Is There Room for the Soul?
New challenges to our most cherished beliefs about self and the human spirit
Edelman's many books on consciousness explore the various ways that neuronal circuits get established. In the developmental stage of the brain, some neuronal assemblies, or maps, are formed according to genetic rules. Experience then reinforces or weakens these assemblies-or gives rise to new ones-according to how efficiently they respond to signals from the world or the body. The last process, re-entry, is the most difficult to explain, Edelman says, but it is also the most important, since it integrates the activities of various assemblies through what he calls "ongoing parallel signaling between separate brain maps along massively parallel anatomical connections." The binding together of the neuronal activities of maps associated with, say, the perception of an object and those associated with, say, memory, yields an integrated yet highly differentiated experience: a "scene" of primary consciousness that researchers call a quale.
But does the biochemistry underlying these qualia (the plural of quale) adequately account for the experience itself, not to mention aspects of higher-order consciousness that we associate with a sense of self and language? Edelman appears to be of two minds. "We evolved structures that invented language," he says. Yet once humans acquired syntax, Edelman adds, "all bets are off." Biology, he seems to suggest, can take us only so far in understanding the symbol-using mind. "It's not totally reductive," he says. At the same time, among the work being done by the some 36 researchers in Edelman's institute is an ongoing effort to build brain-based devices that perform a task-picking up or avoiding different kinds of objects-not according to an elaborately prescriptive program but by learning from experience, altering, creating, strengthening, and sometimes replacing the synthetic "neural" pathways within its program through success or failure at picking up the right kind of blocks. "Brain-based devices will happen if consciousness is a physical, natural process," Edelman says, clearly implying that it is at least a possibility.
Fuzziness. Another Nobel laureate who turned to consciousness research expressed far less ambivalence about the ability of science to explain the whole mystery. That scientist was Francis Crick, the discoverer, along with James Watson, of the double helical structure of DNA. For roughly two decades after that 1953 breakthrough, Crick helped pioneer molecular and developmental biology. But in 1976, Crick moved from Cambridge University to the Salk Institute to work on a subject that had fascinated him since the early 1950s: the biological basis of consciousness. Not long after, he teamed up with Christof Koch, a promising young German-educated scientist with a degree in physics and an interest in neurons, visual processing, and rock climbing. Together they launched the quest for what they came to call the neural correlates of consciousness, which they defined as "the minimal set of neuronal events that gives rise to a specific aspect of a conscious percept."
The title and first sentence of Crick's 1994 book, The Astonishing Hypothesis: The Scientific Search for the Soul, made their ambitious agenda clear: "The Astonishing Hypothesis is that 'You,' your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behavior of a vast assembly of nerve cells and their associated molecules."
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