Atlas of Morphology and Functional Anatomy of the Brain

doi:10.3174/ajnr.A0616

T. Scarabino, U. Salvolini, F. DiSalle, H. Duvernoy, and P. Rabischong, eds. Berlin, Germany: Springer; 2006. 127 pages, 166 illustrations, $99.00.

The rapid expansion of advanced imaging techniques is generating new insights into the clinical neurosciences and has fostered growth in the field of neuroradiology. Techniques, such as functional MR imaging (fMRI) and diffusion tensor imaging (DTI), have already begun to have significant effect on presurgical risk assessments in patients with brain tumors and other respective lesions. Evolving applications of brain mapping for functional neurosurgery and for understanding cognitive and neurodegenerative disorders are just over the horizon. Driven by these imaging developments, neuroradiology is shifting its emphasis toward a greater understanding of the pathophysiology of neurologic disease and the implications of such to brain functions. The integral nature of clinical neuroimaging suggests that neuroradiologists should acquire a thorough appreciation of brain functional organization and the capacity to extract information about brain pathology and disease-induced brain dysfunction, provided by 2D image data. Deeper insights into functional brain imaging anatomy are the critical first steps in realizing the potential of functional imaging.

The Atlas of Morphology and Functional Anatomy of the Brain, edited by T. Scarabino and U. Salvolini, in collaboration with F. DiSalle, H. Duvernoy, and P. Rabischong, is a resource that answers the call of functional neuroradiology training. The atlas includes more than 160 images detailing sulcal and gyral landmarks and functional anatomic regions using both cadaveric and normal imaging anatomic designations. The material is directed at radiologists, neuroradiologists, neurosurgeons, neurologists, and other clinical neuroscientists. The Atlas is intended as a reference and teaching tool for medical students and residents, using cadaveric specimens to reinforce anatomy demonstrated on standard MR imaging of the human brain. Included are 3 main sections: an “Introduction” providing a conceptual framework of functional anatomy, a “Morphology Atlas” containing whole-brain cadaveric views and multiplanar dissections with corresponding imaging views, and a “Functional Atlas” illustrated by using fMRI on sectional and surface-rendered 3D images.

One of the more interesting and readable components of the Atlas is the overview of human brain organization entitled “Comprehensive Anatomy of the Human Brain,” which is included within the “Introduction” section. This section reviews such topics as the neuronal network, cerebrovascular architecture and physiology, sensory filtration, and biologic maintenance, as well as the classic subdivisions of the encephalon. Four main brain functions are also discussed, including mobility, communication, biologic maintenance, and survival. Authored by Pierre Rabischong, this section includes fascinating discussions of the integrated nervous system, providing a conceptual global framework of brain function. This facilitates an understanding of functional anatomy and nicely relates functional organization as a whole to everyday life—a matter likely of interest to a large number of readers. However, appealing as it is, the section is incomplete. There is a relative lack of functional-structural correlates. Diagrams, which could illustrate the well-stated points in this portion of the Atlas, are also lacking.

Moving through the “Introduction,” one’s interest is engaged, but not completely satisfied. For example, the description of sensorimotor system integration is nicely done but lacks a discussion of the relevance to clinical functional imaging or the necessary diagrams to solidify the educational intent of the text. Other important topics are even more superficially treated. This section, if expanded and using illustrations, could have provided a fascinating and unique perspective for understanding functional anatomy and, therefore, the consequences of brain pathology. The sparse, and from a clinical imaging perspective, disconnected nature of this section represents a missed opportunity by the authors.

The “Morphology Atlas” section includes 4 subsections: surface anatomy, axial sectional anatomy, coronal sectional anatomy, and sagittal sectional anatomy. Virtually every sulcal and gyral structure in the normal human brain is designated in this portion of the Atlas. It is indeed a thorough resource for surface and sulcal brain anatomy. More than 300 anatomic designations are included from 3D and cross-sectional perspectives. Each anatomic structure is labeled by a designated letter-numeric code, which is cataloged in an appendix insert that folds out for easy comparison with any page of interest. However, as a matter of style, the need to refer back and forth between an illustration of interest and a letter-numeric designation in an appendix is a cumbersome process, particularly if reading through the text is the intended method of learning. The Atlas is more suitable for identifying a specific structure that has been observed on imaging or for testing one’s skills in brain anatomy. Corresponding anatomic and MR image sections are provided to promote an understanding of brain anatomy as encountered by practicing neuroradiologists.

In some instances, the authors have chosen to exclude subdivisions of certain sulcal landmarks, which have functional and clinical significance. For example, the ascending aspect of the cingulate sulcus is simply designated as the “cingulate sulcus.” Other texts specify this terminal extent of the cingulate sulcus as the “marginal segment” or the “pars marginalis.” Because this segment of the sulcus forms the posterior border of the paracentral lobule and because the paracentral lobule contains primary sensorimotor cortex, a specific designation of this sulcus has utility in describing critical functional spatial relationships of brain pathology. Likewise, the posteriormost extent of the superior temporal sulcus has been specified in other texts as ascending or horizontal posterior segments of the same. Given the significance of the posterior perisylvian cortex to language functions, a specific designation of this particular portion of the sulcus also has common clinical utility. Also, the whole-brain views would benefit from partial cutaways, revealing gyri and sulci deep within the major fissures. For example, designation of the planum polare and the transverse temporal gyrus on the lateral whole-brain view does not give the reader the full understanding of anatomic relationships in this part of the cortex, as would be provided by a partial cutaway of the frontoparietal operculum.

The multiplanar sectional cadaver and MR images are nicely presented, and, with the exception of only a few mislabeled items, provide a complete section-by-section understanding of anatomy in 3 planes–axial, coronal, and sagittal. The labels of the gyral and sulcal landmarks are clear for the most part. However, the lines used to designate brain structures are almost all black. Because some of these lines cross dark sulcal and fissural landmarks, visualizing certain structures to which a label corresponds can be problematic. The cross-sectional views provide detailed anatomic relationships of the deep gray matter and white matter structures that can be visualized with routine MR imaging. However, the Atlas does not present information on the location of white matter tracts and fasciculi that are not clearly visible on standard imaging or cadaveric specimens. Yet they are readily identifiable on DTI. An understanding of cortical landmarks without the appreciation of white matter connectivity yields an incomplete appreciation of functional brain anatomy.

In response to a variety of simple and cognitive tasks, the third and final section of the Atlas–“Functional Anatomy”–uses blood oxygen level–dependent (BOLD) fMRI to illustrate activated gyral and sulcal regions within the brain. Activated areas examined include auditory, sensorimotor, speech and language, dorsolateral prefrontal, and visual cortex. In this section, activated regions are described very briefly, with several illustrations using BOLD fMRI superimposed onto multiplanar imaging and onto 3D surface-rendered views of the brain. These surface-rendered views include standard, inflated, and flat-mapping representations. This section on brain function and functional anatomy is limited by a sparse examination of the various cognitive and sensorimotor functions and a lack of discussion. There is no description of the functional networks, which can be imaged and would promote an understanding of the relationship between anatomically labeled structures and brain function.

In point is the treatment of the speech and language system. A single 3D view of the left hemisphere is provided, showing focal activation in the inferior frontal gyrus (Broca area), the superior temporal sulcus (designated as Wernicke area), and the posterior aspect of the middle frontal gyrus (dorsolateral prefrontal cortex), with little discussion on the topic. This is a grossly simplified representation of the complex networks subserving speech and language functions, which have both functional imaging and clinical significance. An example of vision retinotopy is provided, but there is no discussion or activation views of higher visual functions. An example of bilateral intraparietal sulcus activation in response to imagining clock faces contains no discussion of the implications of visual attention or visuospatial processing. In short, this section shows a few patterns of activation in response to several tasks but in no way provides an understanding of the functional organization of the brain or the relationship of functional networks to anatomic gyral and sulcal landmarks. It is this section that most readily fails to reflect the title of this book.

Despite the shortcomings noted previously, The Atlas of Morphology and Functional Brain Anatomy provides an efficient and useful way to identify sulcal and gyral landmarks that one may encounter in day-to-day clinical practice. It also is designed in a manner effective at testing one’s knowledge of brain anatomy and thus could be useful in training medical students, residents, and neuroradiology fellows. All in all, the Atlas is a useful addition to the neuroradiologist’s library of brain anatomy texts. Although the authors give some attention to brain functional anatomy, a more expanded discussion of the integrated functions of the human brain and associated fMRI activation patterns would have improved the book as a resource for learning by students and others in the field.