people, all competing for your attention. Some stand out more than others, and you don’t control that. It just happens. How does this happen in your brain?” asked computational neuroscientist Moran Cerf of the California Institute of Technology.

For an experiment published October 28 in Nature, Cerf’s team enlisted the help of epileptics whose brains had been temporarily wired to computer monitors, allowing doctors to see where seizure patterns began in anticipation of corrective surgery. Invasive deep-brain procedures aren’t allowed for the sake of basic, non-medical research, but since the epileptics’ brains are already wired, Cerf’s team was able to conduct a unique experiment.

In earlier research, they’d correlated firings of individual neurons in the medial temporal lobes — the brain’s processing centers — with individual people (namely, Halle Berry.) In this study, they linked neurons to easily recognizable people like Monroe, Brolin, Venus Williams and Michael Jackson.

Cerf’s team simultaneously displayed pairs of their pictures on a computer monitor, then asked test subjects to concentrate on one person. As their minds focused, the images flickered back and forth, finally settling on the target image. As this happened, their mental activity was recorded in real-time.

The researchers weren’t particularly interested in specific neurons, or even specific brain regions: Each wired neuron was representative of five million more, spread across the brain. Instead, he was looking for patterns of focus.

“The most exciting thing is that patients sometimes fail in the task. Someone sees a picture of Marilyn Monroe and Josh Brolin, and his task is to focus on Brolin. But, somehow, the image of Marilyn Monroe catches his attention more. The image moves away from Brolin. It’s 90 percent Marilyn. And then, when he’s about to fail, he manages to summon Josh Brolin in his mind,” Cerf said.

“There’s competition between two senses, between vision and imagery. The eyes bring one image, his mind’s eye brings another, and those fight. We can see how one wins over the other. This is a remarkable moment, because it happens every day in our life, and we never saw it firsthand.”

Cerf expected focus would result from an increase in target-focused activity, so with people asked to focus on Josh Brolin, the Brolin-linked parts of the brain would fire more. Instead, he found the Marilyn Monroe-linked regions fired less. Brains narrowed focus not by enhancing their targets, but by diminishing distraction.

As for how that selective diminishing was performed, Cerf couldn’t tell. He likened the experiment to seeing flows of water at a river’s end, without knowing what dam operators were doing upstream. Whatever was responsible for guiding focus wasn’t wired with the electrodes in the patients, nor will it be.

“Upstream? I wish,” said Cerf. “If I could, I’d put electrodes all the way from the vision area, and look at information flow from the moment you get photons hitting the retina to the point where they become concepts. But there isn’t reason” to put those electrons in patients.

In future studies, Cerf hopes to measure associations more completely and see what other parts of the mind are triggered by thinking of larger concepts.

“There’s a cloud of associations that surround each concept. We don’t know how they’re formed, or how far they go. The idea now is to try to find one concept, start moving away from it, and see where the borders are,” he said.

Video: After the researchers map neurons to images in study participants’ brains, on-screen images change depending on their mental focus./Moran Cerf.

See Also:

• Synchronized Brain Waves Focus Our Attention
• A Sketchy Brain Booster: Doodling
• Wireless Brain-to-Computer Connection Synthesizes Speech
• Uncle Sam Wants Your Brain
• Brain Scans Reveal What You’ve Seen

Citation: “On-line, voluntary control of human temporal lobe neurons.” By Moran Cerf, Nikhil Thiruvengadam, Florian Mormann, Alexander Kraskov, Rodrigo Quian Quiroga, Christof Koch & Itzhak Fried. Nature, Volume 467 Number 7319, October 28, 2010.

Brandon’s Twitter stream, reportorial outtakes and citizen-funded White Nose Syndrome story; Wired Science on Twitter.

Authors: Brandon Keim

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