Malcolm Campbell
@malcolmgcampbell.bsky.social
240 followers 180 following 17 posts
Postdoc in Uchida Lab, Harvard (dopamine, learning, circuit computation) | PhD in Giocomo lab, Stanford (grid cells, path integration, navigation) | NIH NIDA K99/R00 | Bridging theory and biology of animal learning and decision making
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malcolmgcampbell.bsky.social
🚨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! 🧵
Reposted by Malcolm Campbell
nickjourjine.bsky.social
Had a blast writing about this new @currentbiology.bsky.social study from @leo-perrier.bsky.social, Lény Lego et al. on African striped mice

The paper: doi.org/10.1016/j.cu...

Dispatch with some context about why it's so cool: authors.elsevier.com/a/1luVG3QW8S...

#bioacoustics
#neuroskyence
nicolasmathevon.bsky.social
Ultrasonic signals support a large-scale communication landscape in wild mice. 👇 New paper by the ENES Bioacoustics Research Team in @currentbiology.bsky.social

authors.elsevier.com/a/1llMH3QW8S...
authors.elsevier.com
Reposted by Malcolm Campbell
fannycazettes.bsky.social
Did you know that facial expressions reveal more than meets the eye? 🤯

Our new study shows that even a mouse's face 🐭 can reflect hidden neural computations🧠. Turns out, facial expressions are more than just emotions!

We're so excited to see this paper out @natneuro.nature.com 🎉
🔗: rdcu.be/eIQzO
Facial expressions in mice reveal latent cognitive variables and their neural correlates
Nature Neuroscience - The face reveals more than just emotion. Cazettes, Reato and colleagues show that subtle facial movements reveal hidden cognitive states, reflecting the brain’s ongoing...
rdcu.be
malcolmgcampbell.bsky.social
Also thank you, I’m really glad you enjoyed it!
malcolmgcampbell.bsky.social
It didn’t make it into the preprint but dopamine neurons respond to D2 stim as a sign-flipped TD error, which fits nicely in that framework
malcolmgcampbell.bsky.social
Great question… my current thinking based on plasticity rules is that they learn pessimistically biased sign-flipped value from dopamine dips, as in @sromeropinto.bsky.social’s and Adam Lowet’s papers
malcolmgcampbell.bsky.social
Thanks Adrien! Yes, that’s exactly right!
malcolmgcampbell.bsky.social
Thank you Sam! It was super fun to present in your lab!
malcolmgcampbell.bsky.social
Thanks so much to all co-authors, especially my mentor Naoshige Uchida @naoshigeuchida.bsky.social! It has been a joy to work on this (ongoing) project!
malcolmgcampbell.bsky.social
I’m excited about this work because it shows how the microcircuit configuration of the dopamine system could control the degree of preference for current versus future rewards (can you resist that marshmallow for two marshmallows later?). Future work is headed in that direction!
malcolmgcampbell.bsky.social
This suggests the exciting possibility that the time horizon of dopaminergic learning (its temporal discount factor) is set by the balance of excitation and inhibition in this pathway.
malcolmgcampbell.bsky.social
We found dopamine neurons are hardwired to automatically take the temporal derivative of their input from striatal neurons—thus accomplishing a key step in TD learning.
malcolmgcampbell.bsky.social
Dopamine neurons famously signal temporal difference (TD) errors, a teaching signal for learning to predict rewards, but the mechanisms that produce these signals are unknown. We also don’t know how the parameters governing dopaminergic learning arise from biological components.
malcolmgcampbell.bsky.social
🚨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! 🧵