Nerve and Muscle: (Real)ized Potential

Abstract

Nerve and Muscle, Third Edition, Richard D. Keynes and David J. Aidley, Cambridge: Cambridge University Press (2001). 192 pp, $59.95 hardback, $19.95 paperbackA concise and engaging summary of a large body of work on the electrical language of the nervous system, the third edition of Nerve and Muscle by Keynes and Aidley makes this complex literature accessible for students and professionals.For more than 160 years, muscle and its neural innervation have served as model systems for studies of electrical excitability as well as cellular and synaptic structure and function. Since the first descriptions of large nerve endings on striated muscle fibers in the arthropod Milnesium tardigradum by Doyere in 1840, the experimental accessibility of presynaptic motor neurons and postsynaptic muscle fibers has been largely unmatched. Descriptions of synaptic structure in the late 1800s and early 1900s were followed by studies of the mechanisms of neurotransmitter release in the 1950s, excitation-contraction coupling in muscle fibers in the 1970s, and regulation of gene expression by innervation and activity over the last two decades. Molecular and genetic approaches have been used to understand the mechanisms of each of these processes and have broken new ground in the understanding and treatment of nerve and muscle diseases, for example, the dystrophinopathies. Many of these studies laid a firm foundation for work on neuronal structure and function in the relatively less accessible CNS.In the third edition of their classic short textbook, Nerve and Muscle (Figure 1(Figure 1), published this year by Cambridge University Press, Richard Darwin Keynes and the late David John Aidley have provided a highly readable primer that describes the fundamental principles underlying nerve and muscle function. The authors are uniquely positioned to offer a historical as well as personal perspective of seminal experiments on electrical excitability of neurons and muscle fibers. Keynes performed studies of action potential generation and propagation with Hodgkin, among others, and was the first to monitor ionic movements during action potential propagation in giant axons from cephalopods, using radioactive sodium and potassium (Keynes, 1951, J. Physiol. 114, 151–182). Aidley conducted groundbreaking work on the role of calcium in excitation-contraction coupling in insect muscle and spent much of his career understanding the biophysical and regulatory aspects of this process.Figure 1View Large Image | View Hi-Res Image | Download PowerPoint SlideThe authors do an admirable job of integrating this classic work with more recent studies, covering the mechanisms underlying action potential generation and propagation, the resting potential, and the structure and function of voltage- and ligand-gated ion channels. This edition includes insights derived from molecular studies, most notably, the mechanisms underlying channel ion selectivity and voltage gating. Neuromuscular synaptic transmission is compared to that at CNS synapses, focusing on excitatory and inhibitory inputs to motor neurons. Muscle anatomy, excitation-contraction coupling, and exercise-induced modulation of function in striated, smooth, and cardiac muscle is covered in three short chapters. Work on muscle ultrastructure is nicely but briefly married to molecular insights into contractile function.By concisely summarizing a huge body of work, the authors make this literature accessible to the nonspecialist or to the undergraduate just beginning to study neuroscience. This is the singular strength of this text; few, if any, comparable efforts have been targeted to such an audience. This strength, however, is also a weakness, in that it limits the text's appeal to advanced students or practicing neuroscientists wanting more comprehensive coverage of the electrical language of neurons. Kandel et al.'s Principles of Neural Science (McGraw Hill Press), Nichols et al.'s From Neuron to Brain (Sinauer Press), or Aidley's Physiology of Excitable Cells (Cambridge University Press) are targeted to this latter audience. The illustrations in Keynes and Aidley leave something to be desired; they are rudimentary and not well integrated into the text. In an era of animated, multicolor PowerPoint presentations, they seem rather uninspired as didactic tools. The brevity of the legends limits their usefulness in providing information that amplifies that presented in the main text. However, the writing is extraordinary—clear, beautifully constructed descriptions of experiments that lead the reader naturally to the major insights derived from the work. The chapter describing membrane permeability changes during the action potential and the sodium hypothesis put forth by Hodgkin and Katz in 1949 (Hodgkin and Katz, 1949, J. Physiol. 108, 37–77) is a particularly good example of this, incorporating simple illustrations, some basic mathematical concepts, and engaging prose. Authors who attempt to provide more experimental insights often sacrifice clarity, and this can blunt understanding of some fundamentally important work. Students approaching this literature for the first time will realize the true “potential” of this little gem of a text.