Authors: Sicheng Dai, Hongwang Xiao, Shan Yu, Qiwei Ye
Organizations: Institute of Automation, Chinese Academy of Sciences · School of Artifcial Intelligence, University of Chinese Academy of Sciences · State Key Laboratory of Brain Cognition and Brain-inspired Intelligence Technology · Beijing Academy of Artificial Intelligence · National Key Laboratory for Multimedia Information Processing, Peking University
Electroencephalogram (EEG) signals have become a popular medium for decoding visual information due to their cost-effectiveness and high temporal resolution. However, current approaches face significant challenges in bridging the modality gap between EEG and image data. These methods typically rely on complex adaptation processes involving multiple stages, making it hard to maintain consistency and manage compounding errors. Furthermore, the computational overhead imposed by large-scale diffusion models limit their practicality in real-world brain-computer interface (BCI) applications. In this work, we present AVDE, a lightweight and efficient framework for visual decoding from EEG signals. First, we leverage LaBraM, a pre-trained EEG model, and fine-tune it via contrastive learning to align EEG and image representations. Second, we adopt an autoregressive generative framework based on a "next-scale prediction" strategy: images are encoded into multi-scale token maps using a pre-trained VQ-VAE, and a transformer is trained to autoregressively predict finer-scale tokens starting from EEG embeddings as the coarsest representation. This design enables coherent generation while preserving a direct connection between the input EEG signals and the reconstructed images. Experiments on two datasets show that AVDE outperforms previous state-of-the-art methods in both image retrieval and reconstruction tasks, while using only 10% of the parameters. In addition, visualization of intermediate outputs shows that the generative process of AVDE reflects the hierarchical nature of human visual perception. These results highlight the potential of autoregressive models as efficient and interpretable tools for practical BCI applications.
Figures & tables
Figure 1: A typical unCLIP framework employed in previous EEG-based visual decoding works Li et al. (2024) ; Zhang et al. (2025) ; Xiao et al. (2025) ; Scotti et al. (2023) . Despite its flexibility, the framework comprises multiple stages (five in this case), each introducing potential sources of error that can accumulate and degrade overall performance. Furthermore, the computational and memory demands of its components present significant challenges for practical implementation in BCIs.
Figure 2: AVDE involves two training stages. Stage 1: A pre-trained EEG encoder is fine-tuned using contrastive learning to more effectively capture visual information embedded in EEG signals. This adaptation aims to provide a more informative initialization for the subsequent visual reconstruction process. Stage 2: A visual autoregressive transformer is trained using the next-scale prediction objective (Equation 7 ). Specifically, the model takes the sequence ([s],R1,R2,…,RK−1) as input and predicts the corresponding sequence (R1,R2,R3,…,RK) . Training is guided by a standard cross-entropy loss.
Method
Low-level
High-level
PixCorr ↑
SSIM ↑
AlexNet(2) ↑
AlexNet(5) ↑
Inception ↑
CLIP ↑
SwAV ↓
Li et al. (2024)
0.160
0.345
0.776
0.866
0.734
0.786
0.582
GeoCap
0.148
0.380
0.813
0.877
0.712
0.791
0.582
CognitionCapturer
0.175
0.366
0.760
0.610
0.721
0.744
0.577
AVDE (Ours)
0.188
0.396
0.817
0.889
0.765
0.795
0.557
Table 2: Quantitative assessments of EEG-based visual reconstruction quality on Subject-08.
Figure 3: Qualitative Comparison of Visual Reconstruction Performance. Selected reconstruction results from subject-08 demonstrate that the visual stimuli reconstructed by our method preserve finer-grained features, suggesting improved fidelity and detail compared to alternative approaches.
Method
Params (M)
Steps
FLOPs (G)
Inference Time (ms)
Memory Usage (MB)
Li et al. (2024)
3818.1
4
8738.6
310.4
4826.73
AVDE (Ours)
425.3
10
1350.5
91.2
1809.63
Table 3: Comparison with state-of-the-art method on inference efficiency. All metrics are evaluated using PyTorch’s built-in profiler on a single NVIDIA A100 GPU. The batch size is fixed at 1, and results are averaged over 200 runs to ensure stability and reliability.
Method
Low-level
High-level
PixCorr ↑
SSIM ↑
AlexNet(2) ↑
AlexNet(5) ↑
Inception ↑
CLIP ↑
SwAV ↓
LaBraM+VAR
0.147
0.366
0.766
0.835
0.724
0.747
0.586
ATM+VAR
0.141
0.351
0.752
0.821
0.711
0.731
0.601
EEGNet+VAR
0.132
0.323
0.733
0.803
0.687
0.712
0.627
NICE+VAR
0.136
0.341
0.742
0.812
0.701
0.719
0.613
LaBraM+ Li et al. (2024)
0.138
0.346
0.746
0.817
0.707
0.726
0.606
Table 4: Impact of using different EEG encoders or generative framework on the reconstruction performance. The results are averaged over all subjects.
Figure 4: Intermediate reconstructions generated by AVDE across 10 progressive scales. Each row corresponds to a distinct EEG-evoked reconstruction instance, and each column represents the cumulative output up to a given scale. This process reflects the hierarchical nature of human visual perception, drawing parallels to the function of successive cortical visual areas (e.g., V1, V2/V4, and IT).
Figure 5: Analysis of similarities between intermediate scales and brain regions. (a) The mean channel embeddings from five brain regions are compared with the intermediate image embeddings. Cosine similarity is used as the measure. (b) Since the generative process is cumulative, the similarities generally increase as more scales are involved. (c) Stepwise increase captures the incremental information contributed by each scale. The step increase for occipital regions peaks at early scales and gradually diminishes thereafter. The temporal and parietal regions exhibit relatively sustained step increases across early and middle scales, followed by a decline in later scales. The frontal and central regions show low step increases initially, which progressively rise and peak at late scales.
Appendix figures & tables13 assets
Supplementary material from the paper’s appendix.
Appendix
Hyperparameters
Values
Temporal Encoder
Iput channels
{1,8,8}
Output channels
{8,8,8}
Kernel size
{15,3,3}
Stride
{8,1,1}
Padding
{7,1,1}
Transformer encoder layers
12
Appendix
Table 5: Hyperparameters for the LaBraM-based EEG encoder.
Hyperparameters
Values
Number of layers
16
Hidden size
1024
MLP size
4096
Number of heads
16
Number of scales/steps
10
Size of scales
(1, 2, 3, 4, 5, 6, 8, 10, 13, 16)
Appendix
Table 6: Hyperparameters for the visual autoregressive transformer.
Subject
Low-level
High-level
PixCorr ↑
SSIM ↑
AlexNet(2) ↑
AlexNet(5) ↑
Inception ↑
CLIP ↑
SwAV ↓
Sub-01
0.106
0.283
0.577
0.664
0.556
0.539
0.626
Sub-02
0.096
0.277
0.564
0.643
0.547
0.527
0.639
Sub-03
0.095
0.264
0.541
0.617
0.525
0.501
0.651
Sub-04
0.080
0.249
0.505
0.578
0.480
0.479
0.677
Sub-05
0.086
0.253
0.528
0.592
0.504
0.482
0.664
Appendix
Table 8: Quantitative assessments of EEG-based visual reconstruction quality on EEG-ImageNet.
Table 9: Reconstruction quality on EEG-ImageNet with baselines.
Table 11: Reconstruction quality on THINGS-MEG with baselines.
Subject
Low-level
High-level
PixCorr ↑
SSIM ↑
AlexNet(2) ↑
AlexNet(5) ↑
Inception ↑
CLIP ↑
SwAV ↓
Sub-01
0.138
0.362
0.750
0.837
0.725
0.721
0.609
Sub-02
0.120
0.388
0.754
0.811
0.710
0.737
0.604
Sub-03
0.168
0.379
0.763
0.827
0.704
0.746
0.603
Sub-04
0.126
0.361
0.748
0.835
0.731
0.765
0.593
Sub-05
0.145
0.373
0.743
0.814
0.691
0.732
0.586
Appendix
Table 13: Quantitative assessments of EEG-based visual reconstruction quality on all subjects.
Table 14: Reconstruction quality on THINGS-EEG with baselines.
Figure 6: Subject-08’s Best, Medium, and Worst reconstructions selected based on PixCorr.
Figure 7: Subject-08’s Best, Medium, and Worst reconstructions selected based on SwAV.
Figure 8: Subject-10’s Best, Medium, and Worst reconstructions selected based on PixCorr.
Figure 9: Subject-10’s Best, Medium, and Worst reconstructions selected based on SwAV.
Figure 10: Subject-03’s Best, Medium, and Worst reconstructions selected based on PixCorr.
Figure 11: Subject-03’s Best, Medium, and Worst reconstructions selected based on SwAV.
Department of Automation Tsinghua University Haidian District, 100084, Beijing, China · China Academy of Information and Communications Technology Haidian District, 100084, Beijing, China