A Nature Machine Intelligence paper from Peking and Tsinghua researchers shows task-evoked fMRI activity can improve language models, not only correlate with them. The team found partial alignment between LLM internals and reasoning-related brain regions, then steered representations along shared brain-model directions at inference and during fine-tuning. Across ten models from 1.5B to 72B parameters, brain guidance lifted deductive reasoning accuracy by up to 13 points, with gains described as orthogonal to language-only training. Why it matters: brain-AI work moves from similarity scores toward usable signals. Caveat: results center on lab reasoning tasks, and fMRI guidance is costly to scale.