In the Sept. 26 issue of Science, Salk Institute professor Terrence Sejnowski and University of Cambridge professor Simon Laughlin argue that the human brain has evolved to operate as an enormously efficient "hybrid device," capable of making far more sophisticated computations than the most powerful computers, and the long-distance communication systems in brains have been optimized by evolution for energy efficiency.
"In the past, we were only able to look at brain function by looking at single neurons or local networks of neurons. We were only able to see the trees, so to speak," said Sejnowski. "With breakthroughs in recording techniques including brain imaging, which gives us a global picture of brain activity, and advances in computational neurobiology, we can now take a more global perspective. We're looking at the entire forest, and we're asking the question: How has the forest evolved?"
As the brain has evolved over millions of years, according to Sejnowski, it has become amazingly efficient and powerful. He says that nature has "optimized the structure and function of cortical networks with design principles similar to those used in electronic networks." To illustrate the brain's tremendous capacity, Sejnowski and Laughlin state that the potential bandwidth of all of the neurons in the human cortex is "comparable to the total world backbone capacity of the Internet in 2002."
But they point out that simply comparing the brain to the digital computers of today does not adequately describe the way it functions and makes computations. The brain, according to Sejnowski, has more of the hallmarks of an "energy efficient hybrid dev
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Contact: Robert Bradford
bradford@salk.edu
858-453-4100 x1290
Salk Institute
25-Sep-2003