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Dezhong Yao

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44 papers
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44

EAAI Journal 2026 Journal Article

A consistency-driven pseudo-labeling framework for robust functional connectivity modeling in neuropsychiatric disorder diagnosis

  • Xin Wen
  • Shijie Guo
  • Li Dong
  • Xiaobo Liu
  • Wenbo Ning
  • Jie Shi
  • Songhua Liu
  • Cheng Luo

The incidence of neuropsychiatric disorders such as Autism Spectrum Disorder (ASD), Attention Deficit Hyperactivity Disorder (ADHD), and Major Depressive Disorder (MDD) continues to rise. Deep learning-based computer-aided diagnosis (CAD) has emerged as a promising approach to alleviate the increasing burden on neuroimaging-based clinical resources. However, neuroimaging modalities such as functional magnetic resonance imaging (fMRI) involve complex spatiotemporal characteristics, making their representations susceptible to various types of noise and interference, which in turn hampers the effectiveness of CAD. To address this challenge, we propose a pseudo-label consistency-driven framework for functional connectivity (FC) reconstruction and discriminative modeling (PL-FCDM), aiming to enhance both the representational quality and discriminative power of FC features. Specifically, two complementary pseudo-labeling models are developed to independently capture discriminative features from the temporal domain (time series) and spatial domain (dynamic functional connectivity), enabling pseudo label prediction from distinct modalities. Then a consistency-based filtering strategy is applied to construct high-confidence reconstructed functional connectivity. These graphs are subsequently fed into a classification model comprising a Feature Optimization Autoencoder and a Depthwise Separable Convolutional Neural Network for efficient identification of neuropsychiatric disorders. Extensive experiments conducted on four publicly available multi-site datasets—ABIDE I, ABIDE II, ADHD-200, and REST-meta-MDD demonstrate that the proposed method achieves classification accuracies of 76. 14%, 74. 37%, 72. 89%, and 71. 15%, respectively. These results consistently outperform several state-of-the-art approaches, validating the effectiveness and robustness of the proposed framework in feature refinement and multi-disorder recognition.

JBHI Journal 2026 Journal Article

Nonparametric Dynamic Granger Causality based on Multi-Space Spectrum Fusion for Time-varying Directed Brain Network Construction

  • Chanlin Yi
  • Jiamin Zhang
  • Zihan Weng
  • Wanjun Chen
  • Dezhong Yao
  • Fali Li
  • Zehong Cao
  • Peiyang Li

Nonparametric estimation of time-varying directed networks can unveil the intricate transient organization of directed brain communication while circumventing constraints imposed by prescribed model driven methods. A robust time-frequency representation – the foundation of its causality inference – is critical for enhancing its reliability. This study proposed a novel method, i. e. , nonparametric dynamic Granger causality based on Multi-space Spectrum Fusion (ndGCMSF), which integrates complementary spectrum information from different spaces to generate enhanced spectral representations to estimate dynamic causalities across brain regions. Systematic simulations and validations demonstrate that ndGCMSF exhibits superior noise resistance and a powerful ability to capture subtle dynamic changes in directed brain networks. Particularly, ndGCMSF revealed that during motor imagery, the laterality in the hemisphere ipsilateral to the hemiplegic limb emerges upon task beginning and diminishes upon task accomplishment. These intrinsic variations further provide features for assessing motor functions. The ndGCMSF offers powerful functional patterns to derive effective brain networks in dynamically changing operational settings and contributes to extensive areas involving dynamical and directed communications.

YNIMG Journal 2026 Journal Article

System-Level Reconfiguration of the Aging Brain: Linking Dynamics, Morphology and Micro-architectures

  • Liming Fan
  • Youjun Li
  • Yutong Wu
  • Simeng An
  • Nan Yao
  • Qian Zhu
  • Yueye Zhao
  • Daqing Guo

Healthy aging involves complex neural reconfigurations across both structural and functional domains. While resting-state functional magnetic resonance imaging (rs-fMRI) has linked static functional connectivity alterations to aging, the whole-brain dynamics of functional activity and their covariance with structural changes remain poorly characterized. To address this gap, we integrated three data-driven approaches to profile functional dynamics in the aging brain and decode their association with structural atrophy. Using rs-fMRI data from 252 participants-145 young adults (22.7 ± 3.4 years) and 107 older adults (68.7 ± 6.5 years)-we made several key observations. First, normalized Shannon entropy revealed a significant reduction in spatiotemporal complexity among older individuals. Second, phase synchronization analysis of BOLD signals indicated enhanced global integration and metastability in older adults, particularly within the dorsal attention (DAN), ventral attention (VAN), and frontoparietal networks (FPN). Third, temporal asymmetry analysis demonstrated increased nonreversibility and a heightened functional hierarchy in the aging brain, again most evident in the FPN. Morphometric analyses confirmed widespread structural atrophy in older participants. Crucially, partial least squares (PLS) analysis uncovered significant covariance between morphometric patterns and dynamic functional metrics, underscoring a tight structure-dynamics coupling in aging. Furthermore, structural atrophy correlated significantly with variations in micro-architecture maps. Finally, we evaluated the behavioral relevance of these dynamics through correlations with cognitive performance. Our findings offer an integrative, multiscale perspective on neural decline in aging, emphasizing the interplay between dynamic functional reorganization and structural atrophy.

YNIMG Journal 2026 Journal Article

Unlocking interbrain neural signatures differences during triadic cooperation and competition: Evidence from EEG hyperscanning

  • Yuqin Li
  • Senqi Li
  • Jiaxin Xie
  • Dezhong Yao
  • Fali Li
  • Peng Xu
  • Jintao Wu
  • Lin Jiang

Cooperation and competition are fundamental to human social interaction. While recent hyperscanning studies have linked stronger interbrain synchrony (IBS) to successful cooperation, most have focused on dyadic interactions, leaving the underlying neural mechanisms of group-level social behavior largely unknown. Here, we employed EEG hyperscanning to investigate interbrain neural dynamics of triadic cooperative and competitive interactions. Distinct interbrain network patterns emerged in the delta and beta bands, with cooperation showing enhanced frontal-parietal IBS and more efficient network properties. Non-parametric cluster-based permutation tests further identified significant regional differences in a left-lateralized frontal-temporal-parietal cluster in both bands. Crucially, increased delta-band frontal-parietal IBS was closely associated with better group-level cooperative performance. Moreover, classification and prediction models based on delta-band interbrain metrics successfully distinguished interaction types and predicted cooperative outcomes. These findings uncover interbrain neurocognitive traits that reflect specific social behavioral contexts, highlighting the pivotal role of frontal-parietal synchrony and delta-band modulations in supporting group cooperation. Together, our results advance the understanding of the neural basis of triadic social interaction and underscore the potential of interbrain network signatures as biomarkers for decoding and predicting complex social behaviors.

TAAS Journal 2025 Journal Article

AdapCP: Collaborative Inference with Adaptive CNN Partition on Distributed Edge Servers

  • Sifan Zhao
  • Dezhong Yao
  • Yao Wan
  • Gang Wu
  • Hai Jin

Due to the limited resources of end devices, the task of Convolutional Neural Network (CNN) inference on the end-side is moving towards edge-end collaboration. However, existing collaborative methods mainly focus on offloading CNN inference tasks from end devices to a single-edge server, which leads to inefficient use of computational resources among nearby edge servers. Moreover, offloading the CNN inference task to a single third-party server may raise privacy concerns. To address these challenges, we propose a framework named AdapCP that introduces a collaborative and adaptive parallel acceleration strategy that utilizes the end device and multiple edge servers. AdapCP consists of two stages: (1) offloading to nearby servers and (2) parallel processing of the CNN inference. For the offloading phase, we use integer linear programming to find the partition points at the inter-layer level. For the parallel phase, we first investigate intra-layer structural splitting methods tailored for both convolutional and fully connected layers. Then, we employ a Deep Deterministic Policy Gradient (DDPG) algorithm based on the Dirichlet distribution to decide the partition points. Finally, we set a periodic update index to enhance AdapCP’s adaptability to dynamic environments. Empirical evaluations conducted on the Jetson nano demonstrate that AdapCP significantly reduces the total latency of CNN inference by an average factor of 2.21 \(\times\) compared to existing solutions.

JBHI Journal 2025 Journal Article

Addressing Multiple Challenges in Early Gait Freezing Prediction for Parkinson's Disease: A Practical Deep Learning Approach

  • Wenan Wang
  • Jingfeng Lin
  • Xinning Le
  • Yaru Li
  • Tao Liu
  • Lunxin Pan
  • Min Li
  • Dezhong Yao

Objective: Freezing of Gait (FOG) significantly impacts daily activities of Parkinson's disease (PD) patients. Despite the potential of wearable sensors in predicting FOG, challenges persist, including the brief prediction interval before FOG onset, limited generalization across patients, and the inconvenience of multiple sensors. Addressing one issue often aggravates others, making it difficult to achieve suitable concurrent solutions to all these challenges. Methods: We introduce the PhysioGait Predictive Network (PhysioGPN), a deep learning framework designed to predict FOG events in PD patients at least 2 seconds prior to onset. The model architecture incorporates four key strategies: 1) Detection of progressive motion changes using large convolutional kernels; 2) Unraveling the complexity of motion coordination and gait dynamics using multi-dimensional and multi-scale convolution; 3) Capture gait self-similarity and asymmetry with twin-tower structure; 4) Promoting cross-domain information exchange with multi-domain attention. Furthermore, we propose a framework based on knowledge distillation (KD), reducing the model's dependence on multiple sensors while maintaining prediction accuracy. Results: The model achieves an 85. 8% Area Under the Curve (AUC) in FOG prediction. When reducing the number of sensors, KD mitigates the decline in performance and increases the AUC by 5. 1%, compared to scenarios without KD. Conclusion: Our research proposes a practical solution to the challenges of FOG prediction, demonstrating the effectiveness of the KD approach for lightweight wearable sensors in rehabilitation engineering. Significance: Our findings offer valuable insights for addressing multiple challenges in the practical application of wearable devices.

YNICL Journal 2025 Journal Article

Disturbed hierarchy and mediation in reward-related circuits in depression

  • Ruikun Yang
  • Junxia Chen
  • Suping Yue
  • Yue Yu
  • Jiamin Fan
  • Yuling Luo
  • Hui He
  • Mingjun Duan

BACKGROUNDS/OBJECTIVE: Deep brain stimulation (DBS) has proved the viability of alleviating depression symptoms by stimulating deep reward-related nuclei. This study aims to investigate the abnormal connectivity profiles among superficial, intermediate, and deep brain regions within the reward circuit in major depressive disorder (MDD) and therefore provides references for identifying potential superficial cortical targets for non-invasive neuromodulation. METHODS: Resting-state functional magnetic resonance imaging data were collected from a cohort of depression patients (N = 52) and demographically matched healthy controls (N = 60). Utilizing existing DBS targets as seeds, we conducted step-wise functional connectivity (sFC) analyses to delineate hierarchical pathways linking to cerebral cortices. Subsequently, the mediation effects of cortical regions on the interaction within reward-related circuits were further explored by constructing mediation models. RESULTS: In both cohorts, sFC analysis revealed two reward-related pathways from the deepest DBS targets to intermediate regions including the thalamus, insula, and anterior cingulate cortex (ACC), then to the superficial cortical cortex including medial frontal cortex, posterior default mode network (pDMN), and right dorsolateral prefrontal cortex (DLPFC). Patients exhibited reduced sFC in bilateral thalamus and medial frontal cortex in short and long steps respectively compared to healthy controls. We also discovered the disappearance of the mediation effects of superficial cortical regions on the interaction between DBS targets and intermediate regions in reward-related pathways in patients with MDD. CONCLUSION: Our findings support abnormal hierarchical connectivity and mediation effects in reward-related brain regions at different depth levels in MDD, which might elucidate the underlying pathophysiological mechanisms and inspire novel targets for non-invasive interventions.

YNIMG Journal 2025 Journal Article

Effects of antagonistic network-targeted tDCS on brain co-activation patterns depends on the networks’ electric field: a simultaneous tDCS-fMRI study

  • Hechun Li
  • Hongru Shi
  • Sisi Jiang
  • Changyue Hou
  • Haonan Pei
  • Hanxi Wu
  • María Luisa Bringas Vega
  • Gang Yao

BACKGROUND: Brain networks should be ideal targets for non-invasive brain stimulation, as network dysfunction is a common feature of various neuropsychiatric disorders. Understanding the mechanisms of network-targeted stimulation is essential for advancing its clinical applications. MATERIAL AND METHOD: The current study utilized simultaneous network-targeted transcranial direct current stimulation(tDCS) and functional magnetic resonance imaging (fMRI) to investigate the effects of tDCS targeting antagonistic networks on brain dynamics. A total of 143 healthy participants were recruited and assigned to receive central executive network (CEN)-targeted tDCS (C-targeted group), default mode network (DMN)-targeted tDCS (D-targeted group), or sham tDCS (sham group). fMRI data with three sections (pre-stimulation, during-stimulation, post-stimulation) were collected across all subjects. Individual electric field (EF) strength was simulated using individual head model. Six recurring brain patterns (co-activation patterns, CAPs) were identified. The temporal indices of these CAPs (occurrence, fraction time, persistence time) and their transition probabilities were calculated. This study first examined the effects of C-targeted / D-targeted / sham tDCS on temporal indices and further explored the contribution of brain networks' EF strength on the altered temporal indices. RESULTS: C-targeted tDCS significantly increased the temporal indices of CAPs dominated by DMN and the transition probabilities from other CAPs to DMN-dominated CAPs during stimulation. Meanwhile, the decreased temporal indices of CAP dominated by CEN, and its transition probabilities to these CAPs were also found during C-targeted tDCS. In contrast, the d-targeted tDCS had only a slight effect on brain dynamics, while sham tDCS showed no significant impact. Further fusion analyses revealed that the EF strength in the salience network made a large contribution to the temporal indices of CAPs during stimulation, highlighting tight interactions within the triple networks. Moreover, integrating the EF strength of networks with large contributions and the pre-stimulation temporal indices effectively predicted the temporal indices of CAPs during stimulation. These findings suggest that C-targeted tDCS can modulate brain dynamics and emphasize the critical role of networks' EF during stimulation. CONCLUSION: This study demonstrates the effectiveness and feasibility of network-targeted tDCS in modulating brain dynamics, providing a new choice for treating neuropsychiatric disorders characterized by aberrant brain dynamics.

YNIMG Journal 2025 Journal Article

ERP-based interbrain causal model reveals closed-loop information interaction in interpersonal negotiations

  • Yuqin Li
  • Genon Sarah
  • Chunli Chen
  • Lin Jiang
  • Baodan Chen
  • Rihui Li
  • Zhen Liang
  • Jing Yu

Uncovering the interbrain neural mechanisms underlying interpersonal negotiation offers insight into social decision-making dynamics in resource allocation. In this study, we used EEG hyperscanning alongside an iterated ultimatum game to investigate interbrain coupling and dyadic exchange behavior during negotiation. Frontal cortex event-related potentials (ERPs) revealed the distinct neural responses driven by partners' behavioral cues: the proposer's N200 differed significantly for fair versus unfair offers, and the responder's feedback-related negativity (FRN) showed a trend toward significance for the same contrast, while the proposer's N500 varied between acceptance and rejection feedback. Our analysis introduced a novel causal model based on directional phase transfer entropy (dPTE) and time-varying ERP amplitudes, illustrating directed neural processes driven by social exchange, where the proposer's brain activity initially exerts a causal impact on the responder's, whose feedback in turn influences the proposer, creating a closed-loop interaction that drives adaptive negotiation strategies. Additionally, our prediction model with autoregression with exogenous input, which incorporated these causal links between brains, demonstrated higher accuracy than single-brain or reverse causal models, underscoring the significance of dynamic interbrain coupling in interpersonal coordination. This causal model provides a mechanistic explanation of how proposer-responder pairs perceive and adapt to each other's decisions, facilitating shared attention and behavioral coordination in reciprocal, asymmetric negotiations. These findings offer a novel theoretical framework for studying complex social behaviors through interbrain dynamics and may inspire future applications in enhancing cooperative decision-making processes.

AIJ Journal 2025 Journal Article

FedHM: Efficient federated learning for heterogeneous models via low-rank factorization

  • Dezhong Yao
  • Wanning Pan
  • Yuexin Shi
  • Michael J. O'Neill
  • Yutong Dai
  • Yao Wan
  • Peilin Zhao
  • Hai Jin

One underlying assumption of recent Federated Learning (FL) paradigms is that all local models share an identical network architecture. However, this assumption is inefficient for heterogeneous systems where devices possess varying computation and communication capabilities. The presence of such heterogeneity among devices negatively impacts the scalability of FL and slows down the training process due to the existence of stragglers. To this end, this paper proposes a novel federated compression framework for heterogeneous models , named FedHM, distributing the heterogeneous low-rank models to clients and then aggregating them into a full-rank global model. Furthermore, FedHM significantly reduces communication costs by utilizing low-rank models. Compared with state-of-the-art heterogeneous FL methods under various FL settings, FedHM is superior in the performance and robustness of models with different sizes. Additionally, the convergence guarantee of FL for heterogeneous devices is first theoretically analyzed.

AAAI Conference 2025 Conference Paper

NumbOD: A Spatial-Frequency Fusion Attack Against Object Detectors

  • Ziqi Zhou
  • Bowen Li
  • Yufei Song
  • Zhifei Yu
  • Shengshan Hu
  • Wei Wan
  • Leo Yu Zhang
  • Dezhong Yao

With the advancement of deep learning, object detectors (ODs) with various architectures have achieved significant success in complex scenarios like autonomous driving. Previous adversarial attacks against ODs have been focused on designing customized attacks targeting their specific structures (eg, NMS and RPN), yielding some results but simultaneously constraining their scalability. Moreover, most efforts against ODs stem from image-level attacks originally designed for classification tasks, resulting in redundant computations and disturbances in object-irrelevant areas (eg, background). Consequently, how to design a model-agnostic efficient attack to comprehensively evaluate the vulnerabilities of ODs remains challenging and unresolved. In this paper, we propose NumbOD, a brand-new spatial-frequency fusion attack against various ODs, aimed at disrupting object detection within images. We directly leverage the features output by the OD without relying on its any internal structures to craft adversarial examples. Specifically, we first design a dual-track attack target selection strategy to select high-quality bounding boxes from OD outputs for targeting. Subsequently, we employ directional perturbations to shift and compress predicted boxes and change classification results to deceive ODs. Additionally, we focus on manipulating the high-frequency components of images to confuse ODs' attention on critical objects, thereby enhancing the attack efficiency. Our extensive experiments on nine ODs and two datasets show that NumbOD achieves powerful attack performance and high stealthiness.

YNIMG Journal 2025 Journal Article

Resting-state EEG network variability predicts individual working memory behavior

  • Chunli Chen
  • Shiyun Xu
  • Jixuan Zhou
  • Chanlin Yi
  • Liang Yu
  • Dezhong Yao
  • Yangsong Zhang
  • Fali Li

Even during periods of rest, the brain exhibits spontaneous activity that dynamically fluctuates across spatially distributed regions in a globally coordinated manner, which has significant cognitive implications. However, the relationship between the temporal variability of resting-state networks and working memory (WM) remains largely unexplored. This study aims to address this gap by employing an EEG-based protocol combined with fuzzy entropy. First, we identified both flexible and robust patterns of dynamic resting-state networks. Subsequently, we observed a significant positive correlation between WM performance and network variability, particularly in connections associated with the frontal, right central, and right parietal lobes. Moreover, we found that the temporal variability of network properties was positively and significantly associated with WM performance. Additionally, distinct patterns of network variability were delineated, contributing to inter-individual differences in WM abilities, with these distinctions becoming more pronounced as task demands increased. Finally, using a multivariable predictive model based on these variability metrics, we effectively predicted individual WM performances. Notably, analogous analyses conducted in the source space validated the reproducibility of the temporal variability of resting-state networks in predicting individual WM behavior at higher spatial resolution, providing more precise anatomical localization of key brain regions. These results suggest that the temporal variability of resting-state networks reflects intrinsic dynamic changes in brain organization supporting WM and can serve as an objective predictor for individual WM behaviors.

NeurIPS Conference 2025 Conference Paper

Vanish into Thin Air: Cross-prompt Universal Adversarial Attacks for SAM2

  • Ziqi Zhou
  • Yifan Hu
  • Yufei Song
  • Zijing Li
  • Shengshan Hu
  • Leo Yu Zhang
  • Dezhong Yao
  • Long Zheng

Recent studies reveal the vulnerability of the image segmentation foundation model SAM to adversarial examples. Its successor, SAM2, has attracted significant attention due to its strong generalization capability in video segmentation. However, its robustness remains unexplored, and it is unclear whether existing attacks on SAM can be directly transferred to SAM2. In this paper, we first analyze the performance gap of existing attacks between SAM and SAM2 and highlight two key challenges arising from their architectural differences: directional guidance from the prompt and semantic entanglement across consecutive frames. To address these issues, we propose UAP-SAM2, the first cross-prompt universal adversarial attack against SAM2 driven by dual semantic deviation. For cross-prompt transferability, we begin by designing a target-scanning strategy that divides each frame into k regions, each randomly assigned a prompt, to reduce prompt dependency during optimization. For effectiveness, we design a dual semantic deviation framework that optimizes a UAP by distorting the semantics within the current frame and disrupting the semantic consistency across consecutive frames. Extensive experiments on six datasets across two segmentation tasks demonstrate the effectiveness of the proposed method for SAM2. The comparative results show that UAP-SAM2 significantly outperforms state-of-the-art (SOTA) attacks by a large margin.

JBHI Journal 2024 Journal Article

Automated Prediction of Infant Cognitive Development Risk by Video: A Pilot Study

  • Shengjie Ji
  • Dan Ma
  • Lunxin Pan
  • Wenan Wang
  • Xiaohang Peng
  • Joan Toluwani Amos
  • Honorine Niyigena Ingabire
  • Min Li

Objective: Cognition is an essential human function, and its development in infancy is crucial. Traditionally, pediatricians used clinical observation or medical imaging to assess infants’ current cognitive development (CD) status. The object of pediatricians’ greater concern is however their future outcomes, because high-risk infants can be identified early in life for intervention. However, this opportunity has not yet been realized. Fortunately, some recent studies have shown that the general movement (GM) performance of infants around 3–4 months after birth might reflect their future CD status, which gives us an opportunity to achieve this goal by cameras and artificial intelligence. Methods: First, infants’ GM videos were recorded by cameras, from which a series of features reflecting their bilateral movement symmetry (BMS) were extracted. Then, after at least eight months of natural growth, the infants’ CD status was evaluated by the Bayley Infant Development Scale, and they were divided into high-risk and low-risk groups. Finally, the BMS features extracted from the early recorded GM videos were fed into the classifiers, using late infant CD risk assessment as the prediction target. Results: The area under the curve, recall and precision values reached 0. 830, 0. 832, and 0. 823 for two-group classification, respectively. Conclusion: This pilot study demonstrates that it is possible to automatically predict the CD of infants around the age of one year based on their GMs recorded early in life. Significance: This study not only helps clinicians better understand infant CD mechanisms, but also provides an economical, portable and non-invasive way to screen infants at high-risk early to facilitate their recovery.

NeurIPS Conference 2024 Conference Paper

DarkSAM: Fooling Segment Anything Model to Segment Nothing

  • Ziqi Zhou
  • Yufei Song
  • Minghui Li
  • Shengshan Hu
  • Xianlong Wang
  • Leo Yu Zhang
  • Dezhong Yao
  • Hai Jin

Segment Anything Model (SAM) has recently gained much attention for its outstanding generalization to unseen data and tasks. Despite its promising prospect, the vulnerabilities of SAM, especially to universal adversarial perturbation (UAP) have not been thoroughly investigated yet. In this paper, we propose DarkSAM, the first prompt-free universal attack framework against SAM, including a semantic decoupling-based spatial attack and a texture distortion-based frequency attack. We first divide the output of SAM into foreground and background. Then, we design a shadow target strategy to obtain the semantic blueprint of the image as the attack target. DarkSAM is dedicated to fooling SAM by extracting and destroying crucial object features from images in both spatial and frequency domains. In the spatial domain, we disrupt the semantics of both the foreground and background in the image to confuse SAM. In the frequency domain, we further enhance the attack effectiveness by distorting the high-frequency components (i. e. , texture information) of the image. Consequently, with a single UAP, DarkSAM renders SAM incapable of segmenting objects across diverse images with varying prompts. Experimental results on four datasets for SAM and its two variant models demonstrate the powerful attack capability and transferability of DarkSAM. Our codes are available at: https: //github. com/CGCL-codes/DarkSAM.

JBHI Journal 2024 Journal Article

Nonparametric Dynamic Granger Causality based on Multi-Space Spectrum Fusion for Time-varying Directed Brain Network Construction

  • Chanlin Yi
  • Jiamin Zhang
  • Zihan Weng
  • Wanjun Chen
  • Dezhong Yao
  • Fali Li
  • Zehong Cao
  • Peiyang Li

Nonparametric estimation of time-varying directed networks can unveil the intricate transient organization of directed brain communication while circumventing constraints imposed by prescribed model-driven methods. A robust time-frequency representation – the foundation of its causality inference – is critical for enhancing its reliability. This study proposed a novel method, i. e. , nonparametric dynamic Granger causality based on Multi-space Spectrum Fusion (ndGCMSF), which integrates complementary spectrum information from different spaces to generate reliable spectral representations to estimate dynamic causalities across brain regions. Systematic simulations and validations demonstrate that ndGCMSF exhibits superior noise resistance and a powerful ability to capture subtle dynamic changes in directed brain networks. Particularly, ndGCMSF revealed that during instruction response movements, the laterality in the hemisphere ipsilateral to the hemiplegic limb emerges upon instruction onset and diminishes upon task accomplishment. These intrinsic variations further provide reliable features for distinguishing two types of hemiplegia (left vs. right) and assessing motor functions. The ndGCMSF offers powerful functional patterns to derive effective brain networks in dynamically changing operational settings and contributes to extensive areas involving dynamical and directed communications.

AAAI Conference 2024 Conference Paper

Revisiting Gradient Pruning: A Dual Realization for Defending against Gradient Attacks

  • Lulu Xue
  • Shengshan Hu
  • Ruizhi Zhao
  • Leo Yu Zhang
  • Shengqing Hu
  • Lichao Sun
  • Dezhong Yao

Collaborative learning (CL) is a distributed learning framework that aims to protect user privacy by allowing users to jointly train a model by sharing their gradient updates only. However, gradient inversion attacks (GIAs), which recover users' training data from shared gradients, impose severe privacy threats to CL. Existing defense methods adopt different techniques, e.g., differential privacy, cryptography, and perturbation defenses, to defend against the GIAs. Nevertheless, all current defense methods suffer from a poor trade-off between privacy, utility, and efficiency. To mitigate the weaknesses of existing solutions, we propose a novel defense method, Dual Gradient Pruning (DGP), based on gradient pruning, which can improve communication efficiency while preserving the utility and privacy of CL. Specifically, DGP slightly changes gradient pruning with a stronger privacy guarantee. And DGP can also significantly improve communication efficiency with a theoretical analysis of its convergence and generalization. Our extensive experiments show that DGP can effectively defend against the most powerful GIAs and reduce the communication cost without sacrificing the model's utility.

YNIMG Journal 2024 Journal Article

Structural and functional alterations in MRI-negative drug-resistant epilepsy and associated gene expression features

  • Ting Liu
  • Sheng Wang
  • Yingjie Tang
  • Sisi Jiang
  • Huixia Lin
  • Fei Li
  • Dezhong Yao
  • Xian Zhu

Neuroimaging techniques have been widely used in the study of epilepsy. However, structural and functional changes in the MRI-negative drug-resistant epilepsy (DRE) and the genetic mechanisms behind the structural alterations remain poorly understood. Using structural and functional MRI, we analyzed gray matter volume (GMV) and regional homogeneity (ReHo) in DRE, drug-sensitive epilepsy (DSE) and healthy controls. Gene expression data from Allen human brain atlas and GMV/ReHo were evaluated to obtain drug resistance-related and epilepsy-associated gene expression and compared with real transcriptional data in blood. We found structural and functional alterations in the cerebellum of DRE patients, which may be related to the mechanisms of drug resistance in DRE. Our study confirms that changes in brain morphology and regional activity in DRE patients may be associated with abnormal gene expression related to nervous system development. And SP1, as an important transcription factor, plays an important role in the mechanism of drug resistance.

YNIMG Journal 2023 Journal Article

Information transmission velocity-based dynamic hierarchical brain networks

  • Lin Jiang
  • Fali Li
  • Zhaojin Chen
  • Bin Zhu
  • Chanlin Yi
  • Yuqin Li
  • Tao Zhang
  • Yueheng Peng

The brain functions as an accurate circuit that regulates information to be sequentially propagated and processed in a hierarchical manner. However, it is still unknown how the brain is hierarchically organized and how information is dynamically propagated during high-level cognition. In this study, we developed a new scheme for quantifying the information transmission velocity (ITV) by combining electroencephalogram (EEG) and diffusion tensor imaging (DTI), and then mapped the cortical ITV network (ITVN) to explore the information transmission mechanism of the human brain. The application in MRI-EEG data of P300 revealed bottom-up and top-down ITVN interactions subserving P300 generation, which was comprised of four hierarchical modules. Among these four modules, information exchange between visual- and attention-activated regions occurred at a high velocity, related cognitive processes could thus be efficiently accomplished due to the heavy myelination of these regions. Moreover, inter-individual variability in P300 was probed to be attributed to the difference in information transmission efficiency of the brain, which may provide new insight into the cognitive degenerations in clinical neurodegenerative disorders, such as Alzheimer's disease, from the transmission velocity perspective. Together, these findings confirm the capacity of ITV to effectively determine the efficiency of information propagation in the brain.

TIST Journal 2022 Journal Article

FedBERT: When Federated Learning Meets Pre-training

  • Yuanyishu Tian
  • Yao Wan
  • Lingjuan Lyu
  • Dezhong Yao
  • Hai Jin
  • Lichao Sun

The fast growth of pre-trained models (PTMs) has brought natural language processing to a new era, which has become a dominant technique for various natural language processing (NLP) applications. Every user can download the weights of PTMs, then fine-tune the weights for a task on the local side. However, the pre-training of a model relies heavily on accessing a large-scale of training data and requires a vast amount of computing resources. These strict requirements make it impossible for any single client to pre-train such a model. To grant clients with limited computing capability to participate in pre-training a large model, we propose a new learning approach, FedBERT, that takes advantage of the federated learning and split learning approaches, resorting to pre-training BERT in a federated way. FedBERT can prevent sharing the raw data information and obtain excellent performance. Extensive experiments on seven GLUE tasks demonstrate that FedBERT can maintain its effectiveness without communicating to the sensitive local data of clients.

YNIMG Journal 2022 Journal Article

Harmonized-Multinational qEEG norms (HarMNqEEG)

  • Min Li
  • Ying Wang
  • Carlos Lopez-Naranjo
  • Shiang Hu
  • Ronaldo César García Reyes
  • Deirel Paz-Linares
  • Ariosky Areces-Gonzalez
  • Aini Ismafairus Abd Hamid

This paper extends frequency domain quantitative electroencephalography (qEEG) methods pursuing higher sensitivity to detect Brain Developmental Disorders. Prior qEEG work lacked integration of cross-spectral information omitting important functional connectivity descriptors. Lack of geographical diversity precluded accounting for site-specific variance, increasing qEEG nuisance variance. We ameliorate these weaknesses. (i) Create lifespan Riemannian multinational qEEG norms for cross-spectral tensors. These norms result from the HarMNqEEG project fostered by the Global Brain Consortium. We calculate the norms with data from 9 countries, 12 devices, and 14 studies, including 1564 subjects. Instead of raw data, only anonymized metadata and EEG cross-spectral tensors were shared. After visual and automatic quality control, developmental equations for the mean and standard deviation of qEEG traditional and Riemannian DPs were calculated using additive mixed-effects models. We demonstrate qEEG "batch effects" and provide methods to calculate harmonized z-scores. (ii) We also show that harmonized Riemannian norms produce z-scores with increased diagnostic accuracy predicting brain dysfunction produced by malnutrition in the first year of life and detecting COVID induced brain dysfunction. (iii) We offer open code and data to calculate different individual z-scores from the HarMNqEEG dataset. These results contribute to developing bias-free, low-cost neuroimaging technologies applicable in various health settings.

YNICL Journal 2022 Journal Article

Linking cerebellar functional gradients to transdiagnostic behavioral dimensions of psychopathology

  • Debo Dong
  • Xavier Guell
  • Sarah Genon
  • Yulin Wang
  • Ji Chen
  • Simon B. Eickhoff
  • Dezhong Yao
  • Cheng Luo

High co-morbidity and substantial overlap across psychiatric disorders encourage a transition in psychiatry research from categorical to dimensional approaches that integrate neuroscience and psychopathology. Converging evidence suggests that the cerebellum is involved in a wide range of cognitive functions and mental disorders. An important question thus centers on the extent to which cerebellar function can be linked to transdiagnostic dimensions of psychopathology. To address this question, we used a multivariate data-driven statistical technique (partial least squares) to identify latent dimensions linking human cerebellar connectome as assessed by functional MRI to a large set of clinical, cognitive, and trait measures across 198 participants, including healthy controls (n = 92) as well as patients diagnosed with attention-deficit/hyperactivity disorder (n = 35), bipolar disorder (n = 36), and schizophrenia (n = 35). Macroscale spatial gradients of connectivity at voxel level were used to characterize cerebellar connectome properties, which provide a low-dimensional representation of cerebellar connectivity, i.e., a sensorimotor-supramodal hierarchical organization. This multivariate analysis revealed significant correlated patterns of cerebellar connectivity gradients and behavioral measures that could be represented into four latent dimensions: general psychopathology, impulsivity and mood, internalizing symptoms and executive dysfunction. Each dimension was associated with a unique spatial pattern of cerebellar connectivity gradients across all participants. Multiple control analyses and 10-fold cross-validation confirmed the robustness and generalizability of the yielded four dimensions. These findings highlight the relevance of cerebellar connectivity as a necessity for the study and classification of transdiagnostic dimensions of psychopathology and call on researcher to pay more attention to the role of cerebellum in the dimensions of psychopathology, not just within the cerebral cortex.

YNIMG Journal 2021 Journal Article

Computational exploration of dynamic mechanisms of steady state visual evoked potentials at the whole brain level

  • Ge Zhang
  • Yan Cui
  • Yangsong Zhang
  • Hefei Cao
  • Guanyu Zhou
  • Haifeng Shu
  • Dezhong Yao
  • Yang Xia

Periodic visual stimulation can induce stable steady-state visual evoked potentials (SSVEPs) distributed in multiple brain regions and has potential applications in both neural engineering and cognitive neuroscience. However, the underlying dynamic mechanisms of SSVEPs at the whole-brain level are still not completely understood. Here, we addressed this issue by simulating the rich dynamics of SSVEPs with a large-scale brain model designed with constraints of neuroimaging data acquired from the human brain. By eliciting activity of the occipital areas using an external periodic stimulus, our model was capable of replicating both the spatial distributions and response features of SSVEPs that were observed in experiments. In particular, we confirmed that alpha-band (8–12 Hz) stimulation could evoke stronger SSVEP responses; this frequency sensitivity was due to nonlinear entrainment and resonance, and could be modulated by endogenous factors in the brain. Interestingly, the stimulus-evoked brain networks also exhibited significant superiority in topological properties near this frequency-sensitivity range, and stronger SSVEP responses were demonstrated to be supported by more efficient functional connectivity at the neural activity level. These findings not only provide insights into the mechanistic understanding of SSVEPs at the whole-brain level but also indicate a bright future for large-scale brain modeling in characterizing the complicated dynamics and functions of the brain.

YNIMG Journal 2021 Journal Article

State-independent and state-dependent patterns in the rat default mode network

  • Wei Jing
  • Yang Xia
  • Min Li
  • Yan Cui
  • Mingming Chen
  • Miaomiao Xue
  • Daqing Guo
  • Bharat B. Biswal

Resting-state studies have typically assumed constant functional connectivity (FC) between brain regions, and these parameters of interest provide meaningful descriptions of the functional organization of the brain. A number of studies have recently provided evidence pointing to dynamic FC fluctuations in the resting brain, especially in higher-order regions such as the default mode network (DMN). The neural activities underlying dynamic FC remain poorly understood. Here, we recorded electrophysiological signals from DMN regions in freely behaving rats. The dynamic FCs between signals within the DMN were estimated by the phase locking value (PLV) method with sliding time windows across vigilance states [quiet wakefulness (QW) and slow-wave and rapid eye movement sleep (SWS and REMS)]. Factor analysis was then performed to reveal the hidden patterns within the DMN. We identified distinct spatial FC patterns according to the similarities between their temporal dynamics. Interestingly, some of these patterns were vigilance state-dependent, while others were independent across states. The temporal contributions of these patterns fluctuated over time, and their interactive relationships were different across vigilance states. These spatial patterns with dynamic temporal contributions and combinations may offer a flexible framework for efficiently integrating information to support cognition and behavior. These findings provide novel insights into the dynamic functional organization of the rat DMN.

YNICL Journal 2021 Journal Article

Structural and functional reorganization of contralateral hippocampus after temporal lobe epilepsy surgery

  • Wei Li
  • Yuchao Jiang
  • Yingjie Qin
  • Baiwan Zhou
  • Du Lei
  • Heng Zhang
  • Ding Lei
  • Dezhong Yao

OBJECTIVE: To explore the structural and functional reorganization of contralateral hippocampus in patients with unilateral mesial temporal lobe epilepsy (mTLE) who achieved seizure-freedom after anterior temporal lobectomy (ATL). METHODS: We obtained high-resolution structural MRI and resting-state functional MRI data in 28 unilateral mTLE patients and 29 healthy controls. Patients were scanned before and three and 24 months after surgery while controls were scanned only once. Hippocampal gray matter volume (GMV) and functional connectivity (FC) were assessed. RESULTS: No obvious GMV changes were observed in contralateral hippocampus before and after successful surgery. Before surgery, ipsilateral hippocampus showed increased FC with ipsilateral insula (INS) and temporoparietal junction (TPJ), but decreased FC with widespread bilateral regions, as well as contralateral hippocampus. After successful ATL, contralateral hippocampus showed: (1) decreased FC with ipsilateral INS at three months follow-up, without further changes; (2) decreased FC with ipsilateral TPJ, postcentral gyrus and rolandic operculum at three months, with an obvious increase at 24 months follow-up; (3) increased FC with bilateral medial prefrontal cortex (MPFC) and superior frontal gyrus (SFG) at three months follow-up, without further changes. CONCLUSIONS: Successful ATL may not lead to an obvious structural reorganization in contralateral hippocampus. Surgical manipulation may lead to a transient FC reduction of contralateral hippocampus. Increased FC between contralateral hippocampus and bilateral MPFC and SFG may be related to postoperative functional remodeling.

YNIMG Journal 2021 Journal Article

WeBrain: A web-based brainformatics platform of computational ecosystem for EEG big data analysis

  • Li Dong
  • Jianfu Li
  • Qiunan Zou
  • Yufan Zhang
  • Lingling Zhao
  • Xin Wen
  • Jinnan Gong
  • Fali Li

The current evolution of 'cloud neuroscience' leads to more efforts with the large-scale EEG applications, by using EEG pipelines to handle the rapidly accumulating EEG data. However, there are a few specific cloud platforms that seek to address the cloud computational challenges of EEG big data analysis to benefit the EEG community. In response to the challenges, a WeBrain cloud platform (https://webrain.uestc.edu.cn/) is designed as a web-based brainformatics platform and computational ecosystem to enable large-scale EEG data storage, exploration and analysis using cloud high-performance computing (HPC) facilities. WeBrain connects researchers from different fields to EEG and multimodal tools that have become the norm in the field and the cloud processing power required to handle those large EEG datasets. This platform provides an easy-to-use system for novice users (even no computer programming skills) and provides satisfactory maintainability, sustainability and flexibility for IT administrators and tool developers. A range of resources are also available on https://webrain.uestc.edu.cn/, including documents, manuals, example datasets related to WeBrain, and collected links to open EEG datasets and tools. It is not necessary for users or administrators to install any software or system, and all that is needed is a modern web browser, which reduces the technical expertise required to use or manage WeBrain. The WeBrain platform is sponsored and driven by the China-Canada-Cuba international brain cooperation project (CCC-Axis, http://ccc-axis.org/), and we hope that WeBrain will be a promising cloud brainformatics platform for exploring brain information in large-scale EEG applications in the EEG community.

YNIMG Journal 2020 Journal Article

Inter-subject P300 variability relates to the efficiency of brain networks reconfigured from resting- to task-state: Evidence from a simultaneous event-related EEG-fMRI study

  • Fali Li
  • Qin Tao
  • Wenjing Peng
  • Tao Zhang
  • Yajing Si
  • Yangsong Zhang
  • Chanlin Yi
  • Bharat Biswal

The P300 event-related potential (ERP) varies across individuals, and exploring this variability deepens our knowledge of the event, and scope for its potential applications. Previous studies exploring the P300 have relied on either electroencephalography (EEG) or functional magnetic resonance imaging (fMRI). We applied simultaneous event-related EEG-fMRI to investigate how the network structure is updated from rest to the P300 task so as to guarantee information processing in the oddball task. We first identified 14 widely distributed regions of interest (ROIs) that were task-associated, including the inferior frontal gyrus and the middle frontal gyrus, etc. The task-activated network was found to closely relate to the concurrent P300 amplitude, and moreover, the individuals with optimized resting-state brain architectures experienced the pruning of network architecture, i. e. decreasing connectivity, when the brain switched from rest to P300 task. Our present simultaneous EEG-fMRI study explored the brain reconfigurations governing the variability in P300 across individuals, which provided the possibility to uncover new biomarkers to predict the potential for personalized control of brain-computer interfaces.

YNIMG Journal 2020 Journal Article

Objects seen as scenes: Neural circuitry for attending whole or parts

  • Mitchell Valdés-Sosa
  • Marlis Ontivero-Ortega
  • Jorge Iglesias-Fuster
  • Agustin Lage-Castellanos
  • Jinnan Gong
  • Cheng Luo
  • Ana Maria Castro-Laguardia
  • Maria Antonieta Bobes

Depending on our goals, we pay attention to the global shape of an object or to the local shape of its parts, since it’s difficult to do both at once. This typically effortless process can be impaired in disease. However, it is not clear which cortical regions carry the information needed to constrain shape processing to a chosen global/local level. Here, novel stimuli were used to dissociate functional MRI responses to global and local shapes. This allowed identification of cortical regions containing information about level (independent from shape). Crucially, these regions overlapped part of the cortical network implicated in scene processing. As expected, shape information (independent of level) was mainly located in category-selective areas specialized for object- and face-processing. Regions with the same informational profile were strongly linked (as measured by functional connectivity), but were weak when the profiles diverged. Specifically, in the ventral-temporal-cortex (VTC) regions favoring level and shape were consistently separated by the mid-fusiform sulcus (MFS). These regions also had limited crosstalk despite their spatial proximity, thus defining two functional pathways within VTC. We hypothesize that object hierarchical level is processed by neural circuitry that also analyses spatial layout in scenes, contributing to the control of the spatial-scale used for shape recognition. Use of level information tolerant to shape changes could guide whole/part attentional selection but facilitate illusory shape/level conjunctions under impoverished vision.

YNIMG Journal 2020 Journal Article

Predicting individual decision-making responses based on single-trial EEG

  • Yajing Si
  • Fali Li
  • Keyi Duan
  • Qin Tao
  • Cunbo Li
  • Zehong Cao
  • Yangsong Zhang
  • Bharat Biswal

Decision-making plays an essential role in the interpersonal interactions and cognitive processing of individuals. There has been increasing interest in being able to predict an individual’s decision-making response (i. e. , acceptance or rejection). We proposed an electroencephalogram (EEG)-based computational intelligence framework to predict individual responses. Specifically, the discriminative spatial network pattern (DSNP), a supervised learning approach, was applied to single-trial EEG data to extract the DSNP feature from the single-trial brain network. A linear discriminate analysis (LDA) trained on the DSNP features was then used to predict the individual response trial-by-trial. To verify the performance of the proposed DSNP, we recruited two independent subject groups, and recorded the EEGs using two types of EEG systems. The performances of the trial-by-trial predictors achieved an accuracy of 0. 88 ± 0. 09 for the first dataset, and 0. 90 ± 0. 10 for the second dataset. These trial-by-trial prediction performances suggested that individual responses could be predicted trial-by-trial by using the specific pattern of single-trial EEG networks, and our proposed method has the potential to establish the biologically inspired artificial intelligence decision system.

YNICL Journal 2019 Journal Article

BOLD-fMRI activity informed by network variation of scalp EEG in juvenile myoclonic epilepsy

  • Yun Qin
  • Sisi Jiang
  • Qiqi Zhang
  • Li Dong
  • Xiaoyan Jia
  • Hui He
  • Yutong Yao
  • Huanghao Yang

Epilepsy is marked by hypersynchronous bursts of neuronal activity, and seizures can propagate variably to any and all areas, leading to brain network dynamic organization. However, the relationship between the network characteristics of scalp EEG and blood oxygenation level-dependent (BOLD) responses in epilepsy patients is still not well known. In this study, simultaneous EEG and fMRI data were acquired in 18 juvenile myoclonic epilepsy (JME) patients. Then, the adapted directed transfer function (ADTF) values between EEG electrodes were calculated to define the time-varying network. The variation of network information flow within sliding windows was used as a temporal regressor in fMRI analysis to predict the BOLD response. To investigate the EEG-dependent functional coupling among the responding regions, modulatory interactions were analyzed for network variation of scalp EEG and BOLD time courses. The results showed that BOLD activations associated with high network variation were mainly located in the thalamus, cerebellum, precuneus, inferior temporal lobe and sensorimotor-related areas, including the middle cingulate cortex (MCC), supplemental motor area (SMA), and paracentral lobule. BOLD deactivations associated with medium network variation were found in the frontal, parietal, and occipital areas. In addition, modulatory interaction analysis demonstrated predominantly directional negative modulation effects among the thalamus, cerebellum, frontal and sensorimotor-related areas. This study described a novel method to link BOLD response with simultaneous functional network organization of scalp EEG. These findings suggested the validity of predicting epileptic activity using functional connectivity variation between electrodes. The functional coupling among the thalamus, frontal regions, cerebellum and sensorimotor-related regions may be characteristically involved in epilepsy generation and propagation, which provides new insight into the pathophysiological mechanisms and intervene targets for JME.

YNIMG Journal 2019 Journal Article

BOLD-fMRI reveals the association between renal oxygenation and functional connectivity in the aging brain

  • Hechun Li
  • Weifang Cao
  • Xingxing Zhang
  • Bo Sun
  • Sisi Jiang
  • Jianfu Li
  • Chang Liu
  • Wenjie Yin

Aging is accompanied by a decline in physical and cognitive function. Vascular aging may provide a major influence on these measures. The purpose of this study was to explore the relationship between renal oxygenation and functional connectivity of the aging brain because of the anatomic and hemodynamic similarities between cerebral and renal vessels. Fifty-two healthy older adults were recruited to undergo a BOLD-fMRI scan of the brain and kidneys, and forty-four healthy younger subjects were recruited as the control group. First, cerebral functional connectivity density (FCD) was used to evaluate functional connectivity. Renal medullary and cortical R2* values were extracted respectively, and the ratio of medullary and cortical R2* values (MCR) was calculated. Then, the association between brain FCD and renal MCR was analyzed. Compared with younger adults, the elderly group showed higher renal medullary R2* and MCR, which might reflect a slight abnormality of renal oxygenation with aging. The older subjects also showed enhanced FCD in bilateral motor-related regions and decreased FCD in regions of the default mode network (DMN). The findings indicated that the functional connectivity in the DMN and motor cortices was vulnerable to aging. Moreover, the altered brain FCD values in the watershed regions, DMN and motor cortices were significantly correlated with the renal MCR value in the elderly group. The association between renal oxygenation abnormalities and spontaneous activity in the brain might reflect vascular aging and its influence on the kidney and brain during aging to some extent. This study provided a new perspective for understanding the relationship between tissue oxygenation and brain functional connectivity.

YNICL Journal 2019 Journal Article

Common increased hippocampal volume but specific changes in functional connectivity in schizophrenia patients in remission and non-remission following electroconvulsive therapy: A preliminary study

  • Yuchao Jiang
  • Lihua Xu
  • Xiangkui Li
  • Yingying Tang
  • Pingfu Wang
  • Chunbo Li
  • Dezhong Yao
  • Jijun Wang

Electroconvulsive therapy (ECT) is considered a treatment option in patients with drug-resistant schizophrenia (SZ). However, approximately one-third of patients do not benefit from ECT in the clinic. Thus, it is critical to investigate differences between ECT responders and non-responders. Accumulated evidence has indicated that one region of ECT action is the hippocampus, which also plays an important role in SZ pathophysiology. To date, no studies have investigated differences in ECT effects in the hippocampus between treatment responders and non-responders. This study recruited twenty-one SZ patients treated for four weeks with ECT (MSZ, n = 21) and twenty-one SZ patients who received pharmaceutical therapy (DSZ, n = 21). The MSZ group was further categorized into responders (MSR, n = 10) or non-responders (MNR, n = 11) based on treatment outcomes by the criterion of a 50% reduction in the Positive and Negative Syndrome Scale total scores. Using structural and resting-state functional MRI, we measured the hippocampal volume and functional connectivity (FC) in all SZ patients (before and after treatment) and 23 healthy controls. In contrast to pharmaceutical therapy, ECT induced bilateral hippocampal volume increases in the MSZ. Both the MSR and MNR exhibited hippocampal expansion after ECT, whereas a lower baseline volume in one of hippocampal subfield (hippocampus-amygdala transition area) was found in the MNR. After ECT, increased FC between the hippocampus and brain networks associated with cognitive function was only observed in the MSR. The mechanism of action of ECT in schizophrenia is complex. A combination of baseline impairment level, ECT-introduced morphological changes and post-ECT FC increases in the hippocampus may jointly contribute to the post-ECT symptom improvements in patients with SZ.

YNICL Journal 2019 Journal Article

Different patterns of white matter changes after successful surgery of mesial temporal lobe epilepsy

  • Wei Li
  • Dongmei An
  • Xin Tong
  • Wenyu Liu
  • Fenglai Xiao
  • Jiechuan Ren
  • Running Niu
  • Yingying Tang

OBJECTIVES: To explore the dynamic changes of white matters following anterior temporal lobectomy (ATL) in mesial temporal lobe epilepsy (MTLE) patients who achieved seizure-free at two-year follow-up. METHODS: Diffusion tensor imaging (DTI) was obtained in ten MTLE patients at five serial time points: before surgery, three months, six months, 12 months and 24 months after surgery, as well as in 11 age- and sex-matched healthy controls at one time point. Regions with significant postoperative fractional anisotropy (FA) changes and their dynamic changes were confirmed by comparing all preoperative and postoperative data using Tract-Based Spatial Statistics (TBSS). RESULTS: After successful ATL, significant FA changes were found in widespread ipsilateral and contralateral white matter regions (P <.05, FWE correction). Ipsilateral external capsule, cingulum, superior corona radiate, body of corpus callosum, inferior longitudinal fasciculus, optic radiation and contralateral inferior cerebellar peduncle, inferior longitudinal fasciculus showed significant FA decrease at three months after surgery, without further changes. Ipsilateral superior cerebellar peduncle and contralateral corpus callosum, anterior corona radiate, external capsule, optic radiation showed significant FA decrease at three months follow up but increase later. Ipsilateral cerebral peduncle and contralateral middle cerebellar peduncle showed significant FA decrease at three months follow up, with further decrease after that. While ipsilateral posterior limb of internal capsule, retrolenticular part of internal capsule and contralateral posterior corona radiate showed significant FA increase after surgery. CONCLUSIONS: FA changes after successful ATL presented as four distinct patterns, reflecting different structural adaptions following epilepsy surgery. Some FA increases indicated the reversibility of preoperative diffusion abnormalities and the possibility of structural reorganization, especially in the contralateral hemisphere.

YNICL Journal 2019 Journal Article

Low-rank network signatures in the triple network separate schizophrenia and major depressive disorder

  • Wei Han
  • Christian Sorg
  • Changgang Zheng
  • Qinli Yang
  • Xiaosong Zhang
  • Arvid Ternblom
  • Cobbinah Bernard Mawuli
  • Lianli Gao

Brain imaging studies have revealed that functional and structural brain connectivity in the so-called triple network (i.e., default mode network (DMN), salience network (SN) and central executive network (CEN)) are consistently altered in schizophrenia. However, similar changes have also been found in patients with major depressive disorder, prompting the question of specific triple network signatures for the two disorders. In this study, we proposed Supervised Convex Nonnegative Matrix Factorization (SCNMF) to extract distributed multi-modal brain patterns. These patterns distinguish schizophrenia and major depressive disorder in a latent low-dimensional space of the triple brain network. Specifically, 21 patients of schizophrenia and 25 patients of major depressive disorder were assessed by T1-weighted, diffusion-weighted, and resting-state functional MRIs. Individual structural and functional connectivity networks, based on pre-defined regions of the triple network were constructed, respectively. Afterwards, SCNMF was employed to extract the discriminative patterns. Experiments indicate that SCNMF allows extracting the low-rank discriminative patterns between the two disorders, achieving a classification accuracy of 82.6% based on the extracted functional and structural abnormalities with support vector machine. Experimental results show the specific brain patterns for schizophrenia and major depressive disorder that are multi-modal, complex, and distributed in the triple network. Parts of the prefrontal cortex including superior frontal gyri showed variation between patients with schizophrenia and major depression due to structural properties. In terms of functional properties, the middle cingulate cortex, inferior parietal lobule, and cingulate cortex were the most discriminative regions.

YNIMG Journal 2019 Journal Article

White-matter functional networks changes in patients with schizophrenia

  • Yuchao Jiang
  • Cheng Luo
  • Xuan Li
  • Yingjia Li
  • Hang Yang
  • Jianfu Li
  • Xin Chang
  • Hechun Li

Resting-state functional MRI (rsfMRI) is a useful technique for investigating the functional organization of human gray-matter in neuroscience and neuropsychiatry. Nevertheless, most studies have demonstrated the functional connectivity and/or task-related functional activity in the gray-matter. White-matter functional networks have been investigated in healthy subjects. Schizophrenia has been hypothesized to be a brain disorder involving insufficient or ineffective communication associated with white-matter abnormalities. However, previous studies have mainly examined the structural architecture of white-matter using MRI or diffusion tensor imaging and failed to uncover any dysfunctional connectivity within the white-matter on rsfMRI. The current study used rsfMRI to evaluate white-matter functional connectivity in a large cohort of ninety-seven schizophrenia patients and 126 healthy controls. Ten large-scale white-matter networks were identified by a cluster analysis of voxel-based white-matter functional connectivity and classified into superficial, middle and deep layers of networks. Evaluation of the spontaneous oscillation of white-matter networks and the functional connectivity between them showed that patients with schizophrenia had decreased amplitudes of low-frequency oscillation and increased functional connectivity in the superficial perception-motor networks. Additionally, we examined the interactions between white-matter and gray-matter networks. The superficial perception-motor white-matter network had decreased functional connectivity with the cortical perception-motor gray-matter networks. In contrast, the middle and deep white-matter networks had increased functional connectivity with the superficial perception-motor white-matter network and the cortical perception-motor gray-matter network. Thus, we presumed that the disrupted association between the gray-matter and white-matter networks in the perception-motor system may be compensated for through the middle-deep white-matter networks, which may be the foundation of the extensively disrupted connections in schizophrenia.

IJCAI Conference 2018 Conference Paper

High-dimensional Similarity Learning via Dual-sparse Random Projection

  • Dezhong Yao
  • Peilin Zhao
  • Tuan-Anh Nguyen Pham
  • Gao Cong

We investigate how to adopt dual random projection for high-dimensional similarity learning. For a high-dimensional similarity learning problem, projection is usually adopted to map high-dimensional features into low-dimensional space, in order to reduce the computational cost. However, dimensionality reduction method sometimes results in unstable performance due to the suboptimal solution in original space. In this paper, we propose a dual random projection framework for similarity learning to recover the original optimal solution from subspace optimal solution. Previous dual random projection methods usually make strong assumptions about the data, which need to be low rank or have a large margin. Those assumptions limit dual random projection applications in similarity learning. Thus, we adopt a dual-sparse regularized random projection method that introduces a sparse regularizer into the reduced dual problem. As the original dual solution is a sparse one, applying a sparse regularizer in the reduced space relaxes the low-rank assumption. Experimental results show that our method enjoys higher effectiveness and efficiency than state-of-the-art solutions.

IJCAI Conference 2017 Conference Paper

Robust Softmax Regression for Multi-class Classification with Self-Paced Learning

  • Yazhou Ren
  • Peng Zhao
  • Yongpan Sheng
  • Dezhong Yao
  • Zenglin Xu

Softmax regression, a generalization of Logistic regression (LR) in the setting of multi-class classification, has been widely used in many machine learning applications. However, the performance of softmax regression is extremely sensitive to the presence of noisy data and outliers. To address this issue, we propose a model of robust softmax regression (RoSR) originated from the self-paced learning (SPL) paradigm for multi-class classification. Concretely, RoSR equipped with the soft weighting scheme is able to evaluate the importance of each data instance. Then, data instances participate in the classification problem according to their weights. In this way, the influence of noisy data and outliers (which are typically with small weights) can be significantly reduced. However, standard SPL may suffer from the imbalanced class influence problem, where some classes may have little influence in the training process if their instances are not sensitive to the loss. To alleviate this problem, we design two novel soft weighting schemes that assign weights and select instances locally for each class. Experimental results demonstrate the effectiveness of the proposed methods.

YNIMG Journal 2016 Journal Article

Structural and functional correlates of motor imagery BCI performance: Insights from the patterns of fronto-parietal attention network

  • Tao Zhang
  • Tiejun Liu
  • Fali Li
  • Mengchen Li
  • Dongbo Liu
  • Rui Zhang
  • Hui He
  • Peiyang Li

Motor imagery (MI)-based brain-computer interfaces (BCIs) have been widely used for rehabilitation of motor abilities and prosthesis control for patients with motor impairments. However, MI-BCI performance exhibits a wide variability across subjects, and the underlying neural mechanism remains unclear. Several studies have demonstrated that both the fronto-parietal attention network (FPAN) and MI are involved in high-level cognitive processes that are crucial for the control of BCIs. Therefore, we hypothesized that the FPAN may play an important role in MI-BCI performance. In our study, we recorded multi-modal datasets consisting of MI electroencephalography (EEG) signals, T1-weighted structural and resting-state functional MRI data for each subject. MI-BCI performance was evaluated using the common spatial pattern to extract the MI features from EEG signals. One cortical structural feature (cortical thickness (CT)) and two measurements (degree centrality (DC) and eigenvector centrality (EC)) of node centrality were derived from the structural and functional MRI data, respectively. Based on the information extracted from the EEG and MRI, a correlation analysis was used to elucidate the relationships between the FPAN and MI-BCI performance. Our results show that the DC of the right ventral intraparietal sulcus, the EC and CT of the left inferior parietal lobe, and the CT of the right dorsolateral prefrontal cortex were significantly associated with MI-BCI performance. Moreover, the receiver operating characteristic analysis and machine learning classification revealed that the EC and CT of the left IPL could effectively predict the low-aptitude BCI users from the high-aptitude BCI users with 83. 3% accuracy. Those findings consistently reveal that the individuals who have efficient FPAN would perform better on MI-BCI. Our findings may deepen the understanding of individual variability in MI-BCI performance, and also may provide a new biomarker to predict individual MI-BCI performance.

YNIMG Journal 2015 Journal Article

Characterizing nonlinear relationships in functional imaging data using eigenspace maximal information canonical correlation analysis (emiCCA)

  • Li Dong
  • Yangsong Zhang
  • Rui Zhang
  • Xingxing Zhang
  • Diankun Gong
  • Pedro A. Valdes-Sosa
  • Peng Xu
  • Cheng Luo

Many important problems in the analysis of neuroimages can be formulated as discovering the relationship between two sets of variables, a task for which linear techniques such as canonical correlation analysis (CCA) have been commonly used. However, to further explore potential nonlinear processes that might co-exist with linear ones in brain function, a more flexible method is required. Here, we propose a new unsupervised and data-driven method, termed the eigenspace maximal information canonical correlation analysis (emiCCA), which is capable of automatically capturing the linear and/or nonlinear relationships between various data sets. A simulation confirmed the superior performance of emiCCA in comparison with linear CCA and kernel CCA (a nonlinear version of CCA). An emiCCA framework for functional magnetic resonance imaging (fMRI) data processing was designed and applied to data from a real motor execution fMRI experiment. This analysis uncovered one linear (in primary motor cortex) and a few nonlinear networks (e. g. , in the supplementary motor area, bilateral insula, and cerebellum). This suggests that these various task-related brain areas are part of networks that also contribute to the execution of movements of the hand. These results suggest that emiCCA is a promising technique for exploring various data.

YNICL Journal 2014 Journal Article

Patient-specific connectivity pattern of epileptic network in frontal lobe epilepsy

  • Cheng Luo
  • Dongmei An
  • Dezhong Yao
  • Jean Gotman

There is evidence that focal epilepsy may involve the dysfunction of a brain network in addition to the focal region. To delineate the characteristics of this epileptic network, we collected EEG/fMRI data from 23 patients with frontal lobe epilepsy. For each patient, EEG/fMRI analysis was first performed to determine the BOLD response to epileptic spikes. The maximum activation cluster in the frontal lobe was then chosen as the seed to identify the epileptic network in fMRI data. Functional connectivity analysis seeded at the same region was also performed in 63 healthy control subjects. Nine features were used to evaluate the differences of epileptic network patterns in three connection levels between patients and controls. Compared with control subjects, patients showed overall more functional connections between the epileptogenic region and the rest of the brain and higher laterality. However, the significantly increased connections were located in the neighborhood of the seed, but the connections between the seed and remote regions actually decreased. Comparing fMRI runs with interictal epileptic discharges (IEDs) and without IEDs, the patient-specific connectivity pattern was not changed significantly. These findings regarding patient-specific connectivity patterns of epileptic networks in FLE reflect local high connectivity and connections with distant regions differing from those of healthy controls. Moreover, the difference between the two groups in most features was observed in the strictest of the three connection levels. The abnormally high connectivity might reflect a predominant attribute of the epileptic network, which may facilitate propagation of epileptic activity among regions in the network.

YNIMG Journal 2014 Journal Article

Simultaneous EEG-fMRI: Trial level spatio-temporal fusion for hierarchically reliable information discovery

  • Li Dong
  • Diankun Gong
  • Pedro A. Valdes-Sosa
  • Yang Xia
  • Cheng Luo
  • Peng Xu
  • Dezhong Yao

Simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) have been pursued in an effort to integrate complementary noninvasive information on brain activity. The primary goal involves better information discovery of the event-related neural activations at a spatial region of the BOLD fluctuation with the temporal resolution of the electrical signal. Many techniques and algorithms have been developed to integrate EEGs and fMRIs; however, the relative reliability of the integrated information is unclear. In this work, we propose a hierarchical framework to ensure the relative reliability of the integrated results and attempt to understand brain activation using this hierarchical ideal. First, spatial Independent Component Analysis (ICA) of fMRI and temporal ICA of EEG were performed to extract features at the trial level. Second, the maximal information coefficient (MIC) was adopted to temporally match them across the modalities for both linear and non-linear associations. Third, fMRI-constrained EEG source imaging was utilized to spatially match components across modalities. The simultaneously occurring events in the above two match steps provided EEG-fMRI spatial–temporal reliable integrated information, resulting in the most reliable components with high spatial and temporal resolution information. The other components discovered in the second or third steps provided second-level complementary information for flexible and cautious explanations. This paper contains two simulations and an example of real data, and the results indicate that the framework is a feasible approach to reveal cognitive processing in the human brain.

YNIMG Journal 2010 Journal Article

A parallel framework for simultaneous EEG/fMRI analysis: Methodology and simulation

  • Xu Lei
  • Chuan Qiu
  • Peng Xu
  • Dezhong Yao

Concurrent EEG/fMRI recordings represent multiple, simultaneously active, regionally overlapping neuronal mass responses. To address the problems caused by the overlapping nature of these responses, we propose a parallel framework for Spatial–Temporal EEG/fMRI Fusion (STEFF). This technique adopts Independent Component Analysis (ICA) to recover the time-course and spatial mapping components from EEG and fMRI separately. These components are then linked concurrently in the spatial and temporal domain using an Empirical Bayesian (EB) model. This approach enables information one modality to be utilized as priors for the other and hence improves the spatial (for EEG) or temporal (for fMRI) resolution of the other modality. Consequently, STEFF achieves flexible and sparse matching among EEG and fMRI components with common neuronal substrates. Simulations under realistic noise conditions indicated that STEFF is a feasible and physiologically reasonable hybrid approach for spatiotemporal mapping of cognitive processing in the human brain.

YNIMG Journal 2010 Journal Article

Neuroelectric source imaging using 3SCO: A space coding algorithm based on particle swarm optimization and l0 norm constraint

  • Peng Xu
  • Yin Tian
  • Xu Lei
  • Dezhong Yao

The electroencephalogram (EEG) neuroelectric sources inverse problem is usually underdetermined and lacks a unique solution, which is due to both the electromagnetism Helmholtz theorem and the fact that there are fewer observations than the unknown variables. One potential choice to tackle this issue is to solve the underdetermined system for a sparse solution. Aiming to the sparse solution, a novel algorithm termed 3SCO (Solution Space Sparse Coding Optimization) is presented in this paper. In 3SCO, after the solution space is coded with some particles, the particle-coded space is compressed by the evolution of particle swarm optimization algorithm, where an l 0 constrained fitness function is introduced to guarantee the selection of a suitable sparse solution for the underdetermined system. 3SCO was first tested by localizing simulated EEG sources with different configurations on a realistic head model, and the comparisons with minimum norm (MN), LORETA (low resolution electromagnetic tomography), l 1 norm solution and FOCUSS (focal underdetermined system solver) confirmed that a good sparse solution for EEG source imaging could be achieved with 3SCO. Finally, 3SCO was applied to localize the neuroelectric sources in a visual stimuli related experiment and the localized areas were basically consistent with those reported in previous studies.