Same basic story for the P24 M1-RN data (Fig. S4) - there's a huge discrepancy between EMG and movement during wake, but for twitches, the correspondence is pretty good.
Big thanks to @sfnjournals.bsky.social for highlighting our upcoming paper! We’re mapping out how the distinct building blocks of REM sleep—tonic and phasic dynamics—actually develop and organize in early life. Can’t wait for the final version to drop soon!
Turns out - we see the same pattern, bursting for some twitches but inhibition for others. What's super cool is that it's sped up. The burst and the inhibition is only ~25% as long as during wake, so it's like the whole motor system is accelerated. So what kind of twitches happen during the bursts?
Now for the unpublished part:
At P24, we found RN neurons that showed activity during specific wake behaviors (Fig. 6). The one we show in this fig fires preferentially during grooming - and shows strong inhibition during other wake movements. So what's that same RN neuron doing during REM sleep?
Unfortunately, the methods we used weren't sensitive enough to pick that up since that kind of detailed kinematics wasn't the point of that study. But we're doing our best to be sure that doesn't happen again! Here's recent data from the lab, showing we can now track limbs in 3D throughout movement.
This has been a long time coming - but our M1 Development/M1-RN paper is finally out in its final form!
Rather than re-hash the original story, I'm going to talk about one of the biggest reviewer-suggested additions, as well as some unpublished data!
www.nature.com/articles/s41...
I keep going back to how tough it would be to explain REM sleep and twitching to an alien (assuming they don't do it too, which maybe isn't a given)
Video
So can you use EMGs to detect twitches. In short - yes. But there's a couple of catches.
1) you're recording from a single muscle (maybe even just a few muscle fibers) so you're getting a limited look at movement.
2) There's WAY more false negatives (only ~20% of twitches are detected vs. video)