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Imran Thobani Profile
Imran Thobani

@cogphilosopher

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Neuroscience postdoc @Stanford, previously philosophy of neuroscience PhD. Building large-scale brain models using deep learning.

Stanford, CA
Joined August 2008
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@cogphilosopher
Imran Thobani
25 days
1/x Our new method, the Inter-Animal Transform Class (IATC), is a principled way to compare neural network models to the brain. It's the first to ensure both accurate brain activity predictions and specific identification of neural mechanisms. Preprint: https://t.co/hPqo5PrZoc
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@cogphilosopher
Imran Thobani
25 days
@AllenInstitute 10/X Overall, our work provides a principled framework for evaluating brain models, improving on previous approaches and contextualizing prior findings. A huge thanks to my incredible co-authors on this work! @jvrsgsty @aran_nayebi @_jacobprince_ @luosha @dyamins
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@cogphilosopher
Imran Thobani
25 days
9/X There’s a lot more to this in the paper, including estimating the IATC on real neural data: a mouse dataset from @AllenInstitute and a human fMRI dataset.
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@cogphilosopher
Imran Thobani
25 days
8/X In fact, while linear regression has been thought to be overly powerful, our work suggests that a *non-linear* mapping is needed to capture the actual relationships between brains in a population.
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@cogphilosopher
Imran Thobani
25 days
7/X One of the striking takeaways of this work is that stricter mapping methods aren’t necessarily better at mechanism identification, and in fact often perform worse, because they aren’t able to align responses across subjects (as required for the IATC).
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@cogphilosopher
Imran Thobani
25 days
6/X Our IATC estimate achieves both high accuracy in predicting neural activity and high specificity in mechanism identification. This shows there is no tradeoff between the engineering goal of predicting brain activity and the scientific goal of identifying neural mechanisms.
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@cogphilosopher
Imran Thobani
25 days
5/X So what is the IATC for the brain? In a simulated setting, we found that the neuronal activation function causes subjects’ activation patterns to diverge at each layer before re-converging. Correctly accounting for this “Zippering Effect” leads to a better IATC estimate.
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@cogphilosopher
Imran Thobani
25 days
4/X We propose the Inter-Animal Transform Class (IATC)—the strictest set of functions needed to map neural responses accurately between any two actual brains. We can use the IATC to align models to brains, effectively asking if a model can masquerade as a typical subject.
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@cogphilosopher
Imran Thobani
25 days
3/X On the other hand, more flexible methods like linear regression, while decent for prediction, seem like they may be too flexible to identify the actual neural mechanism. So what's the right "sweet spot" between strict and flexible?
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@cogphilosopher
Imran Thobani
25 days
2/X A key challenge is that individual brains are all somewhat different. So strict methods that match individual neurons struggle to make accurate predictions when mapping a single model to typical brains.
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@KlemenKotar
Klemen Kotar
2 months
1/ A good world model should be promptable like an LLM, offering flexible control and zero-shot answers to many questions. Language models have benefited greatly from this fact, but it's been slow to come to vision. We introduce PSI: a path to truly interactive visual world
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@cogphilosopher
Imran Thobani
2 months
Sunrise over Prague
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@cogphilosopher
Imran Thobani
2 months
Devoured these pastries from the oldest bakery in Copenhagen today, Skt. Peders Bageri.
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@Rahul_Venkatesh
Rahul Venkatesh
3 months
AI models segment scenes based on how things appear, but babies segment based on what moves together. We utilize a visual world model that our lab has been developing, to capture this concept — and what's cool is that it beats SOTA models on zero-shot segmentation and physical
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@cogphilosopher
Imran Thobani
3 months
It's always surprised me that ketchup flavored chips, which are so widespread in Canada (and delicious!) are not a thing in the US.
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@FlorentinGuth
Florentin Guth
5 months
What is the probability of an image? What do the highest and lowest probability images look like? Do natural images lie on a low-dimensional manifold? In a new preprint with @ZKadkhodaie @EeroSimoncelli, we develop a novel energy-based model in order to answer these questions: 🧵
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@doomie
Dumitru Erhan
11 months
#NeurIPS2024 parties be like this;
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