Colton Casto

@coltoncasto.bsky.social

PhD student at Harvard/MIT interested in neuroscience, language, AI | @kempnerinstitute.bsky.social @mitbcs.bsky.social | previously Princeton neuro | coltoncasto.github.io

If an action results in error, each neuron requires an individualized teaching signal that guides change in its output. This is the credit assignment problem of learning. Are there neurons in the brain that can compute such a sophisticated teaching signal? Yes. www.biorxiv.org/content/10.6...

Climbing fibers encode the gradient of a loss function for the cerebellum

Neurons in the brain are often many synapses away from motoneurons, yet if a movement results in error, each distant neuron needs a teacher that considers its specific contribution to production of th...

biorxiv.org

🚨 New Preprint! 🧠 We gave an AI model one simple rule: rearrange your neurons so that nearby ones respond alike. We never told it what a face, a voice, or a sentence was. It grew brain-like maps for all three anyway. 🧵👇 🌐 Website: topo-omni.epfl.ch

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New preprint as my first post! "Monosynaptic connections link functionally similar regions in human cortex." We use electrical stimulation + fMRI in epilepsy patients to map whole-brain monosynaptic connectivity at 42 cortical sites. doi.org/10.64898/202... 1/n

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How do diverse context structures reshape representations in LLMs? In our new work, we explore this via representational straightening. We found LLMs are like a Swiss Army knife: they select different computational mechanisms reflected in different representational structures. 1/

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Thanks to @kempnerinstitute.bsky.social for highlighting our new study! I'm excited to see where this research will take us in the years to come :)

Kempner Institute at Harvard University@kempnerinstitute.bsky.social · 7mo ago

New in Neuron! A team including #KempnerInstitute’s @coltoncasto.bsky.social & @gretatuckute.bsky.social maps the cerebellum's role beyond motor control as part of an extended language network.🧠🗣️ More here: bit.ly/4rptQ13 #neuroscience #fMRI @gsas.harvard.edu @evfedorenko.bsky.social

Could not be more excited about Colton's @coltoncasto.bsky.social work! A deep dive into the linguistic cerebellum, and a discovery of an area remarkably functionally similar to the core left-hemisphere language areas, including in its selectivity for language. Go Colton and team!

Colton Casto@coltoncasto.bsky.social · 7mo ago

The cerebellum supports high-level language?? Now out in @cp-neuron.bsky.social, we systematically examined language-responsive areas of the cerebellum using precision fMRI and identified a *cerebellar satellite* of the neocortical language network! authors.elsevier.com/a/1mUU83BtfH... 1/n 🧵👇

Why isn’t modern AI built around principles from cognitive science or neuroscience? Starting a substack (infinitefaculty.substack.com/p/why-isnt-m...) by writing down my thoughts on that question: as part of a first series of posts giving my current thoughts on the relation between these fields. 1/3

Why isn’t modern AI built around principles from cognitive science?

First post in a series on cognitive science and AI

infinitefaculty.substack.com

Neuroscience of language has a dilemma: how do we reconcile extensive patient and imaging evidence for **language-specific** processing with the fact that naturalistic language evokes extensive activity all over the brain? We propose a framework that accounts for both.

Colton Casto@coltoncasto.bsky.social · 9mo ago

What does it mean to understand language? We argue that the brain’s core language system is limited, and that *deeply* understanding language requires EXPORTING info to other brain regions. w/ @neuranna.bsky.social @evfedorenko.bsky.social @nancykanwisher.bsky.social arxiv.org/abs/2511.19757 1/n🧵👇

New paper with @rjantonello.bsky.social @csinva.bsky.social, Suna Guo, Gavin Mischler, Jianfeng Gao, & Nima Mesgarani: We use LLMs to generate VERY interpretable embeddings where each dimension corresponds to a scientific theory, & then use these embeddings to predict fMRI and ECoG. It WORKS!

bioRxiv Neuroscience@biorxiv-neursci.bsky.social · last yr.

Evaluating scientific theories as predictive models in language neuroscience https://www.biorxiv.org/content/10.1101/2025.08.12.669958v1

🚨 New Preprint 🚨 Targeting intracranial electrical stimulation (ES) to network regions defined within individuals causes network-level effects By Cyr et al. *** Q: Can we use individualized network maps from precision fMRI to modulate a targeted network via intracranial ES? A: Yes! 🧵:

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New paper with @mujianing.bsky.social & @prestonlab.bsky.social! We propose a simple model for human memory of narratives: we uniformly sample incoming information at a constant rate. This explains behavioral data much better than variable-rate sampling triggered by event segmentation or surprisal.

bioRxiv Neuroscience@biorxiv-neursci.bsky.social · last yr.

Efficient uniform sampling explains non-uniform memory of narrative stories https://www.biorxiv.org/content/10.1101/2025.07.31.667952v1