Book Review
Transcranial Magnetic Stimulation 
Plasticity in the Human Nervous
System. Investigations With Transcranial Magnetic Stimulation Simon Boniface, Ulf Ziemann, editors. Cambridge (UK): Cambridge University Press; 2003. 316 p. US$95.00.
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Reviewer
rating*: Good
Review by: Gary Hasey MD, FRCPC, MSc,
Hamilton Ontario
Traditional notions of the adult brain as an anatomically and to some extent, functionally immutable organ have been abandoned in favour of the concept of “brain plasticity.” However, the neuroanatomic, neurophysiological, and neurochemical underpinnings of this remarkable brain attribute remain somewhat obscure, despite extensive investigation. Are new synaptic connections created? Are preexisting but latent synaptic connections unmasked? Does reduced inhibition lead to changes in the excitability of neurons?
Boniface and Ziemann shed some light on these mysteries by assembling the contributions of a group of neuroscientists studying brain plasticity with transcranial magnetic stimulation (TMS). TMS is a novel technology with the unique capacity to alter the activity of small regions of the cerebral cortex noninvasively in an alert and nonanesthetized volunteer. Single magnetic pulses may stimulate the motor cortex to evoke a muscle twitch or disrupt neuronal activity in nonmotor areas to create a reversible “virtual lesion.” A “train” or series of magnetic pulses delivered at high frequency can increase the excitability of cortical neurons, whereas low frequency trains can effect the reverse change. Though still at an early stage of development, TMS may prove to be as pivotal an approach to understanding brain functioning as the direct electrical stimulation work pioneered by Penfield. Perhaps of even greater interest to clinicians is that early work suggests TMS may be used to modify or even induce brain plasticity. The implications for therapy of psychiatric and neurologic disease are immense.
This volume provides an overview of the basic principles of TMS, the different applications of TMS as a neuroinvestigative tool, and a detailed discourse on recent work using TMS to study cortical plasticity. There is wide-ranging discussion of the neurophysiological principles underlying plasticity within the motor cortex, how this changes from childhood to maturity, how these principles might be used to understand skill acquisition with practice (motor memory), and how they might be applied to optimize poststroke rehabilitation. Although the text largely focuses on motor functioning, the authors also discuss visual discrimination learning, plasticity within the spinal cord, the effects of sensory deprivation, phantom limb syndromes, and the prognostic value of TMS in the period following a stroke. Unfortunately, little is mentioned of the neuromodulatory effects of stress, and the psychiatric readership will find references to psychopathology in only one of this book’s 12 chapters. Though well written, the material in this chapter describing therapeutic applications of TMS for various psychiatric syndromes has been extensively reviewed in widely available psychiatric journals in recent months.
As might be expected from a multiauthored text, the readability varies from chapter to chapter. There is occasional overreliance on abbreviations, which can affect readability for the nonexpert, and a few sentences that were difficult to follow owing to typographical or grammatical errors. Overall, I found the book well written and highly interesting. Probably for some technical reason, the colour plates from all chapters are placed in order but out of context, in about the centre of the book. Although this is inconvenient to the reader, the illustrations and graphs were invariably well done and highly informative.
In its entirety, this book provides the reader with an excellent overview of the concept of plasticity in the human nervous system. However, some of the chapters are replete with detailed experimental evidence and are therefore highly technical. While not problematic to readers already familiar with the literature, a psychiatrically trained reader without a strong neuroscience background will need to exercise some perseverance to get through the book, particularly because most of the material is not directly relevant to psychiatry. This being said, environmentally induced brain remodelling, such as the stress-related synaptic changes seen in the hippocampus, may have clinical significance. These and other plasticity-related issues will almost certainly find their way into the mainstream of biological psychiatry in the near future. Further, TMS is acquiring an increasing profile as a therapeutic intervention for psychiatric illness, and these psychotropic effects are probably mediated through processes involving brain plasticity.
In summary, Boniface and Ziemann have brought together and cogently organized the work of a respected group of neuroscientists who have been examining functional remodelling of the human nervous system. It will become apparent to the reader that brain “plasticity” is not just the consequence of brain injury or developmental neurophysiology; it is also the immediate, indeed unavoidable, consequence of daily activity across the life span. Although this book can be of general interest to many clinicians, the target readership appears to be a group well versed in the neurosciences. Nonetheless, the interested reader will learn not only about brain plasticity but also a great deal about TMS, a newly emerging technology whose clinical potential as a form of therapy for psychiatric and neurologic disorders is immense. The purchase price seems reasonable for this well-executed book.
*Reviewer
Rating Scale/ Échelle d’évaluation du réviseur
Excellent / Excellent
Very Good / Très bon
Good / Bon
Fair / Passable
Not recommended / Pas recommandé
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