It feels weird driving while lying flat on your back.
That's why Toronto neuroscientist Tom Schweizer offers practice sessions to the volunteers in his brain-imaging study. Each person gets time to become accustomed to the driving simulator, which has been engineered to fit inside a brain scanner. The small steering wheel is at the participants' waist, the accelerator and brake pedals at their feet, and their visual field is filled with the images of driving down a road and turning left at a busy intersection.
Dr. Schweizer wants to know what parts of the brain we use when we perform complex driving manoeuvres and whether this changes as we age. His goal is to develop an objective test to help assess whether older drivers, as well as people who have had a stroke or another brain injury, can still safely operate a car or truck. The idea isn't to install functional magnetic resonance imagers at the motor-vehicle-licence offices, says Dr. Schweizer, who works at St. Michael's Hospital. He wants to develop a series of short, cognitive tests to assess whether someone's brain is up to the job of driving.
"Once we have figured out the brain structures involved in different aspects of driving, we can go in with cognitive testing that targets those areas," he says.
As people age, they have a greater chance of developing vision problems or other health conditions that might compromise driving safely. The brain also changes. The frontal cortex, which makes up about 60 per cent of the brain, atrophies, or shrinks, Dr. Schweizer says. Reaction times can slow, and it can become more difficult to multitask.
His imaging study is part of a growing scientific effort to learn how to accommodate and perhaps even retrain older drivers, and to find a better way to determine when it is time for them to give up their keys.
There are now more than 3.25 million licensed drivers aged 65 or older in Canada, about 14 per cent of the total driving population. The proportion of seniors behind the wheel is expected to grow as baby boomers get older.
There is no consensus on how to best test older drivers. Once drivers in Ontario turn 80 they have to complete a vision and knowledge test and do a group education session every two years. But the protocol is different in other provinces and there is little agreement on how to identify and regulate people who may be a risk to themselves or others on the road, says Brenda Vrkljan, an occupational therapist and associate professor in the school of rehabilitation science at McMaster University in Hamilton. She is also part of Candrive, a national initiative to improve the safety of older drivers and to develop an effective method, involving a combination of approaches, for assessing their abilities.
It is a difficult issue. Being able to drive is key to the independence and quality of life of many seniors. It would be exciting, Dr. Vrkljan says, if neuroscience could offer some insight.
Dr. Schweizer does the brain imaging at Sunnybrook Hospital, where he collaborates with Dr. Simon Graham. University of Toronto graduate student Karen Kan worked for two years on a driving simulator that would function in a brain scanner.
So far, Dr. Schweizer has scanned the brains of 16 drivers under the age of 30 while they used the simulator. It's not perfect imitation of the driving experience, but it is as good as it gets, he says.
In one simulation, they drive down a straight road, which is pretty easy on the brain.
But in another, they have to turn left at a busy intersection, which requires looking at the traffic lights, oncoming cars and pedestrians – and timing the turn.
"We are seeing it requires a pretty large network to do the more complicated manoeuvre. That seems intuitive, but the exact areas that are coming online have not been shown before," Dr. Schweizer says.
The next step is to see whether the pattern of activity is different in the brains of drivers who are 70 or older. It may be that more of the brain is activated, or that different areas are recruited. Understanding how the aging brain adapts to the demands of driving will help in the development of new cognitive tests, which would supplement existing assessment tools, such as vision tests or on-road driving tests.
Other researchers are also using driving simulators to better understand older drivers. At Lakehead University in Thunder Bay, Ont., Michel Bédard, wants to see whether their performance on various cognitive tests is linked to how they well they avoid virtual collisions. His study could lead to new approaches to help older drivers improve their skills.
"There may be quite a bit of potential for retraining," he says.