American Scientist

The Neuropsychology of Dreams: A Clinico-Anatomical Study. Mark Solms. 292 pp. Lawrence Erlbaum Associates, 1997. $59.95.

The question of how the brain/mind produces dreaming has not attracted its fair share of scientific research during the past century. The explanation is, in part, because in the past dreams have been associated with questionable metaphysics. That association has caused many scientists to avoid dream research, lest they not be taken seriously or not considered respectable. In addition, access to dream data is indirect, introspective and subjective and is, therefore, mistakenly seen by many to be outside the realm of legitimate science. With some notable exceptions, the result has been few attempts to comprehensively explain the neuronal basis of this common and universal human phenomenon.

Among the notable explications of dreaming have been Sigmund Freud's analyses in The Interpretation of Dreams (1900; 1953), the Charcot-Wilbrand syndrome and the Alan Hobson–Robert McCarley activation synthesis model, as it is explicated in Hobson's The Dreaming Brain (1988). Freud's turn-of-the-century theory of dreaming, which was based on his own and his patients' dreams combined with the neurological knowledge available at that time, was highly metaphorical and posited a psychological origin and function of dreams. The Charcot-Wilbrand syndrome, universally accepted by neuropsychologists but virtually unused in practice, originated with an individual case study by Charcot in 1883 and another by Wilbrand in 1887. Today the term Charcot-Wilbrand syndrome is used for any loss or reduction of dreaming or its imagery; typically bilateral damage to the occipital cortex is implicated as the cause. Hobson and McCarley's much more recent model is based primarily on animal research that explored the neural mechanisms that produce rapid-eye-movement (REM) sleep, as well as the now-questionable assertion that dreaming only takes place during REM.

In The Neuropsychology of Dreams Mark Solms presents original insights based on new research into how the brain/mind produces dreams, research that has both practical neuropsychological application and theoretical importance. With remarkable thoroughness and candor Solms first details the understanding and use of the Charcot-Wilbrand syndrome, and then reviews both the methods and the findings of the relatively scarce research on changes in dreaming following brain insult. From this he shows how he formulated hypotheses that he used as the basis for four years of careful research, during which he questioned his neurological patients about the quality, quantity and character of their dreams. Using classical clinico-anatomical investigational methods, Solms next carefully grouped patients (both his and others whose accounts were detailed in published reports) by the type of change that took place. Then he went on to seek the common neurological and neurobehavioral correlates from the resulting groups. He also carefully considered some negative cases—patients with neural insult but no change in dreaming. The result is an update of the Charcot-Wilbrand syndrome that shows four more-or-less distinct changes in dreaming patterns that can be clearly associated with insult to or abnormality in diverse regions of the brain. He also uses these data to formulate a new model of the normal dream process that differs greatly from the Hobson-McCarley and other contemporary models, although some of its aspects agree with Freud's model.

Although Solms casts a wide net in his review and use of previously published material, he pays incomplete attention to the published data on NREM dreaming, and fails to include any references about lucid dreaming or the dreams of individuals who become blind because of damage to the eyes later in life. He also takes a rather cavalier stand against research on the analysis of the content of dreams. Yet the inclusion of that material would necessitate only minor changes, if any, to his conclusions. Furthermore the fact that none of his data have been published in a refereed journal may be troublesome to some. Finally, his occasional use of Latin phrases where English ones would have served just as well is unnecessary.

The content of this book will be useful on four fronts. First, it makes functional additions to neuropsychology nosology (as well as—to my mind—sleep disorders). Second, it provides new information about the neuroanatomical sources of dreaming. Third, it includes a new model about the source and nature of dreaming. And fourth, in a broader sense, it makes an important contribution to the understanding of an aspect of human perception and cognition.

The book is very well indexed, has ample case details (included in chapters that general readers may want to skip) and includes a useful appendix that defines his use of neuropsychological terms in his case presentations. In addition, Solms commendably points out the weaknesses in his data and the tentativeness of some of his conclusions and inferences. Overall The Neuropsychology of Dreams is an excellent resource offering a new understanding of the production of dreaming by the brain/mind that will be cited for years to come for the data it presents, for its theoretical speculations and as a basis for further research.—William H. Moorcroft, Psychobiology, Sleep and Dreams Laboratory, Luther College