37,366 research outputs found
A model for classification based on the functional connectivity pattern dynamics of the brain
—Synchronized spontaneous low frequency fluctuations of the so called BOLD signal, as measured by functional Magnetic Resonance Imaging (fMRI), are known to represent the functional connections of different brain areas. Dynamic Time Warping (DTW) distance can be used as a similarity measure between BOLD signals of brain regions as an alternative of the traditionally used correlation coefficient and the usage of the DTW algorithm has further advantages: beside the DTW distance, the algorithm generates the warping path, i.e. the time-delay function between the compared two time-series. In this paper, we propose to use the relative length of the warping path as classification feature and demonstrate that the warping path itself carries important information when classifying patients according to cannabis addiction. We discuss biomedical relevance of our findings as well
A Deep Probabilistic Spatiotemporal Framework for Dynamic Graph Representation Learning with Application to Brain Disorder Identification
Recent applications of pattern recognition techniques on brain connectome
classification using functional connectivity (FC) neglect the non-Euclidean
topology and causal dynamics of brain connectivity across time. In this paper,
a deep probabilistic spatiotemporal framework developed based on variational
Bayes (DSVB) is proposed to learn time-varying topological structures in
dynamic brain FC networks for autism spectrum disorder (ASD) identification.
The proposed framework incorporates a spatial-aware recurrent neural network to
capture rich spatiotemporal patterns across dynamic FC networks, followed by a
fully-connected neural network to exploit these learned patterns for
subject-level classification. To overcome model overfitting on limited training
datasets, an adversarial training strategy is introduced to learn graph
embedding models that generalize well to unseen brain networks. Evaluation on
the ABIDE resting-state functional magnetic resonance imaging dataset shows
that our proposed framework significantly outperformed state-of-the-art methods
in identifying ASD. Dynamic FC analyses with DSVB learned embeddings reveal
apparent group difference between ASD and healthy controls in network profiles
and switching dynamics of brain states
The Potential of the Human Connectome as a Biomarker of Brain Disease
The human connectome at the level of fiber tracts between brain regions has
been shown to differ in patients with brain disorders compared to healthy
control groups. Nonetheless, there is a potentially large number of different
network organizations for individual patients that could lead to cognitive
deficits prohibiting correct diagnosis. Therefore changes that can distinguish
groups might not be sufficient to diagnose the disease that an individual
patient suffers from and to indicate the best treatment option for that
patient. We describe the challenges introduced by the large variability of
connectomes within healthy subjects and patients and outline three common
strategies to use connectomes as biomarkers of brain diseases. Finally, we
propose a fourth option in using models of simulated brain activity (the
dynamic connectome) based on structural connectivity rather than the structure
(connectome) itself as a biomarker of disease. Dynamic connectomes, in addition
to currently used structural, functional, or effective connectivity, could be
an important future biomarker for clinical applications.Comment: Perspective Article for special issue on Magnetic Resonance Imaging
of Healthy and Diseased Brain Network
Deep Chronnectome Learning via Full Bidirectional Long Short-Term Memory Networks for MCI Diagnosis
Brain functional connectivity (FC) extracted from resting-state fMRI
(RS-fMRI) has become a popular approach for disease diagnosis, where
discriminating subjects with mild cognitive impairment (MCI) from normal
controls (NC) is still one of the most challenging problems. Dynamic functional
connectivity (dFC), consisting of time-varying spatiotemporal dynamics, may
characterize "chronnectome" diagnostic information for improving MCI
classification. However, most of the current dFC studies are based on detecting
discrete major brain status via spatial clustering, which ignores rich
spatiotemporal dynamics contained in such chronnectome. We propose Deep
Chronnectome Learning for exhaustively mining the comprehensive information,
especially the hidden higher-level features, i.e., the dFC time series that may
add critical diagnostic power for MCI classification. To this end, we devise a
new Fully-connected Bidirectional Long Short-Term Memory Network (Full-BiLSTM)
to effectively learn the periodic brain status changes using both past and
future information for each brief time segment and then fuse them to form the
final output. We have applied our method to a rigorously built large-scale
multi-site database (i.e., with 164 data from NCs and 330 from MCIs, which can
be further augmented by 25 folds). Our method outperforms other
state-of-the-art approaches with an accuracy of 73.6% under solid
cross-validations. We also made extensive comparisons among multiple variants
of LSTM models. The results suggest high feasibility of our method with
promising value also for other brain disorder diagnoses.Comment: The paper has been accepted by MICCAI201
Classification-based prediction of effective connectivity between timeseries with a realistic cortical network model
Effective connectivity measures the pattern of causal interactions between brain regions. Traditionally, these patterns of causality are inferred from brain recordings using either non-parametric, i.e., model-free, or parametric, i.e., model-based, approaches. The latter approaches, when based on biophysically plausible models, have the advantage that they may facilitate the interpretation of causality in terms of underlying neural mechanisms. Recent biophysically plausible neural network models of recurrent microcircuits have shown the ability to reproduce well the characteristics of real neural activity and can be applied to model interacting cortical circuits. Unfortunately, however, it is challenging to invert these models in order to estimate effective connectivity from observed data. Here, we propose to use a classification-based method to approximate the result of such complex model inversion. The classifier predicts the pattern of causal interactions given a multivariate timeseries as input. The classifier is trained on a large number of pairs of multivariate timeseries and the respective pattern of causal interactions, which are generated by simulation from the neural network model. In simulated experiments, we show that the proposed method is much more accurate in detecting the causal structure of timeseries than current best practice methods. Additionally, we present further results to characterize the validity of the neural network model and the ability of the classifier to adapt to the generative model of the data
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The role of HG in the analysis of temporal iteration and interaural correlation
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Estimation of brain dynamics under visuomotor task using functional connectivity analysis based on graph theory
Network studies of brain connectivity have demonstrated that the highly connected area, or hub, is a vital feature of human functional and structural brain organization. Hubs identify which region plays an important role in cognitive/sensorimotor tasks. In addition, a complex visuomotor learning skill causes specific changes of neuronal activation across brain regions. Accordingly, this study utilizes the hub as one of the features to map the visuomotor learning tasks and their dynamic functional connectivity (dFC). The electroencephalogram (EEG) data recorded under three different behavior conditions were investigated: motion only (MO), vision only (VO), and tracking (Tra) conditions. Here, we used the phase locking value (PLV) with a sliding window (50 ms) to calculate the dFC at four distinct frequency bands: 8-12 Hz (alpha), 18-22 Hz (low beta), 26-30 Hz (high beta) and 38-42 Hz (gamma), and the eigenvector centrality to evaluate the hub identification. The Gaussian Mixture Model (GMM) was applied to investigate the dFC patterns. The results showed that the dFC patterns with the hub feature represent the characteristic of neuronal activities under visuomotor coordination
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