Artificial Hippocampus Networks for Efficient Long-Context Modeling
Authors: name: Yunhao Fang, name: Weihao Yu, name: Shu Zhong, name: Qinghao Ye, name: Xuehan Xiong, name: Lai Wei
Organization: ByteDance Seed

Long-sequence modeling faces a fundamental trade-off between the efficiency
of compressive fixed-size memory in RNN-like models and the fidelity of
lossless growing memory in attention-based Transformers. Inspired by the
Multi-Store Model in cognitive science, we introduce a memory framework of
artificial neural networks. Our method maintains a sliding window of the
Transformer's KV cache as lossless short-term memory, while a learnable module
termed Artificial Hippocampus Network (AHN) recurrently compresses
out-of-window information into a fixed-size compact long-term memory. To
validate this framework, we instantiate AHNs using modern RNN-like
architectures, including Mamba2, DeltaNet, and Gated DeltaNet. Extensive
experiments on long-context benchmarks LV-Eval and InfiniteBench demonstrate
that AHN-augmented models consistently outperform sliding window baselines and
achieve performance comparable or even superior to full-attention models, while
substantially reducing computational and memory requirements. For instance,
augmenting the Qwen2.5-3B-Instruct with AHNs reduces inference FLOPs by 40.5%
and memory cache by 74.0%, while improving its average score on LV-Eval (128k
sequence length) from 4.41 to 5.88. Code is available at:
https://github.com/ByteDance-Seed/AHN.