Neuroscientist: Highly nonlinear function-fitting inherently yields hard-to-interpret polysemantic neurons

HistedLab · x · 2026-10-18

Neuroscientist Histed argues that both brains and LLMs face intrinsic interpretability limits: connected networks and transformer blocks naturally produce polysemantic, hard-to-read neurons as a consequence of highly nonlinear function-fitting.

He notes that polysemanticity in brains doesn't prove AI systems can't be trained toward cleaner representations — maybe they can — but his feeling is it's inherent to the approach. Current knowledge of brain and LLM computation is too limited to settle the question.

He expects this to be a research focus in both fields in the coming years.

Related event: Neuroscientist HistedLab on brain polysemanticity and AI interpretability(6 posts)→

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