Dopamine neurons are famously involved in the reward and punishment system of the brain. Lesser known, however, is their contribution to motion control. “For example, the uncontrollable movements seen in Parkinson’s disease are linked to dopamine neuronal loss. But very little is known about their role in insects. Our recent findings show that Drosophila maggots start bending upon artificial activation of dopamine neurons. I am interested in finding out if the neurons responsible for the bending are the same as those involved in the reward-punishment circuit or those with learning and memory,” said Schleyer. “The dopamine system works in similar ways across the animal kingdom, which means understanding Drosophila brains brings us one step closer to understanding ours.” These findings were recently published in the journal Open Biology. 

Schleyer is also credited with developing a game-changing behavior analysis tool for Drosophila larvae: the Individual Maggot Behavior Analyzer (IMBA). “With no visible individual traits, Drosophila larvae are almost indistinguishable from one another, making it hard to track individuals within a group. Unlike other software, the IMBA uses a computational contour-based model to distinguish between individuals, preserving their identities even after collisions,” explains Schleyer. “It calculates more than 90 attributes for each animal and presents plots and graphs for detailed analysis.” The software is free to use and does not require any specialized hardware, just a camera placed above the animals. IMBA is pushing the boundaries for maggot behavior analysis and is quickly gaining popularity in the scientific community.

Animation of a Drosophila larva showing color-coded forward velocity. The optogenetic activation of neurons (starting 10s into the video) makes the animal crawl backwards, represented by the color changing from red (for forward motion) to blue (for backward motion). (Michael Schleyer)

Curiosity might have killed the cat, but it always wins the battle against fear, unlocking doors and leading to new discoveries. Schleyer’s journey started when he questioned the dominant view about how dopamine neurons work in Drosophila larvae. “I was told that dopamine neurons signal if the stimulus is ‘good’ and ‘bad’—if an odor is good or not, for example—but they can’t distinguish between two ‘good’ signals, like tasty food and good odor. That seemed strange to me, and I didn’t agree with this idea. It took me several years to prove that dopamine neurons can indeed differentiate between the ‘quality’ of good signals, and I consider it as one of my biggest achievements,” Schleyer says with a smile. 

The question he had as an undergraduate student in a practical course led him into this field, and he hasn’t looked back since. “That’s what I love about science—it is never boring. It fulfils the natural curiosity drive and is extremely rewarding. My message to anybody interested in science is to be curious and stay curious.”

Scientists at Schleyer lab happily co-exist with a fridge full of flies. (Photo: Sohail Keegan Pinto)

As a Principal Investigator at his new lab in the Faculty of Science, he is also supervising other projects that aim to understand the Drosophila brain, its behavior, and the underlying neuronal mechanisms. Research is conducted on a wide range of topics, including larval learning, the effects of sugars on memory retention and stability, and the role of amino acids in how larvae search for food and form parallel memories, amongst others. More information can be found at Schleyer’s website.

From undergraduate students to interns to post-doctoral researchers, the Schleyer lab is tackling the brain, one larva at a time.

Written by Gauri Kaushik (Science Writing Intern)

Researcher’s contact details:

Michael Schleyer
Assistant Professor

Institute for the Advancement of Higher Education
m.schleyer[at]oia.hokudai.ac.jp