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When asked to review The Thalamus, I immediately agreed, wanting to update and increase my knowledge of this mysterious nucleus at the center of the nervous system. I got more than I bargained for: a 2-volume text running to 1679 pages and weighing in at 14 lbs. This is a very impressive body of work and an immense achievement by the author, Edward G. Jones, who is director of the Center for Neuroscience at University of California Davis. It is the second edition of his book, 2 decades after his initial publication and twice the size and 1 decade after Thalamus: Organization and Function, which he coauthored with Mircea Steriade and David McCormick.1As the most current comprehensive text about the mammalian thalamus, The Thalamusbecomes the reference source for neuroscientists. However, it is not as readable as his collaboration with Steriade and McCormick, which communicates more lucidly such concepts as the integrated function of this structure, or as easy to search for a straight answer to a query, and although published in 2007, the citations peter out after 2003 so it is already perhaps 20% as dated as his collaboration with Steriade and McCormick. For example, the chapter on neurochemistry writes: “There is essentially no dopamine innervation of the thalamus” prior to the demonstration by Sanchez-Gonzalez et al of substantial dopamine innervation of the primate thalamus in 2005. Dr Jones brings a disciplined anatomical and physiologic approach to his accounting. Hundreds of photomicrographs of his own stained sections are shown as well as helpful graphs and tables. The benefits of single authorship include the clear layout and consistent pacing and progression throughout, the lack of unnecessary duplication, the absence of internal contradiction, the cross-referencing across chapters from drilled-down detail to general integrative treatments of a topic, and the consistent writing style. Regarding style, the writing is clear, spare, scientific, and professional, except where it is agreeably leavened with the occasional personal commentary or opinion. Dr Jones' erudition with respect to the classic and modern literature is impressive, and most chapters begin and end with a literary quotation. Some of these work, some not so well, though the overall effect seems a bit self-regarding, like sporting a bow tie. The first volume, which is reviewed in more detail later, is concerned with principles and generalities, with data from individual nuclei used to make the points. The second volume drills down, with a chapter on the specific structure, chemistry, and connectivity of each of the 10 main component nuclei or groups of nuclei, and this volume also rounds out with a comparative anatomy across species and general conclusions about the thalamus. The first chapter is a history, covering both etymology and science. Galen used the word “thalamus” to describe this cerebral structure, based on Greek and Latin terms for an inner room, bedroom, or storeroom of a Greek ship or house. Up to the Enlightenment, the attribution of function to the thalamus is unrecognizable to us. Modern neuroscientific study of the thalamus began with Forel and Meynert and others in the late 1800s and was brought forward by, among others, Mountcastle and Eccles in the mid-1900s and, of course, Llinas in the 1980s. Chapters 2 and 3 review the anatomy of the thalamic subnuclei, the neuronal subtypes, and their connections. To this human clinician, the implications for human cerebral function are of greatest interest, so it is helpful that data from small mammals are supplemented with primate studies and human studies as available. The somewhat simpler structure in rodents provides a basis for grasping the greater complexity in humans. One notable omission is human data regarding the important dichotomy between parvalbumin-containing and calbindin-containing thalamic relay neurons in nonhuman primates. The parvalbumin-containing cells form a core in the primary sensory relay nuclei (ventral posterior nucleus for somatosensation, dorsal lateral geniculate for vision, and medial geniculate for audition). They receive the topographically sharper input (for example, lemniscal) and project tightly to cortical columns in idiotypic cortex. By contrast, the calbindin-containing neurons form a matrix that receives less specific input (for example, spinothalamic) and projects to secondary sensory areas. Chapter 4 is an explication of the dynamics of ion channels and circuits underlying the various states and rhythms of the thalamus, especially the bistable states associated with the low-threshold calcium current active at hyperpolarized membrane potentials. The neuronal and network bases of the brain states of sleep, wakefulness, and rapid eye movement are well taught in terms of their physiology. Little or no treatment is given to another function that logically involves the thalamus: the process by which a particular channel of information is attended to at any particular time. There are some passing references to a “searchlight” mechanism for selective activation of focal cortical areas in the mediation of attention, but Dr Jones discounts the hypothesis and does not provide his preferred explanation for this function of the thalamus. While there are few experimental data to verify the model that transmission of, say, one sensory modality is accompanied by relative inhibition of other modalities, there are some data regarding this thalamic function. Chapter 5 reviews the neurochemistry both of transmitters and histologically important compounds, such as calbindin and parvalbumin. Development of the thalamus is the subject of chapter 6. Points of interest are the origin of relay neurons from part of the wall of the third ventricle, as compared with reticular GABAergic neurons, many of which arise from the same ganglionic eminence that populates the globus pallidus with medium spiny neurons. The development of thalamocortical and corticothalamic axons is described. Distinction is made between topographically sharp thalamocortical projections to middle laminae as compared with more widespread projections to superficial laminae. Distinction is also made between corticothalamic projections from lamina V (direct to relay neurons of an associated thalamic nucleus) and lamina VI (which include collateral to reticular nucleus and terminate on related subnuclei of the thalamus). The figures and pictures are generally helpful and informative and usually but not universally well labeled. The citing of references interfered with readability because they are in the same font, and extended series of references (sometimes multiple series) are embedded in a single long sentence so that the reader has to scan the paragraph to link sequential phrases of the sentence. This tome deserves a place in medical and neuroscience libraries in institutions and laboratories where the mammalian thalamus is studied. A reader will be impressed with the author's scholarship and perhaps be motivated to a similarly disciplined and detailed approach to neuroscience. But the core reader of the Archives, the clinical neurologist, will not require his or her own copy. Prose ★★★★ Illustrations ★★★ Science ★★★ Usefulness ★★ Correspondence:Dr O’Suilleabhain, Department of Neurology, UT Southwestern Medical Center, 5323 Harry Hines Blvd, MC 9036, Dallas, TX 75390-9036 (firstname.lastname@example.org). Financial Disclosure:None reported. References 1. Steriade MJones EGMcCormick DA Thalamus: Organization and Function. Oxford, England Elsevier Science Ltd1997;
Archives of Neurology – American Medical Association
Published: Aug 11, 2008
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