Group independent component analysis (ICA) has been extensively used to extract brain functional networks (FNs) and associated neuroimaging measures from multi-subject functional magnetic resonance imaging (fMRI) data. However, the inherent noise in fMRI data can adversely affect the performance of ICA, often leading to noisy FNs and hindering the identification of network-level biomarkers. To address this challenge, we propose a novel method called group information guided smooth independent component analysis (GIG-sICA). Our method effectively generates smoother functional networks with reduced noise and enhanced functional coherence, while preserving intra-subject independence and inter-subject correspondence of FN. Importantly, GIG-sICA is capable of handling different types of noise either separately or in combination. To validate the efficacy of our approach, we conducted comprehensive experiments, comparing GIG-sICA with traditional group ICA methods on both simulated and real fMRI datasets. Experiments on five simulated datasets, generated by adding various types of noise, demonstrate that GIG-sICA produces smoother functional networks with enhanced spatial accuracy. Additionally, experiments on real fMRI data from 137 schizophrenia patients and 144 healthy controls demonstrate that GIG-sICA more effectively captures functionally meaningful brain networks and reveals clearer group differences. Overall, GIG-sICA produces smooth and precise network estimations, supporting the discovery of robust biomarkers at the network level for neuroscience research.

Dynamic functional connectivity (dFC) analysis investigates how the functional interactions between brain regions change over time by identifying recurring connectivity patterns, known as dFC states, and tracking transitions between them. Non-negative matrix factorization (NMF) has been used in dFC analysis because it produces non-negative dFC states and coefficients, interpreting dFC states and their transitions straightforwardly. However, existing NMF-based methods are limited to processing dFC data with exclusively positive values, failing to align with the functional correlations and anti-correlations between brain regions. This paper proposes an orthogonal semi-nonnegative matrix factorization (OSemiNMF) method, extending NMF to directly handle mixed-sign dFC data. Furthermore, an orthogonality constraint on the bases (i.e., dFC states) is incorporated to enhance the uniqueness of dFC states. For 10 simulated datasets with varying properties, our method outperforms comparison methods, supporting its superior ability to capture dFC states and state transitions. Using four resting-state fMRI datasets consisting of 708 healthy controls (HCs) and 537 schizophrenia patients (SZs), our method identifies reproducible dFC states and state transitions across datasets. Further, our findings reveal that SZs spend less time in high-connectivity states compared to HCs. Our study identifies meaningful and reproducible biomarkers of schizophrenia, mainly involving the connectivity associated with the sub-cortical domain. In summary, the OSemiNMF method facilitates the dFC analysis for understanding brain dynamics.

In low-latency live streaming (LLLS), the adaptive bitrate algorithm plays a critical role in optimizing encoding bitrates to meet the strict end-to-end latency requirement, which is mostly several seconds or less. Existing methods usually rely on a fixed preset latency target, limiting their generalization capabilities across the heterogeneous scenarios. To address this, we propose an offline meta-reinforcement learning-based bitrate decision framework for LLLS, which incorporates the expertise of multiple state-of-the-art LLLS algorithms from their collected experience and constructs a universal bitrate selection policy via the offline training. Specifically, we establish an RL-based policy that adaptively adjusts the network throughput measurements and selects the encoding bitrates for LLLS based on the network conditions. The policy’s performance is enhanced by improving the robustness of short-term throughput estimations. To leverage the expertise of current LLLS algorithms, we collect their decision-making trajectories, and directly train the policy on these offline trajectories with implicit Q-learning. In addition, a meta-RL paradigm is further adopted to learn a universal policy that performs uniformly well across the heterogeneous network conditions and varying target latencies. Experimental results demonstrate that, compared to the other baselines, the proposed method achieves at least a 5.8% performance gain in terms of the overall quality of experience (QoE), across the diverse target-latency scenarios in the real-world throughput traces.

The subjective nature of diagnosing mental disorders complicates achieving accurate diagnoses. The complex relationship among disorders further exacerbates this issue, particularly in clinical practice where conditions like bipolar disorder (BP) and schizophrenia (SZ) can present similar clinical symptoms and cognitive impairments. To address these challenges, this paper proposes a mutualistic multi-network noisy label learning (MMNNLL) method, which aims to enhance diagnostic accuracy by leveraging neuroimaging data under the presence of potential clinical diagnosis bias or errors. MMNNLL effectively utilizes multiple deep neural networks (DNNs) for learning from data with noisy labels by maximizing the consistency among DNNs in identifying and utilizing samples with clean and noisy labels. Experimental results on public CIFAR-10 and PathMNIST datasets demonstrate the effectiveness of our method in classifying independent test data across various types and levels of label noise. Additionally, our MMNNLL method significantly outperforms state-of-the-art noisy label learning methods. When applied to brain functional connectivity data from BP and SZ patients, our method identifies two biotypes that show more pronounced group differences, and improved classification accuracy compared to the original clinical categories, using both traditional machine learning and advanced deep learning techniques. In summary, our method effectively addresses the possible inaccuracy in nosology of mental disorders and achieves transdiagnostic classification through robust noisy label learning via multi-network collaboration and competition.

Abstract Microbiome is closely related to many major human diseases, but it is generally analyzed by the traditional statistical methods such as principal component analysis, principal coordinate analysis, etc. These methods have shortcomings and do not consider the characteristics of the microbiome data itself (i.e., the “probability distribution” of microbiome). A new method based on probabilistic topic model was proposed to mine the information of gut microbiome in this paper, taking gut microbiome of type 2 diabetes patients and healthy subjects as an example. Firstly, different weights were assigned to different microbiome according to the degree of correlation between different microbiome and subjects. Then a probabilistic topic model was employed to obtain the probabilistic distribution of gut microbiome (i.e., per-topic OTU (operational taxonomic units, OTU) distribution and per-patient topic distribution). Experimental results showed that the output topics can be used as the characteristics of gut microbiome, and can describe the differences of gut microbiome over different groups. Furthermore, in order to verify the ability of this method to characterize gut microbiome, clustering and classification operations on the distributions over topics for gut microbiome in each subject were performed, and the experimental results showed that the clustering and classification performance has been improved, and the recognition rate of three groups reached 100%. The proposed method could mine the information hidden in gut microbiome data, and the output topics could describe the characteristics of gut microbiome, which provides a new perspective for the study of gut microbiome.

Feature selection can disclose biomarkers of mental disorders that have unclear biological mechanisms. Although neighborhood rough set (NRS) has been applied to discover important sparse features, it has hardly ever been utilized in neuroimaging-based biomarker identification, probably due to the inadequate feature evaluation metric and incomplete information provided under a single-granularity. Here, we propose a new NRS-based feature selection method and successfully identify brain functional connectivity biomarkers of schizophrenia (SZ) using functional magnetic resonance imaging (fMRI) data. Specifically, we develop a new weighted metric based on NRS combined with information entropy to evaluate the capacity of features in distinguishing different groups. Inspired by multi-granularity information maximization theory, we further take advantage of the complementary information from different neighborhood sizes via a multi-granularity fusion to obtain the most discriminative and stable features. For validation, we compare our method with six popular feature selection methods using three public omics datasets as well as resting-state fMRI data of 393 SZ patients and 429 healthy controls. Results show that our method obtained higher classification accuracies on both omics data (100.0%, 88.6%, and 72.2% for three omics datasets, respectively) and fMRI data (93.9% for main dataset, and 76.3% and 83.8% for two independent datasets, respectively). Moreover, our findings reveal biologically meaningful substrates of SZ, notably involving the connectivity between the thalamus and superior temporal gyrus as well as between the postcentral gyrus and calcarine gyrus. Taken together, we propose a new NRS-based feature selection method that shows the potential of exploring effective and sparse neuroimaging-based biomarkers of mental disorders.

The reliability of functional network connectivity (FNC) measured using independent component analysis (ICA) has frequently been explored within the literature, with results displaying varying levels of reliability and demonstrating that minor changes in data preprocessing procedures can significantly alter FC results and reliability. However, one important avenue of research that has not been explored within the current literature is the effect of spatial normalization techniques on FNC reliability. Spatially constrained independent component analysis techniques such as multi-objective optimization with reference (MOO-ICAR) is one of many methods used to study brain functional connectivity (FC) using fMRI that is theoretically robust to variations which may arise in data as a result of normalization procedures. In this work, we deploy MOO-ICAR across 30 different spatial normalization pipelines varying across participant template, normalization modality (anatomical vs functional), and one vs. two-stage warps to MNI space. Most components display relatively high consistency intraclass-correlation coefficients (ICCs), with the vast majoritv (~80%) ereater than 0.5.

Human brain connectivity is complex. Graph theory based analysis has become a powerful and popular approach for analyzing brain imaging data, largely because of its potential to quantitatively illuminate the networks, the static architecture in structure and function, the organization of dynamic behavior over time, and disease related brain changes. The first step in creating brain graphs is to define the nodes and edges connecting them. We review a number of approaches for defining brain nodes including fixed versus data-driven nodes. Expanding the narrow view of most studies which focus on static and/or single modality brain connectivity, we also survey advanced approaches and their performances in building dynamic and multi-modal brain graphs. We show results from both simulated and real data from healthy controls and patients with mental illnesse. We outline the advantages and challenges of these various techniques. By summarizing and inspecting recent studies which analyzed brain imaging data based on graph theory, this article provides a guide for developing new powerful tools to explore complex brain networks.

By exploiting cross-information among multiple imaging data, multimodal fusion has often been used to better understand brain diseases. However, most current fusion approaches are blind, without adopting any prior information. There is increasing interest to uncover the neurocognitive mapping of specific clinical measurements on enriched brain imaging data; hence, a supervised, goal-directed model that employs prior information as a reference to guide multimodal data fusion is much needed and becomes a natural option. Here, we proposed a fusion with reference model called "multi-site canonical correlation analysis with reference + joint-independent component analysis" (MCCAR+jICA), which can precisely identify co-varying multimodal imaging patterns closely related to the reference, such as cognitive scores. In a three-way fusion simulation, the proposed method was compared with its alternatives on multiple facets; MCCAR+jICA outperforms others with higher estimation precision and high accuracy on identifying a target component with the right correspondence. In human imaging data, working memory performance was utilized as a reference to investigate the co-varying working memory-associated brain patterns among three modalities and how they are impaired in schizophrenia. Two independent cohorts (294 and 83 subjects respectively) were used. Similar brain maps were identified between the two cohorts along with substantial overlaps in the central executive network in fMRI, salience network in sMRI, and major white matter tracts in dMRI. These regions have been linked with working memory deficits in schizophrenia in multiple reports and MCCAR+jICA further verified them in a repeatable, joint manner, demonstrating the ability of the proposed method to identify potential neuromarkers for mental disorders.

Numerous studies have shown that brain functional connectivity patterns can be time-varying over periods of tens of seconds. It is important to capture inherent non-stationary connectivity states for a better understanding of the influence of disease on brain connectivity. K-means has been widely used to extract the connectivity states from dynamic functional connectivity. However, K-means is dependent on initialization and can be exponentially slow in converging due to extensive noise in dynamic functional connectivity. In this work, we propose to use an affinity propagation clustering method to estimate the connectivity states. By applying K-means and the new method separately, we analyzed dynamic functional connectivity of 82 healthy controls and 82 schizophrenia patients, and then explored group differences between schizophrenia patients and healthy controls in the identified connectivity states. Both methods revealed that group differences mainly lay in visual, sensorimotor and frontal cortices. However, the new approach found more meaningful group differences than K-means. Our finding supports that our method is promising in exploring biomarkers of mental disorders.