Scientists Just Transferred Memories… Between Sea Slugs


Sometimes, scientists do things that kinda
seem impossible. Like, in a paper that came out on Monday,
they took memories from one group of sea slugs and stuck them in other sea slugs — so that
the second group seemed to remember something that had never happened to them. It’s an amazing feat of science, and it
could someday help us understand human memory… but it’s also a little spooky. This experiment, which was published the journal
eNeuro, was part of our decades-long search for an engram: a physical thing in our brains
that contains our memories. For the record, we haven’t found one. The most common idea says that long-term memories
are probably housed in the connections between neurons. But some researchers believe they’re stored
in your non-coding RNA somehow. RNA is best known for helping your cells create
proteins. It’s kind of like a recipe created from
the information in DNA. But non-coding RNA isn’t involved in making
proteins. There are lots of different types, and we’re
still figuring out everything those molecules can do. And with this new paper, we have more evidence
that one of their jobs could involve memory. In this study, scientists repeatedly prodded
the tails of 34 sea slugs, called California sea hares. Each poke triggered a defense reflex where
they suck their tails inside their bodies. Normally, they probably do this to protect
their sensitive, squishy parts from predators. But y’know, it’s good for science, too. The more the researchers poked, the longer
that reflex lasted. And after two days of this, the sea slugs
had been trained to keep their tails in about 60 seconds longer than they had at the start. Then, the scientists took samples of RNA from
the sea slugs’ nervous systems and injected them into the circulatory systems of another
group of sea slugs — ones who didn’t get any tail prods. And after the injection, these new sea slugs
also performed the tail reflex about 40 seconds longer than normal. It wasn’t quite as long as the trained group,
but the change was big enough to suggest that the sea slugs had basically been injected
with the memories of the first group. Or at least, something in their nervous systems
changed and made their tail reflexes last longer. After follow-up experiments, the researchers
believed this happened because that non-coding RNA somehow triggered DNA methylation. This is when methyl groups get attached to
specific parts of DNA, and it usually stops the production of certain proteins. So maybe that, in turn, altered something
in the sea slugs’ neurons. There’s still a lot to figure out — like
how non-coding RNAs cause methylation, and how methylation changes sea slug neurons and,
ultimately, memories. And we can’t say for sure that this works
the same way in humans. But if it did, it would put us one step closer
to understanding where our memories live inside our heads, and how we might even be able to
alter them. Which is all kinds of weird. If you need a breather after all that, well,
we’ve got the study for you. For years, scientists have noticed that controlled
breathing — like from certain meditation practices — can provide all kinds of cognitive
benefits, including improved focus. And according to a paper published last Thursday
in the journal Psychophysiology, we might’ve figured out why. It all has to do with a little structure in
your brainstem called the locus coeruleus, or the LC. And the LC affects a lot of things, including
your respiratory system. It’s linked to nerves that remind your body
to keep breathing even when you’re not thinking about it. As a result, the activity of this region is
influenced by how much carbon dioxide is in your body. When there’s more CO2, like when you inhale,
your LC fires more often. And the opposite is true when you exhale and
your CO2 levels drop. Now, the LC has another job too: It’s your
brain’s main producer of a neurotransmitter called noradrenaline or norepinephrine, which
is a major player in your ability to focus. The tricky thing is, your brain has kind of
a sweet spot for noradrenaline levels. If there’s not enough of it, you don’t
feel stimulated, so it’s hard to focus. But if there’s too much, you feel overstimulated
or anxious, so you still can’t focus. According to this study, controlled breathing
could help. See, as you inhale and your LC fires faster,
it also produces slightly more noradrenaline. And it produces slightly less as you exhale. So by controlling your breathing, the authors
suggest that you can actually optimize those noradrenaline levels — and your focus. In their study, they tracked the locus coeruleus
activity of 14 participants during two phases: an 8-minute rest, and a 20-minute listening
task. In the task, they had to pay attention and
respond as fast as possible to mostly random tones, which could pop up anywhere between
2.5 and 3.5 seconds apart. To monitor their brain activity, the team
used fMRI scans and also tracked participants’ pupil dilation, since previous work has shown
that’s a good indicator of locus coeruleus activity. They found that participants who were better
at the listening activity had more synchronization between their breathing and the task. Their inhales and exhales were more in phase
with those 2-3 second intervals. And they probably weren’t trying to do that. Instead, the scientists thought that their
focus levels were actually changing their breathing — to have the right amount of
CO2 for the amount of LC activity. The researchers suggested this wasn’t a
one-way street, either — that controlling your breathing can influence noradrenaline
production and how focused you are. This was the first study to find a biological
link between breathing and cognition in humans, so we need more papers to know anything for
sure. But the next time you’re struggling to pay
attention in class or a meeting, maybe try taking a deep breath or two. Thanks for watching this episode of SciShow! If you’d like to keep up with the latest
science news — and all the other mind-boggling stuff out there — you can go to youtube.com/scishow
and subscribe.

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