Ever wondered how we are able to focus so sharply to find that contact lens on the bathroom floor or a lost set of car keys?
Scientists have discovered that when we embark on a targeted search, various visual and non-visual regions of the brain mobilise to track down a person, animal or thing.
This means that if we're looking for a youngster lost in a crowd, the brain areas usually dedicated to recognising other objects, or even the areas attuned to abstract thought, shift their focus and join the search party.
Thus, the brain rapidly switches into a highly focused child-finder, and redirects resources it uses for other mental tasks.
"Our results show that our brains are much more dynamic than previously thought, rapidly reallocating resources based on behavioural demands, and optimising our performance by increasing the precision with which we can perform relevant tasks," said Tolga Cukur,lead author of the study from the University of California, Berkeley.
"As you plan your day at work, for example, more of the brain is devoted to processing time, tasks, goals and rewards, and as you search for your cat, more of the brain becomes involved in recognition of animals," he added.
The findings may help explain why we find it difficult to concentrate on more than one task at a time. The results also shed light on how people are able to shift their attention to challenging tasks, and may provide greater insight into neurobehavioral and attention deficit disorders.
The results were obtained in studies that used functional Magnetic Resonance Imaging (fMRI) to record the brain activity of study participants as they searched for people or vehicles in movie clips.
In one experiment, participants held down a button whenever a person appeared in the movie. In another, they did the same with vehicles.
The brain scans simultaneously measured neural activity via blood flow in thousands of locations across the brain.
The team compared how much of the cortex was devoted to detecting humans or vehicles depending on whether or not each of those categories was the search target.
They found that when participants searched for humans, relatively more of the cortex was devoted to humans, and when they searched for vehicles, more of the cortex was devoted to vehicles.
For example, areas that were normally involved in recognising specific visual categories such as plants or buildings switched to become tuned to humans or vehicles, vastly expanding the area of the brain engaged in the search.
"These changes occur across many brain regions, not only those devoted to vision. In fact, the largest changes are seen in the prefrontal cortex, which is usually thought to be involved in abstract thought, long-term planning and other complex mental tasks," Cukur said.
The study was published in the journal Nature Neuroscience.
