Lightnews — Scholar-powered news

Reposted by Caitlin Mallory

Angelo Forli @aforli89.bsky.social · 14d

Interested in the brain, circuits, and behavior?
Enjoy tinkering and asking bold questions in neuroscience?

The Forli Lab (IIT, Genova, Italy) is hiring!

🧠 🔬 🟩◻️🟥->🍕🚫🍍

Check out our website for updates:
sites.google.com/view/forli-lab

2 7 13

Reposted by Caitlin Mallory

Sam Gershman @gershbrain.bsky.social · 19d

This is one of the most outstanding examples of circuit understanding I've seen in a long time. The unification of theory and experiment is beautiful.

When Malcolm presented this in my lab, the audience was cheering at the end, and one person shouted (non-ironically) "You did it!"

Malcolm Campbell @malcolmgcampbell.bsky.social · 19d

🚨Our preprint is online!🚨

www.biorxiv.org/content/10.1...

How do #dopamine neurons perform the key calculations in reinforcement #learning?

Read on to find out more! 🧵

4 21 110

Caitlin Mallory @caitlinmallory.bsky.social · 19d

Congratulations Malcolm!!! Can't wait to read :)

1

Reposted by Caitlin Mallory

Malcolm Campbell @malcolmgcampbell.bsky.social · Aug 7

Our paper on foraging is now published in Neuron! Read it here:

www.cell.com/neuron/fullt...

This project was co-led by Michael Bukwich (not on Bluesky) and me, with major contributions from all co-authors. Huge thanks to the whole team!

Competitive integration of time and reward explains value-sensitive foraging decisions and frontal cortex ramping dynamics

Bukwich and Campbell et al. show that mice integrate elapsed time and reward intake, scaled by a latent patience variable, to decide when to leave virtual “patches.” Frontal cortex ramping activity ma...

www.cell.com

2 19 75

Caitlin Mallory @caitlinmallory.bsky.social · Aug 8

This is amazing 😅

Reposted by Caitlin Mallory

UC Davis Physiology @ucd-physiology.bsky.social · Jun 19

Congratulations to all the amazing scientists named 2025 Freeman Hrabowski Scholars by HHMI. We’re immensely honored to have two #PMB faculty members, @doctheagrif.bsky.social and @elisazhang.bsky.social , among this inspiring group. An incredible and well-deserved achievement! @ucdavis.bsky.social

The 2025 Freeman Hrabowski Scholars | HHMI

Freeman Hrabowski Scholars are outstanding early career faculty who have the potential to become leaders in their research fields.

www.hhmi.org

1 7 27

Caitlin Mallory @caitlinmallory.bsky.social · Feb 2

Thank you!!

Caitlin Mallory @caitlinmallory.bsky.social · Feb 1

Thanks so much Kevin!

1

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

Thank you, Dan!

1

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

Ha, it most definitely is. When you do get a chance, let me know what you think!

1

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

Thank you Anna! :)

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

19/19 And of course, a huge thank you to my postdoc mentor, David Foster, for his guidance and invaluable input along the journey!

I welcome your thoughts and would love to chat with anyone about our findings!

3

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

18/19 John had conceived of similar adaptation models of replay and theta sequences before. When we teamed up to look at whether a neuronal fatigue model could explain replay's perplexing ‘past-avoidance’, everything began to click into place.

1 3

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

17/19 This project unfolded like a fun but super challenging puzzle. For a long time we wondered, why would replay avoid the recent past? I want to give a HUGE shout out to co-author John Widloski for his tremendous contribution in helping put the final pieces together.

1 2

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

16/19 When we added a source of facilitation onto cells that had been activated along the animal’s prior path, we were able to subtly increase the rate of retrospective replays overall and recapitulate the eventual emergence of a past bias.

1 3

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

15/19 The model produced replays that both avoided each other and the animal’s recent past (for a period of time related to time constant adaptation). Notably, without an additional input (presumably from MEC), the model did not produce the eventual bias for past-going replays.

1 2

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

14/19 Finally, we considered whether a recurrent network endowed with neuronal fatigue could recapitulate this counterintuitive organization of replay. We found that, in our model, adaptation not only *generates* replay, but it also organizes it.

1 3

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

13/19 We optogenetically (or chemogenetically) shut down MEC as rats consumed reward. We indeed found that retrospective replays became less frequent with MEC suppressed, although they were not altogether abolished.

1 3

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

12/19 How does the prior path eventually become preferentially replayed later in the stopping period? We wondered whether the medial entorhinal cortex, a cortical region highly interconnected with hippocampus, might play a role in biasing replay for the animal’s recent past.

1 2

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

11/19 This made us wonder, would *replay* of a path also fatigue the participating cells and prevent a subsequent replay of the same path? Consistent with the idea, we found that when two replays occur back-to-back (within about 1 sec), the second replay avoids the first.

1 5

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

10/19 We hypothesized that neuronal fatigue effectively takes recently activated place cells ‘out of commission’ for a few seconds. If replay is going to occur after the animal stops, it has to recruit different cells/represent a different path from that just taken.

2 5

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

9/19 So, which did we observe? Clearly, the latter- when the past and future paths overlapped, replay avoided them both for the first few seconds.

1 5

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

8/19 But sometimes rats turned around, retracing their steps so that the future and past paths overlapped. In this particular case, future-preferring versus past-avoiding replays would point in opposite directions.

1 5

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

7/19 We suspected that the primary factor influencing replay’s direction in the first few seconds after stopping is ‘past-avoidance’, rather than ‘future-preference'. This can be hard to distinguish, since rats often continue moving in the same direction after pausing.

1 4

Caitlin Mallory @caitlinmallory.bsky.social · Jan 31

6/19 But now you can more easily see that what changes most dramatically over the stopping period is the angle of replays relative to the animal’s past path. It starts off large and decreases with a time course that is strikingly similar across subjects…

1 4