Yoo's experiments center on an area in the brain's temporal lobe that's involved in auditory attention. Subjects lie in an MRI scanner while listening for specific sounds. As they listen, they watch a monitor that displays the activity in this auditory brain area and try to consciously increase it. "We wanted to enhance the brain's ability to concentrate (or tune) to specific sounds in the middle of a noisy MRI scanner," says Yoo. "It's not easy. People have to watch a plot and listen to the sounds. All these things can be very distracting, but people eventually learn to control their thought processes."

Preliminary results show that subjects who recieved fMRI feedback were more likely to be able to increase brain activity in the target region than controls.

John Gabrieli, a neuroscientist at MIT, is planning similar tests, focusing on training the basal ganglia, a structure deep in the brain that's frequently abnormal in children with ADHD. This brain structure is involved in motor function and learning, and also the part of the brain where Ritalin, a common drug treatment for the disorder, binds most readily. "I think this will be one of the most striking applications [for real-time fMRI]," says Gabrieli.

Other scientists plan to use fMRI feedback to determine why some people have an exceptionally high capacity for attention. Rainer Goebel, a scientist at Maastricht University in the Netherlands, has used real-time fMRI to teach people to play the video game Pong entirely with their minds. He plans to use the technology to study people who seem to be able to put themselves into a hyper-focused state, such as race car drivers, as well as monks who consciously control their cognitive processes in a meditative state. (Preliminary evidence using traditional brain imaging has shown that experienced monks undergo unique changes in their brain activity during meditation, compared with novice meditators.) Goebel will determine how well these types of people perform during feedback training -- and try to discover what makes them different from most people.

The findings might shed light on how best to train attention and other aspects of cognitive processing. "Buddhist monks go sit on mountains for 30 years to find enlightenment in meditation. What if we can jump-start [the brain] without spending 30 years on a mountain?" asks Mackey. "That is still science fiction -- but it's an exciting thought."