Former OpenAI researcher Nick Cammarata says most AI neurons are now interpretable

Nick Cammarata, a researcher at interpretability startup Goodfire and formerly with OpenAI, argues that most neurons in large models can now be understood, and that our grasp of neural circuits has improved significantly. Cammarata laid out the case in an essay published October 15, 2026, titled “Neural Networks Are Already Clean.” His central claim is that modern large networks have a clearer internal structure than earlier research suggested, with the majority of neurons performing distinct roles rather than being “polysemantic” — firing for a grab bag of unrelated concepts. Using advanced agentic methods, recent analyses found that nearly 90% of neurons in models like Qwen3-32B serve a single primary function. Another 7% cover two related roles. Only 2–4% remain unexplained, according to the preliminary findings. From 2% to 90% in three years Cammarata is, in part, revising his own earlier conclusions. In 2023, he worked on a project at OpenAI that found only about 1.7–2% of neurons were legible with the tools available at the time. He also revisits older examples of so-called “tangled” neurons, including cases noted in InceptionV1, an image recognition model studied in earlier ...