Search Results (94)

Background: Short-term facilitation (STF) is a key form of synaptic plasticity driven by activity-dependent increases in presynaptic release probability. However, estimating core synaptic parameters—quantal size ($q$), vesicle pool size ($N$), and release probability ($p_i$)—remains challenging due to nonlinear dynamics and unobservable presynaptic states, limiting the applicability of conventional methods. Methods: We developed a fast analytical framework based on first- and second-order statistical moments of evoked EPSCs, including mean, variance, and cross-stimulus covariance. By constructing composite moment relationships, latent variables were algebraically eliminated, yielding closed-form estimators of synaptic parameters. To improve robustness under strong facilitation, a Tsodyks–Markram (T–M) model-based calibration step was introduced to refine $N$ and $p_i$ using the estimated $q$ as a constraint. Results: Applied to hippocampal CA3–CA1 synapses, the method produced accurate and stable estimates of q across varying noise and sampling conditions. Incorporation of cross-stimulus covariance enabled effective characterization of structured variability that is neglected in classical approaches. While direct estimates of $N$ and $p_i$ showed dispersion, T–M calibration significantly improved stability and physiological consistency. Compared with mean–variance analysis, the proposed method achieved superior performance under facilitating conditions. Conclusions: This hybrid framework enables rapid and reliable estimation of synaptic parameters in STF synapses by exploiting second-order statistical structure. It provides a practical tool for investigating presynaptic mechanisms and may facilitate quantitative studies of synaptic dysfunction in neurological and psychiatric disorders. Full article

The formability of AA7021-T4 sheets under changing strain paths was investigated via a novel crystal plasticity model and associated experimentation. The motivation was to advance simulation tools for process design of limited-ductility 7xxx alloys, with important applications in the automotive industry. Pre-strains were applied in biaxial and plane-strain tension using Marciniak tooling, followed by uniaxial tensile testing to failure. Strain measurements were obtained by digital image correlation, while dislocation structures were characterized using high-resolution EBSD. A strain-gradient elasto-plastic self-consistent (SG-EPSC) model incorporating dislocation density-based hardening and backstress from geometrically necessary dislocations (GNDs) was employed to predict the stress–strain response and dislocation evolution. Results showed that pre-strains normalized by forming limit diagram (FLD) criteria produced comparable residual uniaxial tensile ductility, regardless of whether biaxial or plane-strain tension was applied, despite differences in absolute pre-strain levels. Both experiments and simulations revealed that GND density correlated with remaining ductility better than simple strain magnitude values. These findings indicate that AA7021-T4 retains greater formability under multiaxial strain path changes than expected from FLD-based considerations. The combined experimental–modeling approach demonstrates the value of incorporating microstructure-based variables, such as GNDs, into forming assessments of high-strength aluminum alloys, with implications for their potential use in automotive lightweighting development. Full article

The ascomycete fungus Clonostachys rosea is a promising biocontrol agent against root-knot nematodes. To develop a more effective and stable biocontrol strategy, we rationally constructed a co-culture system by partnering C. rosea with the plant growth-promoting bacterium Bacillus velezensis. Through systematic optimization of the medium and inoculation protocol, the co-culture demonstrated significantly enhanced performance, achieving 95.3% mortality of Meloidogyne incognita juveniles, a 78.0% increase in tomato shoot dry weight, and 69.2% disease control efficacy in pot trials. Metabolomic profiling indicated that the co-culture triggered a distinct metabolic profile compared to the respective monocultures. The enhanced efficacy was associated with the accumulation of two functional metabolite groups. First, the co-culture synergistically accumulated direct-effect compounds with reported nematicidal (e.g., daidzin, L-tryptophan) and plant-growth-promoting (e.g., isopentenyladenine, melatonin, and indole-3-propionic acid) activities. In parallel, L-proline emerged as a critical microbial interaction modulator. Targeted quantification showed a clear proline abundance gradient: highest in the C. rosea monoculture, intermediate in co-culture, and lowest in the B. velezensis monoculture. This gradient suggests that proline produced by C. rosea is likely utilized by B. velezensis, a finding further supported by the observation that proline enhanced bacterial biofilm formation and upregulated the matrix genes epsC and tasA. Accordingly, the co-culture itself formed significantly more robust biofilms. Thus, the enhanced biocontrol can be attributed to synergistic metabolite accumulation together with proline-mediated fitness gains in the bacterial partner, establishing a metabolic basis for rationally engineering microbial consortia. Full article

The Wnt/β-catenin signaling pathway is involved in regulating the pluripotency of mammalian stem cells. Fine-tuning of Wnt/β-catenin modulates the transition of naïve, formative or primed states with distinct lineage bias. However, its specific function in large domestic animals such as bovines remains unclear. Here we systematically investigated the role of Wnt/β-catenin signaling and its key effector TCF1 in bovine expanded pluripotent stem cells (bEPSCs) using a combination of small molecules (CHIR99021, XAV939, IWR-1, iCRT3). The results showed that prolonged Wnt/β-catenin activation with CHIR99021 induced morphological changes and downregulated the expression of core pluripotency genes POU5F1 (OCT4) and SOX2 in bEPSCs, while the existence of Wnt/β-catenin inhibitors XAV939 and IWR-1 upregulated these two genes. Knockdown of TCF1, a major nuclear effector of CTNNB1 (β-catenin), reduced the expression of pluripotency genes (POU5F1, SOX2) and key Wnt/β-catenin components (TCF3, LEF1 and CTNNB1). Combined treatment with CHIR99021 and the canonical β-catenin/TCF inhibitor iCRT3 resulted in the overactivation of Wnt/β-catenin signaling, and promoted the expression of core pluripotency genes, revealing extensive rewiring of the Wnt/β-catenin pathway in bovines. Consistent with these findings, global transcriptomics revealed that CHIR99021 combined with iCRT3 enhanced the expression of key pluripotency-related genes and further activated Wnt/β-catenin signaling target genes while simultaneously suppressing mitogenic pathways such as PI3K-Akt and MAPK signaling. Transcriptome profiling also demonstrated that this combination drives bEPSCs toward a hybrid naïve/formative pluripotency state. Together, these results demonstrate that Wnt/β-catenin signaling homeostasis is critical for bovine pluripotency regulation, which provides a foundation for refining livestock stem cell culture conditions and understanding the evolution of pluripotency networks. Full article

Optical synaptic transistors employing polymer dielectrics have emerged as promising building blocks for neuromorphic computing due to their low power consumption and rich photo-induced memory behaviors. While extensive experimental studies have demonstrated various synaptic functions, a unified physical understanding of the coupled charge trapping and ionic polarization processes governing device dynamics remains incomplete. In this work, we develop a unified physical model to investigate optical synaptic behaviors in polymer-based transistors with oxide interlayers. The model explicitly describes the time-dependent evolution of photo-induced charge trapping at the semiconductor–dielectric interface and ionic polarization within the polymer dielectric, which jointly modulate the effective threshold voltage of the transistor channel. Based on this framework, key synaptic functions including excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), and pulse-dependent potentiation are quantitatively reproduced. The model further reveals how dielectric structure and trapping strength govern the transition between short-term and long-term plasticity. This study provides a physically intuitive and experimentally relevant modeling framework for understanding optical synaptic transistors, offering guidance for the rational design and optimization of polymer-based neuromorphic devices. Although simplified, the proposed model captures the essential physics governing optical synaptic behaviors and provides a general framework applicable to a wide class of ion–electronic neuromorphic devices. Experimental measurements are used as physically motivated proxies to validate the multi-timescale structure of the model rather than direct numerical fitting. Full article

Patients with systemic lupus erythematosus (SLE) often suffer from chronic pain due to a lack of effective and safe analgesics. In this study, we investigated the role of spinal TLR7 in the pathogenesis of chronic pain using female MRL lupus prone (MRL/lpr) mice, a SLE mouse model. We found that from 11 weeks of age, MRL/lpr mice exhibited thermal hypersensitivity in the hind paw, which reached plateau between 14 and 16 weeks. MRL/lpr mice with thermal hypersensitivity had increased expression of TLR7 in the spinal dorsal horn. TLR7 was located in microglia in this region. Intrathecal administration of a TLR7 antagonist attenuated the thermal hypersensitivity in MRL/lpr mice, while administration of the TLR7 agonist induced thermal hypersensitivity in control mice. Pharmacological activation of spinal TLR7 in control mice recapitulated molecular, synaptic, and cellular changes in the spinal dorsal horn of MRL/lpr mice with thermal hyperalgesia. These alterations included activation of microglia and astrocytes, increased production of IL-1β and IL-18, upregulated expression of N-type voltage-gated calcium channels (Cav2.2), enhanced glutamatergic synaptic activity, and elevated neuronal activation. Our findings suggest that targeting TLR7 or downstream effectors may represent a promising strategy to alleviate chronic pain induced by SLE. Full article

Organic electrochemical transistors (OECTs) are compelling artificial synapses because mixed ionic–electronic coupling and transport enables low-voltage, analog weight updates that mirror biological plasticity. Here, we engineered solid-state, polymer electrolyte-gated vertical OECTs (vOECTs) and elucidate how electrolyte molecular weight influences synaptic dynamics. Using Pg2T-T as the redox-active channel and pDADMAC polymer electrolytes spanning low- (~100 k), medium- (~300 k), and high- (~500 k) molecular weights, cyclic voltammetry reveals reversible Pg2T-T redox, while peak separation and current density systematically track ion transport kinetics. Increasing electrolyte molecular weight enlarges the transfer curve hysteresis (memory window ΔV_mem from ~0.15 V to ~0.50 V) but suppresses on-current, consistent with slower, more confining ion motion and stabilized partially doped states. Devices exhibit rich short- and long-term plasticity: paired-pulse facilitation (A₂/A₁ ≈ 1.75 at Δt = 50 ms), frequency-dependent EPSCs (low-pass accumulation), cumulative potentiation, and reversible LTP/LTD. A device-aware CrossSim framework built from continuous write/erase cycles (probabilistic LUT) supports Fashion-MNIST inference with high accuracy and bounded update errors (mean −0.02; asymmetry 0.198), validating that measured nonidealities remain algorithm-compatible. These results provide a materials-level handle on polymer–ion coupling to deterministically tailor temporal learning in compact, robust neuromorphic hardware. Full article

We examined whether an increase in synaptic activity resulted in an increase in quantal size at the neuromuscular junction (NMJ) of third-instar Drosophila larvae. Spontaneous miniature excitatory postsynaptic currents (mEPSCs) or miniature excitatory postsynaptic potentials (mEPSPs) were recorded before and after nerve stimulation. We found that prolonged (60 s) or brief (1.25 s) nerve stimulation produced an increase in quantal size; this appears to be a general property of these synapses since it was seen at all four muscle fibers (MFs) used in this study. The effect was examined along Is and Ib terminals by expressing GCaMP in the MF membrane and examining postsynaptic Ca²⁺ signals produced by spontaneous transmitter release. The activity-dependent increase in quantal size occurred at both Is and Ib terminals, and the increase in frequency and amplitude of quantal events at individual synaptic boutons was correlated. Both the increase in quantal size and frequency were found to be dependent upon an increase in postsynaptic Ca²⁺, based on studies in which MFs were preinjected with the Ca²⁺ chelator BAPTA (1,2-Bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid). To examine the effect of postsynaptic activity on glutamate sensitivity, we iontophoresed glutamate pulses at the NMJ and recorded the glutamate-evoked excitatory postsynaptic potentials (gEPSPs). Trains of glutamate pulses produced an increase in gEPSP amplitude; this potentiation was not seen when Ca²⁺ was eliminated from the bath or after inhibiting calmodulin or CaMKII. The activity-dependent increase in quantal size may result from an increase in postsynaptic sensitivity due to activation of CaMKII. Full article

We report Al/ZnO/Al optoelectronic synaptic devices fabricated on c-plane and m-plane sapphire substrates using a sol–gel process. The devices exhibit essential synaptic behaviors such as excitatory postsynaptic current modulation, paired-pulse facilitation, and long-term learning–forgetting dynamics described by Wickelgren’s power law. Comparative analysis reveals that substrate orientation strongly influences memory performance: devices on m-plane consistently show higher EPSCs, slower decay rates, and superior retention compared to c-plane counterparts. These characteristics are attributed to crystallographic effects that enhance carrier trapping and persistent photoconductivity. To demonstrate their practical applicability, 3 × 3-pixel arrays of adjacent devices were constructed, where a “T”-shaped optical pattern was successfully encoded, learned, and retained across repeated stimulation cycles. These results highlight the critical role of substrate orientation in tailoring synaptic plasticity and memory retention, offering promising prospects for ZnO-based optoelectronic synaptic arrays in in-sensor neuromorphic computing and artificial visual memory systems. Full article

Two-dimensional (2D) materials are promising candidates for neuromorphic computing owing to their atomically thin structure and tunable optoelectronic properties. However, achieving controllable synaptic behavior via defect engineering remains challenging. In this work, we introduce X-ray irradiation as a facile strategy to modulate defect states and enhance synaptic plasticity in WSe₂-based optoelectronic synapses. The introduction of selenium vacancies via irradiation significantly improved both electrical and optical responses. Under electrical stimulation, short-term potentiation (STP) exhibited enhanced excitatory postsynaptic current (EPSC) retention exceeding 10%, measured 20 s after the stimulation peak. In addition, the nonlinearity of long-term potentiation (LTP) and long-term depression (LTD) was reduced, and the signal decay time was extended. Under optical stimulation, STP showed more than 4% improvement in EPSC retention at 16 s with similar relaxation enhancement. These effects are attributed to irradiation-induced defect states that facilitate charge carrier trapping and extend signal persistence. Moreover, the reduced nonlinearity in synaptic weight modulation improved the recognition accuracy of handwritten digits in a CrossSim-simulated MNIST task, increasing from 88.5% to 93.75%. This study demonstrates that X-ray irradiation is an effective method for modulating synaptic weights in 2D materials, offering a universal strategy for defect engineering in neuromorphic device applications. Full article

In the era of artificial intelligence, neuromorphic devices that simulate brain functions have received increasingly widespread attention. In this paper, an artificial neural synapse device based on ZnAlSnO thin-film transistors was fabricated, and its electrical properties were tested: the current-switching ratio was 1.18 × 10⁷, the subthreshold oscillation was 1.48 V/decade, the mobility was 2.51 cm²V⁻¹s⁻¹, and the threshold voltage was −9.40 V. Stimulating artificial synaptic devices with optical signals has the advantages of fast response speed and good anti-interference ability. The basic biological synaptic characteristics of the devices were tested under 365 nm light stimulation, including excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), short-term plasticity (STP), and long-term plasticity (LTP). This device shows good synaptic plasticity. In addition, by changing the gate voltage, the excitatory postsynaptic current of the device at different gate voltages was tested, two different logical operations of “AND” and “OR” were achieved, and the influence of different synaptic states on memory was simulated. This work verifies the application potential of the device in the integrated memory and computing architecture, which is of great significance for promoting the high-quality development of neuromorphic computing hardware. Full article

We explore recent advancements in optoelectronic synaptic devices across four key aspects: mechanisms, materials, synaptic properties, and applications. First, we discuss fundamental working principles, including oxygen vacancy ionization, defect trapping, and heterojunction-based charge modulation, which contribute to synaptic plasticity. Next, we examine the role of 0D, 1D, and 2D materials in optimizing device performance, focusing on their unique electronic, optical, and mechanical properties. We then analyze synaptic properties such as excitatory post-synaptic current (EPSC), visual adaptation, transition from short-term to long-term plasticity (STP to LTP), nociceptor-inspired responses, and associative learning mechanisms. Finally, we highlight real-world applications, including artificial vision systems, reservoir computing for temporal data processing, adaptive neuromorphic computing for exoplanet detection, and colored image recognition. By consolidating recent developments, this paper provides insights into the potential of optoelectronic synaptic devices for next-generation computing architectures, bridging the gap between optics and neuromorphic engineering. Full article

Cardiotonic steroids (CTS), including the endogenous compound ouabain, modulate neuronal Na/K-ATPase (NKA) activity in a concentration-dependent manner, affecting neuronal survival and function. While high concentrations of ouabain are neurotoxic, endogenous levels of 0.1–1 nM exert neuroprotective effects and influence intracellular signaling. However, the effects of physiologically relevant ouabain concentrations on excitatory synaptic transmission remain unclear. In this study, we examined how 1 nM ouabain affects synaptic responses in rat hippocampal CA1 neurons. Using whole-cell patch-clamp recordings of evoked excitatory postsynaptic currents (EPSCs) and extracellular recordings of field excitatory postsynaptic potentials (fEPSPs), we found that ouabain enhances excitatory synaptic transmission, increasing EPSC amplitude and fEPSP slope by 35–50%. This effect was independent of NMDA receptor (NMDAR) activity. Ouabain reduced the magnitude of NMDAR-dependent long-term potentiation (LTP), but still augmented fEPSPs when applied after LTP induction. This implies separate additive mechanisms. These observations exhibit that ouabain, at concentrations corresponding to endogenous levels, facilitates basal excitatory synaptic transmission while partially suppressing LTP. We propose that ouabain exerts dual modulatory effects in hippocampal networks via distinct synaptic mechanisms. Full article

In this work, research on liquid-based resistive switching devices is carried out, using bottom printable electrodes fabricated from Silver (Ag) paste and silver nitrate (AgNO₃) solution. The self-crossing I-V curves are observed and repeatedly shown by applying 100 sweep cycles, demonstrating repeatability and stability. This liquid device can be refreshed by adding extra droplets of AgNO₃ so that self-crossing I-V hysteresis with up to 493 dual sweeps can be obtained. The ability to be refreshed by supplying a new liquid solution demonstrates an advantage of liquid-based memristive devices, in comparison to their solid counterparts, where the switching layer is fixed after fabrication. The switching mechanism is attributed to Ag migration in the liquid, which narrows the gap between electrodes, giving rise to the observed phenomenon. The devices further show some synaptic properties including excitatory post-synaptic current (EPSC) and potentiation-depression, presenting opportunities to utilize the devices in mimicking some functions of biological neurons. The simplicity and cost-effectiveness of these devices may advance research into fluidic memristors, in which devices with versatile forms and shapes could be fabricated. Full article

B-raf (rapidly accelerated fibrosarcoma) is a crucial player within the ERK/MAPK signaling pathway. In the CNS, B-raf has been implicated in neuronal differentiation, long-term memory, and major depression. Mice with forebrain neuron-specific B-raf knockout show behavioral deficits in spatial learning tasks and impaired hippocampal long-term potentiation (LTP). To elucidate the mechanism(s) underlying diminished synaptic plasticity in B-raf-deficient mice, we performed whole-cell recordings from CA1 pyramidal cells in hippocampal slices of control and B-raf mutant mice. We found that the NMDA/AMPA ratio of excitatory postsynaptic currents (EPSCs) at the Schaffer collateral—CA1 pyramidal cell synapses was significantly reduced in B-raf mutants, which would at least partially account for their impaired LTP. Interestingly, the reduced NMDA component of field postsynaptic potentials in mutant preparations was partially reinstated by blocking the apamin-sensitive small-conductance Ca²⁺-activated K⁺ (SK) channels, which have also been reported to modulate hippocampal LTP and learning tasks. To determine the impact of B-raf-dependent signaling on SK current, we isolated the apamin-sensitive tail current after a strong depolarizing event and found indeed a significantly bigger SK current in B-raf-deficient cells compared to controls, which is consistent with the reduced action potential firing and the stronger facilitating effect of apamin on CA1 somatic excitability in B-raf-mutant hippocampus. Our data suggest that B-raf signaling readjusts the delicate balance between NMDA receptors and SK channels to promote synaptic plasticity and facilitate hippocampal learning and memory. Full article