People's success at doing a particular task correlates with the level of activity triggered by irrelevant stimuli in the background in a diffuse group of brain areas known as the default network. The results, published online in Nature Neuroscience, suggest a new role for this group of brain areas.
Often, performing a task involves ignoring distracting information that may be irrelevant to the task at hand. Adam Gazzaley and colleagues used functional magnetic resonance imaging to track peoples' brain activity as they saw superimposed pictures of faces and houses. During some trials, the subjects had to remember the faces and ignore the houses, and on others, the reverse.
In keeping with previous work, the authors found changes in visual parts of the brain related to whether participants are paying attention to faces or houses. More interestingly, they found coordinated decreases in activity between these parts of the brain and a group of brain areas known as the default network. Unlike other brain areas, the default network is known to be more active during rest compared to when people are engaged in a task. Gazzaley and colleagues found that the less activity in the default network as participants tried to ignore irrelevant stimuli, the faster they were at doing the task. This suggests that the default network has a previously undiscovered role in suppressing information irrelevant to the task.