Bridging the brain gap: a scientist explores the biology of isolated minds and mutual trust - Cover Story

Science News, Nov 2, 1996 by Bruce Bower

When a rabbit whiffs an onion, glimpses another rabbit, hears a loud sound, feels itself enveloped by a pair of hands, or otherwise encounters the world through its senses, electrical activity crackles through the creature's brain in a curious way. Within a fraction of a second, groups of neurons that greet incoming sensations generate a distinctive electrical burst that materializes again in the brain's outer layer, or cortex. There, the activity vanishes, poof, "just like the rabbit down the rabbit hole in Alice in Wonderland," remarks neurophysiologist Walter J. Freeman of the University of California, Berkeley.

Freeman, who has described this electrical disappearing act in rabbit brains since 1982, now suspects that the analogy to Lewis Carroll's classic children's tale runs even deeper. Much as the white rabbit's hasty departure turned Alice's world upside down, transient electrical responses to sensation may preface life-altering changes in the brain, he proposes.

More precisely, new patterns of brief cortical activity scurry forth one after another following a short-lived sensory outburst. They produce no less than a perception of what a particular sensation means, constructed in accordance with past experiences and other relevant knowledge. Mammals--including the two-legged, talkative ones--learn about the world through constant sensory and perceptual updates, Freeman theorizes.

But learning does not always proceed in an orderly, cumulative fashion, he argues. Mammalian brains contain a mechanism that can loosen the grip of previously acquired perspectives on the world and lay the neural groundwork for securing crucial new knowledge.

Having such a delete mechanism in the brain pays reproductive dividends, in Freeman's view. At appropriate ages, male and female mammals must jettison many habitual behaviors of their youth and forge the mutual trust necessary for mating and developing expertise at raising off-spring. Humans have exploited the biology of pair bonding to form larger groups, from bands of foragers to modern civilizations, the Berkeley scientist maintains.

Freeman's theory, which he elaborates in Societies of Brains (1995, Hillsdale, N.J.: Lawrence Erlbaum), contains plenty of speculation. For that matter, it's not even clear yet how best to measure and interpret the brain's electrical landscape. Nonetheless, Freeman hopes to nudge neuroscientists toward a consideration of what brains do in groups, not just inside individual skulls.

"Despite notable successes in recent years, brain science is in crisis because our models neglect the most important function of human brains, which is to interact with each other to form families and societies," Freeman contends. "The importance of this function is shown by the need for education and cultural learning in bringing young people to maturity."

Freeman's perspective clashes with materialist theories, which conceive of the mind as a by-product of biological happenings in the brain--the interplay of billions of neurons for most neurobiologists, a cerebral stew of chemical and hormonal interactions for geneticists and pharmacologists, and the commingling of quantum forces for physicists.

The Berkeley researcher also rejects the view, widespread in cognitive psychology, that the mind contains representations of the world in the form of thoughts, ideas, images, and symbols that are processed according to sets of rules. This assumption has spurred attempts to simulate various facets of language, vision, and other mental functions in computers.

Both materialist and cognitive approaches assume that the brain, in an as-yet-unspecified way, binds together parallel strands of neural activity or related representations to compose the perception of, say, a fragrant bouquet of flowers in a vase.

In contrast, Freeman regards the mind as the product of an unfolding sequence of goal-directed behaviors that provides the individual with constant feedback, thus shaping perceptions and future actions. He endorses the view of existentialist philosophers such as Jean-Paul Sartre, who argued that each of us constructs a self through his or her own actions and that we know that self as it is revealed in our actions.

This perspective harks back at least to the 13th century Italian philosopher Thomas Aquinas, who wrote that achieving one's objectives requires a "stretching forth" and shaping of the self to the world.

Psychologist James J. Gibson, who died in 1980, pursued the perceptual implications of that theme. He asserted that through their actions, humans and other animals perceive meanings in sights, sounds, and other stimuli that contain essential information about particular environments. His ideas now influence psychologists who study how people gauge their physical movements through space (SN: 8/12/95, p. 104) and discern the personality traits of themselves and others (SN: 10/29/94, p. 280).

If the mind indeed emerges at the crossroads of action, perception, and learning, researchers who want to locate its biological roots face a stiff challenge. Electroencephalograms (EEGs) of brain waves in rabbits, whose nervous system can be treated as a rudimentary model of the human variety, offer some intriguing clues, Freeman maintains.