The Transfer Neurons Hypothesis: An Underlying Mechanism for Language Latent Space Transitions in Multilingual LLMs

• URL: http://arxiv.org/abs/2509.17030v1
• Date: Sun, 21 Sep 2025 10:44:16 GMT
• Title: The Transfer Neurons Hypothesis: An Underlying Mechanism for Language Latent Space Transitions in Multilingual LLMs
• Abstract summary: Recent studies have suggested a processing framework for multilingual inputs in decoder-based LLMs.<n>We show that certain neurons in the Neuron module are responsible for transferring representations between language-specific latent spaces and a shared semantic latent space.
• Score: 5.152664482521929
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Recent studies have suggested a processing framework for multilingual inputs in decoder-based LLMs: early layers convert inputs into English-centric and language-agnostic representations; middle layers perform reasoning within an English-centric latent space; and final layers generate outputs by transforming these representations back into language-specific latent spaces. However, the internal dynamics of such transformation and the underlying mechanism remain underexplored. Towards a deeper understanding of this framework, we propose and empirically validate The Transfer Neurons Hypothesis: certain neurons in the MLP module are responsible for transferring representations between language-specific latent spaces and a shared semantic latent space. Furthermore, we show that one function of language-specific neurons, as identified in recent studies, is to facilitate movement between latent spaces. Finally, we show that transfer neurons are critical for reasoning in multilingual LLMs.

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