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"What we needed to do was stimulate an area of the brain and see if it talks to another part. We have a tool to do that now," says Tononi, referencing one of only a handful of machines in the world capable of stimulating precise regions of the brain from outside the skull while recording the resulting electrical responses.

The paddle-like device is placed over the head of a subject and generates a magnetic field. The magnetic field, in turn, produces pulses of electricity lasting less than a millisecond and that are capable of penetrating the skull to stimulate brain cells.

"Essentially, we activate an area," Tononi says. "We can do this anywhere in the brain. Once an area is activated, it responds by sending signals, waves that travel through the axons (nerve fibers) to other regions of the brain. At the same time, we can record how the rest of the brain is responding."

The new technique promises science a way to see how the different areas of the brain communicate, Tononi says.

Beyond helping illuminate the secrets of consciousness, the new study, which was directed in part by Marcello Massimini, a research associate in the UW Psychiatric Institute and Clinics, may aid in the development of diagnostic and therapeutic tools for neurological and psychiatric disorders that affect consciousness, such as schizophrenia. That work is now being pursued by the Wisconsin group.

In addition to Tononi and Massimini, co-authors of the Science paper include Fabio Ferrarelli, Reto Huber, Steve K. Esser and Harpreet Singh, all of UW-Madison.