Electricity theft is a major source of non-technical losses and poses a significant operational challenge for distribution system operators. While advanced metering infrastructure offers large-scale electricity consumption (EC) data, existing deep learning methods remain computationally expensive, prone to overfitting, and sensitive to class imbalance and high-dimensional inputs. This work proposes a computationally efficient surrogate-activated spiking neural network (SSNet) for electricity theft detection (ETD). SSNet employs leaky integrate-and-fire (LIF) neurons with surrogate gradients to capture temporal patterns in discrete EC measurements while substantially reducing computational overhead compared with conventional deep neural networks. To mitigate class imbalance, the proximity-weighted synthetic oversampling (ProWSyn) technique is integrated to generate informative minority-class samples. In addition, a set of discriminative time-series features is extracted using the time series feature extraction library (TSFEL) to address high-dimensionality and enhance the separability of theft and non-theft profiles. SSNet is evaluated against several deep learning baselines and demonstrates superior performance, achieving 96.64% accuracy, 99.34% area under the curve (AUC), and 93.28% Matthews Correlation Coefficient (MCC). Moreover, SSNet operations per second (OPs) comparison with the floating-point operations per second (FLOPs) of deep learning networks demonstrates the sparsity and energy efficiency of the proposed network. The results highlight the potential of spiking neural architectures as efficient and high-performance solutions for large-scale ETD.

Recently, automated Interictal Epileptiform Discharge (IED) detection has attracted significant attention as a challenging predictive data analysis task aimed at improving early epilepsy diagnosis. Automated IED detection simplifies visual inspection and assists clinicians in identifying crucial IED waveform patterns in Electroencephalographic (EEG) brain activities. However, IEDs are vastly outnumbered by non-IED or background data, directly training on such data leads to a detrimental impact on model performance. Moreover, most existing methods lack high precision when tested on cross-institution datasets and this will lead to time wasted by the neurologist having to look at predicted IEDs that are not IEDs. To address these issues, we propose a novel approach that employs probabilistic diffusion models for data augmentation alongside Area Under the Precision–Recall Curve (AUPRC) maximization methods. This approach effectively addresses data scarcity and imbalance by combining real and synthesized IEDs to fully balance the training dataset, resulting in a 4.5% increase in precision and a 0.7% improvement in the F1-score during within-data evaluation. Additionally, it proves to be robust and generalizable, as evidenced by a 40.04% and 18.74% enhancement in precision and F1-score when applied to cross-data evaluation using data from another hospital.

The Spiking Neural Network (SNN) has drawn increasing attention for its energy-efficient, event-driven processing and biological plausibility. To train SNNs via backpropagation, surrogate gradients are used to approximate the non-differentiable spike function, but they only maintain nonzero derivatives within a narrow range of membrane potentials near the firing threshold—referred to as the surrogate gradient support width gamma. We identify a major challenge, termed the dilemma of gamma: a relatively large gamma leads to overactivation, characterized by excessive neuron firing, which in turn increases energy consumption, whereas a small gamma causes vanishing gradients and weakens temporal dependencies. To address this, we propose a temporal Inhibitory Leaky Integrate-and-Fire (ILIF) neuron model, inspired by biological inhibitory mechanisms. This model incorporates interconnected inhibitory units for membrane potential and current, effectively mitigating overactivation while preserving gradient propagation. Theoretical analysis demonstrates ILIF’s effectiveness in overcoming the gamma dilemma, and extensive experiments on multiple datasets show that ILIF improves energy efficiency by reducing firing rates, stabilizes training, and enhances accuracy. The code is available at github.com/kaisun1/ILIF.

Forecasting events in multichannel electroencephalographic (EEG) brain recordings remains a formidable task given the noise and complexity in neural systems. Here we compare two dynamical systems motivated approaches to forecasting brain events. The first follows previous state-of-the-art (SOTA) research of time-series features of critical slowing down (autocorrelation, variance) as biomarkers of impending events. The second involves a novel long-term-short-term (LSTM) neural network-based filter to estimate the neurophysiological feature variables of mathematical neural population models of the EEG. Previous critical slowing research presented forecasting results for the best EEG channel, however, in practice the best channel cannot be known a priori. Therefore, here we also consider forecasting by combining the different features across the different EEG channels using logistic regression. One application area where forecasting brain events is important is epileptic seizure prediction. Epileptic seizures are debilitating events and up to 50 million people worldwide with drug-resistant epilepsy could benefit by receiving warnings of impending seizures. Here we apply the above methods to a long-term epileptic seizure prediction dataset from 15 patients. It was found that seizure forecasting with (1) logistic regression and critical slowing features, (2) logistic regression and neurophysiological features, and (3) the best channel using critical slowing features, respectively, achieved median sensitivities of 70,54 and $67 \%$ and median time in low seizure risk of 84,84, and $81 \%$. This indicates that a multichannel model approach can perform as well as the best channel approach, removing the need to find the best channel. It also suggests neurophysiological features could be used to increase time in low risk. Future work exploring other features, machine learning models and their various combinations could yield further improvements.

This paper introduces a new inference-based framework for time-resolved chaos analysis of brain models and demonstrates its application to focal epileptic seizures. The intermittent nature of epileptic seizures exhibits an unpredictable behavior that shares some characteristics with chaotic systems. Epilepsy research often uses concepts from chaos theory and nonlinear dynamics to better understand the mechanisms of seizure initiation, propagation, and termination. Traditional methods estimate the degree of chaos in brain dynamics directly from time series data. This provides neither an accurate estimate of the chaos nor insights into the key neurophysiological processes driving brain dynamics during epileptic seizures. Therefore, this study proposes a new method to calculate Lyapunov spectra by combining time series data with neurophysiological brain models and a specialised nonlinear Kalman filter. This study thereby provides insights into the temporal evolution of chaos in epileptogenic regions during epileptic seizures and identifies external inputs from adjacent and distant brain regions as major drivers of altered levels of chaoticity. This paper underscores the importance of fusion of neurophysiological computational models and clinical time series data in understanding the dynamic and chaotic aspects of epilepsy to develop more effective diagnostic and treatment strategies.

Even though the engagement in self-regulated learning (SRL) has been shown to boost academic performance, SRL skills of many learners remain underdeveloped. They often struggle to productively navigate multiple cognitive, affective, metacognitive and motivational (CAMM) processes in SRL. To provide learners with the required SRL support, it is essential to understand how learners enact CAMM processes as they study. More research is needed to advance the measurement of affective and motivational processes within SRL, and investigate how these processes influence learners’ cognition and metacognition. With this in mind, we conducted a lab study involving 22 university students who worked on a 45-minute reading and writing task in digital learning environment. We used a wearable electroencephalogram device to record learner academic emotional and motivational states, and digital trace data to record learner cognitive and metacognitive processes. We harnessed time series prediction and explainable artificial intelligence methods to examine how learner’s emotional and motivational states influence their choice of cognitive and metacognitive processes. Our results indicate that emotional and motivational states can predict learners’ use of low cognitive, high cognitive and metacognitive processes with considerable classification accuracy (F1 > 0.73), and that higher values of interest, engagement and excitement promote cognitive processing.

Deep learning for automated interictal epileptiform discharge (IED) detection has been topical with many published papers in recent years. All existing works viewed EEG signals as time-series and developed specific models for IED classification; however, general time-series classification (TSC) methods were not considered. Moreover, none of these methods were evaluated on any public datasets, making direct comparisons challenging. This paper explored two state-of-the-art convolutional-based TSC algorithms, InceptionTime and Minirocket, on IED detection. We fine-tuned and cross-evaluated them on a public (Temple University Events - TUEV) and two private datasets and provided ready metrics for benchmarking future work. We observed that the optimal parameters correlated with the clinical duration of an IED and achieved the best area under precision-recall curve (AUPRC) of 0.98 and F1 of 0.80 on the private datasets, respectively. The AUPRC and F1 on the TUEV dataset were 0.99 and 0.97, respectively. While algorithms trained on the private sets maintained their performance when tested on the TUEV data, those trained on TUEV could not generalize well to the private data. These results emerge from differences in the class distributions across datasets and indicate a need for public datasets with a better diversity of IED waveforms, background activities and artifacts to facilitate standardization and benchmarking of algorithms.

Recent work presented a framework for space-time-resolved neurophysiological process imaging that augments existing electromagnetic source imaging techniques. In particular, a nonlinear Analytic Kalman filter (AKF) has been developed to efficiently infer the states and parameters of neural mass models believed to underlie the generation of electromagnetic source currents. Unfortunately, as the initialization determines the performance of the Kalman filter, and the ground truth is typically unavailable for initialization, this framework might produce suboptimal results unless significant effort is spent on tuning the initialization. Notably, the relation between the initialization and overall filter performance is only given implicitly and is expensive to evaluate; implying that conventional optimization techniques, e.g. gradient or sampling based, are inapplicable. To address this problem, a novel efficient framework based on blackbox optimization has been developed to find the optimal initialization by reducing the signal prediction error. Multiple state-of-the-art optimization methods were compared and distinctively, Gaussian process optimization decreased the objective function by 82.1% and parameter estimation error by 62.5% on average with the simulation data compared to no optimization applied. The framework took only 1.6[Formula: see text]h and reduced the objective function by an average of 13.2% on 3.75[Formula: see text]min 4714-source channel magnetoencephalography data. This yields an improved method of neurophysiological process imaging that can be used to uncover complex underpinnings of brain dynamics.

Vicious cycles of anxiety responses underlie the onset of increasingly prevalent and highly impairing anxiety disorders and also contribute to their maintenance. Our goal is to evaluate whether different anxiety responses are evident in temporal patterns of physiological and behavioral features. Consequently, we established a rich multimodal-multisensor dataset of cardiac, electrodermal, movement, posture, and speech measures from 95 young adults during two anxiety experiments that induce social anxiety and bug-phobic anxiety. A subset of this dataset is publicly available at “Anxiety Phases Dataset” Figshare repository. We adopted a generalized mixed model approach and found that 10 out of 14 feature trajectories modeled for high- and low-anxiety groups differ significantly at 0.001 level in magnitude, creating at least two temporal phases in both groups. Further differences in magnitude, duration and the number of phases were observed for responses of confrontation, safety behaviors, escape, and avoidance in the high-anxiety group. Our findings contribute to the long-term aim of designing multimodal systems that have great potential to reduce the impacts of anxiety disorders and improve therapy.

We present the results of a model inversion algorithm for electrocorticography (ECoG) data recorded during epileptic seizures. The states and parameters of neural mass models were tracked during a total of over 3000 seizures from twelve patients with focal epilepsy. These models provide an estimate of the effective connectivity within intracortical circuits over the time course of seizures. Observing the dynamics of effective connectivity provides insight into mechanisms of seizures. Estimation of patients seizure dynamics revealed: 1) a highly stereotyped pattern of evolution for each patient, 2) distinct sub-groups of onset mechanisms amongst patients, and 3) different offset mechanisms for long and short seizures. Stereotypical dynamics suggest that, once initiated, seizures follow a deterministic path through the parameter space of a neural model. Furthermore, distinct sub-populations of patients were identified based on characteristic motifs in the dynamics at seizure onset. There were also distinct patterns between long and short duration seizures that were related to seizure offset. Understanding how these different patterns of seizure evolution arise may provide new insights into brain function and guide treatment for epilepsy, since specific therapies may have preferential effects on the various parameters that could potentially be individualized. Methods that unite computational models with data provide a powerful means to generate testable hypotheses for further experimental research. This work provides a demonstration that the hidden connectivity parameters of a neural mass model can be dynamically inferred from data. Our results underscore the power of theoretical models to inform epilepsy management. It is our hope that this work guides further efforts to apply computational models to clinical data.

Detecting seizure using brain neuroactivations recorded by intracranial electroencephalogram (iEEG) has been widely used for monitoring, diagnosing, and closed-loop therapy of epileptic patients, however, computational efficiency gains are needed if state-of-the-art methods are to be implemented in implanted devices. We present a novel method for automatic seizure detection based on iEEG data that outperforms current state-of-the-art seizure detection methods in terms of computational efficiency while maintaining the accuracy. The proposed algorithm incorporates an automatic channel selection (ACS) engine as a pre-processing stage to the seizure detection procedure. The ACS engine consists of supervised classifiers which aim to find iEEG channels which contribute the most to a seizure. Seizure detection stage involves feature extraction and classification. Feature extraction is performed in both frequency and time domains where spectral power and correlation between channel pairs are calculated. Random Forest is used in classification of interictal, ictal and early ictal periods of iEEG signals. Seizure detection in this paper is retrospective and patient-specific. iEEG data is accessed via Kaggle, provided by International Epilepsy Electro-physiology Portal. The dataset includes a training set of 6.5 h of interictal data and 41 min in ictal data and a test set of 9.14 h. Compared to the state-of-the-art on the same dataset, we achieve 2 times faster in run-time seizure detection. The proposed model is able to detect a seizure onset at 89.40% sensitivity and 89.24% specificity with a mean detection delay of 2.63 s for the test set. The area under the ROC curve (AUC) is 96.94%, that is comparable to the current state-of-the-art with AUC of 96.29%.

Data-driven model-based analysis of electrophysiological data is an emerging technique for understanding the mechanisms of seizures. Model-based analysis enables tracking of hidden brain states that are represented by the dynamics of neural mass models. Neural mass models describe the mean firing rates and mean membrane potentials of populations of neurons. Various neural mass models exist with different levels of complexity and realism. An ideal data-driven model-based analysis framework will incorporate the most realistic model possible, enabling accurate imaging of the physiological variables. However, models must be sufficiently parsimonious to enable tracking of important variables using data. This paper provides tools to inform the realism versus parsimony trade-off, the Bayesian Cramer-Rao (lower) Bound (BCRB). We demonstrate how the BCRB can be used to assess the feasibility of using various popular neural mass models to track epilepsy-related dynamics via stochastic filtering methods. A series of simulations show how optimal state estimates relate to measurement noise, model error and initial state uncertainty. We also demonstrate that state estimation accuracy will vary between seizure-like and normal rhythms. The performance of the extended Kalman filter (EKF) is assessed against the BCRB. This work lays a foundation for assessing feasibility of model-based analysis. We discuss how the framework can be used to design experiments to better understand epilepsy.

The expansion of frontiers in neural engineering is dependent on the ability to track, detect and predict dynamics in neural tissue. Recent innovations to elucidate information from electrical recordings of brain dynamics, such as epileptic seizure prediction, have involved switching to an active probing paradigm using electrically evoked recordings rather than traditional passive measurements. This paper positions the advantage of probing in terms of information extraction, by using a coupled oscillator Kuramoto model to represent brain dynamics. While active probing performs better at observing underlying system synchrony in Kuramoto networks, especially in non-Gaussian measurement environments, the benefits diminish with increasing relative size of electrode spatial resolution compared to synchrony area. This suggests probing will be useful for improved characterization of synchrony for suitably dense electrode recordings.

Bayesian spiking neurons (BSNs) provide a probabilistic interpretation of how neurons perform inference and learning. Online learning in BSNs typically involves parameter estimation based on maximum-likelihood expectation-maximization (ML-EM) which is computationally slow and limits the potential of studying networks of BSNs. An online learning algorithm, fast learning (FL), is presented that is more computationally efficient than the benchmark ML-EM for a fixed number of time steps as the number of inputs to a BSN increases (e.g., 16.5 times faster run times for 20 inputs). Although ML-EM appears to converge 2.0 to 3.6 times faster than FL, the computational cost of ML-EM means that ML-EM takes longer to simulate to convergence than FL. FL also provides reasonable convergence performance that is robust to initialization of parameter estimates that are far from the true parameter values. However, parameter estimation depends on the range of true parameter values. Nevertheless, for a physiologically meaningful range of parameter values, FL gives very good average estimation accuracy, despite its approximate nature. The FL algorithm therefore provides an efficient tool, complementary to ML-EM, for exploring BSN networks in more detail in order to better understand their biological relevance. Moreover, the simplicity of the FL algorithm means it can be easily implemented in neuromorphic VLSI such that one can take advantage of the energy-efficient spike coding of BSNs.

Bayesian Spiking Neurons (BSNs) provide a probabilistic interpretation of how neurons can perform inference and learning. Learning in a single BSN can be formulated as an online maximum-likelihood expectation-maximisation (ML-EM) algorithm. This form of learning is quite slow. Here, an alternative to this learning algorithm, called Fast Learning (FL), is presented. The FL algorithm is shown to have acceptable convergence performance when compared to the ML-EM algorithm. Moreover, for our implementations the FL algorithm is approximately 25 times faster than the ML-EM algorithm. Although only approximate, the FL algorithm therefore makes learning in hierarchical BSN networks much more tractable.