Australian scientist gets baby fish to bust a move to MC Hammer classic

What happens inside the brain of a baby zebrafish when you play MC Hammer’s timeless 1990 hip-hop track, U Can’t Touch This, and why is this even a question?

“I’ve spent a lot of time looking at the video over and over again to see if there are neurons that respond to the bass or the vocal. In my opinion, there’s something there.”

As Australia’s first female dance music producer and DJ, Rebecca Poulsen – aka BeXta – is a pioneer, with scores of tracks, mixes and hundreds of gigs around the globe under her belt.

But between DJ gigs, the 46-year-old is now back at university studying neuroscience at Queensland Brain Institute at the University of Queensland in Brisbane.

And part of this involves gently securing baby zebrafish inside a chamber and then playing them sounds while scanning their brains with a laser and looking at what happens through a microscope.

The results of Poulsen’s sound experiments have been published in the journal Current Biology.

The analysis for the study doesn’t look at how the fish larvae react during Hammer time, but how their brain cells react to simple single-frequency sounds.

“It told us their hearing range was broader than we thought it was before,” she says.

Poulsen also tried more complex sounds, like white noise and “frequency sweeps”, which she describes as “like the sound when Wile E Coyote falls off a cliff” in the Road Runner cartoons.

“When you look at the neurons that light up at each sound, they’re unique. The fish can tell the difference between complex and different sounds.”

This is, happily, where MC Hammer comes in.

Out of professional and scientific curiosity – and also presumably just because she could – Poulsen played music to the fish.

She composed her own piece of dance music and that did seem to light things up.

But what about U Can’t Touch This?

“You can see when the vocal goes ‘ohhh-oh’, specific neurons light up and you can see it pulses to the beat. To me it looks like neurons responding to different parts of the music.

“I do like the track. I was pretty little when it came out and I loved it. I didn’t have the harem pants, though, but I did used to do the dance.”

And so, when Poulsen published an early version of her research before it had been through peer review, she tagged MC Hammer on Twitter with a video of the fish brain lighting up to his song.

Later that day, MC Hammer tweeted a link to Poulsen’s work-in-progress. “That was awesome,” says Poulsen.

Carrying out this research presented two big problems.

How do you stop the fish from swimming away while you play them sounds? And how do you get a speaker small enough to deliver different volumes and frequencies without startling the fish?

For the first problem, the baby zebrafish – just 3mm long – are contained in a jelly-like substance that lets them breathe “but stops them from swimming away and keeps them nice and still so we can image them”.

For the second problem, Poulsen and colleagues used a speaker just 1cm wide and stuck it to the glass of the 2cm-cubed chamber the fish was contained in.

Using fish larvae has its advantages. “They’re so tiny we can see their whole brain … we can see the whole brain live in real time.”

The idea that fish can hear and react to music isn’t new, Poulsen points out.

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Because zebrafish are a common subject for experiments, another group of researchers have claimed playing them a couple of hours of Vivaldi twice a day for 15 days made them calmer and helped part of their immune system.

“So why would fish be happy hearing music?” asks Poulsen.

“It’s not something that’s in their environment. Is this something that’s fundamental to animals? That raises some big philosophical questions in my mind.”

Poulsen says all animals need to be able to understand the information coming in to them through sound.

“They need to do that to survive. For a fish, that might be to know a predator is approaching, or if there’s something hitting the water. That goes all the way up to humans where we have to be able to discriminate between different sounds.”

When Poulsen left school, she studied sonology at Griffith University’s Queensland Conservatorium and then did a graduate certificate in autism and a masters in education. And then she went off touring and making music for 20 years.

Ultimately, Poulsen is using the zebrafish brains as a model because she thinks they could tell us something about how different sounds could help people with autism to better understand their world.

But before that, she has a DJ gig to get ready for in Brisbane this weekend.