What Dreams Are Made Of

The Dreaming Brain

by J. Allan Hobson
Basic Books, 319 pp., $29.95

Dreams have been explained as divine revelations, as prophecies, as messages revealing that the dreamer’s soul has temporarily left his body to roam. According to the Azande of Central Africa, when a person has a bad dream, he is experiencing the efforts of a witch to devour the soul of his flesh. But dreams have also been the subject of extensive rational and scientific inquiry, and The Dreaming Brain is the most recent scientific attempt to explain an experience that has always attracted and yet defeated explanation.

Hobson, a professor of psychiatry at Harvard Medical School, begins his book by explaining he is taking “a brain-based approach to dreaming,” i.e., an approach that seeks to show how dreams result from states and processes within the brain. He goes on to give a summary of the work on dreaming by a number of thinkers and scientists in the nineteenth century—a century that was notable for research into dreams and an interest in them. Thus Hermann von Helmholtz, best known perhaps as the inventor of the ophthalmoscope, and the founder of perceptual physiology, suggested that the brain commands the body’s movements in sleep as well as in the waking state, and that these movements give rise to the images of dreams.

But, Hobson claims, the growing body of nineteenth-century research into the physiological and psychological origin of dreams was to a large extent displaced by Freud’s The Interpretation of Dreams, first published in 1900, which, in its exclusive reliance on personal reports, redirected the study of dream research. The Interpretation of Dreams was “anti-scientific,” Hobson alleges, because in it “Freud so forcefully dismissed all previous writers that he actually aborted an emerging experimental tradition.”

Scientific inquiry was in any case handicapped by lack of knowledge about the brain and of techniques for investigating it. Still, in the decades just after World War II, important advances were made. In investigating the brain stem (that is, the lower part of the brain connected to the spinal cord), researchers found that it contained a network of neurons, known as the reticular formation, in which increased electrical activity was correlated with both arousal from sleep and continued wakefulness. Then, in 1953, a breakthrough occurred. Eugene Aserinsky and Nathaniel Kleitman discovered that intermittent periods of rapid eye movement (REM) took place during sleep, and that these periods were closely associated with visual dreaming. The next step consisted of discoveries suggesting that these periods of REM sleep were connected with neural activity in an upper region of the brain stem, known as the pons.

Hobson presents a clear account of these developments in psychoneurology and neurophysiology. This is important because they provide the background to a major advance that later occurred in developing techniques of neuropsychological investigation, and in our knowledge of brain functions. During the 1950s and early 1960s, neurophysiologists and psychologists were able to record the electrical activity of a single neuron in the brain with a microelectrode, giving us …

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