Former President George H.W. Bush's "Decade of the Brain" has come and gone, but many mysteries remain. And scientists continue to help the world better understand the brain's role in both health and behavior.
For example, research has shown it takes one part of the brain to start concentrating and another to be distracted. Our brains pay attention in one of two ways — either willfully, which is goal oriented; or reflexive, which may be in response to sensory information (think bright lights or loud noises).
Our ability to focus our attention is physically separate in the brain from the distracting things that grab our attention. Although scientists have known that paying attention involves multiple brain regions, they did not know how we concentrate because studies have always examined one region at a time.
In a 2007 study, monkeys were trained to take attention tests on a video screen in return for a treat of apple juice. Sometimes they had to concentrate, choosing only the left-leaning red rectangle from a field of red rectangles the same way we single out a friend's face in a crowd. Other times, attention-grabbing bright rectangles flashed off the screen at the monkeys.
The study demonstrated that when the monkeys voluntarily concentrated, the so-called executive center in the front of the brain — the prefrontal cortex — was in charge. But when something distracting grabbed the monkeys' attention, that signal originated in the parietal cortex, toward the back of the brain.
The theory that the brain concentrates on one thing at a time is important when it comes to multitasking, such as driving while talking or texting.
According to the National Highway Traffic Safety Administration (NHTSA), Americans continue to use electronic devices while driving, despite warnings that it causes their own driving to deteriorate and can lead to crashes, injuries and even death. In fact, an NHTSA survey found that 660,000 drivers are using cellphones or other electronic devices while driving at any given moment of the day.
Recent research confirms that we can only concentrate on one thing at a time — bad news for multitaskers. When we are busy with something that requires the use of sight, the brain reduces hearing to make it easy for us, screening out distractions that have nothing to do with the task. When tasks require minimal concentration, we may be aware of sounds and sights around us, but when tasks are more difficult, we are less likely to detect what is happening in the background.
In a new study, 32 students were recruited from Linkӧping University to help researchers who were particularly interested in the effects of visual-verbal cognitive load with respect to the activity in the auditory cortex and the amygdale. The students were given a visual task to work on — some in quiet surroundings and others in areas with distracting background noise.
Images of the students' brains were taken with an MRI scanner as they worked. The results showed brain activity in the auditory cortex continues without any problems, but the neural activity of the primary auditory cortex was more suppressed when the difficulty of the visual task was high, even though the sensory input was the same in the two task difficulty conditions.
In other words, according to Jerker Rӧnnberg of Linkӧping University, a professor of psychology focusing on disability research, a high cognitive load in the form of a visual task impairs the brain's response to sound in the cortex as well as parts of the brain that deal with emotions.
The study's results have implications that could impact the future design of hearing aids or how impaired hearing influences the way we solve visual tasks. In addition, research such as this has implications for better understanding and treatment of conditions such as schizophrenia, Alzheimer's disease and attention-deficit disorder.
