Neuroscience in Medicine (eBook)

P. Michael Conn (Herausgeber)

eBook Download: PDF

2008 | 3. Auflage
XIII, 820 Seiten
Humana Press (Verlag)
978-1-60327-455-5 (ISBN)

Infos

Continuing progress has been made in understanding the brain at the molecular, anatomic, and physiological levels in the years following the "Decade of the Brain," with the results providing insight into the underlying basis of many neurological disease processes. In Neuroscience in Medicine, Third Edition, a distinguished panel of basic and clinical investigators, noted for their teaching excellence, provide thoroughly updated and revised chapters to reflect these remarkable advances. Designed specifically for medical students and allied health professionals, this up-to-date edition alternates scientific and clinical chapters that explain the basic science underlying neurological processes and then relate that science to the understanding of neurological disorders and their treatment. These popular and now expanded "clinical correlations" cover, in detail, disorders of the spinal cord, neuronal migration, the autonomic nervous system, the limbic system, ocular motility, and the basal ganglia, as well as demyelinating disorders, stroke, dementia and abnormalities of cognition, congenital chromosomal and genetic abnormalities, Parkinson's disease, nerve trauma, peripheral neuropathy, aphasias, sleep disorders and myasthenia gravis. In addition to concise summaries of the most recent biochemical, physiological, anatomical, and behavioral advances, the chapters summarize current findings on neuronal gene expression and protein synthesis at the molecular level.

Authoritative and comprehensive, Neuroscience in Medicine, Third Edition provides a fully up-to-date and readily accessible guide to brain functions at the cellular and molecular level, as well as clearly demonstrating their emerging diagnostic and therapeutic importance.

Inhalt

PREFACE 5
CONTENTS 6
CONTRIBUTORS 9
LIST OF COLOR PLATES 11
Cytology and Organization of Cell Types: Light and Electron Microscopy 12
1. NEURONAL RESPONSE TO A CHANGING ENVIRONMENT 12
2. MECHANISMS OF NEURONAL FUNCTION 15
3. CYTOSKELETON DETERMINATION OF NEURONAL FORM 21
4. NEURONAL SYNAPSES 24
5. GLIAL CELLS 29
Anatomy of the Spinal Cord and Brain 35
1. INTRODUCTION 35
2. SPINAL CORD EXTERNAL ANATOMY 35
3. BRAIN 42
SELECTED READINGS 61
Ion Channels, Transporters, and Electrical Signaling 62
OVERVIEW 63
1. RESTING MEMBRANE POTENTIALS 63
2. ELECTRICAL EXCITABILITY OF THE CELL MEMBRANE 69
3. VOLTAGE-GATED CHANNELS 73
4. EXTRACELLULAR LIGAND-GATED CHANNELS 85
5. ENaC/DEGENERIN FAMILY OF CHANNELS 90
6. INTRACELLULAR AND INTERCELLULAR CHANNELS 91
7. ACTIVE TRANSPORTERS 94
8. A CROSS-COMMUNICATION BETWEEN ELECTRICAL AND RECEPTOR- MEDIATED SIGNALING PATHWAYS 97
SELECTED READINGS 98
Demyelinating Disorders 99
IMPAIRED OR BLOCKED IMPULSE CONDUCTION 99
DISEASES THAT AFFECT MYELIN 99
MS HAS A DISTINCT AGE, GENDER, RACE, AND GEOGRAPHIC PROFILE 100
MS IS CHARACTERIZED BY THE PRESENCE OF NUMEROUS DISCRETE AREAS OF DEMYELINATION THROUGHOUT THE BRAIN AND SPINAL CORD 100
THE SYMPTOMS OF MS REMIT AND REAPPEAR IN CHARACTERISTIC FASHION 100
THE DIAGNOSIS OF MS CAN BE AIDED BY IMAGING STUDIES AND LABORATORY TESTS IMMUNOSUPPRESSION IS THE MOST 101
COMMON FORM OF THERAPY USED IN MS 101
SELECTED READINGS 102
Synaptic Transmission 103
OVERVIEW 103
1. PROPERTIES OF CHEMICAL AND ELECTRICAL SYNAPSES 104
2. A MODEL SYNAPSE: THE NEUROMUSCULAR JUNCTION 109
3. PRESYNAPTIC EXOCYTOSIS IS CA DEPENDENT 109
4. NEUROTRANSMITTERS AND THEIR RECEPTORS IN THE MAMMALIAN BRAIN 111
5. THE INTERPLAY OF EXCITATION AND INHIBITION 112
6. SYNAPSES ARE HETEROGENEOUS AND CAN BE SPECIALIZED 113
7. SHORT-TERM AND LONG-TERM SYNAPTIC PLASTICITY 116
SELECTED READINGS 117
Presynaptic and Postsynaptic Receptors 118
1. RECEPTOR CLASSIFICATION SCHEMES: ANATOMIC, PHARMACOLOGIC, AND STRUCTURAL/ MECHANISTIC 118
2. RECEPTOR STRUCTURE AND FUNCTION 119
3. NEUROTRANSMITTERS AND THEIR RECEPTORS 126
4. CONCLUSION 137
SUGGESTED READINGS 137
Neuroembryology and Neurogenesis 138
1. INTRODUCTION 138
2. EMBRYONIC DEVELOPMENT OR THE NERVOUS SYSTEM 139
3. NEUROGENESIS IN THE EMBRYONIC NERVOUS SYSTEM 147
4. NEURONAL APOPTOSIS IN THE DEVELOPING NERVOUS SYSTEM 149
SELECTED READINGS 150
Disorders of Neuronal Migration 151
CORTICAL NEURONS IN NEURONAL MIGRATION DISORDERS 151
EPILEPSY AS A SYMPTOM OF ABNORMAL CORTICAL NEURONAL MIGRATION 151
KALLMANN’S SYNDROME AS A PROTOTYPE OF THE HERITABLE DISORDERS OF NEURONAL MIGRATION 152
SELECTED READINGS 152
The Vasculature of the Human Brain 153
1. INTRODUCTION 153
2. INTRACRANIAL ARTERIAL SYSTEM ( TABLE 1) 155
3. COLLATERAL CIRCULATION (TABLE 8) 164
4. CAPILLARIES 165
5. INTRACRANIAL VENOUS SYSTEM ( TABLE 9) 167
SELECTED READINGS 172
Stroke 173
PATHOLOGIC MECHANISMS OF STROKE 173
THE NORMAL BLOOD SUPPLY TO THE BRAIN CAN BE DISRUPTED BY SEVERAL MECHANISMS 173
TRANSIENT ISCHEMIC SYMPTOMS OFTEN PRECEDE CEREBRAL INFARCTION 174
THE NEUROLOGIC DEFICIT IN ISCHEMIC STROKE DEPENDS ON WHICH BLOOD VESSEL IS INVOLVED 174
LACUNAR INFARCTIONS DO NOT CONFORM TO THE DISTRIBUTION OF MAJOR CEREBRAL ARTERIES 176
TREATMENT OF STROKE 176
SELECTED READINGS 177
Choroid Plexus–Cerebrospinal Fluid Circulatory Dynamics: Impact on Brain Growth, Metabolism, and Repair 178
1. STRUCTURAL AND FUNCTIONAL COMPONENTS OF THE CEREBROSPINAL FLUID 178
2. DIVERSE ROLES OF CSF IN EFFECTING BRAIN WELL- BEING 179
3. PIVOTAL MODULATORY FUNCTIONS OF THE CSF IN FETAL BRAIN DEVELOPMENT 182
4. PHYSICAL DIMENSIONS OF THE ADULT CSF SYSTEM 183
5. CSF-BORDERING CELLS THAT DEMARCATE THE VENTRICULO- SUBARACHNOID SYSTEM 186
6. CIRCUMVENTRICULAR ORGANS OUTSIDE BLOOD- BRAIN BARRIER 187
7. ELABORATION OF CSF 189
8. INTERACTIVE BLOOD-CSF AND BLOOD- BRAIN INTERFACES IN MILIEU STABILIZATION 193
9. FLUID IMBALANCES: EFFECTS ON BRAIN AND CSF VOLUMES 195
10. CIRCULATION OF CSF 195
11. DRAINAGE OF CSF 196
12. CSF PRESSURE-VOLUME RELATIONSHIPS 198
13. CELLULAR COMPOSITION OF CSF 200
14. CLINICAL USAGE OF CSF 201
15. NEW OUTLOOKS FOR CSF TRANSLATIONAL RESEARCH AND THERAPY 202
REFERENCES 203
Organization of the Spinal Cord 206
1. THE SPINAL CORD 206
2. SPINAL NEURONS ORGANIZED INTO NUCLEI AND INTO LAMINAE 208
3. ASCENDING AND DESCENDING TRACTS IN WHITE MATTER 208
4. MOTOR NEURONS 213
5. REGIONAL SPECIALIZATIONS 214
6. SPINAL REFLEXES 215
7. SPINAL LESIONS 218
8. STRATEGIES TO REPAIR INJURED SPINAL CORD 219
SELECTED READINGS 220
Disorders of the Spinal Cord 221
CAUSES OF SPINAL CORD DISORDERS 221
LOCALIZATION OF THE CAUSATIVE LESION 221
SPARING OF SACRAL SENSATION MAY HELP DIFFERENTIATE A LESION IN THE CENTER OF THE SPINAL CORD FROM ONE ON ITS CIRCUMFERENCE 222
LESIONS INVOLVING HALF THE SPINAL CORD PRODUCE A DISTINCT CLINICAL SYNDROME 222
A CAPE-LIKE SENSORY LOSS MAY ALSO BE A CLUE TO THE LOCALIZATION OF A SPINAL- CORD LESION 222
THE ANTERIOR PORTION OF THE SPINAL CORD CAN BE PREFERENTIALLY INVOLVED IN ISCHEMIC LESIONS 222
PATHOLOGY BELOW THE L1 THROUGH L2 VERTEBRAL LEVEL AFFECTS THE CAUDA EQUINA BUT NOT THE SPINAL CORD 223
DIAGNOSTIC NEUROIMAGING PROCEDURES AND ELECTROPHYSIOLOGIC TESTS 223
TREATMENT OF SPINAL CORD INJURY 223
SELECTED READINGS 224
The Cerebellum 225
1. OVERVIEW 225
2. THE GENERAL ORGANIZATION OF THE CEREBELLUM 226
3. THE CYTOARCHITECTURE OF THE CEREBELLAR CORTEX IS CONSPICUOUSLY UNIFORM 233
4. THE INPUT AND OUTPUT SYSTEMS OF THE CEREBELLUM 237
5. THE CEREBELLUM AND MOTOR LEARNING 242
6. CEREBELLAR DYSFUNCTION 244
7. SUMMARY 247
REFERENCES 248
The Brain Stem and Cranial Nerves 250
1. INTRODUCTION 250
2. EXTERNAL ANATOMY OF THE BRAIN STEM 250
3. VENTRICULAR SYSTEM OF THE BRAIN STEM 254
4. INTERNAL STRUCTURE OF THE BRAIN STEM 257
5. PERIPHERAL DISTRIBUTIONS OF THE CRANIAL NERVES 262
6. NUCLEAR COMPONENTS OF THE CRANIAL NERVES AND THEIR FUNCTIONS 264
7. CEREBELLUM 270
8. OTHER PROMINENT BRAIN STEM STRUCTURES 270
SUGGESTED READINGS 272
Disorders of the Autonomic Nervous System 273
PERIPHERAL-NERVE DYSFUNCTION 273
CENTRAL NERVOUS SYSTEM DISORDERS 273
ABNORMALITIES OF NEUROTRANSMITTER METABOLISM 274
CLINICAL TESTS USEFUL IN DOCUMENTING AUTONOMIC DYSFUNCTION 274
SELECTED READINGS 275
The Brain Stem Reticular Formation 276
1. INTRODUCTION 276
2. ANATOMIC CHARACTERISTICS OF RETICULAR FORMATION NEURONS 277
3. RETICULAR FORMATION PATHWAYS 280
4. OTHERS RELATED BRAIN STEM NUCLEI 283
5. RETICULAR FORMATION FUNCTIONS AND INTERACTIONS 284
SELECTED READINGS 288
The Trigeminal System 290
1. INTRODUCTION 290
2. PERIPHERIAL DISTRIBUTION OF THE TRIGEMINAL NERVE 290
3. CENTRAL CONNECTIONS OF THE TRIGEMINAL SYSTEM 294
4. ASCENDING TRIGEMINAL PATHWAYS 298
5. FUNCTIONS OF THE TRIGEMINAL SYSTEM 299
6. TRIGEMINAL SYSTEM LESIONS 300
SELECTED READINGS 301
The Hypothalamus 303
1. INTRODUCTION 303
2. ANATOMY OF THE HYPOTHALAMUS 306
3. TECHNIQUES FOR STUDYING HYPOTHALAMIC FUNCTION 331
4. PHYSIOLOGIC PROCESSES CONTROLLED BY THE HYPOTHALAMUS 342
5. CONCLUSION 360
SELECTED READING 360
The Cerebral Cortex 361
1. INTRODUCTION 361
2. SURFACE FEATURES OF THE CEREBRAL CORTEX 361
3. CORTICAL CYTOLOGY 363
4. STRUCTURE AND DISTRIBUTION OF CORTICAL AREAS 367
5. FUNCTIONAL SUBDIVISIONS OF THE CEREBRAL CORTEX 370
6. CORTICAL CONNECTIVITY 373
7. SUMMARY OF THE ORGANIZATION OF THE CEREBRAL CORTEX 377
SELECTED READING 378
Dementia and Abnormalities of Cognition 379
REGIONAL BRAIN PATHOLOGY ALZHEIMER’S DISEASE 379
SUDDEN ABNORMALITIES OF MEMORY AND COGNITION 380
SELECTED READINGS 380
The Limbic System 381
1. HISTORY OF THE NEUROANATOMY OF THE LIMBIC SYSTEM 381
2. NEUROANATOMY OF THE LIMBIC SYSTEM 383
3. MAJOR CONNECTIONS OF THE LIMBIC SYSTEM 389
4. FUNCTIONAL CONSIDERATIONS 394
5. LIMBIC SYSTEM OVERVIEW 398
SUGGESTED READINGS 398
Disorders of the Limbic System 399
THE LIMBIC SYSTEM PLAYS A ROLE IN EPILEPSY 399
THE LIMBIC SYSTEM ALSO PLAYS A ROLE IN ALZHEIMER’S DISEASE 399
THE LIMBIC SYSTEM PLAYS A ROLE IN WERNICKE- KORSAKOFF’S SYNDROME 400
SELECTED READINGS 401
The Basal Ganglia 402
1. INTRODUCTION 402
2. ANATOMY OF THE BASAL GANGLIA 403
3. INTRINSIC CIRCUITS OF THE BASAL GANGLIA 406
4. BASAL GANGLIA–THALAMOCORTICAL CIRCUITS 408
5. FUNCTION AND PHYSIOLOGY OF THE BASAL GANGLIA 410
6. PHARMACOLOGY OF THE BASAL GANGLIA 412
SELECTED READINGS 414
Disorders of the Basal Ganglia 416
CHOREA 416
DYSTONIA 417
TICS 417
BASAL GANGLIA DISORDERS CAUSING MULTIPLE FORMS OF ABNORMAL MOVEMENT 418
SELECTED READINGS 418
The Thalamus 419
1. INTRODUCTION 419
2. HISTORY 420
3. NUCLEAR SUBDIVISIONS OF THE THALAMUS 421
4. CELL TYPES OF THE THALAMUS 422
5. BASIC SYNAPTIC ORGANIZATION OF THE DORSAL THALAMUS 424
6. SYNAPTIC CONNECTIVITY OF THE RETICULAR NUCLEUS 425
7. NEUROTRANSMITTERS IN THE THALAMUS 426
8. SPECIFIC CONNECTIONS OF THALAMIC NUCLEAR GROUPS 429
9. THE CORTICOTHALAMIC SYSTEM 437
10. THE THALAMOSTRIATAL SYSTEMS 438
11. SYMPTOMS AFTER THALAMIC LESIONS 440
12. THALAMOTOMY AND THALAMIC DEEP BRAIN STIMULATION FOR BRAIN DISEASES 441
13. CONCLUDING REMARKS 441
SELECTED READINGS 442
Spinal Mechanisms for Control of Muscle Length and Force 443
1. A BRIEF REVIEW OF MUSCLE FUNCTION 443
2. MECHANICAL PROPERTIES OF WHOLE MUSCLE 447
3. MUSCLE RECEPTORS 450
4. AFFERENT PATHWAYS TO THE SPINAL CORD 458
5. MOTONEURONS AND MOTOR UNITS 464
6. NEUROMODULATION OF SPINAL CIRCUITS 472
7. SPINAL REGULATION OF MOVEMENT 474
SELECTED READINGS 478
Chemical Messenger Systems 479
1. NEUROTRANSMITTERS, NEUROHORMONES, AND NEUROMODULATORS 479
2. NEUROTRANSMITTERS ARE SMALL ORGANIC MOLECULES THAT CARRY A CHEMICAL MESSAGE FROM A NEURONAL AXON OR DENDRITE TO ANOTHER CELL OR NERVE 479
3. NEUROHORMONES ARE CHEMICAL MESSENGERS THAT ARE SECRETED BY THE BRAIN INTO THE CIRCULATORY SYSTEM AND ALTER CELLULAR FUNCTION AT A DISTANCE 480
4. NEUROMODULATORS ARE TRANSMITTERS OR NEUROPEPTIDES THAT ALTER THE ENDOGENOUS ACTIVITY OF THE TARGET CELL 480
5. THE RESPONSE TO TRANSMITTERS CAN BE EITHER FAST OR SLOW 482
6. NERVE ACTIVITY CAN BE MEASURED BY DETERMINING THE FIRING RATE OR RATE OF NEUROTRANSMITTER RELEASE OR TURNOVER 482
7. SMALL-MOLECULAR-WEIGHT NEUROTRANSMITTERS 483
8. AMINO ACID NEUROTRANSMITTERS: GABA, GLUTAMATE, AND GLYCINE 497
9. ENDOCANNABINOIDS 501
10. NITRIC OXIDE 502
11. NEUROACTIVE PEPTIDES 502
12. CONCLUSION 506
REFERENCES 506
SELECTED READINGS 507
Parkinson’s Disease 508
PARKINSON’S DISEASE SYMPTOMS 508
AGE-RELATED INCIDENCE OF PARKINSON’S DISEASE 509
THE LEWY BODY IS THE PATHOLOGIC HALLMARK OF PARKINSON’S DISEASE 510
ETIOLOGY AND TREATMENT 510
SELECTED READINGS 512
Pain 513
1. PAIN IS A COMPLEX SENSORY EVENT 513
2. SOMATOSENSORY PRIMARY AFFERENTS TRANSDUCE STIMULUS ENERGY AND TRANSMIT INFORMATION FROM THE PERIPHERAL TISSUES INTO THE CENTRAL NERVOUS SYSTEM 514
3. NOCICEPTIVE SENSORY NEURONS PROJECT TO THE DORSAL HORN 517
4. PARALLEL ASCENDING PATHWAYS UNDERLIE DISTRIBUTED PROCESSING OF NOCICEPTIVE INFORMATION 518
5. VISCERAL NOCICEPTION 520
6. PAIN PROCESSES IN INJURED OR INFLAMED TISSUE 521
7. REGULATORY MECHANISMS: GATE CONTROL AND DESCENDING MODULATION 522
8. PAIN DUE TO INJURY TO PERIPHERAL OR CENTRAL NERVOUS SYSTEM 523
SELECTED READINGS 525
Physical Trauma to Nerves 526
NERVE SEVERANCE RESULTS IN A PREDICTABLE SEQUENCE OF CHANGES IN THE NERVE AND MUSCLE NERVE- CONDUCTION TESTING IS USEFUL IN DETERMINING THE EXTENT 526
AND LOCATION OF NERVE DAMAGE 526
CHRONIC COMPRESSION AND ENTRAPMENT ARE AMONG THE MOST COMMON FORMS OF NERVE INJURY 527
RECOVERY AFTER NERVE TRAUMA MAY DEPEND ON NERVE REGENERATION 527
SELECTED READING 527
Peripheral Neuropathy 528
AXONAL DEGENERATION CAN TAKE SEVERAL FORMS 528
DEMYELINATION OF PERIPHERAL NERVES MAY BE PRIMARY OR SECONDARY 528
THE TYPICAL SYMPTOMS OF PERIPHERAL NEUROPATHY INCLUDE POSITIVE AND NEGATIVE PHENOMENA 529
NERVE-CONDUCTION TESTING IS USEFUL IN ANALYZING PERIPHERAL NEUROPATHIES 529
PERIPHERAL NEUROPATHY MAY DEVELOP ACUTELY OR CHRONICALLY 530
THERAPY FOR NEUROPATHIES CAN BE DIRECTED AT THE SYMPTOMS AND THE CAUSE 530
SELECTED READING 530
Vision 531
1. INTRODUCTION 531
2. REFRACTION 532
3. THE RETINA 533
4. PHOTOTRANSDUCTION 534
5. THE OPTIC PATHWAYS 537
6. CRITICAL PERIODS IN VISUAL SYSTEM DEVELOPMENT 541
7. ADULT ORGANIZATION OF THE VISUAL PATHWAY FROM RETINA TO CORTEX 542
8. ACTIVITY-INDEPENDENT DEVELOPMENT OF ORDER IN THE VISUAL SYSTEM 542
9. ACTIVITY-DEPENDENT DEVELOPMENT OF ORDER IN THE VISUAL SYSTEM 544
10. DEFINITION OF THE OCULOMOTOR SYSTEM 555
11. TYPES OF EYE MOVEMENTS 555
12. EXTRAOCULAR MUSCLES 556
13. EXTRAOCULAR MOTOR NUCLEI 556
14. PRE-OCULOMOTOR NUCLEI 559
15. ROLE OF THE CEREBRAL CORTEX AND CEREBELLUM IN EYE MOVEMENT 562
16. ROLE OF THE BASAL GANGLIA IN EYE MOVEMENT 565
17. CONTROL OF VERGENCE EYE MOVEMENTS 565
18. BASIS OF DISEASE STATES 565
19. DISORDERS OF OCULAR MOTILITY 568
SELECTED READINGS 571
Disorders of Ocular Motility 572
SEVERAL SUPRANUCLEAR SYSTEMS GUIDE EYE MOVEMENT 572
ABNORMALITIES OF CONJUGATE GAZE IMPLY BRAIN- STEM PATHOLOGY 573
DISTINCT PATTERNS OF IMPAIRED OCULAR MOTILITY RESULT FROM LESIONS OF INDIVIDUAL CRANIAL NERVES 573
DISORDERS OF MUSCLE OR NEUROMUSCULAR TRANSMISSION CAN AFFECT OCULAR MOTILITY 573
NYSTAGMUS IS AN ABNORMAL PATTERN OF REPETITIVE EYE MOVEMENTS 574
SELECTED READINGS 574
Audition 575
1. INTRODUCTION 575
2. THE PHYSICAL NATURE OF SOUND 575
3. THE PERIPHERAL AUDITORY SYSTEM 576
4. FREQUENCY TUNING AND TEMPORAL INFORMATION ARE TRANSMITTED BY AUDITORY NERVE FIBERS 581
5. CENTRAL AUDITORY SYSTEM 582
SELECTED READINGS 589
The Vestibular System 590
1. INTRODUCTION 590
2. VESTIBULAR REFLEXES 590
3. THE VESTIBULAR RECEPTORS 591
4. CENTRAL VESTIBULAR CONNECTIONS AND PATHWAYS ARE RELATED TO THE CONTROL OF EYE MOVEMENTS, BALANCE, AND POSTURE 594
5. NYSTAGMUS 597
6. VESTIBULAR ASSESSMENT 599
SELECTED READINGS 599
The Gustatory System 600
1. INTRODUCTION 600
2. PERIPHERAL TASTE SYSTEM 602
3. CENTRAL TASTE SYSTEM 606
SELECTED READINGS 609
The Olfactory System 610
1. INTRODUCTION 610
2. THE OLFACTORY EPITHELIUM 610
3. THE MAIN OLFACTORY BULB 613
4. THE PRIMARY OLFACTORY CORTEX ( FIG. 4) 617
5. THE ACCESSORY OLFACTORY SYSTEM 620
6. OLFACTION AND BEHAVIOR 620
Sleep, Dreams, and States of Consciousness 622
1. INTRODUCTION AND ORGANIZATION OF SLEEP- WAKEFULNESS 622
2. SLEEP HAS DISTINCTIVE ONTOGENETIC AND PHYLOGENETIC FEATURES 626
3. SLEEP ONSET AND SLEEPINESS IS DETERMINED BY CIRCADIAN TIME OF DAY AND BY PRIOR WAKEFULNESS 626
4. SLOW-WAVE SLEEP FACTORS 628
5. CONTROL OF EEG SYNCHRONIZATION AND DESYNCHRONIZATION 632
6. REM SLEEP PHYSIOLOGY AND RELEVANT BRAIN ANATOMY 633
7. OREXIN, NARCOLEPSY, AND THE CONTROL OF SLEEP AND WAKEFULNESS 640
8. MOLECULAR BIOLOGY OF SLEEP 641
9. THE FORM OF DREAMS AND THE BIOLOGY OF REM SLEEP 642
10. FUNCTION(S) OF NON-REM AND REM SLEEP 643
Disorders of Sleep 646
Higher Brain Functions 649
1. INTRODUCTION 649
2. BRAIN AND BEHAVIOR ASSOCIATIONS 650
3. THE OCCIPITAL LOBES 654
4. THE TEMPORAL LOBES 655
5. THE PARIETAL LOBES 658
6. THE FRONTAL LOBES 659
7. SUBCORTICAL STRUCTURES 662
8. CLOSING REMARKS SELECTED READINGS 663
The Aphasias and Other Disorders of Language 665
Neuroimmunology: An Overview 668
1. INTRODUCTION 668
2. INNERVATION OF LYMPHOID ORGANS 668
3. CYTOKINES IN THE NERVOUS SYSTEM 670
4. PRESENCE OF NEUROENDOCRINE PEPTIDES IN IMMUNE CELLS 671
5. NEUROIMMUNOMODULATION BY NEUROENDOCRINE PEPTIDES 672
6. AUTOIMMUNITY AND NEUROIMMUNOLOGY 672
SELECTED READINGS 672
Nervous System–Immune System Interactions 673
1. INTRODUCTION 673
2. INTERACTIONS OF THE NERVOUS AND IMMUNE SYSTEMS IN THE PERIPHERY 673
3. IMMUNE INTERACTIONS WITHIN THE CNS 676
4. INFLAMMATORY RESPONSES IN THE CNS DURING TRAUMA OR DISEASE 679
5. CONCLUSION 682
SELECTED READINGS 683
Myasthenia Gravis 684
Degeneration, Regeneration, and Plasticity in the Nervous System 687
1. INTRODUCTION 687
2. BASIC CELLULAR RESPONSES IN THE PNS AND CNS TO AXONAL DAMAGE: GENERAL PRINCIPLES 688
3. NEURONAL RESPONSES TO AXONAL INJURY IN THE PERIPHERAL NERVOUS SYSTEM 696
4. NEURONAL RESPONSES TO INJURY OR DISEASE IN THE CENTRAL NERVOUS SYSTEM 701
5. CNS NEURONS CAN EXPRESS CONSIDERABLE INTRINSIC GROWTH CAPACITIES UNDER CERTAIN CONDITIONS 705
6. A BALANCE BETWEEN INTRINSIC AND EXTRINSIC FACTORS GOVERNING AXONAL REGENERATION IN THE CNS 706
7. THE INJURED CNS HAS SOME INTRINSIC POTENTIAL FOR SELF- REPAIR: CONCEPT OF NEUROPLASTICITY 710
8. POTENTIAL INTERVENTIONS TO PROMOTE CNS REPAIR ARE BASED ON CELLULAR RESPONSES TO INJURY AND DISEASE 714
9. CAN CELLS THAT DIE BECAUSE OF NECROSIS OR APOPTOSIS BE REPLACED? 717
10. ARE CNS CIRCUITS AND PATHWAYS RIGIDLY WIRED? 721
11. SUMMARY 722
SELECTED READINGS 723
Congenital Chromosomal and Genetic Abnormalities 724
The Biology of Drug Addiction 727
1. INTRODUCTION 727
2. TECHNIQUES USED TO STUDY ADDICTION 729
3. SEX DIFFERENCES AND THE NEUROENDOCRINE SYSTEM IN ADDICTION 730
4. CIRCADIAN RHYTHMS AND ADDICTION 732
5. MECHANISMS OF ACTION FOR SPECIFIC ADDICTIVE DRUGS 734
6. GENERAL MOLECULAR AND CELLULAR MECHANISMS OF ADDICTION 740
SELECTED READINGS 743
The Neuropathology of Disease 744
1. INTRODUCTION 744
2. VASCULAR-RELATED PATHOLOGY 744
3. TUMORS 755
4. INFECTIONS 758
5. PERINATAL ABNORMALITIES: HYDROCEPHALUS 760
6. CONGENITAL MALFORMATIONS 761
7. OTHER COMMON PATHOLOGIES 766
SELECTED READINGS 769
INDEX 770

Textauszug

4 Synaptic Transmission (p. 95-96)

Henrique von Gersdorff

OVERVIEW

The nervous system is composed of specialized cellular circuits that allow an animal to perform tasks essential for survival. Neurons are organized to form these circuits, and they transmit electrical and chemical signals among themselves to process sensory input, initiate behavioral responses, and regulate an animal’s internal physiology. The critical link between neurons that permits communication and establishes the foundation for neuronal circuitry is called the synapse, and this chapter will discuss fundamental synaptic properties.

Synapses are sites of close cellular contact where fast, highly localized transmission of chemical and electrical signals can occur. The human brain has approximately 1011neurons that form about 1015 synapses. By comparison, the simple nematode worm C. elegans has exactly 320 neurons with only about 7600 synapses. The capacity of the human brain to form such an astronomical number of synapses has surely contributed to the success of our species and its vast repertoire of behaviors. In order to understand how synapses confer such complexity of neuronal circuitry, it is important to explore the details of information transfer at the synapse.

The process of communication between neurons, termed synaptic transmission, is also key to developing better medical treatments of neurologic conditions for several reasons. The causes of severalmental disorders and neuromuscular diseases can be traced to dysfunctional synapses. Synapses are also the locus of action for several neurotoxins and psychoactive drugs (some of which can cause debilitating and life-long addictions).

Finally, determining how synapses transmit signals and how neuronal circuits are remodeled and modulated at the synaptic level will eventually allow us to understand the basis of neuronal learning and memory.

Synapses vary widely in shape, size, and functional capability. Presumably, such architectural and functional diversities are tailored for the specialized information transfer and processing needs of individual neurons and circuits. For example, many synapses function as high-fidelity relay stations. The connection between motor neurons and muscle fibers (termed the neuromuscular junction), the giant synapses in the mammalian and aviary auditory systems involved in sound localization, and the squid giant synapse, which allows a rapid escape behavior, are all examples of high-fidelity relays. These are synapses where reliability is at a premium, and the synaptic architecture is designed as a fail-safe mechanism for information transfer.

Other synapses, such as the bouton-type synapses of the cortex and hippocampus, often fail to transmit signals and are thus considered comparatively unreliable. These bouton synapses, however, have the capacity to become more fail-safe with repetitive use. This type of change in synaptic strength is an example of plasticity and is thought to underlie the long-lasting storage of information acquired through repetitive use of an associated neuronal circuit. In other words, the specific strengthening of a particular set of synaptic connections may form the basis for some types of learning and memory. Equally important may be the weakening of synaptic connections, a process that could either cause the loss of certain synaptic memory or endow the freedom for retasking a particular neuronal circuit. Thus, synapses must be considered as highly dynamic and plastic structures that can adapt their output to match the demands imposed by their current information processing needs.

Produkt-Details

• Erscheint lt. Verlag: 8.10.2008
• Zusatzinfo: XIII, 816 p.
• Verlagsort: Totowa
• Sprache: englisch
• Themenwelt: Medizin / Pharmazie ► Medizinische Fachgebiete ► Chirurgie
• Themenwelt: Medizin / Pharmazie ► Medizinische Fachgebiete ► Neurologie
• Themenwelt: Studium ► 1. Studienabschnitt (Vorklinik) ► Biochemie / Molekularbiologie
• Themenwelt: Naturwissenschaften ► Biologie ► Humanbiologie
• Themenwelt: Naturwissenschaften ► Biologie ► Zoologie
• Themenwelt: Technik
• Schlagworte: brain function • Brainstem • nervous system • Neurobiology • Neuropathology • Neuroscience • Parkinson • spinal mechanisms
• ISBN-10: 1-60327-455-3 / 1603274553
• ISBN-13: 978-1-60327-455-5 / 9781603274555