Measure gradients, not activations! Enhancing neuronal activity in deep reinforcement learning

Fuente: arXiv
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Hauptverfasser: Liu, Jiashun, Wu, Zihao, Obando-Ceron, Johan, Castro, Pablo Samuel, Courville, Aaron, Pan, Ling
Format: Preprint
Veröffentlicht: 2025
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author Liu, Jiashun
Wu, Zihao
Obando-Ceron, Johan
Castro, Pablo Samuel
Courville, Aaron
Pan, Ling
author_facet Liu, Jiashun
Wu, Zihao
Obando-Ceron, Johan
Castro, Pablo Samuel
Courville, Aaron
Pan, Ling
contents Deep reinforcement learning (RL) agents frequently suffer from neuronal activity loss, which impairs their ability to adapt to new data and learn continually. A common method to quantify and address this issue is the tau-dormant neuron ratio, which uses activation statistics to measure the expressive ability of neurons. While effective for simple MLP-based agents, this approach loses statistical power in more complex architectures. To address this, we argue that in advanced RL agents, maintaining a neuron's learning capacity, its ability to adapt via gradient updates, is more critical than preserving its expressive ability. Based on this insight, we shift the statistical objective from activations to gradients, and introduce GraMa (Gradient Magnitude Neural Activity Metric), a lightweight, architecture-agnostic metric for quantifying neuron-level learning capacity. We show that GraMa effectively reveals persistent neuron inactivity across diverse architectures, including residual networks, diffusion models, and agents with varied activation functions. Moreover, resetting neurons guided by GraMa (ReGraMa) consistently improves learning performance across multiple deep RL algorithms and benchmarks, such as MuJoCo and the DeepMind Control Suite.
format Preprint
id arxiv_https___arxiv_org_abs_2505_24061
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Measure gradients, not activations! Enhancing neuronal activity in deep reinforcement learning
Liu, Jiashun
Wu, Zihao
Obando-Ceron, Johan
Castro, Pablo Samuel
Courville, Aaron
Pan, Ling
Machine Learning
Deep reinforcement learning (RL) agents frequently suffer from neuronal activity loss, which impairs their ability to adapt to new data and learn continually. A common method to quantify and address this issue is the tau-dormant neuron ratio, which uses activation statistics to measure the expressive ability of neurons. While effective for simple MLP-based agents, this approach loses statistical power in more complex architectures. To address this, we argue that in advanced RL agents, maintaining a neuron's learning capacity, its ability to adapt via gradient updates, is more critical than preserving its expressive ability. Based on this insight, we shift the statistical objective from activations to gradients, and introduce GraMa (Gradient Magnitude Neural Activity Metric), a lightweight, architecture-agnostic metric for quantifying neuron-level learning capacity. We show that GraMa effectively reveals persistent neuron inactivity across diverse architectures, including residual networks, diffusion models, and agents with varied activation functions. Moreover, resetting neurons guided by GraMa (ReGraMa) consistently improves learning performance across multiple deep RL algorithms and benchmarks, such as MuJoCo and the DeepMind Control Suite.
title Measure gradients, not activations! Enhancing neuronal activity in deep reinforcement learning
topic Machine Learning
url https://arxiv.org/abs/2505.24061