Unveiling Instruction-Specific Neurons & Experts: An Analytical Framework for LLM's Instruction-Following Capabilities

Fuente: arXiv
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Main Authors: Zhang, Junyan, Gao, Yubo, Yan, Yibo, Li, Jungang, Hou, Zhaorui, Tao, Sicheng, Liu, Shuliang, Dai, Song, Hei, Yonghua, Li, Junzhuo, Hu, Xuming
Format: Preprint
Published: 2025
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author Zhang, Junyan
Gao, Yubo
Yan, Yibo
Li, Jungang
Hou, Zhaorui
Tao, Sicheng
Liu, Shuliang
Dai, Song
Hei, Yonghua
Li, Junzhuo
Hu, Xuming
author_facet Zhang, Junyan
Gao, Yubo
Yan, Yibo
Li, Jungang
Hou, Zhaorui
Tao, Sicheng
Liu, Shuliang
Dai, Song
Hei, Yonghua
Li, Junzhuo
Hu, Xuming
contents The finetuning of Large Language Models (LLMs) has significantly advanced their instruction-following capabilities, yet the underlying computational mechanisms driving these improvements remain poorly understood. This study systematically examines how fine-tuning reconfigures LLM computations by isolating and analyzing instruction-specific sparse components, i.e., neurons in dense models and both neurons and experts in Mixture-of-Experts (MoE) architectures. In particular, we introduce HexaInst, a carefully curated and balanced instructional dataset spanning six distinct categories, and propose SPARCOM, a novel analytical framework comprising three key contributions: (1) a method for identifying these sparse components, (2) an evaluation of their functional generality and uniqueness, and (3) a systematic comparison of their alterations. Through experiments, we demonstrate functional generality, uniqueness, and the critical role of these components in instruction execution. By elucidating the relationship between fine-tuning-induced adaptations and sparse computational substrates, this work provides deeper insights into how LLMs internalize instruction-following behavior for the trustworthy LLM community.
format Preprint
id arxiv_https___arxiv_org_abs_2505_21191
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Unveiling Instruction-Specific Neurons & Experts: An Analytical Framework for LLM's Instruction-Following Capabilities
Zhang, Junyan
Gao, Yubo
Yan, Yibo
Li, Jungang
Hou, Zhaorui
Tao, Sicheng
Liu, Shuliang
Dai, Song
Hei, Yonghua
Li, Junzhuo
Hu, Xuming
Computation and Language
Machine Learning
The finetuning of Large Language Models (LLMs) has significantly advanced their instruction-following capabilities, yet the underlying computational mechanisms driving these improvements remain poorly understood. This study systematically examines how fine-tuning reconfigures LLM computations by isolating and analyzing instruction-specific sparse components, i.e., neurons in dense models and both neurons and experts in Mixture-of-Experts (MoE) architectures. In particular, we introduce HexaInst, a carefully curated and balanced instructional dataset spanning six distinct categories, and propose SPARCOM, a novel analytical framework comprising three key contributions: (1) a method for identifying these sparse components, (2) an evaluation of their functional generality and uniqueness, and (3) a systematic comparison of their alterations. Through experiments, we demonstrate functional generality, uniqueness, and the critical role of these components in instruction execution. By elucidating the relationship between fine-tuning-induced adaptations and sparse computational substrates, this work provides deeper insights into how LLMs internalize instruction-following behavior for the trustworthy LLM community.
title Unveiling Instruction-Specific Neurons & Experts: An Analytical Framework for LLM's Instruction-Following Capabilities
topic Computation and Language
Machine Learning
url https://arxiv.org/abs/2505.21191