HMT-Net: A Hybrid Mamba–Transformer Network for Motor Imagery EEG Decoding

Electroencephalography (EEG) is widely used in brain-computer interfaces (BCIs) for decoding motor imagery (MI) signals. However, existing methods remain limited in extracting multi-scale local spatiotemporal features and effectively integrating them with global feature information, leaving room for further improvement in classification accuracy. To address this issue, we propose HMT-Net, a hybrid architecture that integrates multi-scale convolution, the Mamba state-space model, and a self-attention mechanism. The model consists of a shallow feature embedding (SFE) module for spatiotemporal feature extraction, a multi-scale local feature extractor (MSLFE), and a Mamba–transformer global feature encoder (MTGFE). Specifically, the MSLFE employs dual-branch convolutions and channel attention to achieve adaptive multi-scale perception, while the MTGFE combines Mamba’s linear sequence modeling capability with multi-head attention to efficiently capture global dependencies. Unlike conventional Mamba or transformer EEG models, HMT-Net couples linear state-space modeling with global pairwise attention, avoiding the representational limits inherent in each individual architecture. Experiments on the BCI-IV-2a, BCI-IV-2b, and HGD datasets show that HMT-Net achieves subject-dependent accuracies of 84.07%, 89.60%, and 96.02%, respectively, outperforming EEGNet, FBCNet, EEGConformer, and ATCNet by 11.65%, 5.02%, 5.13%, and 6.60%, respectively, on BCI-IV-2a. Furthermore, HMT-Net achieves the best accuracy in subject-independent experiments, demonstrating strong generalization capability. Ablation studies and visualizations further validate the effectiveness and interpretability of the proposed model.