Magazine article Science News

Automatic Networking: Brain Systems Charge Up in Unconscious Monkeys

Magazine article Science News

Automatic Networking: Brain Systems Charge Up in Unconscious Monkeys

Article excerpt

Anesthetized monkeys may be dead to the world, but their brains remain surprisingly lively. Organized patterns of activity continually course through neural networks that during waking life control the animals' eye movements and other critical functions, a new brain-scan investigation finds.

Unconscious monkeys also display a type of spontaneous brain activity that until now had been observed only in people at rest, say neuroscientist Marcus E. Raichle of Washington University in St. Louis and his colleagues. Some researchers suspect that this so-called default network supports the capacity to imagine the future, daydream, and think about oneself and others (SN: 2/17/07, p. 104).

"These findings are consistent with the perspective that the [primate] brain is governed primarily by internal dynamics," the researchers conclude in the May 3 Nature. If they're correct, events external to the individual play only a supporting role in ongoing brain activity.

Raichle's team used functional magnetic resonance imaging in a new way to investigate spontaneous fluctuations of neural activity in the brains of 11 anesthetized macaque monkeys. This technology measures blood-flow changes in the brain, which reflect cells' activity.

The scientists first looked for correspondences between spontaneous neural activity in a section of the frontal brain, known as the frontal eye field, and in regions in the rest of the brain. A few areas displayed rises and falls in activity that correlated with those in the frontal eye field.

Earlier studies had indicated that this set of correlated regions is anatomically interconnected and belongs to a system that controls eye movements in alert monkeys. The network is active when monkeys perform learned eye movements.

Raichle and his coworkers also observed two other networks active in anesthetized monkeys. …

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