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Scientists have found that as we age, our brains start to pay too much attention to things that might not be important. As this ScienCentral News video explains, this hyper-attention can actually make us more distractible.
Distracted Brains
Staying focused in a world full of ticking clocks, clicking keyboards, and beeping smoke detectors is not as easy as you might think. Our brains have to decide what information is important enough to be introduced into our conscious minds and filter out all the rest. In other words, it has to know to tune out the sound of that crinkling paper and keep streaming in the words you're trying to read. If you've ever tried reading with a dripping faucet in the background, you probably know that sometimes this process doesn't always work perfectly.
"All of us can be annoyed by something like that at times, but most of us are able to block such things out," says Monica Fabiani, a cognitive neuroscientist at the University of Illinois.
But Fabiani has shown that how successful we are at ignoring background information might actually be connected to how old we are. In a recent study, she showed that people over seventy years of age have a tougher time tuning out such distractions.
Fabiani and her team at the Beckman Institute used a new brain imaging technique known as EROS. Fabiani and her husband Gabriele Gratton are pioneering the use of EROS, which has some distinct advantages over other imaging methods.
"EROS is a technique for looking at the brain in action," says Fabiani. "It's based on the diffusion of light into the tissue." Using reflected light patterns to show brain activity, EROS gives the researchers a good idea of both the timing and location of brain events, all in a single technology.
Fabiani and her team measured brain activity in sixteen young and sixteen older volunteers who read a book of their choice while distracting tones played in the background. They adjusted the volume of the tones so that all the volunteers heard them at the same level, irrelevant of the quality their hearing.
"The tones come in trains of fives, so that you have basically beep beep beep beep beep and then there is a pause," explains Fabiani.
The researchers took two different measurements of brain activity -- both EROS and a measurement of electrical activity in the brain. Both techniques produced similar brain activity patterns -- volunteers in their twenties only responded to the first tone in each sequence and then ignored the rest, but the older adults' brains responded to all five of the tones. "And so presumably that might have an influence on their reading, and on their performance of their main task," Fabiani says.
With EROS, the researchers could also see which regions of the older adults' brains kept responding to the sounds. Fabiani describes the electrical measurements as being diffused over the cortex. EROS, on the other hand, allowed them to see where in the brain activity occured - in this case, in the auditory cortex. Without EROS, she says, "We would not have the information that there are clear patterns of this type in auditory cortex, we would know that there are responses of this type, but we wouldn't be sure where they are coming from."
It might seem intuitive to guess that the patterns would be found in the auditory cortex, since the responses are directly related to hearing, but Fabiani says this provides validation for using EROS in more complicated experiments where it would be impossible to guess in advance where the brain activity will happen.
Fabiani says their study helps to reveal why our mental performance starts to naturally deteriorate as we age. She says there are many different changes in our brains as we age, but this simple experiment shows one of those ground-level changes. "This suggests that older adults may be more distractible and therefore some of their resources might be devoted to things that are not as important," she says.
And figuring out what's normal is the first step in being able to diagnose abnormal diseases -- like Alzheimer's disease. Although Fabiani says EROS is not yet suitable as a diagnostic tool, the kind of information it provides about brain activity may one day be very useful in many clinical situations.
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