Summary: Older people have longer reaction times, slower decision times, and greater activation of brain areas involved in inhibition and task switching. The results may shed light on why many older drivers confuse the accelerator with the brake pedal.
Source: Nagoya University
By scanning the brains of elderly people and college students while performing simulations of braking and accelerating, Japanese researchers found that older participants had longer reaction times, slower decision times and greater great brain activation in parts of the brain involved in inhibition and switching tasks.
These results suggest insight into the causes of crashes involving older drivers who confuse the brake with the accelerator.
As the media reports, the number of accidents in which older drivers mistakenly press the accelerator instead of the brake has increased.
Fearing that cognitive decline is one of the main causes of such incidents, the National Police Agency of Japan, a country with one of the oldest populations in the world, requires adults over 75 take periodic cognitive tests.
However, few studies have investigated executive functions and brain activity in older adults in terms of foot responses during braking and acceleration.
To fill this gap, a group led by Professor Nobuyuki Kawai from the Graduate School of Informatics at Nagoya University in Japan scanned the brains of elderly people and students while performing simulations of pedal presses.
The researchers were particularly interested in the left dorsolateral prefrontal cortex, the part of the brain associated with inhibition and switching responses.
To simulate the response of a person’s feet and hands while driving a car, they created a new task in the lab called the bimanual and bipedal response selection and response-position compatibility task. During this task, a cue prompted participants to press the left or right button with their left or right foot, or their left or right hand.
Sometimes participants pressed the pedal in front of them, while at other times they had to press diagonally. This was done to allow researchers to assess how participants reacted in situations where the cognitive load was higher.
Administering this task to both college students and elderly participants, the researchers then monitored blood flow in their brains.
The results were published in Behavioral brain research.
They found that older participants had longer reaction times, slower decision times, and greater brain activation than younger people. Additionally, pressing the diagonal pedal required longer reaction times and greater brain activation than pressing directly forward in the left dorsolateral prefrontal cortex.
Interestingly, this was only found when people were asked to use their feet but not their hands. In short, older people had to think more actively than younger people to decide which “pedal” to press with their feet.
“This indicates that the cognitive load is higher when pressing the pedal diagonally with the foot, such as when pressing the brake,” says Professor Kawai.
“When you push a pedal diagonally with your foot, you use the frontal lobe more than when you push the pedal straight ahead. In particular, the left dorsolateral frontal lobe, which is important for response switching, is more active when the foot is depressed at an angle than when the pedal is depressed in a straight line.
“In these tasks, older adults have higher neural activity throughout the frontal lobe than students.”
The results of this study suggest that to compensate for the decline in cognitive functions, greater brain activation may be needed in older people. Older adults may experience difficulty in situations with high cognitive load, such as parking a vehicle in a narrow space.
“This study suggests that older people’s performance is vulnerable in these situations,” says Professor Kawai.
“Older drivers shouldn’t be overconfident about their safe driving. Even older people who are normally able to drive without problems, when cognitive load is applied, such as when switching from one parking space to another or when talking with a passenger, things can be different and there there is a chance of pressing the wrong pedal. We believe it is important to educate older drivers about this fact.
Funding: This work was supported by JSPS KAKENHI.
About this neuroscience research news
Author: Matthew Coslet
Source: Nagoya University
Contact: Matthew Coslett – University of Nagoya
Image: The image is attributed to Dr. Nobuyuki Kawai, Reiko Matsushita
Original research: Free access.
“Do older people confuse the accelerator with the brake pedal?: Older people use greater prefrontal cortical activity during a bipedal/bimanual response position selection task” by Nobuyuki Kawai et al. Behavioral brain research
Do older people confuse the accelerator with the brake pedal? : Older adults use greater prefrontal cortical activity during a bipedal/bimanual response position selection task
Successful aging depends on the maintenance of executive functions, which enable flexible coordination of responses. Although flexible responses are needed for the hands and feet, as in driving, few studies have examined executive functions and brain activity in older adults, in terms of foot responses.
In this study, younger (mean age = 20.8) and older (mean age = 68.7) participants performed a newly developed bimanual/bipedal position selection compatibility task while we measured their brain activity at using functional near-infrared spectroscopy.
Participants were asked to press a left or right button using their left or right foot (or hand), as indicated by a two-dimensional cue signal. They performed a straight or diagonal press response that mimicked pressing the accelerator or brake pedal in a car. Foot responses produced more errors, longer reaction times, and greater brain activation than hand responses.
Greater brain activation in the left dorsolateral prefrontal cortex (BA 46) was observed in incongruent (i.e., diagonal) trials than in congruent (right) trials for foot responses, but not for hand responses, suggesting that participants had difficulty executing a diagonal foot response (like braking in a car), but not a diagonal hand response.
Older participants showed greater brain activation in the PFC than younger participants, indicating that older adults are activating additional brain circuits to compensate for declining executive functions.
We discuss the potential relationships between declining executive function in older adults and the frequent motor vehicle crashes (i.e. missteps) in which they are involved.
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