources

Closed-Loop Control

Conclusions

20: Customized Modeling and Simulations for the Control of FES-Assisted Walking of Individuals with Hemiplegia

Introduction and Background

Methodology and Results

Conclusions

21: ActiGait®: A Partly Implantable Drop-Foot Stimulator System

Introduction and Background

Methodology

Results

Discussion

Conclusion

22: Selectivity of Peripheral Neural Interfaces

Introduction and Background

Two Neural Prosthesis Applications Where Stimulation Selectivity Plays an Important Role

Assessment of Selectivity

Comparison of the Selectivity Performance of Two Intraneural Electrodes

Methods

Results

Discussion and Conclusions

Acknowledgments

PART V: Rehabilitation through Neuromodulation

23: Brain–Computer Interface Applied to Motor Recovery after Brain Injury

Introduction

Brain–Computer Interfaces

Neuroscience Evidence of Brain Plasticity and Relationship to Use of BCIs for Motor Training

Theoretical Strategies for BCIs in Motor Learning

Feasibility Studies

Conclusions

24: Functional Electrical Therapy of Upper Extremities

Introduction and Background

Methodology

Results

Conclusions

Future Directions

Acknowledgments

25: Gait Rehabilitation Using Nociceptive Withdrawal Reflex–Based Functional Electrical Therapy in Stroke Patients

Introduction

Materials and Methods

Results

Conclusions

Acknowledgments

26: Robot–Assisted Neurorehabilitation

Introduction and Background

Methodology

Results

Conclusions

Acknowlegment

27: Paired Associative Stimulation

Introduction and Background

Methodology

Results

Conclusions

28: Operant Conditioning of Spinal Reflexes for Motor Rehabilitation after CNS Damage

Introduction and Background

Methods and Results

Discussion

Conclusions

Acknowledgments

Index

IEEE Press Series in Biomedical Engineering

IEEE Press

445 Hoes Lane

Piscataway, NJ 08854

IEEE Press Editorial Board 2013

John Anderson, Editor in Chief

Linda ShaferSaeid NahavandiGeorge ZobristGeorge W. ArnoldDavid JacobsonTariq SamadEkram HossainMary LanzerottiDmitry GoldgofOm P. Malik

Kenneth Moore, Director of IEEE Book and Information Services (BIS)

Copyright © 2013 The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.

Published by John Wiley & Sons, Inc., Hoboken, New Jersey.

Published simultaneously in Canada.

No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, [phone], fax [phone], or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, [phone], fax [phone], or online at http://www.wiley.com/go/permissions.

Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages.

For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at [phone], outside the United States at [phone] or fax [phone].

Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic formats. For more information about Wiley products, visit our web site at www.wiley.com.

Library of Congress Cataloging-in-Publication Data:

Introduction to neural engineering for motor rehabilitation / edited by Dario Farina, Winnie Jensen, Metin Akay.

p. ; cm.

ISBN 978-0-470-91673-5 (cloth)

I. Farina, Dario. II. Jensen, Winnie. III. Akay, Metin.

[DNLM: 1. Biomedical Engineering. 2. Nervous System. 3. Neural Networks (Computer) 4. Signal Processing, Computer-Assisted. 5. Trauma, Nervous System–rehabilitation. 6. User-Computer Interface. QT 36]

610.28–dc23

2012041247

Contributors

Ole K. Andersen, Integrative Neuroscience Group, Center for Sensory–Motor Interaction, Aalborg University, Aalborg, Denmark

Felix Biessmann, Machine Learning Group, Technische Universität Berlin, Berlin, Germany

Alberto Botter, Laboratory for Engineering of the Neuromuscular System (LISiN), Politecnico di Torino, Torino, Italy

Germana Cappellini, Laboratory of Neuromotor Physiology, Santa Lucia Foundation, Rome, Italy

Jacopo Carpaneto, Biorobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy

Maura Casadio, Department of Informatics, Systems and Telematics, University of Genoa, Italy; Sensory Motor Performance Program, Rehabilitation Institute of Chicago and Department of Physiology, Northwestern University Medical School, Chicago, IL, USA

Luca Citi, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA; Biorobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy

Elaine A. Corbett, Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA

Janis J. Daly, Director, Brain Rehabilitation Research Center of Excellence, MR Gainesville DVA Medical Center; Research Career Scientist, DVA; Professor, Department of Neurology, College of Medicine, University of Florida, Gainesville, FL, USA; Director, Brain Rehabilitation Research Program, McKnight Brain Institute, University of Florida, Gainesville, FL, USA

Peter Detemple, Institut für Mikrotechnik Mainz GmbH, Mainz, Germany

Hans Dietl, Otto Bock HealthCare GmbH, Duderstadt, Germany; Otto Bock HealthCare Products GmbH, Vienna, Austria

Omar Feix do Nascimento, Center for Sensory–Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark

Strahinja Došen, Department of Neurorehabilitation Engineering, University Medical Center, Georg-August University, Göttingen, Germany

Kim Dremstrup, Center for Sensory–Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark

Günter Edlinger, g.tec medical engineering GmbH/Guger Technologies OG Schiedlberg, Austria

Kevin Englehart, Institute of Biomedical Engineering, University of New Brunswick, Fredericton, NB, Canada

Christian Ethier, Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA

Dario Farina, Department of Neurorehabilitation Engineering, Bernstein Focus Neurotechnology Göttingen, Bernstein Center for Computational Neuroscience, University Medical Center Göttingen, Georg-August University, Göttingen, Germany

Marco Gazzoni, Laboratory for Engineering of the Neuromuscular System (LISiN), Politecnico di Torino, Torino, Italy

Di Ge, Glaizer Groupe, Malakoff, France

Bernhard Graimann, Otto Bock HealthCare GmbH, Duderstadt, Germany

Ying Gu, Center for Sensory–Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark

Christoph Guger, g.tec medical engineering GmbH/Guger Technologies OG, Schiedlberg, Austria

Levi Hargrove, Center for Bionic Medicine, Rehabilitation Institute of Chicago, Chicago, IL, USA; Department of Physical Medicine and Rehabilitation, Northwestern University Feinberg School of Medicine, Chicago, IL, USA

Kristian Rauhe Harreby, Center for Sensory–Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark

Ulrich G. Hofmann, Neuroelectronic Systems, Department for Neurosurgery, University Hospital Freiburg, Freiburg, Germany; Graduate School for Computing in Medicine and Life Sciences, University of Lübeck, Lübeck, Germany

Yuri P. Ivanenko, Laboratory of Neuromotor Physiology, Santa Lucia Foundation, Rome, Italy

Winnie Jensen, Center for Sensory–Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark

Konrad Kording, Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA; Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA

Francesco Lacquaniti, Department of Neuroscience and Centre of Space BioMedicine, University of Rome Tor Vergata, Rome, Italy; Laboratory of Neuromotor Physiology, Santa Lucia Foundation, Rome, Italy

Birgit Larsen, Neurodan A/S, Aalborg, Denmark

Lorenzo Masia, Department of Robotics, Brain and Cognitive Sciences, Italian Institute of Technology, Genoa, Italy

Kevin A. Mauser, Biomedical Engineering Department, Indiana University–Purdue University Indianapolis, Indianapolis, IN, USA

Frank C. Meinecke, Machine Learning Group, Technische Universität Berlin, Berlin, Germany

Roberto Merletti, Laboratory for Engineering of the Neuromuscular System (LISiN), Politecnico di Torino, Torino, Italy

Silvestro Micera, Biorobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy; Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland

José del R. Millán, Center for Neuroprosthetics, School of Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland

Lee E. Miller, Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA; Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA; Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA

Marco Molinari, Spinal Cord Unit, Santa Lucia Foundation, Rome, Italy

Pietro G. Morasso, Department of Robotics, Brain and Cognitive Sciences, Italian Institute of Technology, Genoa, Italy

Juan C. Moreno, Bioengineering Group, Spanish Research Council, CSIC, Arganda del Rey, Spain

Natalie Mrachacz-Kersting, Center for Sensory–Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark

Klaus-Robert Müller, Machine Learning Group, Technische Universität Berlin, Berlin, Germany

Xavier Navarro, Institute of Neurosciences and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona; Centro de Investigación en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain

Emily R. Oby, Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA

António R.C. Paiva, Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT, USA; presently at ExxonMobil Upstream Research Company, Houston, TX, USA

Il Park, Center for Perceptual Systems and Institute for Neuroscience, University of Texas, Austin, TX, USA

Andrei Patriciu, Neurodan A/S, Aalborg, Denmark

Eric J. Perreault, Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA; Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA

José Luis Pons, Bioengineering Group, Spanish Research Council, CSIC, Arganda del Rey, Spain

Dejan B. Popović, Center for Sensory–Motor Interaction, Aalborg University, Aalborg, Denmark; University of Belgrade, Faculty of Electrical Engineering, Belgrade, Serbia

Mirjana B. Popović, University of Belgrade, Faculty of Electrical Engineering, Belgrade, Serbia; Aalborg University, Department for Health Science and Engineering, Aalborg, Denmark; University of Belgrade, Institute for Multidisciplinary Research, Belgrade, Serbia

José C. Príncipe, Department of Electrical and Computer Engineering, University of Florida, Gainesville, FL, USA

Shaoyu Qiao, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA

Stanisa Raspopovic, Biorobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy; Center for Neuroprosthetics and Institute of Bioengineering, School of Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland

Jacopo Rigosa, Biorobotics Institute, Scuola Superiore Sant'Anna, Pisa, Italy

Eduardo Rocon, Bioengineering Group, Spanish Research Council, CSIC, Arganda del Rey, Spain

Justin C. Sanchez, Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA

Vittorio Sanguineti, Department of Informatics, Systems and Telematics, University of Genoa, Italy; Department of Robotics, Brain and Cognitive Sciences, Italian Institute of Technology, Genoa, Italy

Erik Scheme, Institute of Biomedical Engineering, University of New Brunswick, Fredericton, NB, Canada

Thomas Sinkjær, Center for Sensory–Motor Interaction, Aalborg University, Aalborg, Denmark

Erika G. Spaich, Integrative Neuroscience Group, Center for Sensory–Motor Interaction, Aalborg University, Aalborg, Denmark

Valentina Squeri, Department of Robotics, Brain and Cognitive Sciences, Italian Institute of Technology, Genoa, Italy

Aiko K. Thompson, Program for Translational Neurological Research, Helen Hayes Hospital and the Wadsworth Center, New York State Department of Health, New York, NY, USA

Jonathan R. Wolpaw, Program for Translational Neurological Research, Helen Hayes Hospital and the Wadsworth Center, New York State Department of Health, New York, NY, USA

Yijing Xie, Graduate School for Computing in Medicine and Life Sciences, University of Lübeck, Lübeck, Germany

Ken Yoshida, Biomedical Engineering Department, Indiana University–Purdue University Indianapolis, Indianapolis, IN, USA; Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA; Center for Sensory–Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark

Preface

Neural engineering is an interdisciplinary research area that brings to bear methods from neuroscience and engineering to analyze neurological functions and to design solutions to problems associated with neurological limitations and dysfunctions (definition by the Editorial Board of the Journal of Neural Engineering [Durand, 2007]). Despite neural engineering's being a relatively new research area, the field is developing rapidly. This development requires continuously updated didactic material for the increasing number of undergraduate, graduate, and Ph.D. courses on the topic. The applications of neural engineering to rehabilitation of movement cover a broad range of engineering challenges, from electrode design to signal processing and from the neurophysiology of movement to robotics.

The three main approaches of neural engineering used for rehabilitation of impaired motor functions are restoration, replacement, and neuromodulation. Restoration consists in retaining existing neural and anatomical structures and in controlling them for reestablishing a motor function. An example of such an approach is functional electrical stimulation (FES). Replacement consists in substituting the impaired motor apparatus with an artificial one, controlled by residual, but still functional, neural or muscular structures. An example of these methods is the control of artificial limbs (active prostheses). The aim of neuromodulation is (re)training the central nervous system to induce plasticity through artificial stimulation of afferent pathways and/or by artificial enhancement of efferent neural and muscular signals provided as feedback. Examples of such an approach are the application of patterned peripheral electrical neuromuscular stimulation (e.g., transcutaneous electrical nerve stimulation, TENS), mechanical stimulation using robots, or repetitive transcranial magnetic stimulation for retraining the diseased central nervous system.

The aim of this book is to present the state of the art in technologies for motor neurorehabilitation and to give an overview of the current challenges and recent advances within neural rehabilitation technology. The book is intended for undergraduate, graduate, and Ph.D. students as well as senior researchers who work in the field of biomedical engineering, and it is organized in five parts. Part I reviews aspects related to injuries of the nervous system that determine motor impairments. It is considered as a prerequisite that the reader is familiar with the physiology of the neuromuscular system, which is not included in this book. Part II reviews engineering methods for interfacing the neuromuscular system and for conditioning and processing neural and muscular signals. The methods described in Part II are also used in the last three parts of the book, which describe examples of neurotechnologies within the areas of restoration, replacement, and neuromodulation. The topics in each part are collected with the focus on the application (e.g., replacement of function) rather than on the principle on which such application is exploited. Therefore, for example, the principle of brain-interfacing is used in applications described in both Parts III (replacement) and V (neuromodulation), according to the different uses of brain-interfacing in these two sections. Each part begins with a short introduction that serves to put into perspective the topics addressed in that part and to guide the reader to the research areas detailed there. The book's parts comprise introductory chapters, which provide a broad perspective (review chapters), and chapters with a strong focus on more specialized topics (focused chapters), as indicated at the beginning of each chapter.

The book is intended to provide a broad perspective within the field of motor neurorehabilitation engineering by including several topics that in most other books are treated separately. At the same time, the book does not intend to provide an exhaustive treatment of all methods and approaches for motor neurorehabilitation. Rather, the topics presented have been selected to be representative of the field and thus to provide the reader with a general broad overview and understanding of the research area. Readers who approach neural rehabilitation engineering for the first time will find the review chapters as an overview of the state of the art, whereas senior researchers or experts within the field may have further interest in the focused chapters that provide a detailed analysis of specific topics with recent solutions. As indicated, the physiology of the neuromuscular system is not presented in this book, which has as its starting point the injuries of the system. Therefore, readers approaching neural engineering for the first time are advised to first consult references on human physiology.

The editors are very grateful to all the contributing authors for enthusiastically accepting the invitation to contribute to this project and to Dr. Antonietta Stango (University Medical Center Göttingen, Germany) for the important contribution of assisting with the editorial tasks.

Dario Farina thanks the European Research Council (ERC), which has awarded him the Advanced Research Grant DEMOVE (“Decoding the Neural Code of Human Movements for a New Generation of Man–Machine Interfaces”; contract #267888). This grant has supported Dario Farina for the time invested in editing this book.

Dario Farina

Winnie Jensen

Metin Akay

Reference

Durand D.M. (2007). What is neural engineering? J Neural Eng. 4. http://dx.doi.org/10.1088/1741-2552/4/4/E01.

PART I

Injuries of the Nervous System

Part I contains three chapters that examine the type of neural injuries that may lead to sensory–motor impairment, as well as aspects of plasticity, as a relatively novel conceptual theme in the field of neural rehabilitation. Damage to the nervous system is typically associated with the loss of motor drive and of afferent input to the central nervous system. The severity of the neural damage depends on the location of the injury, which may lead to adaptation of the movement pattern, paresis, or complete paralysis. Plasticity has been defined as changes in the strength, number, and location of synaptic connections in response to either an environmental stimulus or an alteration in synaptic activity in a network; our fundamental understanding of what underlies neural plasticity is believed to be one of the key elements in devising strategies for rehabilitation or repair of injuries.

Chapter 1, by Popović and Sinkjær, provides a review of the incidence and the pathology of major diseases and injuries within the central nervous system that lead to impairment of the sensory–motor system, such as stroke and spinal cord injury. The chapter also briefly introduces the types of injuries that lead to loss of sensory–motor functions at the peripheral level.

Chapter 2, by Navarro, more specifically examines injuries at the peripheral level that may result in partial or total loss of motor, sensory, and autonomic functions. Functional deficits may be compensated by reinnervation of denervated targets by regenerating the injured axons, by collateral branching of undamaged axons, or by remodeling of nervous system circuitries. Plasticity of central connections may compensate functionally for the lack of adequate target reinnervation; however, plasticity has limited effects on disturbed sensory localization or fine motor control after injuries, and it may even result in maladaptive changes, such as neuropathic pain and hyperreflexia.

Obtaining evidence for spinal or cortical plasticity in the human is very difficult without using invasive recording techniques. Chapter 3, by Ivanenko and collaborators, reports on motor primitives to provide a novel perspective on how the neural control system operates under locomotion in healthy subjects and in patients. They find that building blocks with which the central nervous system constructs motor patterns can be preserved in patients with various motor disorders despite the fact that they often modify their muscle activity and adopt motor equivalent solutions. Our understanding of these motor primitives may be useful in driving neuroprostheses or entraining locomotor circuits in disabled people in the future.

Review Chapter

1

Diseases and Injuries of the Central Nervous System Leading to Sensory–Motor Impairment

Dejan B. Popović and Thomas Sinkjær

Center for Sensory–Motor Interaction, Aalborg University, Aalborg, Denmark

Summary

Damage to the central and peripheral nervous systems is associated with a loss of motor drive and a defective afferent input to the central nervous system (CNS). Depending on the location and severity of the neural damage this leads to anything from a complete paralysis to a paresis and a maladaptation of the movement pattern. This chapter starts with a presentation of neuron injury. Such injuries are categorized based on the extent and type of damage to the nerve and the surrounding connective tissue. This chapter addresses sensory–motor deficits that are caused by neuron injury or disease: (a) cerebrovascular accident (CVA), or stroke, which causes impairments due to changes in blood supply to the brain; (b) spinal cord injuries (SCIs), which result in total or partial obstruction of flow of both sensory and motor information between the peripheral and central nervous systems; (c) nontraumatic disorders of the CNS (amyotrophic lateral sclerosis and multiple sclerosis); and (d) cerebral palsy. At the end of the chapter we present the incidence of CNS diseases.

Neuron Injury

A neuron injury is categorized based on the extent and type of damage to the nerve and the surrounding connective tissue (Fig. 1.1): neuropraxia, a nerve injury in which the nerve remains intact but with its signaling ability damaged; axonotmesis, in which the nerve remains intact but there with an interruption in conduction of the impulse along the nerve fiber; and neurotmesis, which follows a severe contusion, stretch, laceration, or similar damage. In this case both the axon and the encapsulating connective tissue lose their continuity.

Figure 1.1. Sketch of nerve injury.

In some injuries, the presynaptic neurons that synapse on the damaged cells are also affected. Transneuronal changes of various kinds are important in explaining why a lesion at one site in the central nervous system (CNS) can have effects on sites distant to the lesion, sites that are distributed according to the connections that the lesion interrupts.

The zone of trauma is a place where a bundle of axons is cut, either by sectioning of a tract within the CNS or by sectioning a peripheral nerve. The part of the axon still connected to the cell body is the proximal segment, and the part isolated from the rest of the cell is the distal segment.

At a zone of trauma in the CNS, the axon and myelin sheath undergo rapid local degeneration. Because a lesion usually interrupts blood vessels, macrophages from the general circulation can enter the area and phagocytose axonal debris. Astrocytes and microglia proliferate and act as phagocytes. In the CNS, however, the proliferation of fibrous astrocytes leads to the formation of a glial scar around the zone of trauma. Scarring can block the course taken by regenerating axons and establish an effective barrier against the reformation of central connections.

The degeneration spreads in both directions along the axon from the zone of trauma, but only for a short distance in the proximal segment, usually up to the point of origin of the first axon collateral. After few days, a retrograde reaction is seen in the cell body. If the entire cell body dies, then degeneration spreads from the axon hillock down along the remainder of the proximal segment. In the distal segment, outside the zone of trauma, the degeneration first appears in the axon terminal about one day after the occurrence of the lesion. In approximately two weeks, the synapses formed by the distal segment degenerate completely. The process is called terminal degeneration. Degeneration of the distal axon, termed Wallerian degeneration, takes place over a period of about two months. Sometime cells that are prior postsynaptic to the injured neuron may also be affected.