Cellular and Molecular Neurophysiology

Constance Hammond

• Publisher: Academic Press
• Year: 2014
• eBook ISBN: 9780123973221
• Edition: 4
• Topic: Biological Sciences
• Subtopic: Neuroscience
• Index: Biological Sciences

Cellular and Molecular Neurophysiology, Fourth Edition, is the only up-to-date textbook on the market that focuses on the molecular and cellular physiology of neurons and synapses. Hypothesis-driven rather than a dry presentation of the facts, the book promotes a real understanding of the function of nerve cells that is useful for practicing neurophysiologists and students in a graduate-level course on the topic alike. This new edition explains the molecular properties and functions of excitable cells in detail and teaches students how to construct and conduct intelligent research experiments. The content is firmly based on numerous experiments performed by top experts in the field This book will be a useful resource for neurophysiologists, neurobiologists, neurologists, and students taking graduate-level courses on neurophysiology. - 70% new or updated material in full color throughout, with more than 350 carefully selected and constructed illustrations - Fifteen appendices describing neurobiological techniques are interspersed in the text

I

Neurons: excitable and secretory cells that establish synapses

Chapter 1: Neurons

Chapter 2: Neuron–glial cell cooperation

Chapter 3: Ionic gradients, membrane potential and ionic currents

Chapter 4: The voltage-gated channels of Na+ action potentials

Chapter 5: The voltage-gated channels of Ca2+ action potentials: Generalization

Chapter 6: The chemical synapses

Chapter 7: Neurotransmitter release

Chapter 1

Neurons

Constance Hammond

Abstract

Neurons are independent cells making specific contacts called synapses, with hundreds or thousands of other neurons sometimes greatly distant from their cell bodies. The neurons connected together form circuits, and so the nervous system is composed of neuronal networks which transmit and process information. Neurons are excitable cells. Depending on the information they receive, neurons generate electrical signals and propagate them along their processes. This capacity is due to the presence of particular proteins in their plasma membrane which allow the selective passage of ions: the ion channels. Neurons are also secretory cells. Their secretory product is called a neurotransmitter. The release of a neurotransmitter occurs only in restricted regions, the synapses. The neurotransmitter is released in the extracellular space. The synaptic secretion is highly focalized and directed specifically on cell regions to which the neuron is connected. The synaptic secretion is then different (with only a few exceptions) from other secretory cells, such as from hormonal and exocrine cells which respectively release their secretory products into the general circulation (endocrine secretion) or the external environment (exocrine secretion).

Keywords

axon

axon terminal

axonal transport

dendrite, dendritic spine

dendritic transport

dynein

excitable cell

Golgi type I neuron

Golgi type II neuron

kinesin

network

secretory cell

synapse

Outline

1.1 Neurons have a cell body from which emerge two types of processes: the dendrites and the axon 4

1.2 Neurons are highly polarized cells with a differential distribution of organelles and proteins 6

1.3 Axonal transport allows bidirectional communication between the cell body and the axon terminals 11

1.4 Neurons connected by synapses form networks or circuits 18

1.5 Summary: the neuron is an excitable and secretory cell presenting an extreme functional regionalization 22

Further reading 23

By using the silver impregnation method developed by Golgi (1873), Ramon y Cajal studied neurons, and their connections, in the nervous system of numerous species. Based on his own work (1888) and that of others (e.g. Forel, His, Kölliker and Lenhossék), he proposed the concept that neurons are isolated units connected to each other by contacts formed by their processes: ‘The terminal arborizations of neurons are free and are not joined to other terminal arborizations. They make contacts with the cell bodies and protoplasmic processes of other cellular elements.’

As proposed by Cajal, neurons are independent cells making specific contacts called synapses, with hundreds or thousands of other neurons sometimes greatly distant from their cell bodies. The neurons connected together form circuits, and so the nervous system is composed of neuronal networks which transmit and process information. In the nervous system, there is another class of cells, the glial cells, which surround the various parts of neurons and cooperate with them. Glial cells are discussed in Chapter 2.

Neurons are excitable cells. Depending on the information they receive, neurons generate electrical signals and propagate them along their processes. This capacity is due to the presence of particular proteins in their plasma membrane which allow the selective passage of ions: the ion channels.

Neurons are also secretory cells. Their secretory product is called a neurotransmitter. The release of a neurotransmitter occurs only in restricted regions, the synapses. The neurotransmitter is released in the extracellular space. The synaptic secretion is highly focalized and directed specifically on cell regions to which the neuron is connected. The synaptic secretion is then different (with only a few exceptions) from other secretory cells, such as from hormonal and exocrine cells which respectively release their secretory products into the general circulation (endocrine secretion) or the external environment (exocrine secretion). Synapses are discussed in Chapter 6.

Neurons are quiescent cells. When lesioned, most neurons cannot be replaced, since they are postmitotic cells. Thus, they renew their constituents during their entire life, involving the precise targeting of mRNAs and proteins to particular cytoplasmic domains or membrane areas.

1.1. Neurons have a cell body from which emerge two types of processes: the dendrites and the axon

Although neurons present varied morphologies, they all share features that identify them as neurons. The cell body or soma gives rise to processes which give the neuron the regionalization of its functions, its polarity and its capacity to connect to other neurons, to sensory cells or to effector cells.

1.1.1. The somatodendritic tree is the neuron’s receptive pole

The soma of the neuron contains the nucleus and its surrounding cytoplasm (or perikaryon). Its shape is variable: pyramidal soma for pyramidal cells in the cerebral cortex and hippocampus; ovoid soma for Purkinje cells in the cerebellar cortex; granular soma for small multipolar cells in the cerebral...

Table of contents

• Cover
• Title page
• Table of Contents
• Copyright
• Foreword
• Acknowledgments
• I: Neurons: excitable and secretory cells that establish synapses
• II: Ionotropic and metabotropic receptors in synaptic transmission
• III: Somato-dendritic processing and plasticity of postsynaptic potentials
• IV: The hippocampal network
• Contributors
• Index