The New York Review of Books

We are now beginning to understand the physical basis of normal and abnormal mental activity largely because of recent advances in the neurosciences. Among the concerns of The Oxford Companion to the Mind, edited by Richard L. Gregory and the late Oliver L. Zangwill, both well-known British psychologists, is to describe these advances. The book includes many entries on important writers in the history of philosophy and psychology. It has several well-informed and skeptical entries on telepathy, clairvoyance, and paranormal phenomena. It takes account of modern developments in linguistics and learning theory. But the heart of the book is its numerous entries on the neurosciences; the longest, “Nervous System,” by the English neurologist Peter Nathan, gives a twenty-page account of current knowledge of the brain, and it is supplemented by such articles as “Brain Development,” “Brain Function and Awareness,” “Neurotransmitters,” and “Neuronal Connectivity and Brain Function.” Articles on Parkinsonism, schizophrenia, depression, and dementia discuss the breakdown of normal function.

Some of these articles describe current knowledge of the mechanisms by which nerve cells interact, for example, the ways in which the fifty or more chemical transmitters communicate information from one nerve cell to another, and, for another, the possible relation of these transmitters to some forms of brain disease. As exciting as these discoveries are, many central questions remain unanswered, such as what are the purposes of these mechanisms in the overall functioning of the brain. The discovery, for example, in the 1970s of the “natural opiates,” the endorphins, led to the suggestion that their release within the brain may be responsible for the “high” experienced by joggers; and an endorphin malfunction may explain why some people suffer from claustrophobia and therefore develop severe anxiety in elevators and other enclosed spaces, but the precise connections between the chemicals and such feelings remain to be established. (The entry on endorphins itself is fairly brief and the physiological and psychological effects of chemical transmitters in general are discussed in the entry “Neurotransmitters.”)

It has been suggested that neurotransmitters may provide the key to our understanding of the biochemical basis of normal and abnormal psychology. In the entry “Parkinsonism” K.A. Flowers of the University of Hull writes, for example, of the various possible functions of the neurotransmitter dopamine:

Of particular interest is the finding that while a deficiency of dopamine is associated with Parkinsonism, over-activity in the dopamine system produces schizophrenia-like behavioural effects. This opens up the possibility that it is the biochemical status of the nervous system that underlies psychological and psychiatric changes in Parkinsonian patients and schizophrenics. It also holds out hope for the continued development of effective treatment, but as with studies of the biochemical basis of schizophrenia, the exact relation of the mechanisms of the nervous system to the characteristics of the mind remains elusive. Progress in this problem may well depend as much on advances in our understanding of the latter as of the former.

As this entry makes clear, research on neurotransmitters is still far from …