对比两种神经模型在生物动力系统中的表现,揭示物理约束对稳定性的重要性。
Comparing Physics-Informed and Neural ODE Approaches for Modeling Nonlinear Biological Systems: A Case Study Based on the Morris-Lecar Model
- PINN通过损失函数嵌入物理方程,NODE直接从数据学习向量场。
- 在刚性与敏感分岔下,PINN的误差更低,更稳定可靠。
- 适合需要物理可解释性的建模场景,如神经动力学研究。
物理信息神经网络(PINNs)和神经常微分方程(NODEs)是两类用于建模非线性神经动力系统的机器学习框架。本研究系统评估了它们在二维莫里斯-莱卡尔模型上的表现,涵盖霍普夫、极限环上的鞍结点及同宿轨道三种典型分岔情形。合成时间序列数据通过数值积分生成,训练中分别采用配点法(PINNs)和自适应求解器(Dormand-Prince方法,适用于NODEs)。PINNs利用自动微分将控制方程融入损失函数,确保训练过程中的物理一致性;而NODEs则直接从数据中学习系统向量场,无先验结构假设或对物理定律的归纳偏置。性能评估采用均方误差(MSE)、平均绝对误差(MAE)、平均绝对百分比误差(MAPE)及决定系数等标准回归指标。结果表明,在刚性或敏感分岔条件下,由于嵌入了物理结构,PINNs表现出更高的精度与鲁棒性;而尽管NODEs更具表达力与灵活性,但作为黑箱近似器,缺乏结构约束,可能导致可解释性下降与稳定性不足。虽然高级变体(如ANODEs、潜变量NODEs)试图缓解这些问题,其在刚性动态下的表现仍待验证。研究强调了物理信息模型在结构与可解释性方面的优势,与纯数据驱动方法在灵活性与物理一致性间的权衡。
原文摘要 · Abstract (English)
Physics-Informed Neural Networks (PINNs) and Neural Ordinary Differential Equations (NODEs) represent two distinct machine learning frameworks for modeling nonlinear neuronal dynamics. This study systematically evaluates their performance on the two-dimensional Morris-Lecar model across three canonical bifurcation regimes: Hopf, Saddle-Node on Limit Cycle, and homoclinic orbit. Synthetic time-series data are generated via numerical integration under controlled conditions, and training is performed using collocation points for PINNs and adaptive solvers for NODEs (Dormand-Prince method). PINNs incorporate the governing differential equations into the loss function using automatic differentiation, which enforces physical consistency during training. In contrast, NODEs learn the system's vector field directly from data, without prior structural assumptions or inductive bias toward physical laws. Model performance is assessed using standard regression metrics, including Mean Squared Error (MSE), Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), and the coefficient of determination. Results indicate that PINNs tend to achieve higher accuracy and robustness in scenarios involving stiffness or sensitive bifurcations, owing to their embedded physical structure. NODEs, while more expressive and flexible, operate as black-box approximators without structural constraints, which can lead to reduced interpretability and stability in these regimes. Although advanced variants of NODEs (e.g., ANODEs, latent NODEs) aim to mitigate such limitations, their performance under stiff dynamics remains an open question. These findings emphasize the trade-offs between physics-informed models, which embed structure and interpretability, and purely data-driven approaches, which prioritize flexibility at the cost of physical consistency.
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