Mice And Milkshakes Give Neuroscientists A Tool To Understand Autism

Getting mice to stay still long enough to test the way their attention is focused is no easy task, but neuroscientists have achieved it for the first time, opening doors to researh into the effect of genes and drugs on autism and other attention-related conditions. The Florey Institute

The quest to understand the differences in how people with and without autism perceive the world has received a boost after scientists found a way to study attention in mice. Rodents playing with ipads may seem far removed from the immense complexity of the human brain but could represent a window neuroscientists have been lacking.

“Different attention is one of the earliest signs of autism,” Dr Emma Burrows of Australia’s The Florey Institute told IFLScience. People with autism focus differently from those considered neurotypical. Humanity probably benefited from the diversity as we evolved. However, in a world designed around more common brain wiring, “struggling to disengage one’s attention from something makes it difficult to navigate a world of chaos,” Burrows said.

Scientists have sought animal models to understand these differences, but have run into trouble with mice not wanting to stay still long enough to be tested. Monkeys and even rats have proven more amenable, but Burrows says they are more expensive to keep and much harder to genetically engineer in genes thought to play a role in autism.

On the other hand, it takes just a click of a different sort of mouse for Burrows to order mice modified with suspected autism genes. If she could find a way to test differences in the way wild-type mice focus their attention from their genetically modified counterparts, she could open new doors for her own team, and other autism researchers around the world.

In Neuropsychopharmacology, Burrows and her PhD student Shuting Li have announced just that, adapting a test used to study attention in humans to mice.

The Posner test is a widely used attention test, including by Burrows’ co-author Dr Katherine Johnson. Participants focus on the center of a screen before responding to a target either to the left or right. Prior to the target’s appearance, a cue is given. Usually this is on the same side as the target, priming the subject but sometimes the tester plays tricks, having the cue appear on the opposite side. Differences in response times depending on the cue’s honesty provide important insight into the way attention operates.

As in Pavlov’s famous experiments, Li sounded a tone before giving mice a taste of much-sought strawberry milkshake. The mice were first taught to stand in the correct spot to receive their reward. Once this had been mastered, the task was extended to nose-poking touchscreens. When their target appeared, the mice had to press the box on the appropriate side, with the researchers slowly increasing the time the mice had to wait for the target to appear.

Burrows used infrared beams “like in a diamond heist” to keep the mice in position. If the mice abandoned their position, then the beams connected and a light came on forcing the mice to await an opportunity to try again. The mice took to the project with such enthusiasm, Burrows told IFLScience, some jumped into their testing boxes when it came testing time each day.

 

Eventually, the mice became so disciplined that their wait time became long enough for Burrows to show them a cue before the target appeared. Results of the first tests run in this way were exploring the effects of drugs used to focus attention on mice and were included in the paper. Burrows told IFLScience she thinks those findings are far less significant than the potential the technique offers to test the effect of genes thought to play a role in autism on attention for the first time.

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