Jimmy Dooley
@jimmycdooley.bsky.social
Purdue Assistant Professor seeing how infant movements teach our brains about our bodies. At home, I'm ~1.5 years into an 18+ year developmental experiment named Elaina.
Views are my own (but think what it says about society that I have to say that...)
Views are my own (but think what it says about society that I have to say that...)
We argue that instead of focusing on when in development "REM sleep" can be unambiguously called REM sleep, we should focus on how these REM sleep features map onto REM sleep functions. Understanding the relationships of features to functions is a key part of the next decade of sleep science.
June 13, 2025 at 4:50 PM
We argue that instead of focusing on when in development "REM sleep" can be unambiguously called REM sleep, we should focus on how these REM sleep features map onto REM sleep functions. Understanding the relationships of features to functions is a key part of the next decade of sleep science.
Basically, REM sleep (as it's defined in adults) has a bunch of components, or features, that all develop at their own rate. Gao et al.'s recent publication (Ontogenetic development of PGO waves during paradoxical sleep in kittens) shows us that PGO waves are the last of these features to show up
June 13, 2025 at 4:50 PM
Basically, REM sleep (as it's defined in adults) has a bunch of components, or features, that all develop at their own rate. Gao et al.'s recent publication (Ontogenetic development of PGO waves during paradoxical sleep in kittens) shows us that PGO waves are the last of these features to show up
There's a very decent case to be made for no AI overviews for medical searches.
Someone is going to search for this and panic...
Someone is going to search for this and panic...
May 31, 2025 at 1:14 PM
There's a very decent case to be made for no AI overviews for medical searches.
Someone is going to search for this and panic...
Someone is going to search for this and panic...
Just pre-ordered! So glad you did an audiobook. Otherwise with a 16 month old at home I don't stand a chance
May 31, 2025 at 1:12 AM
Just pre-ordered! So glad you did an audiobook. Otherwise with a 16 month old at home I don't stand a chance
RN neurons showed way more variability in their wake responses than M1 neurons.
So we asked: Which neurons encode movement trajectory?
Answer: RN wins again.
“Tuned” M1 neurons only care about how big the movement was. But RN neurons? Nearly all the tuned ones cared about both size and direction.
So we asked: Which neurons encode movement trajectory?
Answer: RN wins again.
“Tuned” M1 neurons only care about how big the movement was. But RN neurons? Nearly all the tuned ones cared about both size and direction.
May 30, 2025 at 8:31 PM
RN neurons showed way more variability in their wake responses than M1 neurons.
So we asked: Which neurons encode movement trajectory?
Answer: RN wins again.
“Tuned” M1 neurons only care about how big the movement was. But RN neurons? Nearly all the tuned ones cared about both size and direction.
So we asked: Which neurons encode movement trajectory?
Answer: RN wins again.
“Tuned” M1 neurons only care about how big the movement was. But RN neurons? Nearly all the tuned ones cared about both size and direction.
We tracked limb trajectories and matched them to neural spikes from both M1 and RN in P24 rats. The results?
RN neurons weren’t just responsive. They were selective.
Take one RN neuron: Some wake movements (bilateral facial grooming) made it fire like crazy. Others suppressed it.
What about M1?
RN neurons weren’t just responsive. They were selective.
Take one RN neuron: Some wake movements (bilateral facial grooming) made it fire like crazy. Others suppressed it.
What about M1?
May 30, 2025 at 8:31 PM
We tracked limb trajectories and matched them to neural spikes from both M1 and RN in P24 rats. The results?
RN neurons weren’t just responsive. They were selective.
Take one RN neuron: Some wake movements (bilateral facial grooming) made it fire like crazy. Others suppressed it.
What about M1?
RN neurons weren’t just responsive. They were selective.
Take one RN neuron: Some wake movements (bilateral facial grooming) made it fire like crazy. Others suppressed it.
What about M1?
two adorable distinguished ladies
February 25, 2025 at 11:13 PM
two adorable distinguished ladies
Turns out for the two RN neurons showed here, responsive wake movements involved bringing both paws to the pup’s face. The inhibitory wake movements were all other wake movements. We think this is feed-forward inhibition of RN motor neurons, but stay tuned, we're still exploring this story!
February 3, 2025 at 8:22 PM
Turns out for the two RN neurons showed here, responsive wake movements involved bringing both paws to the pup’s face. The inhibitory wake movements were all other wake movements. We think this is feed-forward inhibition of RN motor neurons, but stay tuned, we're still exploring this story!
Finally, one more cool thing we found in RN (that we’re still exploring!) In M1, neurons either responded to wake movements or didn’t. But in RN, some neurons showed a “bimodal response” to wake movements. Some wake movements drove the RN neuron, while others inhibited it. What’s going on here?
February 3, 2025 at 8:22 PM
Finally, one more cool thing we found in RN (that we’re still exploring!) In M1, neurons either responded to wake movements or didn’t. But in RN, some neurons showed a “bimodal response” to wake movements. Some wake movements drove the RN neuron, while others inhibited it. What’s going on here?
To test if 20% is a lot, we took some more P24 rats and recorded from M1 and the Red Nucleus (RN; the brainstem motor nucleus that produces forelimb twitches at this age).
First, we confirmed that the RN shows twitch- and wake-movement-related activity at P24 (no one looked at that age before).
First, we confirmed that the RN shows twitch- and wake-movement-related activity at P24 (no one looked at that age before).
February 3, 2025 at 8:22 PM
To test if 20% is a lot, we took some more P24 rats and recorded from M1 and the Red Nucleus (RN; the brainstem motor nucleus that produces forelimb twitches at this age).
First, we confirmed that the RN shows twitch- and wake-movement-related activity at P24 (no one looked at that age before).
First, we confirmed that the RN shows twitch- and wake-movement-related activity at P24 (no one looked at that age before).
So how did twitch-related activity change with age. As rats got older, activity peaked quicker (faster response), responses were narrower (temporally refined) and more activity preceded the movement (motor?) At P20 and P24, about 20% of spikes occurred before the twitch started.
But is that a lot?
But is that a lot?
February 3, 2025 at 8:22 PM
So how did twitch-related activity change with age. As rats got older, activity peaked quicker (faster response), responses were narrower (temporally refined) and more activity preceded the movement (motor?) At P20 and P24, about 20% of spikes occurred before the twitch started.
But is that a lot?
But is that a lot?
We also used twitches to map M1's somatotopic development. We saw which twitches (from forelimb, hindlimb, whisker, or tail) drove activity in the "forelimb" part of M1. Even at P12, the forelimb twitches were the only ones that drove M1 activity. That means M1 is already somatotopic at 12 days old!
February 3, 2025 at 8:22 PM
We also used twitches to map M1's somatotopic development. We saw which twitches (from forelimb, hindlimb, whisker, or tail) drove activity in the "forelimb" part of M1. Even at P12, the forelimb twitches were the only ones that drove M1 activity. That means M1 is already somatotopic at 12 days old!
At all ages, M1 neurons responded to wake movements and REM sleep twitches. At P12, almost all M1 neurons responded to twitches, but by P20, only about a third of them did. Because twitches are highly stereotyped, we also saw that the response to twitches got more precise as the rats got older.
February 3, 2025 at 8:22 PM
At all ages, M1 neurons responded to wake movements and REM sleep twitches. At P12, almost all M1 neurons responded to twitches, but by P20, only about a third of them did. Because twitches are highly stereotyped, we also saw that the response to twitches got more precise as the rats got older.
We know neural activity is important for M1 to develop its motor functions. But (until now) we didn’t know how that activity is patterned. In this paper, we recorded neural activity in M1 from P12 to P24 as they cycled between REM sleep, NREM sleep, and wake.
So what did we learn?
So what did we learn?
February 3, 2025 at 8:22 PM
We know neural activity is important for M1 to develop its motor functions. But (until now) we didn’t know how that activity is patterned. In this paper, we recorded neural activity in M1 from P12 to P24 as they cycled between REM sleep, NREM sleep, and wake.
So what did we learn?
So what did we learn?
First, background.
M1 becomes “motor” late.
Like, really late.
Later than you probably think it does.
Experiments in rats put the start of motor control by motor cortex at 25-days-old. That’s after they're typically weaned! Before that, it seems like brainstem motor nuclei produce movements.
M1 becomes “motor” late.
Like, really late.
Later than you probably think it does.
Experiments in rats put the start of motor control by motor cortex at 25-days-old. That’s after they're typically weaned! Before that, it seems like brainstem motor nuclei produce movements.
February 3, 2025 at 8:22 PM
First, background.
M1 becomes “motor” late.
Like, really late.
Later than you probably think it does.
Experiments in rats put the start of motor control by motor cortex at 25-days-old. That’s after they're typically weaned! Before that, it seems like brainstem motor nuclei produce movements.
M1 becomes “motor” late.
Like, really late.
Later than you probably think it does.
Experiments in rats put the start of motor control by motor cortex at 25-days-old. That’s after they're typically weaned! Before that, it seems like brainstem motor nuclei produce movements.
Wikipedia rabbitholes are worth it for those moments when the objective, neutral, wikipedia tone breaks down...
January 8, 2025 at 1:27 AM
Wikipedia rabbitholes are worth it for those moments when the objective, neutral, wikipedia tone breaks down...
Here it is in the rig. It's the black cylinder on a gooseneck in the top right.
December 17, 2024 at 8:51 PM
Here it is in the rig. It's the black cylinder on a gooseneck in the top right.
There has to be someone who (like me) didn't know this.
I just learned that for ~$40 you can buy a USB "microscope" that works great for electrode placement.
Here's the one that we just got for the lab that recorded this video:
www.amazon.com/Plugable-Mic...
I just learned that for ~$40 you can buy a USB "microscope" that works great for electrode placement.
Here's the one that we just got for the lab that recorded this video:
www.amazon.com/Plugable-Mic...
December 17, 2024 at 8:51 PM
There has to be someone who (like me) didn't know this.
I just learned that for ~$40 you can buy a USB "microscope" that works great for electrode placement.
Here's the one that we just got for the lab that recorded this video:
www.amazon.com/Plugable-Mic...
I just learned that for ~$40 you can buy a USB "microscope" that works great for electrode placement.
Here's the one that we just got for the lab that recorded this video:
www.amazon.com/Plugable-Mic...
Definitely getting Star Wars or Lord of the Rings vibes (and not Matrix or Jurassic Park)
December 6, 2024 at 9:14 PM
Definitely getting Star Wars or Lord of the Rings vibes (and not Matrix or Jurassic Park)
And finally, a figure that looks simple, until you learn how it was made. Apparently, Bob Muller spent days programming this entire figure with equations. According to @JohnKubie, getting the curve on the wire was the hardest part
Muller et al, 1987
Muller et al, 1987
December 4, 2024 at 8:55 PM
And finally, a figure that looks simple, until you learn how it was made. Apparently, Bob Muller spent days programming this entire figure with equations. According to @JohnKubie, getting the curve on the wire was the hardest part
Muller et al, 1987
Muller et al, 1987
Jokes aside, figures are a great way of showing the reader what you did in your experiment. In this figure, the authors did what scientists do best and explained the design of their experiment using 2 detailed drawings
Keller et al., 1996
Keller et al., 1996
December 4, 2024 at 8:55 PM
Jokes aside, figures are a great way of showing the reader what you did in your experiment. In this figure, the authors did what scientists do best and explained the design of their experiment using 2 detailed drawings
Keller et al., 1996
Keller et al., 1996
A lot of non-scientists don't know this, but on occasion, different authors can contribute to the same figure, each bringing their own artistic abilities. See if you can spot the subtle difference in artistic style between the infant rat in panel A and panel B
Luhmann 2016
Luhmann 2016
December 4, 2024 at 8:55 PM
A lot of non-scientists don't know this, but on occasion, different authors can contribute to the same figure, each bringing their own artistic abilities. See if you can spot the subtle difference in artistic style between the infant rat in panel A and panel B
Luhmann 2016
Luhmann 2016
As technology improved, so did the artwork. Why limit yourself to 2D ovals, when 3 dimensional art is possible.
Meyer et al. 2018
Meyer et al. 2018
December 4, 2024 at 8:55 PM
As technology improved, so did the artwork. Why limit yourself to 2D ovals, when 3 dimensional art is possible.
Meyer et al. 2018
Meyer et al. 2018
Another oval mouse (provided by @Hagar_k_Solisman), this time with some 3d perspective in the head
Patten et al, 2014
Patten et al, 2014
December 4, 2024 at 8:55 PM
Another oval mouse (provided by @Hagar_k_Solisman), this time with some 3d perspective in the head
Patten et al, 2014
Patten et al, 2014