In recent years, electroencephalography (EEG)-based visual decoding research has become a key direction for revealing brain processing mechanisms and realizing brain-computer interfaces. This emerging field has attracted extensive attention in the fields of brain science, cognitive neuroscience, and artificial intelligence. Among various approaches, contrastive learning has demonstrated strong performance in aligning multi-modal data, effectively enabling unified representations across modalities. However, during human visual perception, images are often subject to varying degrees of blurring due to the uneven distribution of retinal photoreceptor cells and the limited speed of lens accommodation. To address the mismatch between EEG and visual representations, we propose a novel visual decoding framework inspired by human perceptual blurring. Specifically, multi-level Gaussian blurring is applied to the visual stimuli to simulate human visual characteristics, followed by a feature selection module to construct robust visual representations. For EEG decoding, we design a lightweight and efficient network employing positively constrained spatial convolutions to identify channels associated with visual processing. The EEG and visual features are then aligned using contrastive learning. We evaluate the proposed framework on the Things-EEG dataset. Experimental results show significant improvements in the zero-shot brain-to-image retrieval task, achieving a top-1 accuracy of 80% and a top-5 accuracy of 96.9%, surpassing previous state-of-the-art methods by margins of 29.1% and 17.2%, respectively. These findings highlight the potential of incorporating perceptual properties into EEG-based visual decoding.

Electroencephalography (EEG), a technique that uses electrodes on the scalp to record changes in cerebral electrical potentials, plays a key role in various brain-computer interface applications. However, due to the large differences in EEG distribution across subjects, how to accurately classify cross-subject EEG is still a challenge. In practice, it is unavoidable to collect data for each subject to perform calibration, which is cumbersome and expensive. In this paper, we propose a Cross Subject EEG Prototypical Network (CS-EEGPNet) for accurate few-shot EEG classification. To the best of our knowledge, we are the first to eliminate inter-subject distribution shift in few-shot EEG classification through multiple feature layers computation. Specifically, to avoid the effect of individual differences, we propose a few-shot feature normalization (FSFN) method, which uses the mean and variance of the same subject’s support set features to normalize the query set features. Meanwhile, we design a prototypical module based on auxiliary factors. This module utilizes learnable vectors to store category-related information for assisting the construction of prototypes, thus mitigating the effects of EEG’s randomness and non-stationary characteristics on cross-subject few shot classification. To validate the effectiveness of the method, we selecte the motor imagery paradigm, which is relatively complex in brain-computer interfaces, and test our method on the BCIC IV 2a and HGD datasets. The results demonstrate that our method significantly enhances EEG classification performance, achieving the state-of-the-art accuracies.

Micro-expressions (MEs) are involuntary and quickly displayed facial expressions that reveal subtle psychological activities. Most previous research typically focused on two separate tasks: micro-expression spotting and recognition. We aim to propose a high-precision "spotting+recognition" method that can spot ME intervals from long videos and recognize their emotional categories. Due to the occurrence sparsity of MEs, there is a significant imbalance between the number of micro-expression intervals and non-micro-expression intervals in long videos. This imbalance makes it challenging for models trained using conventional strategies to distinguish true MEs from noise samples caused by head movements, blinking, and macro-expressions, resulting in a high false-positive-rate and reducing the overall performance. We reduce the number of smooth segments to alter the data distribution within the non-micro-expression (non-ME) category. This adjustment enables the model to focus more on the subtle differences between noise samples and ME samples. To achieve this, we design an ingenious training data preparation strategy: using false positive samples from the initial spotting results as non-ME category samples, and using true positive and false negative samples from the initial spotting as emotion category samples. These are combined as the training data, creating a recognition model capable of both emotion classification and non-ME category determination. Additionally, we propose a three-stage micro-expression analysis method, including ME spotting, ME recognition and non-ME intervals removal module. Our method is validated through five-fold cross-validation experiments on the CAS(ME)² and SAMM Long Video datasets, achieving a overall STRS metric of 0.16, which significantly outperformed baseline methods and demonstrated the effectiveness of our approach.

Electroencephalography (EEG) is crucial for recording brain activity, with applications in medicine, neuroscience, and brain-computer interfaces (BCI). However, challenges such as low signal-to-noise ratio (SNR), high inter-subject variability, and channel mismatch complicate the extraction of robust, universal EEG representations. We propose EEGPT, a novel 10-million-parameter pretrained transformer model designed for universal EEG feature extraction. In EEGPT, a mask-based dual self-supervised learning method for efficient feature extraction is designed. Compared to other mask-based self-supervised learning methods, EEGPT introduces spatio-temporal representation alignment. This involves constructing a self-supervised task based on EEG representations that possess high SNR and rich semantic information, rather than on raw signals. Consequently, this approach mitigates the issue of poor feature quality typically extracted from low SNR signals. Additionally, EEGPT's hierarchical structure processes spatial and temporal information separately, reducing computational complexity while increasing flexibility and adaptability for BCI applications. By training on a large mixed multi-task EEG dataset, we fully exploit EEGPT's capabilities. The experiment validates the efficacy and scalability of EEGPT, achieving state-of-the-art performance on a range of downstream tasks with linear-probing. Our research advances EEG representation learning, offering innovative solutions for bio-signal processing and AI applications. The code for this paper is available at: https://github.com/BINE022/EEGPT