216 research outputs found
Left hemisphere predominance of pilocarpine-induced rat epileptiform discharges
<p>Abstract</p> <p>Background</p> <p>The left cerebral hemisphere predominance in human focal epilepsy has been observed in a few studies, however, there is no related systematic study in epileptic animal on hemisphere predominance. The main goal of this paper is to observe if the epileptiform discharges (EDs) of Pilocarpine-induced epileptic rats could present difference between left hemisphere and right hemisphere or not.</p> <p>Methods</p> <p>The electrocorticogram (ECoG) and electrohippocampogram (EHG) from Pilocarpine-induced epileptic rats were recorded and analyzed using Synchronization likelihood (SL) in order to determine the synchronization relation between different brain regions, then visual check and cross-correlation analysis were adopted to evaluate if the EDs were originated more frequently from the left hemisphere than the right hemisphere.</p> <p>Results</p> <p>The data show that the synchronization between left-EHG and right-EHG, left-ECoG and left-EHG, right-ECoG and right-EHG, left-ECoG and right-ECoG, are significantly strengthened after the brain functional state transforms from non-epileptiform discharges to continuous-epileptiform discharges(p < 0.05). When the state transforms from continuous EDs to periodic EDs, the synchronization is significantly weakened between left-ECoG and left-EHG, left-EHG and right-EHG (p < 0.05). Visual check and the time delay (Ï„) based cross-correlation analysis finds that 10 out of 13 EDs have a left predominance (77%) and 3 out of 13 EDs are right predominance (23%).</p> <p>Conclusion</p> <p>The results suggest that the left hemisphere may be more prone to EDs in the Pilocarpine-induced rat epilepsy model and implicate that the left hemisphere might play an important role in epilepsy states transition.</p
An Enhanced Probabilistic LDA for Multi-Class Brain Computer Interface
There is a growing interest in the study of signal processing and machine learning methods, which may make the brain computer interface (BCI) a new communication channel. A variety of classification methods have been utilized to convert the brain information into control commands. However, most of the methods only produce uncalibrated values and uncertain results.In this study, we presented a probabilistic method "enhanced BLDA" (EBLDA) for multi-class motor imagery BCI, which utilized Bayesian linear discriminant analysis (BLDA) with probabilistic output to improve the classification performance. EBLDA builds a new classifier that enlarges training dataset by adding test samples with high probability. EBLDA is based on the hypothesis that unlabeled samples with high probability provide valuable information to enhance learning process and generate a classifier with refined decision boundaries. To investigate the performance of EBLDA, we first used carefully designed simulated datasets to study how EBLDA works. Then, we adopted a real BCI dataset for further evaluation. The current study shows that: 1) Probabilistic information can improve the performance of BCI for subjects with high kappa coefficient; 2) With supplementary training samples from the test samples of high probability, EBLDA is significantly better than BLDA in classification, especially for small training datasets, in which EBLDA can obtain a refined decision boundary by a shift of BLDA decision boundary with the support of the information from test samples.The proposed EBLDA could potentially reduce training effort. Therefore, it is valuable for us to realize an effective online BCI system, especially for multi-class BCI systems
Regulation of Irregular Neuronal Firing by Autaptic Transmission
The importance of self-feedback autaptic transmission in modulating
spike-time irregularity is still poorly understood. By using a biophysical
model that incorporates autaptic coupling, we here show that self-innervation
of neurons participates in the modulation of irregular neuronal firing,
primarily by regulating the occurrence frequency of burst firing. In
particular, we find that both excitatory and electrical autapses increase the
occurrence of burst firing, thus reducing neuronal firing regularity. In
contrast, inhibitory autapses suppress burst firing and therefore tend to
improve the regularity of neuronal firing. Importantly, we show that these
findings are independent of the firing properties of individual neurons, and as
such can be observed for neurons operating in different modes. Our results
provide an insightful mechanistic understanding of how different types of
autapses shape irregular firing at the single-neuron level, and they highlight
the functional importance of autaptic self-innervation in taming and modulating
neurodynamics.Comment: 27 pages, 8 figure
A Synapse-Threshold Synergistic Learning Approach for Spiking Neural Networks
Spiking neural networks (SNNs) have demonstrated excellent capabilities in
various intelligent scenarios. Most existing methods for training SNNs are
based on the concept of synaptic plasticity; however, learning in the realistic
brain also utilizes intrinsic non-synaptic mechanisms of neurons. The spike
threshold of biological neurons is a critical intrinsic neuronal feature that
exhibits rich dynamics on a millisecond timescale and has been proposed as an
underlying mechanism that facilitates neural information processing. In this
study, we develop a novel synergistic learning approach that simultaneously
trains synaptic weights and spike thresholds in SNNs. SNNs trained with
synapse-threshold synergistic learning (STL-SNNs) achieve significantly higher
accuracies on various static and neuromorphic datasets than SNNs trained with
two single-learning models of the synaptic learning (SL) and the threshold
learning (TL). During training, the synergistic learning approach optimizes
neural thresholds, providing the network with stable signal transmission via
appropriate firing rates. Further analysis indicates that STL-SNNs are robust
to noisy data and exhibit low energy consumption for deep network structures.
Additionally, the performance of STL-SNN can be further improved by introducing
a generalized joint decision framework (JDF). Overall, our findings indicate
that biologically plausible synergies between synaptic and intrinsic
non-synaptic mechanisms may provide a promising approach for developing highly
efficient SNN learning methods.Comment: 13 pages, 9 figures, submitted for publicatio
Decoupled Contrastive Multi-view Clustering with High-order Random Walks
In recent, some robust contrastive multi-view clustering (MvC) methods have
been proposed, which construct data pairs from neighborhoods to alleviate the
false negative issue, i.e., some intra-cluster samples are wrongly treated as
negative pairs. Although promising performance has been achieved by these
methods, the false negative issue is still far from addressed and the false
positive issue emerges because all in- and out-of-neighborhood samples are
simply treated as positive and negative, respectively. To address the issues,
we propose a novel robust method, dubbed decoupled contrastive multi-view
clustering with high-order random walks (DIVIDE). In brief, DIVIDE leverages
random walks to progressively identify data pairs in a global instead of local
manner. As a result, DIVIDE could identify in-neighborhood negatives and
out-of-neighborhood positives. Moreover, DIVIDE embraces a novel MvC
architecture to perform inter- and intra-view contrastive learning in different
embedding spaces, thus boosting clustering performance and embracing the
robustness against missing views. To verify the efficacy of DIVIDE, we carry
out extensive experiments on four benchmark datasets comparing with nine
state-of-the-art MvC methods in both complete and incomplete MvC settings
Precoding-based blind separation of MIMO FIR mixtures
This paper focuses on the problem of blind separation of sources mixed by multi-input multi-output finite impulse response channels, which is also called convolutive blind source separation (BSS) in short. This problem has been intensively studied in the context that the sources possess certain favourable properties, such as independence and sparsity. However, these properties may not exist in some practical applications. In this paper, we propose a precoding-based convolutive BSS method, which can deal with mutually correlated sources without requiring the sources to be sparse. It is also applicable to mutually independent sources. In the proposed method, the sources are preprocessed in transmitters prior to transmission by order-one precoders. At the receiving side, the second-order statistics of the sources and the Z -domain features of the precoders are exploited to estimate the coded signals, from which the sources are recovered. Simulation results demonstrate the effectiveness of the new convolutive BSS method
Cross-modal Active Complementary Learning with Self-refining Correspondence
Recently, image-text matching has attracted more and more attention from
academia and industry, which is fundamental to understanding the latent
correspondence across visual and textual modalities. However, most existing
methods implicitly assume the training pairs are well-aligned while ignoring
the ubiquitous annotation noise, a.k.a noisy correspondence (NC), thereby
inevitably leading to a performance drop. Although some methods attempt to
address such noise, they still face two challenging problems: excessive
memorizing/overfitting and unreliable correction for NC, especially under high
noise. To address the two problems, we propose a generalized Cross-modal Robust
Complementary Learning framework (CRCL), which benefits from a novel Active
Complementary Loss (ACL) and an efficient Self-refining Correspondence
Correction (SCC) to improve the robustness of existing methods. Specifically,
ACL exploits active and complementary learning losses to reduce the risk of
providing erroneous supervision, leading to theoretically and experimentally
demonstrated robustness against NC. SCC utilizes multiple self-refining
processes with momentum correction to enlarge the receptive field for
correcting correspondences, thereby alleviating error accumulation and
achieving accurate and stable corrections. We carry out extensive experiments
on three image-text benchmarks, i.e., Flickr30K, MS-COCO, and CC152K, to verify
the superior robustness of our CRCL against synthetic and real-world noisy
correspondences.Comment: This paper is accepted by NeurIPS 202
Husformer: A Multi-Modal Transformer for Multi-Modal Human State Recognition
Human state recognition is a critical topic with pervasive and important
applications in human-machine systems.Multi-modal fusion, the combination of
metrics from multiple data sources, has been shown as a sound method for
improving the recognition performance. However, while promising results have
been reported by recent multi-modal-based models, they generally fail to
leverage the sophisticated fusion strategies that would model sufficient
cross-modal interactions when producing the fusion representation; instead,
current methods rely on lengthy and inconsistent data preprocessing and feature
crafting. To address this limitation, we propose an end-to-end multi-modal
transformer framework for multi-modal human state recognition called
Husformer.Specifically, we propose to use cross-modal transformers, which
inspire one modality to reinforce itself through directly attending to latent
relevance revealed in other modalities, to fuse different modalities while
ensuring sufficient awareness of the cross-modal interactions introduced.
Subsequently, we utilize a self-attention transformer to further prioritize
contextual information in the fusion representation. Using two such attention
mechanisms enables effective and adaptive adjustments to noise and
interruptions in multi-modal signals during the fusion process and in relation
to high-level features. Extensive experiments on two human emotion corpora
(DEAP and WESAD) and two cognitive workload datasets (MOCAS and CogLoad)
demonstrate that in the recognition of human state, our Husformer outperforms
both state-of-the-art multi-modal baselines and the use of a single modality by
a large margin, especially when dealing with raw multi-modal signals. We also
conducted an ablation study to show the benefits of each component in
Husformer
A Spatial-channel-temporal-fused Attention for Spiking Neural Networks
Spiking neural networks (SNNs) mimic brain computational strategies, and
exhibit substantial capabilities in spatiotemporal information processing. As
an essential factor for human perception, visual attention refers to the
dynamic selection process of salient regions in biological vision systems.
Although mechanisms of visual attention have achieved great success in computer
vision, they are rarely introduced into SNNs. Inspired by experimental
observations on predictive attentional remapping, we here propose a new
spatial-channel-temporal-fused attention (SCTFA) module that can guide SNNs to
efficiently capture underlying target regions by utilizing historically
accumulated spatial-channel information. Through a systematic evaluation on
three event stream datasets (DVS Gesture, SL-Animals-DVS and MNIST-DVS), we
demonstrate that the SNN with the SCTFA module (SCTFA-SNN) not only
significantly outperforms the baseline SNN (BL-SNN) and other two SNN models
with degenerated attention modules, but also achieves competitive accuracy with
existing state-of-the-art methods. Additionally, our detailed analysis shows
that the proposed SCTFA-SNN model has strong robustness to noise and
outstanding stability to incomplete data, while maintaining acceptable
complexity and efficiency. Overall, these findings indicate that appropriately
incorporating cognitive mechanisms of the brain may provide a promising
approach to elevate the capability of SNNs.Comment: 12 pages, 8 figures, 5 tabes; This work has been submitted to the
IEEE for possible publication. Copyright may be transferred without notice,
after which this version may no longer be accessibl
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