In Search for Intelligence, a Silicon Brain Twitches

For the last four years, Henry Markram has been building a biologically accurate artificial brain. Powered by a supercomputer, his software model closely mimics the activity of a vital section of a rat's gray matter.

Dubbed Blue Brain, the simulation shows some strange behavior. The artificial "cells" respond to stimuli and suddenly pulse and flash in spooky unison, a pattern that isn't programmed but emerges spontaneously.

Blue Brain is based at the École Polytechnique Fédérale de Lausanne in Switzerland. The project hopes to tackle one of the most perplexing mysteries of neuroscience: How does human intelligence emerge? The Blue Brain scientists hope their computer model can shed light on the puzzle, and possibly even replicate intelligence in some way.

We're building the brain from the bottom up, but in silicon," says Dr. Markram, the leader of Blue Brain, which is powered by a supercomputer provided by International Business Machines Corp. "We want to understand how the brain learns, how it perceives things, how intelligence emerges."

Despite the challenges, the push to understand, replicate and even re-enact higher behaviors in the brain has become one of the hottest areas of neuroscience. With the help of a $4.9 million grant from the U.S. Department of Defense, IBM is working on a separate project with five U.S. universities to build a tiny, low-power microchip that simulates the behavior of one million neurons and ten billion synapses. The goal, says IBM, is to develop brainy computers that can better predict the behavior of complex systems, such as weather or the financial markets.

The scientists behind Blue Brain hope to have a virtual human brain functioning in ten years -- a lengthy time period that underscores the scientific challenge. The human brain has 100 billion neurons that send electrical signals to each other via a network of at least 100 trillion connections, or synapses. How could this dizzying complexity ever be recreated in a virtual model?

Dr. Markram has adopted a systematic, if painstaking approach. He decided to work out the blueprint of its wiring and then use that map to rebuild the brain in an artificial form. He focused on a rat's neocortical column, or NCC, an elementary building block of the brain's neocortex, which is responsible for higher functions and thought. In a rat's case, that includes planning to obtain food.

A rat's NCC, comprised of about 10,000 neurons and their 10 million connections, functions much like a computer microprocessor. All mammals have NCCs, and the ones in humans aren't all that different from the ones in rats. However, humans have far more NCCs, which means far greater brain power. Dr. Markram figured that if a rat simulation did a good job of correctly mimicking activity in a real rat's brain, he could use the same model as a road map for simulating the human brain.

The rat's NCC has 10,000 neurons, and it takes the power of one desktop computer to mimic the behavior of a single neuron. To model the entire NCC, Dr. Markram relies on an IBM computer that can perform 22.8 trillion operations a second. This enables the simulation to be rendered as a three-dimensional object. Thus, when Blue Brain is running, its deepest inner workings are seen in astonishing detail, in the form of a 3-D simulation that unfolds on a computer screen.

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