This series of discussions held by Krishnamurti with physicist David Bohm and with psychiatrist David Shainbert explores how fragmentation of the mind has resulted in division, fear, and conflict.

    We do that not because we have a commit- ment to bear witness to the boring issue of reductionism but be- cause we want to know more about what it's all about. How, in- deed, does the brain work? How does it allow us to love, hate, see, cry, suffer, and ultimately understand Kepler's laws? We try to uncover clues to these staggering questions by con- sidering the results of our studies on the bisected brain. Several years back, one of us wrote a book with that title, and the ap- proach was to describe how brain and behavior are affected when one takes the brain apart. In the present book, we are ready to put it back together, and go beyond, for we feel that split-brain studies are now at the point of contributing to an understanding of the workings of the integrated mind. We are grateful to Dr. Donald Wilson of the Dartmouth Medi- cal School for allowing us to test his patients. We would also like to thank our past and present colleagues, including Richard Naka- mura, Gail Risse, Pamela Greenwood, Andy Francis, Andrea El- berger, Nick Brecha, Lynn Bengston, and Sally Springer, who have been involved in various facets of the experimental studies on the bisected brain described in this book.

    Between them, they examine from different but complementary directions the relationships that connect the higher brain--memory, learning, perception, thinking--with what goes on at the most basic levels of neural activity, with particular stress on the role of local neuronal circuits.Edelman's major hypothesis is that the conscious state results from phasic reentrant signaling occurring in parallel processes that involve associations between stored patterns and current sensory or internal input. This selective process occurs by the polling of degenerate primary repertoires of neuronal groups that are formed during embryogenesis and development. Edelman's theory extrapolates to the brain the selectionistic immunological theories for which he was awarded the 1972 Nobel Prize in Physiology or Medicine. Mountcastle's paper reviews what is known about the actual structure of various parts of the neo cortex. He relates the large entities of the neocortex to their component modules--the local neuronal circuits--and shows how the complex interrelationships of such a distributed system can yield dynamic distributed functioning. There are strong conceptual parallels between Mountcastle's idea of cortical columns and their functional subunits and Edelman's concept of populations of neurons functioning as processors in a brain system based on selectional rather than instructional principles. These parallels are traced and put into perspective in Francis Schmitt's Introduction.

    In previous editions, the text was essentially confined to a section dealing with the various functional systems of the brain. This section, which has been rewritten and updated, is now preceded by 15 newly written chapters, which introduce the pictorial material of the gross anatomy, the blood vessels and meninges and the microstructure of its various parts and deal with the development, topography and functional anatomy of the spinal cord, the brain stem and the cerebellum, the diencephalon and the telencephalon. Great pains have been taken to cover the most recent concepts and data. As suggested by the front cover, there is a focus on the evolutionary development of the human brain. Throughout the text numerous correlations with neuropathology and clinical n- rology have been made. After much thought, we decided to replace the full Latin terminology, cherished in all previous editions, with English and Anglicized Latin terms. It has been an emotional farewell from beautiful terms such as decussatio hipposideriformis W- nekinkii and pontes grisei caudatolenticulares. Not only the text, but also the p- torial material has been extended and brought into harmony with the present state of knowledge. More than 230 new illustrations have been added and many others have been revised. The number of macroscopical sections through the brain has been extended considerably. Together, these illustrations now comprise a complete and convenient atlas for interpreting neuroimaging studies.