Lightnews — Scholar-powered news

Kiah Hardcastle @kiahhardcastle.bsky.social · 19d

Yayyyy!!!

Kiah Hardcastle @kiahhardcastle.bsky.social · Sep 3

A niche and somewhat personal question but it’s desperate times over here - has anyone been pregnant (or know someone who has been pregnant) and done animal surgeries with iso? If so, how (what precautions were taken)? DMs open!

(Pregnant with my second 😳 So will also take 2 under 2 advice 😅)

2 3

Reposted by Kiah Hardcastle

Bence Ölveczky @olveczky.bsky.social · Aug 25

Wrote a eulogy for the yellow letters in my office window. www.thecrimson.com/article/2025...

My Lab Displayed A Message of Solidarity on Our Windows. Harvard Took It Down. | Opinion | The Harvard Crimson

If we continue down this path, we risk not only Harvard’s future as an institution of free inquiry and expression but also its integrity and trustworthiness.

www.thecrimson.com

4 52 120

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

Also, check out this cool write-up in Harvard Gazette on this work!
news.harvard.edu/gazette/stor...

Possible clue into movement disorders like Parkinson’s, others — Harvard Gazette

Rodent study suggests different signaling “languages” in parts of brain for learned skills, natural behaviors.

news.harvard.edu

1 2 5

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

BIG shout-out to my co-first author Jesse Marshall, who got the ball rolling and collected tons of data, to my labmates who helped me keep the ball rolling, especially when the birth of my kid coincided with experiments, and to my mentor @olveczky.bsky.social, without whom none of this would exist!

a group of people hugging each other in a living room with the words group hug above them

ALT: a group of people hugging each other in a living room with the words group hug above them

media.tenor.com

1 4

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

Another question – what *exactly* triggers this change in the neural code? Does it happen quickly, at the start of a new context that requires learning, or does it emerge slowly as a new skill develops? TBD, but with any luck we will have a better idea soon 

1 1

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

There are lots of interesting questions and ideas that come from this. For one, what the heck is DLS activity doing during free exploration?! Why is it so locked to motor output if it’s not required for it? We’re thinking about this now, but lmk if you have any ideas!

1 1

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

But then, we compared mapping from neural activity to movement – and saw a big difference!

🤩

While neurons in both cases represented ongoing movement, they did so in radically different ways.

1 4

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

What could explain this change in function? We next turned to neural activity, recording from DLS neurons from animals in both contexts.

Maybe neurons were more active in the task, or activity was more locked to behavior?

At first, we saw a whole lotta nothing that screamed “big difference”.

🤨

1 2

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

But even with the latest and greatest tracking and behavioral quantification, we couldn’t find effects of lesioning DLS 😶‍🌫️. This is a big contrast to the huge effect in the task. This suggests DLS is not an essential part of the motor control machinery, but specializing in shaping learned behaviors.

1 4

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

We first examined DLS function by taking it away (via lesion).

We already know DLS impacts learned movements – but what about innate ones?

Prior work has implicated DLS, but to know for sure, we needed to track these behaviors in detail. And thanks to advances in tracking, this is now easy-peasy!

1 2

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

To examine this, we considered two behavioral contexts on each end of the learning spectrum:
(1) free exploration, where a rat goes about their business expressing innate behaviors like rearing
(2) task execution, where the rat expresses a sequence of arm movements it learned to solve a lever task

1 1

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

But… is this just because rats *always* need their DLS for motor output, learned or otherwise?

... or ...

Does it play a special role for *learned* movements, only becoming involved when a movement is tailored to a task?

Basically – does DLS function change with learning?

a woman says quick q while holding a glass of water

ALT: a woman says quick q while holding a glass of water

media.tenor.com

1 1

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

We focused on changes within the sensorimotor striatum – also called dorsolateral striatum (DLS) in rats – which is a big input region in the basal ganglia.

We know DLS is required for learned skills: if a rat learns a new motor skill and then you mess with DLS, they can no longer execute it.

1 2

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

Excited to announce that my first postdoc paper is now online!

Links:
www.nature.com/articles/s41...
rdcu.be/eAcN7

In it, we examine the perennial question: what changes in the brain when learning a new motor skill?

Read more below to find out 👇

Differential kinematic coding in sensorimotor striatum across behavioral domains reflects different contributions to movement - Nature Neuroscience

Hardcastle and Marshall et al. show that striatal function is domain specific, required for task-related but not spontaneously expressed movements. This functional distinction is reflected in starkly ...

www.nature.com

9 35 140

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

Another question – what *exactly* triggers this change in the neural code? Does it happen quickly, at the start of a new context that requires learning, or does it emerge slowly as a new skill develops? TBD, but with any luck we will have a better idea soon :)

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

There are lots of interesting questions and ideas that come from this. For one, what the heck is DLS activity doing during free exploration?! Why is it so locked to motor output if it’s not required for it? We’re thinking about this now, but lmk if you have any ideas!

1

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

But then, we compared mapping from neural activity to movement – and saw a big difference!

🤩

While neurons in both cases represented ongoing movement, they did so in radically different ways.

1

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

What could explain this change in function? We next turned to neural activity, recording from DLS neurons from rats in both contexts.

Maybe neurons were more active in the task, or activity was more locked to behavior?

At first, we saw a whole lotta nothing that screamed “big difference”.

🤨

1

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

But even with the latest and greatest tracking and behavioral quantification, we couldn’t find effects of lesioning DLS 😶‍🌫️. This is a big contrast to the huge effect in the task. This suggests DLS is not an essential part of the motor control machinery, but specializing in shaping learned behaviors.

1

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

We first examined DLS function by taking it away (via lesion).

We already know DLS impacts learned movements – but what about innate ones?

Prior work has implicated DLS, but to know for sure, we needed to track these behaviors in detail. And thanks to advances in tracking, this is now easy-peasy!

1

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

We considered two behavioral contexts on each end of the learning spectrum:

(1) free exploration, where a rat goes about their business expressing innate behaviors like rearing and grooming

(2) task execution, where the rat expresses a sequence of arm movements it learned to solve a lever task

1

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

But… is this just because rats *always* need their DLS for motor output, learned or otherwise?

... or ...

Does it play a special role for *learned* movements, only becoming involved when a movement is tailored to a task?

Basically – does DLS function change with learning?

a woman says quick q while holding a glass of water

ALT: a woman says quick q while holding a glass of water

media.tenor.com

1

Kiah Hardcastle @kiahhardcastle.bsky.social · Aug 12

We focused on changes within the sensorimotor striatum – also called dorsolateral striatum (DLS) in rats – which is a big input region in the basal ganglia.

We know DLS is required for learned skills: if a rat learns a new motor skill and then you mess with DLS, they can no longer execute it

1

Kiah Hardcastle @kiahhardcastle.bsky.social · Mar 4

A little timeline cleanse for you — A rat party 🎉 with beautifully tracked behavior 😍

Bence Ölveczky @olveczky.bsky.social · Mar 4

As Warhol said though: one's company, two's a crowd, and three is a party. So yes, we can track a little party as well. 4/8

6 25