Memory neurons lull us to sleep in order to consolidate what we've learned, say researchers from Brandeis University in the US, who advise students against pulling all-nighters to prepare for tests.
Knowing that sleep, memory and learning are deeply intertwined, the Brandeis team set out to find out whether memory is consolidated during sleep simply because the brain happens to be at rest or whether those neurons provoke sleep in order to do their job.
In the study, which was
published in the journal
eLife, the researchers focused on a specific group of neurons called the dorsal paired medial (DPM), which are well known to implant memories in fruit flies
.
In what's thought to be a first-of-its-kind observation, the flies slept more when the DPM neurons were activated, yet continued to buzz about when these neurons were switched off.
As these neurons start to convert short-term memory to long-term memory, they do their best to make sure you stay sleeping and actually hinder wakefulness, according to the study.
In the case of the fruit flies, the part of their brain in charge of memory and learning -- called the mushroom body -- is also what determines wakefulness and, consequently, it's where the DPM are housed.
"It's almost as if that section of the mushroom body were saying 'hey, stay awake and learn this,'" says co-author Bethany Christmann, a graduate student at Brandeis. "Then, after a while, the DPM neurons start signaling to suppress that section, as if to say 'you're going to need sleep if you want to remember this later.'"
Christmann points out that knowing how sleep, memory and learning work together in the fruit fly brain can help researchers know what to look for when working with human participants.
"Eventually, it could help us figure out how sleep or memory is affected when things go wrong, as in the case of insomnia or memory disorders," she says.