by Melanie Moran
With a thousand distractions vying for your attention, how do you stay focused? Just who, or rather what, is in charge of your brain? New research into how the brain manages information has found that an area previously thought to be just an information collector in fact plays the role of an executive, helping to filter out extraneous information to help you stay focused. The findings offer potential insights into helping people with attention disorders.
The research will be published in the July issue of Nature Neuroscience. An advance edition of the paper is available now on the journal’s Web site, www.nature.com/neuro.
The brain area in question is the supplementary eye field, located in the frontal lobe. E. Bronson Ingram Professor of Neuroscience Jeffrey Schall and his colleagues Veit Stuphorn and Tracy Taylor discovered in 2000 that the supplementary eye field registers conflict, rewards and mistakes, earning it the nickname the “oops center.”
In their new research, Schall and Stuphorn wanted to know if the supplementary eye field does more than just monitor rewards and mistakes – can it also influence behavior?
“We discovered that weak electrical stimulation of the ‘oops center’ improves one’s ability to control impulses,” Schall said. “These new results show for the first time how the brain controls impulses to act. We believe it will be important for understanding how to treat impulse control disorders, such as attention deficit hyperactivity disorder, schizophrenia and others.”
To determine the supplementary eye field’s role in behavior, Stuphorn and Schall used a weak electrical current to stimulate this area in macaque monkeys while the monkeys were performing a task. The task, known as a stop sign task, requires the subject to not look at a target at which it had been planning to look. The task has been used to study how action control develops in humans and in patients with attention disorders.
In this task, the monkeys were trained to look at a central spot of light and to then shift their gaze to a target spot that appeared on a computer display. When they did this, they were rewarded with juice.
Sometimes a stop sign was presented after the target appeared but before the monkey’s eyes moved, interrupting its planned eye movement. The monkeys were rewarded when they responded to the stop sign by not shifting their gaze to the target.
If the supplementary eye field is involved in controlling behavior, then Stuphorn and Schall reasoned that stimulating it should improve the monkeys’ performance, making it easier for them to control their gaze when they saw the stop sign rather than looking at the target as they had planned. Their hypothesis proved correct – the monkeys were better able to control their gaze when the supplementary eye field was stimulated than when it was not. The findings indicate this brain area does play an executive role in controlling behavior.
Part of the explanation for how the supplementary eye field influences behavior has to do with its effect on delaying movement. People and monkeys respond to stimuli after a curiously long and variable reaction time, illustrated by the delay between a starter’s gun firing and runners leaving the blocks. When monkeys were performing the stop signal task, weak stimulation of the supplementary eye field caused reaction times to get longer, giving the monkeys enough time to process the interruption and withhold the movement. It slowed them down in order to improve their accuracy.
“But, when we stimulated the supplementary eye field and didn’t show any stop signs, the monkeys carried out the whole task much faster,” Schall said. “This shows us that how the brain’s executive system influences performance depends very much on context. I think this is why we are careful sometimes and careless other times – it depends on what else is happening.”
The new work also expands our understanding of how we learn from mistakes and the role of the “oops center” in that process.
“We learn by monitoring what happens in response to our actions,” Schall said. “When we do something, we pay attention to the consequences and then modify future actions based on this experience. Our new research identifies the supplementary eye field as being a key player in this learning process.”
Schall is the director of Vanderbilt’s Center for Integrative and Cognitive Neuroscience and the Vanderbilt Vision Center and is an investigator at the Vanderbilt Kennedy Center for Research on Human Development. Stuphorn is an assistant professor at Johns Hopkins University’s Krieger Mind/Brain Institute.
The research was supported with funds from a Deutsche Forschungsgemeinschaft research fellowship and by the National Institutes of Mental Health.