Building a Brain: Three-Dimensional Reconstructions

The interior of the forebrain is occupied by a series of structures that fit neatly together in three-dimensional space. As a consequence of the embryological development of the brain, some cerebral structures (e.g., lateral ventricle , caudate nucleus ) curve around in a great C-shaped arc ( Fig. 4.1 ), whereas others are more centrally located. One of the greatest impediments to understanding the interrelationships of cerebral structures in three dimensions is the typical presentation of the nervous system in a series of two-dimensional sections cut in various planes (as it is presented in much of this book).

As a partial solution to this dilemma, this chapter presents an overview of the arrangement of cerebral structures in the form of a series of computer-generated reconstructions kindly provided by Dr. John W. Sundsten and his colleagues (Department of Biological Structure, University of Washington School of Medicine). The images were made by cutting serial sections of a single human brain, digitizing outlines of structures of interest, and using these outlines to reconstruct (by computer) individual structures or groups of structures. Beginning with the reconstruction of the brainstem, cerebellum, and diencephalon shown in Fig. 4.2 , major structures of the cerebral hemispheres are added sequentially in Fig. 4.3 . Similar three-dimensional reconstructions are used in Chapter 5, Chapter 6, Chapter 7 to indicate the planes of sections through the forebrain.