For nearly a century we’ve thought about the human brain almost solely in terms of its hundred billion neurons. Electrical signals pulse between millions of those long, slender cells, as though through the microprocessors in a computer, and bingo - we see; we think; we fall in love.
But only about 15 percent of all the cells in our brains are neurons. So how can we be sure that the microprocessor analogy is accurate? What about the other 85 percent?
A new book by R. Douglas Fields, a National Institute of Health neuroscientist, suggests that the other 85 percent - cells called glia that we have long dismissed as mere bubble wrap - may be far more important than we realized.
In “The Other Brain: From Dementia to Schizophrenia, How New Discoveries about the Brain Are Revolutionizing Medicine and Science,’’ Fields argues that glia represent a barely explored territory that should not be overlooked.
Labs around the country are finding that glial cells are involved in epilepsy, fetal brain development, mental illness, and even the generation of new neurons in adults. Others form a kind of super-aggressive commando unit that can tunnel through the snarls of dendrites and attack intruding organisms. Still others serve more like maniacal sidewalk sweepers, collecting and absorbing discarded potassium ions that are released by neurons when they fire.
All these roles, Fields believes, suggest the possibility that information travels not only through our neurons, but through a much vaster cellular network. “What would it mean to our current understanding of the mind and medicine,’’ he wonders, “if information flowed not only through neural circuits, but through glia as well?’’
Einstein’s brain, after all, contained as many neurons as yours or mine. But the numbers of Einstein’s glia? Off the charts.
Indeed, the glia that serve as guards, monitors, traffic cops, and overseers may knit together our entire nervous system. They might even learn, or sleep, or vary between men and women. As Fields puts it, “A revolution in our understanding of how the brain is built, how it functions, how it fails in mental illness and disease, and how it is repaired has been ignited with the recent exploration of these long-neglected brain cells.’’
In a less scientific new book, “The Hidden Brain: How Our Unconscious Minds Elect Presidents, Control Markets, Wage Wars, and Save Our Lives,’’ Shankar Vedantam, a Washington Post reporter, argues that another element of our brains has been neglected for too long: our unconscious minds. Vedantam argues that our “rational mind is unequal to the machinations’’ of this “hidden brain,’’ and that we “are being constantly fooled, tricked, and hoodwinked’’ by it.