Students find link between sleep and memory in fruit flies

by Kristen Green ’14, Features Editor

A team of Wellesley students recently discovered a link between disrupted sleep and memory in fruit flies. Their findings were published earlier this semester in Impulse, an online undergraduate journal for publications in neuroscience.

Mika Maeda ’14, Mika Asaba ’14, Kitaia Dao ’14 and Adrian Bates ’13 conducted their research as part of the lab component for NEUR 325: Sleep, Learning and Memory, which they took with Professor Sharon Gobes last fall.

Instead of submitting a series of reports for the lab component of the course, the students were charged with designing a novel scientific experiment—and then submitting a paper describing their findings to an undergraduate research journal.

The students discovered that a new strain of Restless Leg Syndrome (RLS) had been developed for Drosophila melanogaster, commonly known as the fruit fly. They decided to test how well the RLS flies, which were plagued by chronic sleep disruption, would function cognitively compared to flies who slept normally.

Maeda explained that RLS is a condition that affects many humans as well.

“Because with restless leg syndrome your legs are always moving, this can keep you awake at night,” she said. “These flies actually showed reduced sleep at night, which is what you can actually see in humans with RLS.”

To test how disturbed sleep of the RLS flies affected their cognitive abilities, the students set out designing an experiment based on Pavlovian olfactory conditioning. They set up a T shaped maze using tubes. At either side of the T, the group placed a different aversive odor, and paired one odor with a shock. Flies who went to the “shock” odor would be whisked away to a vortex and spun around quickly.

Maeda explained that some flies learn to avoid the shock odor, while others do not.

“So, if they learn it, they go to the other side. They still go to the aversive odor, but it’s the one that wasn’t paired with a shock,” she said.

Although the students expected the RLS flies to perform worse on the task, according to Maeda, the RLS flies instead showed “matched and slightly better performance.”

“We thought that maybe because the flies were a weaker strain that maybe they were more physiologically alert,” Maeda explained. “They might have been more affected by the shock because they were weaker, and this might have caused them to learn it better.”

Gobes was intrigued by the students’ results.

“Sometimes we say that the brain works as advertised, and these flies worked as advertised,” she said. “If you teach them something they will form a memory, which is already amazing that you can show that. You can present them with an odor and give them a shock and they all go dizzy and they remember that that’s a bad odor. It’s just unbelievable that they learn that that quickly.”

However, working in a lab with flies presented challenges for a group of students not yet skilled at handling tiny winged insects.

Dao said that the group received plenty of guidance from faculty members. She credits Ginny Quinan of the Neuroscience Department and Jonathan Cheek of the Psychology Department with providing technical support and research guidance, respectively.

“We wouldn’t have been able to carry out the experiment at all [without them], since none of us had ever worked with fruit flies before,” Dao said.

Asaba confirmed that working with fruit flies was a challenging aspect of the experiment in practice.

“In the beginning, it was a lot slower because of all the handling,” Asaba said. She described sucking flies up using a small vacuum, which they then used to transfer the flies into the maze. However, the students also had to deal with practical issues, such as keeping flies alive and stopping flies from escaping into the lab.

And after overcoming the struggles of fly-handling, the group aspect of the experiment also proved a challenging but key component of the students’ experience.

“I think it’s the number-one skill you need to learn and practice in a safe environment like Wellesley, where you can fail and you can try new things,” Gobes said. “You may get into a fight with your group, but then you get the opportunity to fix it and you’re not going to lose your job.”

Asaba said that her group had to work through communication issues, but added that the long-term group experience was valuable.

“I think I learned a lot from working with the same group of people for four months, and it’s not as though we were just in a research team together. We were also in a classroom setting together,” she said.

After working with the same group members for months, the students still had to submit their paper to Impulse, a process that required them to grapple with many pages of revisions.

For Gobes, the submission process was also an important experience for these students.

“You’re going to get from the level where you’ve given the absolute best you can, get feedback, use the feedback and therefore improve and really get something out of it. You’ll really learn how to write a better scientific paper than if you had just handed it in and gotten a ‘B’ for it at the end of the course,” she said.

Gobes is proud of the accomplishments of her students, but adds that it’s not just the experimental conclusions she views as accomplishments.

“Adding to the body of scientific knowledge is a major achievement, but the personal achievement of how you get there is almost bigger than the scientific one,” she said.

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