Minimal neuron ablation triggers catastrophic collapse in the language core of Large Vision-Language Models

Fuente: arXiv
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Auteurs principaux: Lu, Cen, Tang, Yung-Chen, Cavallaro, Andrea
Format: Preprint
Publié: 2025
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author Lu, Cen
Tang, Yung-Chen
Cavallaro, Andrea
author_facet Lu, Cen
Tang, Yung-Chen
Cavallaro, Andrea
contents Large Vision-Language Models (LVLMs) have shown impressive multimodal understanding capabilities, yet their robustness is poorly understood. In this paper, we investigate the structural vulnerabilities of LVLMs to identify any critical neurons whose removal triggers catastrophic collapse. In this context, we propose CAN, a method to detect Consistently Activated Neurons and to locate critical neurons by progressive masking. Experiments on LLaVA-1.5-7b-hf and InstructBLIP-Vicuna-7b reveal that masking only a tiny portion of the language model's feed-forward networks (just as few as four neurons in extreme cases) suffices to trigger catastrophic collapse. Notably, critical neurons are predominantly localized in the language model rather than in the vision components, and the down-projection layer is a particularly vulnerable structure. We also observe a consistent two-stage collapse pattern: initial expressive degradation followed by sudden, complete collapse. Our findings provide important insights for safety research in LVLMs.
format Preprint
id arxiv_https___arxiv_org_abs_2512_00918
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Minimal neuron ablation triggers catastrophic collapse in the language core of Large Vision-Language Models
Lu, Cen
Tang, Yung-Chen
Cavallaro, Andrea
Artificial Intelligence
Large Vision-Language Models (LVLMs) have shown impressive multimodal understanding capabilities, yet their robustness is poorly understood. In this paper, we investigate the structural vulnerabilities of LVLMs to identify any critical neurons whose removal triggers catastrophic collapse. In this context, we propose CAN, a method to detect Consistently Activated Neurons and to locate critical neurons by progressive masking. Experiments on LLaVA-1.5-7b-hf and InstructBLIP-Vicuna-7b reveal that masking only a tiny portion of the language model's feed-forward networks (just as few as four neurons in extreme cases) suffices to trigger catastrophic collapse. Notably, critical neurons are predominantly localized in the language model rather than in the vision components, and the down-projection layer is a particularly vulnerable structure. We also observe a consistent two-stage collapse pattern: initial expressive degradation followed by sudden, complete collapse. Our findings provide important insights for safety research in LVLMs.
title Minimal neuron ablation triggers catastrophic collapse in the language core of Large Vision-Language Models
topic Artificial Intelligence
url https://arxiv.org/abs/2512.00918