Our brains are constantly flooded with sensory information, much of which is irrelevant to the task at hand. The ability to filter out these distractions and to attend selectively to relevant stimuli is an essential skill, one that is impaired in many brain disorders.
Robert Desimone wants to understand how the brain deals with the challenge of information overload. By studying the visual systems of humans and experimental animals, he has shown that information relevant to an ongoing task is selectively amplified in certain brain regions, while irrelevant information is suppressed. This happens in part because neurons whose activity reflects the relevant information become synchronized with each other. In effect, the rhythmic activity produced by a group of synchronized neurons resembles a chorus chanting a tune that rises above the background chatter of the crowd, thus allowing the relevant information to be ‘heard’ more efficiently by other brain regions. How are these rhythms entrained in the first place? Desimone’s work suggests that they are controlled by the prefrontal cortex, a brain region known to be involved in planning and executive control of behavior. Like the conductor of an orchestra, the prefrontal cortex provides a top-down signal that coordinates rhythmic activity across multiple brain regions, thus deploying the brain’s resources in service of the overall goal of the organism.
Staying on Message -- Sometimes, of course, distraction is a good thing – a car rushing towards us should grab our attention regardless of what else we are doing. But such bottom-up distractions must normally be balanced against the need to stay ‘on message’. If this balance is disrupted, as happens in conditions such as attention deficit disorder, Parkinson’s disease or schizophrenia, many aspects of life may be impaired as a result. Desimone believes that altered neural synchrony may underlie many brain disorders that disrupt attention, and that searching for ways to enhance synchrony may be a useful strategy for developing new treatments for these conditions.