An official website of the United States government
Brain-computer interface (BCI) actively translates the brain signals into executable actions by establishing direct communication between the human brain and external devices. Recording brain activity through electroencephalography (EEG) is generally contaminated with both physiological and nonphysiological artifacts, which significantly hinders the BCI performance. Artifact subspace reconstruction (ASR) is a well-known statistical technique that automatically removes artifact components by determining the rejection threshold based on the initial reference EEG segment in multichannel EEG recordings. In real-world applications, the fixed threshold may limit the efficacy of the artifact correction, especially when the quality of the reference data is poor. This study proposes an adaptive online ASR technique by integrating the Hebbian/anti-Hebbian neural networks into the ASR algorithm, namely, principle subspace projection ASR (PSP-ASR) and principal subspace whitening ASR (PSW-ASR) that segmentwise self-organize the artifact subspace by updating the synaptic weights according to the Hebbian and anti-Hebbian learning rules. The effectiveness of the proposed algorithm is compared to the conventional ASR approaches on benchmark EEG dataset and three BCI frameworks, including steady-state visual evoked potential (SSVEP), rapid serial visual presentation (RSVP), and motor imagery (MI) by evaluating the root-mean-square error (RMSE), the signal-to-noise ratio (SNR), the Pearson correlation, and classification accuracy. The results demonstrated that the PSW-ASR algorithm effectively removed the EEG artifacts and retained the activity-specific brain signals compared to the PSP-ASR, standard ASR (Init-ASR), and moving-window ASR (MW-ASR) methods, thereby enhancing the SSVEP, RSVP, and MI BCI performances. Finally, our empirical results from the PSW-ASR algorithm suggested the choice of an aggressive cutoff range of c = 1-10 for activity-specific BCI applications and a moderate range of for the benchmark dataset and general BCI applications.
more »
« less
This content will become publicly available on July 1, 2026
Towards Analysis of Covariance Descriptors via Bures–Wasserstein Distance
A brain–computer interface (BCI) provides a direct communication pathway between the human brain and external devices, enabling users to control them through thought. It records brain signals and classifies them into specific commands for external devices. Among various classifiers used in BCI, those directly classifying covariance matrices using Riemannian geometry find broad applications not only in BCI, but also in diverse fields such as computer vision, natural language processing, domain adaption, and remote sensing. However, the existing Riemannian-based methods exhibit limitations, including time-intensive computations, susceptibility to disturbances, and convergence challenges in scenarios involving high-dimensional matrices. In this paper, we tackle these issues by introducing the Bures–Wasserstein (BW) distance for covariance matrices analysis and demonstrating its advantages in BCI applications. Both theoretical and computational aspects of BW distance are investigated, along with algorithms for Fréchet Mean (or barycenter) estimation using BW distance. Extensive simulations are conducted to evaluate the effectiveness, efficiency, and robustness of the BW distance and barycenter. Additionally, by integrating BW barycenter into the Minimum Distance to Riemannian Mean classifier, we showcase its superior classification performance through evaluations on five real datasets.
more »
« less
- Award ID(s):
- 2153492
- PAR ID:
- 10612444
- Publisher / Repository:
- MDPI
- Date Published:
- Journal Name:
- Mathematics
- Volume:
- 13
- Issue:
- 13
- ISSN:
- 2227-7390
- Page Range / eLocation ID:
- 2157
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
We present a method for computing an approximate Rieman-nian barycenter of a collection of points lying on a Riemannian mani-fold. Our approach relies on the use of theoretically proven under- and over-approximations of the Riemannian distance function. We compare it to Riemannian steepest descent on the exact objective function of the Riemannian barycenter and to an approach that approximates the Rie-mannian logarithm using lifting maps. Experiments are conducted on the Stiefel manifold.more » « less
-
Neural networks (NN) has been adopted by brain-computer interfaces (BCI) to encode brain signals acquired using electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS). However, it has been found that NN models are vulnerable to adversarial examples, i.e., corrupted samples with imperceptible noise. Once attacked, it could impact medical diagnosis and patients’ quality of life. While early work focuses on interference using external devices at the time of signal acquisition, recent research shifts to collected signals, features, and learning models under various attack modes (e.g., white-, grey-, and black-box). However, existing work only considers single-modality attacks and ignores the topological relationships among different observations, e.g., samples having strong similarities. Different from previous approaches, we introduce graph neural networks (GNN) to multimodal BCI-based classification and explore its performance and robustness against adversarial attacks. This study will evaluate the robustness of NN models with and without graph knowledge on both single and multimodal data.more » « less
-
Abstract Modern data collection often entails longitudinal repeated measurements that assume values on a Riemannian manifold. Analyzing such longitudinal Riemannian data is challenging, because of both the sparsity of the observations and the nonlinear manifold constraint. Addressing this challenge, we propose an intrinsic functional principal component analysis for longitudinal Riemannian data. Information is pooled across subjects by estimating the mean curve with local Fréchet regression and smoothing the covariance structure of the linearized data on tangent spaces around the mean. Dimension reduction and imputation of the manifold‐valued trajectories are achieved by utilizing the leading principal components and applying best linear unbiased prediction. We show that the proposed mean and covariance function estimates achieve state‐of‐the‐art convergence rates. For illustration, we study the development of brain connectivity in a longitudinal cohort of Alzheimer's disease and normal participants by modeling the connectivity on the manifold of symmetric positive definite matrices with the affine‐invariant metric. In a second illustration for irregularly recorded longitudinal emotion compositional data for unemployed workers, we show that the proposed method leads to nicely interpretable eigenfunctions and principal component scores. Data used in preparation of this article were obtained from the Alzheimer's Disease Neuroimaging Initiative database.more » « less
-
The past four years have seen major advances in the field of brain–computer interfaces (BCIs) (also known as brain–machine interfaces or BMIs). The journal Brain–Computer Interfaces published its first issue in January 2014. The Brain–Computer Interface Society was founded in 2015. And the number of BCI articles in journals continued to increase; these studies explore a broad range of BCIs that replace, restore, enhance, supplement, or improve natural brain outputs or that are used in other scientific research. The new BCI Society organized the Sixth International Brain–Computer Interface Meeting, held 30 May–3 June 2016 at the Asilomar Conference Center in Pacific Grove, California, USA. Papers resulting from that Meeting appear in this special issue. A subscription to the BCI journal will now be a benefit for BCI Society members.more » « less
