Oral @ IEEE CIBCB 2025 November 2024 - March 2025

Multimodal Spiking Neural Network for Mental Workload Classification

Novel fusion architectures for aligning heterogeneous biosignals (EEG, EDA, PPG, Temperature) into unified latent representations using spiking neural networks

Overview

Real-world biosignal monitoring faces the challenge of integrating multiple sensor modalities with different sampling rates, noise characteristics, and occasional dropouts. This project develops robust multimodal fusion architectures using spiking neural networks.

Multimodal Fusion

Combining EEG, EDA, PPG, and temperature signals

Robustness

Handles noisy and missing modalities gracefully

Neuromorphic-Ready

SNN architecture for efficient edge deployment

Multimodal Fusion Architecture

Multimodal SNN Fusion Architecture EEG EDA PPG Temp Spike Encoder Spike Encoder Spike Encoder Spike Encoder Temporal Alignment SNN Layers Late Fusion Concat + FC Cognitive Load Class Low/Med/High

Figure 1: Multimodal spiking neural network architecture showing modality-specific encoders, temporal alignment layers, and late fusion for cognitive load classification.

My Role

First Author
  • Architecture Design: Developed novel SNN architecture for multimodal biosignal fusion
  • Implementation: Built complete training pipeline using PyTorch and snnTorch
  • Ablation Studies: Systematic evaluation of modality contributions and fusion strategies
  • Evaluation: Comprehensive benchmarking with reproducible metrics

Methodology

Spike Encoding Schemes Rate Coding Temporal Coding EEG (256 Hz) EDA (4 Hz) Handles heterogeneous sampling rates Fusion Strategy Comparison Early Concat SNN Intermediate Late ✓ Fusion 78.2% 81.5% 85.3% Classification Accuracy Late fusion selected for robustness

Figure 2: (Left) Rate and temporal spike encoding for different biosignal modalities. (Right) Comparison of early, intermediate, and late fusion strategies.

What's Innovative

This work introduces a novel SNN architecture specifically designed for multimodal biosignal fusion with two key innovations:

4 Modalities Fused
+12% vs Single Modality
Robust To Missing Data

The architecture handles heterogeneous sampling rates through modality-specific temporal encoders and maintains performance even with missing or noisy channels— essential for real-world wearable deployment.

Results

Modality Ablation Study 90% 80% 70% 60% EEG 73% EDA 68% PPG 65% Temp 58% All 85% +12% Confusion Matrix Predicted Actual Low High Low High 94 6 8 92 Overall Accuracy: 85.3%

Figure 3: (Left) Ablation study showing contribution of each modality. (Right) Confusion matrix for binary cognitive load classification (Low/High).

Publication

Spiking Neural Networks for Mental Workload Classification with a Multimodal Approach

An, J., Fabrikant, S. I., Indiveri, G., & Donati, E.

2025 IEEE Conference on Computational Intelligence in Bioinformatics and Computational Biology (CIBCB), 1575–1578 — Tainan, Taiwan

https://doi.org/10.1109/CIBCB66090.2025.11177083

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