Frontiers in Neuroscience最新文献

Spiking Neural Networks (SNNs) offer a paradigm of energy-efficient, event-driven computation that is well-suited for processing asynchronous sensory streams. However, training deep SNNs robustly in an online and continual manner remains a formidable challenge. Standard Backpropagation-through-Time (BPTT) suffers from a prohibitive memory bottleneck due to the storage of temporal histories, while local plasticity rules often fail to balance the trade-off between rapid acquisition of new information and the retention of old knowledge (the stability-plasticity dilemma). Motivated by the tripartite synapse in biological systems, where astrocytes regulate synaptic efficacy over slow timescales, we propose Astrocyte-Gated Multi-Timescale Plasticity (AGMP). AGMP is a scalable, online learning framework that augments eligibility traces with a broadcast teaching signal and a novel astrocyte-mediated gating mechanism. This slow astrocytic variable integrates neuronal activity to dynamically modulate plasticity, suppressing updates in stable regimes while enabling adaptation during distribution shifts. We evaluate AGMP on a comprehensive suite of neuromorphic benchmarks, including N-Caltech101, DVS128 Gesture, and Spiking Heidelberg Digits (SHD). Experimental results demonstrate that AGMP achieves accuracy competitive with offline BPTT while maintaining constant $O\left(1\right)$ temporal memory complexity. Furthermore, in rigorous Class-Incremental Continual Learning scenarios (e.g., Split CIFAR-100), AGMP significantly mitigates catastrophic forgetting without requiring replay buffers, outperforming state-of-the-art online learning rules. This work provides a biologically grounded, hardware-friendly path toward autonomous learning agents capable of lifelong adaptation.

Introduction: Resting-state functional magnetic resonance imaging (rs-fMRI) is a widely used non-invasive technique for investigating brain function and identifying potential disease biomarkers. Compared with task-based fMRI, rs-fMRI is easier to acquire because it does not require explicit task paradigms. However, functional connectivity measures derived from rs-fMRI often exhibit poor reliability, which substantially limits their clinical applicability.

Methods: To address this limitation, we propose a novel method termed time-enhanced functional connectivity, which improves reliability by identifying and removing poor-quality time points from rs-fMRI time series. This approach aims to enhance the quality of functional connectivity estimation without extending scan duration or relying on dataset-specific constraints.

Results: Experimental results demonstrate that the proposed method significantly improves performance in downstream machine learning tasks, such as sex classification. In addition, time-enhanced functional connectivity yields higher test-retest reliability and reveals more pronounced statistical differences between groups compared with conventional functional connectivity measures.

Discussion: These findings suggest that selectively removing low-quality time points provides a practical and effective strategy for improving the reliability and sensitivity of functional connectivity measurements in rs-fMRI, thereby enhancing their potential utility in both neuroscience research and clinical applications.

The autonomic nervous system (ANS) is a central regulator of cardiovascular function, coordinating involuntary control of heart rate, vascular tone, and blood pressure through its sympathetic (SNS) and parasympathetic (PNS) subdivisions. The SNS mediates the "fight or flight" response via catecholamines, increasing heart rate, contractility, and vasoconstriction, whereas the PNS promotes restorative processes through acetylcholine, decreasing heart rate and enhancing vasodilation. Nitric oxide further modulates vascular tone and autonomic balance, serving as a key neuromodulator. Assessment of cardiovascular autonomic function relies on heart rate variability, baroreflex sensitivity, and other physiological tests, which provide insight into the dynamic interplay between sympathetic and parasympathetic activity. Dysregulation of the ANS contributes to cardiovascular pathologies, including cardiovascular autonomic neuropathy, hypertension, and heart failure, where sympathetic overactivity and impaired parasympathetic modulation exacerbate disease progression. Pharmacologic interventions, such as β-blockers and ivabradine, alongside non-pharmacologic approaches, including structured exercise and respiratory training, aim to restore autonomic balance and improve clinical outcomes. Understanding the exact mechanisms of autonomic neurotransmission is essential for identifying novel therapeutic targets and optimizing cardiovascular care. Future research integrating molecular, genetic, and systems-level analyses will further elucidate autonomic regulation, guiding personalized interventions to mitigate cardiovascular morbidity and mortality.

Aim: This study aimed to investigate the brain activity involved in visually evoked auditory response (vEAR) using high-density electroencephalography (EEG) and explore the differences in connections between visual and auditory cortex.

Methods: Thirty-seven subjects with vEAR and Thirty four subjects without vEAR, matched by age and gender, were recruited. The hearing threshold, years of education, and the Trail Making Test (versions A and B) results were collected from all patients. All participants underwent a 256-channel EEG, and neurophysiological differences were evaluated using standardized low-resolution brain electromagnetic tomography (sLORETA).

Results: Trail Making Test scores in vEAR group were 17.3 ± 2.70 s and 26.28 ± 3.83 s for versions A and B, respectively, and 20.13 ± 6.88 s and 46.65 ± 5.971 s, respectively, in non-vEAR group. Significant difference in version B score was observed between two groups. Compared with non-vEAR group, significant differences were observed at the delta (p = 0.005), theta (p = 0.016), alpha1 (p = 0.016), alpha2 (p = 0.011), beta3 (p = 0.024), and gamma (p = 0.048) frequency bands in vEAR group. In addition, vEAR group showed significantly reduced activation of the posterior cingulate cortex (BA31, p = 0.0306) at the alpha2 frequency band and the insular cortex (BA13, p = 0.0306) at the beta2 frequency band. Moreover, significantly increased synchronized beta3 connectivity was found between the right part of the cingulate cortex (BA30) and the right primary auditory cortex (BA41) in vEAR group (p = 0.045).

Conclusion: vEAR group showed stronger regional connection characteristics than non-vEAR group, which may represent a neural signature associated with vEAR.

Background/objectives: The existing literature on normative data for accommodative facility (AF) in African populations is limited to high school students. There is no normative data for vergence facility (VF) in African children, so there are no benchmarks for comparison in case analysis, diagnosis, and management. The study aimed to establish normative data for AF in children aged 8-12 years. Additionally, the study sought to determine normative data for VF in children aged 8-17 years in the Cape Coast metropolis, Ghana.

Methods: Normal children (510) were recruited through a comprehensive oculo-visual examination of 2,300 basic school-going children, aged 8-17 years. AF was measured with a ± 2D flipper lens for 1 min. VF was measured with a 3-base-in/12 base-out flipper prism for 1 min. Normative data were derived using the median with interquartile ranges (IQR) and considering the spread of data within the minimum and maximum ranges.

Results: A median value of 13 cpm with IQR of 4 cpm was determined for monocular accommodative facility (MAF). The normative central tendency for MAF for school children 8-17 years ranges from 9 to 17 cpm; data were widely spread, with a minimum of 4 and a maximum of 20 cpm. A median value of 13 cpm with IQR of 3 cpm was determined for the binocular accommodative facility (BAF). The normative central tendency for BAF for school children aged 8-17 years ranged from 9 to 14 cpm; data were widely spread, with a minimum of 5 and a maximum of 20 cpm. A median value of 14 cpm with IQR of 4 cpm was determined for VF. The normative central tendency for VF for school children 8-17 years ranged from 10 to 18 cpm; data were widely spread, with a minimum of 6 and a maximum of 21 cpm.

Conclusion: The normative data apply only to similarly aged Ghanaian children and serve as standards for comparison to clinical data for MAF, BAF, and VF during case analysis.

This paper presents a neuromorphic, event-driven tactile sensing system for soft, large-area skin, based on the Dynamic Vision Sensors (DVS) integrated with a flexible silicone optical waveguide skin. Instead of repetitively scanning embedded photoreceivers, this design uses a stereo vision setup comprising two DVS cameras looking sideways through the skin. Such a design produces events as changes in brightness are detected, and estimates press positions on the 2D skin surface through triangulation, utilizing Density-Based Spatial Clustering of Applications with Noise (DBSCAN) to find the center of mass of contact events resulting from pressing actions. The system is evaluated over a 4,620 mm probed area of the skin using a meander raster scan. Across 95 % of the presses visible to both cameras, the press localization achieved a Root-Mean-Squared Error (RMSE) of 4.66 mm. The results highlight the potential of this approach for wide-area flexible and responsive tactile sensors in soft robotics and interactive environments. Moreover, we examined how the system performs when the amount of event data is strongly reduced. Using stochastic down-sampling, the event stream was reduced to 1/1,024 of its original size. Under this extreme reduction, the average localization error increased only slightly (from 4.66 mm to 9.33 mm), and the system still produced valid press localizations for 85 % of the trials. This reduction in pass rate is expected, as some presses no longer produce enough events to form a reliable cluster for triangulation. These results show that the sensing approach remains functional even with very sparse event data, which is promising for reducing power consumption and computational load in future implementations. The system exhibits a detection latency distribution with a characteristic width of 31 ms.

Introduction: Functional near-infrared spectroscopy (fNIRS) has emerged as a promising neuroimaging modality for investigating cortical activity in auditory and vestibular domains. Its portability, device compatibility, and motion tolerance make it particularly suited for use in populations that are challenging to study with conventional neuroimaging techniques, such as infants and cochlear implant (CI) users. The present study aims to explore the potential and limitations of this neuroimaging technique in the audiological and vestibular fields, offering an integrated perspective across pediatric, adult and elderly populations.

Methods: A narrative review of studies using fNIRS in hearing loss, tinnitus, and vestibular disorders was conducted through searches in PubMed and Scopus up to March 2025. Studies were included if they employed fNIRS to investigate cortical responses in individuals with diagnosed hearing loss, chronic tinnitus or to investigate vestibular function.

Results: A total of 60 studies were reviewed: 36 on hearing loss, 11 on tinnitus, and 13 on vestibular disorders. In hearing research, fNIRS successfully identified cortical activation patterns related to auditory perception, speech processing, and cross-modal plasticity in CI users across development, adulthood and aging. The technique showed prognostic potential in predicting CI outcomes and monitoring listening effort and cognitive load. In tinnitus research, fNIRS consistently demonstrate hyper-activation in the auditory cortex and altered functional connectivity with frontal-limbic networks, reflecting sensory, cognitive, and emotional involvement. The technique was sensitive to treatment effects following interventions such as transcranial stimulation, acupuncture, and cochlear implantation. In vestibular research, fNIRS enabled the mapping of cortical networks involved in balance control and multisensory integration during various stimulation paradigms, including caloric testing, motion platforms, and optic flow in virtual environments. Although current applications are mostly exploratory, findings suggest fNIRS can capture vestibular-related cortical activity in real-world conditions.

Conclusion: fNIRS offers a valuable, non-invasive, and ecologically valid method for investigating auditory and vestibular function across the lifespan. In hearing and tinnitus research, it shows strong potential for clinical translation, especially if methodological standardization is achieved. Applications in vestibular research remain preliminary but promising.

Introduction: Perception operates as rhythmically structured sampling in which temporal predictions determine when incoming signals are weighted. Fixational eye movements carry opposing consequences, enhancing acuity yet inducing brief peri-saccadic suppression, suggesting that their timing is paced by expected, salient rhythms. Auditory scenes can be parsed into competing streams that unfold over time. If fixation dynamics are shaped by temporal expectation, and auditory streaming imposes a percept-dependent temporal structure on otherwise identical acoustics, then fixational eye movements might provide a window into how listeners parse sound over time. We asked whether fixational eye movements reflect the perceived rather than the physical temporal organization of an ambiguous ABA- pattern.

Methods: While listeners fixated and either attended High, Low, or All tones (Experiment 1, n = 15) or freely reported their percept (Experiment 2, n = 15), we recorded binocular eye position (500 Hz) and quantified microsaccade (MS) dynamics and eye-velocity spectra.

Results: Across both experiments, eye-velocity spectra showed a percept-dependent redistribution between 2 and 4 Hz, with relative power shifting with the instructed/reported stream. A normalized 4-2 Hz index (ΔPSD) separated Low-tone from High-tone percepts across procedures. Time-resolved analyses further revealed within-trial waxing-and-waning of 2 vs. 4 Hz dominance, consistent with bistable fluctuations in maintaining a stream. Moreover, microsaccade reaction time (msRT), aligned to the onset of the sound sequence, differed significantly depending on the percept.

Discussion: These findings extend oculomotor inhibition beyond discrete events, positioning fixation dynamics as a sensitive, report-free marker of auditory scene organization. We discuss mechanistic links to temporal attention and active sensing, and implications for a multisensory timing framework.