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Background noise: Elderly drivers might have a brain region to blame for declining driving skills

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seniors driving can have trouble seeing close objects moving because of brainDebate about older adults’ driving skills often touches on obvious impairments, such as failing vision and heavy medication use. But a new study suggests a deeper neurological explanation for why seniors have a hard time spotting obvious objects on the road: They might actually just be better at perceiving large-scale movement in the background, an ability that could compete with attention paid to smaller objects in the foreground.

"The amount of visual information around us is huge, and we don’t have the brain power to process it all," Duje Tadin, of University of Rochester’s Department of Brain and Cognitive Sciences, said in a prepared statement. So, to prioritize, the brain uses "spatial suppression" to filter out what it deems less relevant visual information, which is often that coming from the background.

Tadin and his colleagues hypothesized that this spatial suppression was being mediated at least in part by the middle temporal visual area and so by turning down this area’s function—as might happen in older adults—they could also reduce spatial suppression. The results were published online January 25 in The Journal of Neuroscience.

The research team used transcranial magnetic stimulation to send mild electrical current to the middle temporal visual area of the cortex. After 15 minutes of the 1 Hz stimulation to the noggins of six young healthy volunteers, the researchers found that the subjects were much more attuned to broader movements in the background than they had previously been. "Disruption of [the middle temporal visual area] improved motion discrimination of large, moving stimuli," the researchers wrote in their paper.

The tamping down of the middle temporal visual area did not, however, seem to affect perception of small foreground objects’ movement. Thus, with the brain receiving even more visual data, it might become less efficient at focusing on the important stuff—such as a person dashing across the road. 

The findings also might have implications for populations other than the elderly, including people with schizophrenia or depression. "These paradoxical results mimic special population findings," the researchers noted. "Particularly patients with a history of depression who exhibit better-than-normal motion perception of large patterns coupled with normal perception of small, moving stimuli." By better understanding what parts of the brain might be contributing to altered visual processing, researchers might some day be able to develop improved disease models and possibly even treatments. 

Image courtesy of iStockphoto/CWImages

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  1. 1. ennui 2:04 am 01/27/2011

    Elderly people should, when they are driving, have something in their mouth.
    A Mint for short distances, chewing gum for longer distances.
    We are still part animal.
    An animal is most alert when it is eating, as some other one will try to steal his food. So you will be more alert when you are chewing something (Up to 40 % more!).

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  2. 2. 4karats 11:19 am 01/27/2011

    Have you ever fallen asleep while driving a vehicle? Talking to some friends of mine, I found that sleep and drive is fairly common among all adults (not just seniors). After being performed in sleep labs, some people were diagnosed with obstructive apnia and were given a CPAP machine. Doctors explained that one of the affects of obstructive apnia on human bodies is the deficiency in oxygen level in the day time, causing drowsiness in driving, reading books, and watching TV. Doctors further explained that snoring doesn’t necessarily mean that the patients were sound asleep, and that the noise of snoring comes from the passage of air into the nose and out from the mouth without going into the lungs 100%, causing vibrations of the bones in the passage, and drop in oxygen contents absorbed in the blood circulated from the lungs. I am not sure if this occurs only in older adults or not, but some children who may not have a driver’s license also snore while sleeping, and require more sleep hours.

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  3. 3. bucketofsquid 12:18 pm 02/1/2011

    This is very true! When I used to drive cross country, I could only stay awake if I had something to chew on such as sunflower seeds or gum. Otherwise I had to pull over and nap every couple of hours.

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