Synaptic plasticity: multiple forms, functions, and mechanisms

Brain microenvironment-remodeling nanomedicine improves cerebral glucose metabolism, mitochondrial activity and synaptic function in a mouse model of Alzheimer's disease

The development of disease-modifying therapeutics for Alzheimer's disease remains challenging due to the complex pathology and the presence of the blood-brain barrier. Previously we have described the investigation of a brain-penetrating multifunctional bioreactive nanoparticle system capable of remodeling the hypoxic and inflammatory brain microenvironment and reducing beta-amyloid plaques improving cognitive function in a mouse model of Alzheimer's disease. Despite the linkage of hypoxia and inflammation to metabolic alteration, the effects of this system on modulating cerebral glucose metabolism, mitochondrial activity and synaptic function remained to be elucidated. To examine this, a transgenic mouse model of Alzheimer's disease (TgCRND8) in vivo were treated intravenously with beta-amyloid antibody-conjugated (Ab), blood-brain barrier-crossing terpolymer (TP) containing polymer-lipid based manganese dioxide nanoparticles (Ab-TP-MDNPs). Alterations in cerebral glucose utilization were determined by [1⁸F]FDG-PET imaging in vivo, with glucose metabolism and mitochondrial activity analyzed by biomarkers and studies with primary neurons in vitro. Synaptic function was evaluated by both biomarkers and electrophysiologic analysis. Current study shows that intravenously administered Ab-TP-MDNPs enhanced cerebral glucose utilization, improved glucose metabolism, mitochondrial activity, and increased the levels of neprilysin, O-glycosylation. The consequence of this was enhanced glucose and ATP availability, resulting in improved long-term potentiation for promoting neuronal synaptic function. This study highlights the importance of targeting the metabolism of complex disease pathologies in addressing disease-modifying therapeutics for neurodegenerative disorders such as Alzheimer's disease.

An overview of extracellular field potentials: Different potentiation and measurable components, interpretations, and hippocampal synaptic activity models

The hippocampus and some other brain regions are critically involved in synaptic plasticity. Electrophysiological recordings using extracellular field potentials (EFPs) reveal diverse synaptic activity within the hippocampus, including input/output functions (reflecting neural excitability), paired-pulse responses (reflecting short-term plasticity), and long-term potentiation (reflecting long-term plasticity). EFP techniques offer various measurable components for assessing multiple neural functions. These include fEPSP slope, amplitude, and area under curve (AUC), as well as latency (fEPSP onset or peak after stimulation), width at half amplitude, fiber volley, decay time, time-course (fEPSP rise and decay time constants; tau), initial slope/initial area and -/late area derived from a fEPSP waveform sample. Each of these parameters is separately evaluated and provides distinct electrophysiological interpretations. Despite the rich data offered by EFP techniques, many studies adopt a limited approach, focusing solely on fEPSP slope, amplitude, and occasionally AUC, thereby neglecting the potential insights provided by other parameters. Given the inherent variability of fEPSP components within a single recording and timeframe, a comprehensive analysis of synaptic activity within a specific hippocampal region is necessary for obtaining the full spectrum of fEPSP-related data. Researchers should consider the potential influence of additional factors contributing to the variability of synaptic activity magnitude. A detailed analysis considering different parts of extracellular fEPSP recordings and their properties is crucial for a deeper understanding of synaptic activity changes within the brain. Therefore, this review aims to provide a comprehensive overview of diverse forms of hippocampal synaptic activity, measurable components of EFP recordings, and their corresponding interpretations.

Chronic stress-related behavioral and synaptic changes require caspase-3 activation in the ventral hippocampus of male mice

Although numerous studies have suggested that chronic stress is a major risk factor for major depressive disorder, the process by which stress causes depression is still not fully understood. Previously, we investigated glucocorticoids, which are stress response hormones that activate a synapse-weakening pathway. Therefore, we hypothesized that chronic stress may cause synaptic depression, which could reduce excitability related to emotions. Animals underwent chronic restraint stress (CRS), followed by basal synaptic transmission measurement in hippocampal slices to assess synaptic function. Drugs were infused into the ventral hippocampus via cannulation before behavioral tests, including forced swimming, tail suspension, and sucrose intake tests, which evaluated depressive-like behaviors and anhedonia. The field excitatory postsynaptic potentials (fEPSPs) are reduced by chronic restraint stress (CRS) in the ventral hippocampus. The ventral hippocampi of mice treated with CRS showed low levels of fEPSP after the forced swim test (FST). In the FST and tail suspension test, CRS-induced increases in immobility time were prevented by the acute inhibition of AMPAR internalization by Tat-GluA23y, which also prevented fEPSP reduction. Mice lacking caspase-3 exhibited resilience to CRS-induced increases in immobility time in the FST, as well as changes in the functionality of synaptic AMPAR. Finally, the caspase-3 inhibitor Z-DEVD-FMK rapidly blocked the CRS-induced increase in immobility time in the FST and the CRS-induced decrease in sucrose preference. These findings suggest that chronic stress-related behavioral changes may require caspase-3-dependent alterations in ventral hippocampal synapses.

Spiking neural networks on FPGA: A survey of methodologies and recent advancements

The mimicry of the biological brain's structure in information processing enables spiking neural networks (SNNs) to exhibit significantly reduced power consumption compared to conventional systems. Consequently, these networks have garnered heightened attention and spurred extensive research endeavors in recent years, proposing various structures to achieve low power consumption, high speed, and improved recognition ability. However, researchers are still in the early stages of developing more efficient neural networks that more closely resemble the biological brain. This development and research require suitable hardware for execution with appropriate capabilities, and field-programmable gate array (FPGA) serves as a highly qualified candidate compared to existing hardware such as central processing unit (CPU) and graphics processing unit (GPU). FPGA, with parallel processing capabilities similar to the brain, lower latency and power consumption, and higher throughput, is highly eligible hardware for assisting in the development of spiking neural networks. In this review, an attempt has been made to facilitate researchers' path to further develop this field by collecting and examining recent works and the challenges that hinder the implementation of these networks on FPGA.

Auditory processing deficits in autism spectrum disorder: mechanisms, animal models, and therapeutic directions

Auditory processing abnormalities are a prominent feature of Autism Spectrum Disorder (ASD), significantly affecting sensory integration, communication, and social interaction. This review delves into the neurobiological mechanisms underlying these deficits, including structural and functional disruptions in the auditory cortex, imbalances in excitatory and inhibitory signaling, and synaptic dysfunction. Genetic contributions from mutations in CNTNAP2, SHANK3, FMR1, and FOXP2 are explored, highlighting their roles in auditory abnormalities. Animal models, such as BTBRT+tf/J mice (BTBR) and valproic acid (VPA)-exposed rodents, provide critical insights into the sensory abnormalities observed in ASD. In addition, the review discusses current pharmacological strategies and emerging interventions targeting neurotransmitter systems and synaptic plasticity. Notably, future directions are emphasized, highlighting the need for integrated pharmacological and auditory-specific therapies to enhance sensory processing and communication outcomes in ASD. Overall, this review aims to bridge the gap between basic neurobiological research and clinical application, guiding future studies and therapeutic developments in ASD-related auditory processing deficits.

Obstructive sleep apnea and memory impairments: Clinical characterization, treatment strategies, and mechanisms

Obstructive sleep apnea (OSA), is associated with dysfunction in the cardiovascular, metabolic and neurological systems. However, the relationship between OSA and memory impairment, intervention effects, and underlying pathways are not well understood. This review summarizes recent advances in the clinical characterization, treatment strategies, and mechanisms of OSA-induced memory impairments. OSA patients may exhibit significant memory declines, including impairments in working memory from visual and verbal sources. The underlying mechanisms behind OSA-related memory impairment are complex and multifactorial with poorly understood aspects that require further investigation. Neuroinflammation, oxidative stress, neuronal damage, synaptic plasticity, and blood-brain barrier dysfunction, as observed under exposures to intermittent hypoxia and sleep fragmentation are likely contributors to learning and memory dysfunction. Continuous positive airway pressure treatment can provide remarkable relief from memory impairment in OSA patients. Other treatments are emerging but need to be rigorously evaluated for cognitive improvement. Clinically, reliable and objective diagnostic tools are necessary for accurate diagnosis and clinical characterization of cognitive impairments in OSA patients. The complex links between gut-brain axis, epigenetic landscape, genetic susceptibility, and OSA-induced memory impairments suggest new directions for research. Characterization of clinical phenotypic clusters can facilitate advances in precision medicine to predict and treat OSA-related memory deficits.

The optoelectronic synergistic properties based on indium-gallium-zinc oxide neuromorphic transistors

Inspired by the human visual perception system, optoelectronic devices have attracted growing interest in advanced machine vision systems. Despite significant advancements in optical sensors, the synergy between optoelectronics remains underdeveloped. In this study, we propose a transistor fabricated via magnetron sputtering of indium-gallium-zinc oxide (In: Ga: Zn = 1:1:1 mol%) that serves as an inhibitory device, simulating key biological synaptic functions through its electrical properties, including excitatory postsynaptic currents and paired-pulse facilitation. Furthermore, by exploiting the intrinsic photoresponse characteristics of IGZO and the short-term and long-term memory behaviors induced by optical stimulation, we simulate synapses modulated by light of varying wavelengths. As a phototransistor, this device successfully simulates complex synaptic behaviors, including Morse code. It also simulates the Mach bands, a phenomenon of lateral inhibition observed in biology. Additionally, the optoelectronic effect of the phototransistor is applied in neural network recognition, achieving a recognition rate of 85.8%.

Neuroplasticity After Hypoxic-Ischemic Brain Injury in Neonatal Pigs Based on Time-Dependent Behavior of 1H-MRS-Tau Protein and Synaptic Associated Proteins and Synaptic Structure Analysis

This study investigated the effects of hypoxic-ischemic (HI) injury on neonatal neuroplasticity using the following approaches: Magnetic Resonance Spectroscopy (1H-MRS) imaging to analyze dynamic changes in tau protein levels, immunofluorescence staining to evaluate synaptophysin (SYP), neurocan (Neu), and tau protein, and utilizing transmission electron microscopy (TEM) to examine synaptic ultrastructure at multiple time points. A total of 59 healthy neonatal pigs were included, with 10 in the control group and 43 in the HI model group. The results demonstrated that SYP immunostaining intensity peaked at 6-12 h after HI before declining. Neu expression exhibited an initial decrease, followed by a transient increase and subsequent reduction, reaching its lowest level at 6-12 h after HI. Tau protein levels increased initially after HI, peaked at 24-48 h after HI, and subsequently decreased. SYP was negatively correlated with Neu with a correlation coefficient of -0.877. SYP was not correlated with Tau, neither was Neu with Tau. Compared with the control group, the number of synaptic vesicles decreased, and Post-Synaptic Density (PSD) thickness increased 6-12 h after HI. At 12-24 h after HI, the number of synaptic vesicles increased, and PSD thickness slightly decreased. At 24-48 h after HI, the vesicle number decreased, PSD became thinner, interrupting continuity, mitochondria swelled, and mitochondrial cristae blurred and disappeared. The findings suggest that the expression of Tau, SYP, and Neu is linked to alterations in synaptic and myelin structures, reflecting varying aspects of neural plasticity following HI injury.

Unravelling the Brain Resilience Following Stroke: From injury to rewiring of the brain through pathway activation, drug targets, and therapeutic interventions

Synaptic plasticity is a neuron's intrinsic ability to make new connections throughout life. The morphology and function of synapses are highly susceptible to any pathological condition. Ischemic stroke is a cerebrovascular event that affects various brain regions, resulting in the loss of neural networks. Stroke can alter both structural and functional plasticity of synapses, leading to long-term functional disability. Upon ischemic insult, numerous glutamate-mediated synaptic destruction pathways and glial-mediated phagocytic activity are triggered, resulting in excessive synapse loss, altering synaptic plasticity. The conventional stroke therapies to improve synaptic plasticity are still limited and ineffectual, leading to sub-optimal recovery in patients. Therefore, promoting synaptic plasticity to ameliorate sensory-motor function may be a promising strategy for long-term recovery in stroke patients. Here, we review the involvement of different molecular pathways of glutamate and glia-mediated synapse loss, current pharmacological targets, and the emerging novel approaches to improve synaptic plasticity and sensory-motor impairment post-stroke.

Bioactive ketamine metabolite exerts in vivo neuroplastogenic effects to improve hippocampal function in a treatment-resistant depression model

An acute increase in excitatory synaptic transmission contributes to the rapid antidepressant actions of neuroplastogens, including ketamine and its bioactive metabolite, (2R,6R)-hydroxynorketamine (HNK). It is hypothesized that drug-induced metaplastic changes in synaptic strength account for therapeutically relevant behavioral adaptations in vivo. Using the plasticity-deficient Wistar Kyoto model of treatment-resistant depression, we demonstrate that (2R,6R)-HNK potentiates glutamatergic transmission, promotes synaptic strength, restores long-term potentiation (LTP), and reverses deficits in hippocampal-dependent synaptic activity and behavior. (2R,6R)-HNK selectively potentiated CA1 pyramidal neuron activity during novelty exploration and restored Schaffer collateral-dependent spatial recognition memory. Prior experience with spatial learning partially occluded LTP in control rats, an effect mimicked in LTP-impaired rats in which spatial learning deficits were reversed by (2R,6R)-HNK. These findings demonstrate that (2R,6R)-HNK exerts rapid neuroplastogenic effects in vivo, which improve cognitive function and promote adaptive changes in synaptic strength at functionally impaired synapses.

From Genetics to Function: the Role of ABCA12 in Autism Neurobiology

ASD is a complex neurodevelopmental disorder with genetic, environmental, and molecular roots. Among the thousands of genes that have been associated with ASD, one critical factor has emerged as ABCA12, which plays an important role in lipid transport and metabolism. Traditionally, it has been related to skin disorders but has only recently been implicated in broader brain development and function. Some of the implicated effects include dysregulated lipid homeostasis, neuroinflammation, oxidative stress, and abnormalities in synaptic when the ABCA12 system is dysregulated. All the above processes are related to pathology in ASD. In this review, the emerging function of ABCA12 in autism neurobiology has been discussed; the core base is derived from in vivo models and preclinical studies. In vivo models such as mice and zebrafish that, in the previous studies had earlier shown impairments of ABCA12 which results in social deficiency behaviors but also perform repetitive actions. Based on the effects of the gene on molecular pathways, including neuronal signalling and membrane integrity, and identifying therapeutic approaches targeting ABCA12 or its downstream effects, preclinical studies have contributed to the integration of genetic, functional, and therapeutic perspectives for understanding the contribution of ABCA12 to ASD. These findings may unlock further investigations geared toward unravelling how lipid metabolism intricately influences neurodevelopment with regards to interventions available for use in ASD.

Scaled-down ionic liquid-functionalized geopolymer memristors

Whereas most memristors are fabricated using sophisticated and expensive manufacturing methods, we recently introduced low-cost memristors constructed from sustainable, porous geopolymers (GP) at room temperature via simple casting processes. These devices exhibit resistive switching via electroosmosis and voltage-driven ion mobility inside water-filled channels within the porous material, enabling promising synaptic properties. However, GP memristors were previously fabricated at the centimeter scale, too large for space-efficient neuromorphic computing applications, and displayed limited memory retention durations due to water evaporation from the pores of the GP material. In this work, we overcome these limitations by implementing (i) an inexpensive manufacturing method that allows fabrication at micron-scale (99.998% smaller in volume than their centimeter-scale counterparts) and (ii) functionalization of GPs with EMIM+ Otf- ionic liquid (IL), which prolonged retention of the memristive switching properties by 50%. This improved class of GP-based memristors also demonstrated ideal synaptic properties in terms of paired-pulse facilitation (PPF), paired-pulse depression (PPD), and spike time dependent plasticity (STDP). These improvements pave the way for using IL-functionalized GP memristors in neuromorphic computing applications, including reservoir computing, in-memory computing, memristors crossbar arrays, and more.

Role of posterior medial thalamus in the modulation of striatal circuitry and choice behavior

The posterior medial (POm) thalamus is heavily interconnected with sensory and motor circuitry and is likely involved in behavioral modulation and sensorimotor integration. POm provides axonal projections to the dorsal striatum, a hotspot of sensorimotor processing, yet the role of POm-striatal projections has remained undetermined. Using optogenetics with mouse brain slice electrophysiology, we found that POm provides robust synaptic input to direct and indirect pathway striatal spiny projection neurons (D1- and D2-SPNs, respectively) and parvalbumin-expressing fast spiking interneurons (PVs). During the performance of a whisker-based tactile discrimination task in head-restrained mice, POm-striatal projections displayed learning-related activation correlating with anticipatory, but not reward-related, pupil dilation. Inhibition of POm-striatal axons across learning caused slower reaction times and an increase in the number of training sessions for expert performance. Our data indicate that POm-striatal inputs provide a behaviorally relevant arousal-related signal, which may prime striatal circuitry for efficient integration of subsequent choice-related inputs.

Neuromorphic Light-Responsive Organic Matter for in Materia Reservoir Computing

Materials able to sense and respond to external stimuli by adapting their internal state to process and store information, represent promising candidates for implementing neuromorphic functionalities and brain-inspired computing paradigms. In this context, neuromorphic systems based on light-responsive materials enable the use of light as information carrier, allowing to emulate basic functions of the human retina. In this work it is demonstrated that optically-induced molecular dynamics in azopolymers can be exploited for neuromorphic-type of data processing in the analog domain and for computing at the matter level (i.e., in materia). Besides showing that azopolymers can be exploited for data storage, it is demonstrated that the adaptiveness of these materials enables the implementation of synaptic functionalities including short-term memory, long-term memory, and visual memory. Results show that azopolymers allow event detection and motion perception, enabling physical implementation of information processing schemes requiring real-time analysis of spatio-temporal inputs. Furthermore, it is shown that light-induced dynamics can be exploited for the in materia implementation of the unconventional computing paradigm denoted as reservoir computing. This work underscores the potential of azopolymers as promising materials for developing adaptive, intelligent photo-responsive systems that mimic some of the complex processing abilities of biological systems.

Van der Waals Antiferroelectric CuCrP2S6-Based Artificial Synapse for High-Precision Neuromorphic Computation

2D van der Waals heterostructure-based artificial synapses have emerged as a compelling platform for next-generation neuromorphic systems, owing to their tunable electrical conductivity and layer-engineered functionality through controlled stacking of 2D materials. In this work, an engineered SnS₂/h-BN/CuCrP₂S₆ van der Waals antiferroelectric field-effect transistor (AFe-FET) is presented that implements synaptic weight modulation through the synergistic interplay of charge trapping dynamics and electric-field-controlled ferroelectric polarization switching. The AFe-FET architecture successfully emulates essential neuroplasticity features, including paired-pulse facilitation, short-term plasticity, and long-term plasticity. The device exhibits exceptional long-term potentiation (LTP) and long-term depression (LTD), with an ultralow nonlinearity coefficient of 1.1 for both LTP and LTD operations, high symmetricity (30), and broad dynamic range (Gmax/Gmin = 10). The AFe-FET-based neuromorphic system demonstrates an outstanding computational efficacy, i.e. a classification accuracy of 97.7% on the MNIST benchmark. Furthermore, implementing reservoir computing architectures enables cognitive process emulation, attaining 94.7% task recognition accuracy in brain-inspired decision-making simulations. This investigation establishes new design paradigms for high-fidelity synaptic devices, providing a strategy for energy-efficient neuromorphic computing systems with biological plausibility.

Fatty acid binding proteins and their involvement in anxiety and mood disorders

Anxiety and mood disorders represent the most prevalent neuropsychiatric conditions. Nevertheless, current pharmacotherapies often have a host of adverse side effects. Emerging evidence suggests modulation of lipid signaling pathways - particularly those involved in the endocannabinoid (eCB) system, may offer promising new targets for the treatment of anxiety and depression. Polyunsaturated fatty acids (PUFA) and their metabolic derivatives, including the eCB ligands, have garnered significant attention for their roles in neuropsychiatric disease mechanisms. Intracellular transportation of these lipids is facilitated by fatty acid binding proteins (FABP), which are increasingly recognized as key regulators of lipid signaling. Accumulating evidence indicates that FABPs may impact the development of neuropsychiatric disorders by mediating the signaling pathways of PUFAs and eCB ligands. In this review, we investigate the role of FABPs in two major categories of neuropsychiatric conditions - anxiety disorders and clinical depression. We begin by examining several neuropathophysiological mechanisms through which FABPs can impact these conditions, focusing on their role as lipid chaperones. These mechanisms include the trafficking of eCB ligands, as well as oleoylethanolamide and palmitoylethanolamide; modulation of inflammatory responses through PUFA transport and PPAR activation; regulation of PUFA availability to support neurogenesis; influence on stress-related pathways, including NMDA receptor activation and the hypothalamic-pituitary-adrenal axis; and the facilitation of dopamine receptor trafficking and localization. Next, we discuss preclinical evidence linking FABP function to anxiety- and depression-related behaviours. Finally, we propose that pharmacologically targeting FABP-mediated pathways holds considerable potential as a novel therapeutic strategy for addressing the symptoms associated with mood and anxiety disorders.

Exploring the Connection Between BDNF/TrkB and AC/cAMP/PKA/CREB Signaling Pathways: Potential for Neuroprotection and Therapeutic Targets for Neurological Disorders

The BDNF/TrkB and AC/cAMP/PKA/CREB signaling pathways play a vital role in neuroplasticity, neuronal survival, and cognitive functions. This review explores its physiological and pathological implications in neurological disorders, with a focus on neurodegenerative diseases (NDDs) and neuropsychiatric disorders (NPDs). Neurological conditions increasingly burden public health, making understanding the biochemical mechanisms that underpin these diseases critical. BDNF, a neurotrophic factor, binds to the TrkB receptor, activating multiple intracellular signaling cascades that regulate cellular responses essential for neurogenesis, memory, and learning. Dysregulation within this pathway has been linked to various NDDs, as well as NPDs. Key components of the path, including adenylyl cyclase and cyclic AMP, mediate the effects of neurotransmitters and growth factors, influencing downstream targets like PKA and CREB, which are crucial for gene expression and synaptic changes. Furthermore, the review discusses the challenges of targeting this pathway for therapeutic interventions, including receptor isoform diversity, blood-brain barrier penetration, and potential side effects. Future strategies may include the development of selective TrkB modulators, nanoparticle carriers for drug delivery, and innovative gene therapy techniques. Advancing the understanding of this complex signaling network holds promise for effective interventions in treating neurological and psychiatric disorders, ultimately enhancing neuroprotection and cognitive resilience.

Mixed binary supporting electrolyte approach for enhanced synaptic functionality in one-shot integrable electropolymerized synaptic transistors

The limitations of traditional von Neumann architectures have driven interest in organic mixed ionic-electronic conductors (OMIECs) for integrating memory and computation. Organic electrochemical synaptic transistors (OESTs) are particularly promising for emulating biological synaptic behaviors because they offer low power consumption, flexibility, and scalability. One-shot integrable electropolymerization (OSIEP) has emerged as a promising approach for fabricating OESTs owing to its simplicity and integrative capabilities. However, OSIEP-fabricated devices often exhibit inferior memory characteristics, largely due to suboptimal control of channel crystallinity-a key factor influencing memory retention. In this study, we addressed this challenge by fabricating poly(3,4-ethylenedioxythiphene) (PEDOT)-based OESTs using a mixed binary supporting electrolyte via the OSIEP method. A binary system comprising tetrabutylammonium tetrafluoroborate (BF4-) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (TFSI-) was adopted to balance crystallinity and ionic conductivity. PEDOT:Blend films achieved enhanced synaptic functionality by combining the high de-doping efficiency and charge transport of PEDOT:BF4 with the superior molecular orientation of PEDOT:TFSI. This synergistic approach significantly improved the long-term depression/potentiation characteristics and prolonged memory retention. PEDOT:Blend-based synaptic transistors achieved a recognition accuracy of 95.58% on the MNIST dataset, surpassing devices fabricated with single electrolytes. These findings highlight a scalable strategy for tuning the synaptic properties in OMIEC-based devices, thereby advancing their potential for neuromorphic computing applications.

Fully hardware-oriented physical reservoir computing using 3D vertical resistive switching memory with different bottom electrodes

Reservoir computing (RC) is a promising machine learning paradigm that processes input data using a fixed random network. However, implementing both reservoir and readout layers typically requires multiple devices and additional fabrication steps. To overcome this, we introduce a fully integrated RC system based on a vertically stacked Ta/Ta2O5/HfO2/W and TiN vertical-resistive random-access memory (VRRAM) structure, which can select short-term and long-term memory in VRRAM structure with different bottom electrodes. The volatile VRRAM serves as a physical reservoir, utilizing its fading memory and nonlinearity to capture temporal dependencies, while the nonvolatile VRRAM functions as a readout network with multi-level storage capability and high linearity. Neuromorphic simulations show that using conductance variations as synaptic weights enables pattern recognition accuracy above 93.14%, successfully replicating biological synaptic behaviors. Finally, the proposed Cyclic RC structure effectively processes temporal patterns, achieving strong performance with an NRMSE of 0.2123 for waveform classification and 0.2377 for Hénon map prediction. These findings underscore the potential of hardware-efficient, short-term memory-based architectures for forecasting nonlinear dynamical systems and advancing neuromorphic computing applications.

Neuromodulatory signaling contributing to the encoding of aversion

The appropriate and rapid encoding of stimuli bearing a negative valence enables behaviors that are essential for survival. Recent advances in neuroscience using rodents as a model system highlight the relevance of cell type-specific neuronal activities in diverse brain networks for the encoding of aversion, as well as their importance for subsequent behavioral strategies. Within these networks, neuromodulators influence cell excitability, adjust fast synaptic neurotransmission, and affect plasticity, ultimately modulating behaviors. In this review we first discuss contemporary findings leveraging the use of cutting-edge neurotechnologies to define aversion-related neural circuits. The spatial and temporal dynamics of the release of neuromodulators and neuropeptides upon exposure to aversive stimuli are described within defined brain circuits. Together, these mechanistic insights update the present neural framework through which aversion drives motivated behaviors.

Differences and Commonalities of Electrical Stimulation Paradigms After Central Paralysis and Amputation

BACKGROUND

Patients with spinal cord injury (SCI) or with severe brain stroke suffer from life-lasting functional and sensory impairments. Other traumatic injuries such as limb loss after an accident or disease also affect motor function and sensory feedback and impair quality of life in those individuals. Invasive and non-invasive functional electrical stimulation (FES) is a well-established method to partially restore function and sensory feedback of paralyzed and phantom limbs. It is also a supporting technology for the rehabilitation of the neuromuscular system and for complementing assistive devices.

METHODS

This work reviews the current state-of-the-art of FES as a technology for restoring function and supporting rehabilitation therapy and assistive devices.

RESULTS

Electrodes, electrical stimulation, use of brain signals for rehabilitation and control, and sensory feedback are covered as parts of the whole. A perspective is given on how clinical and research protocols developed for patients with SCI and brain injuries can be translated to the treatment of patients with an amputation and vice versa. We further elaborate on how motor learning strategies with quantitative electrophysiological and kinematic measurements may help caregivers in the rehabilitation process. Insights from practitioners (collected during a workshop of the IFESS 2025) have been integrated to summarize common needs, open questions, and challenges.

CONCLUSIONS

The information from the literature and from practitioners was integrated to propose the next steps towards establishing common guidelines and measures of FES in clinical practice towards evidence-driven treatment and objective assessments.

HDAC4 Inhibits NMDA Receptor-mediated Stimulation of Neurogranin Expression

The coordination of neuronal wiring and activity within the central nervous system (CNS) is crucial for cognitive function, particularly in the context of aging and neurological disorders. Neurogranin (Ng), an abundant forebrain protein, modulates calmodulin (CaM) activity and deeply influences synaptic plasticity and neuronal processing. This study investigates the regulatory mechanisms of Ng expression, a critical but underexplored area for combating cognitive impairment. Utilizing both in vitro and in vivo hippocampal models, we show that Ng expression arises during late developmental stages, coinciding with the processes of synaptic maturation and neuronal circuit consolidation. We observed that Ng expression increases in neuronal networks with heightened synaptic activity and identified GluN2B-containing N-methyl-D-aspartate (NMDA) receptors as key drivers of this expression. Additionally, we discovered that nuclear-localized HDAC4 inhibits Ng expression, establishing a regulatory axis that is counteracted by NMDA receptor stimulation. Analysis of the Ng gene promoter activity revealed regulatory elements between the - 2.4 and - 0.85 Kbp region, including a binding site for RE1-Silencing Transcription factor (REST), which may mediate HDAC4's repressive effect on Ng expression. Further analysis of the promoter sequence revealed conserved binding sites for the myocyte enhancer factor-2 (MEF2) transcription factor, a target of HDAC4-mediated transcription regulation. Our findings elucidate the interplay between synaptic activity, NMDAR function, and transcriptional regulation in controlling Ng expression, offering insights into synaptic plasticity mechanisms and potential therapeutic strategies to prevent cognitive dysfunction.

Unraveling the Interplay Between Memristive and Magnetoresistive Behaviors in LaCoO3/SrTiO3 Superlattice-Based Neural Synaptic Devices

Memristors and magnetic tunnel junctions are showing great potential in data storage and computing applications. A magnetoelectrically coupled memristor utilizing electron spin and electric field-induced ion migration can facilitate their operation, uncover new phenomena, and expand applications. In this study, devices consisting of Pt/(LaCoO3/SrTiO3)n/LaCoO3/Nb:SrTiO3 (Pt/(LCO/STO)n/LCO/NSTO) are engineered using pulsed laser deposition to form the LCO/STO superlattice layer, with Pt and NSTO serving as the top and bottom electrodes, respectively. The results show that both memristive and magnetoresistive properties can coexist without any compromise in performance, and the values of ROFF/RON and tunnel magnetoresistance (TMR) ratio are both improved by ≈1000% compared to a single-period heterostructure. Notably, the Pt/(LCO/STO)5/LCO/NSTO device demonstrates superior multilevel storage performance, characterized by extended endurance, reliable retention, high ROFF/RON ratio, significant TMR ratio, and fundamental synaptic behaviors. Furthermore, density functional theory (DFT) is employed to calculate the changes in oxygen vacancies, affecting the overall energy bands and magnetic moments in the monolayer and multi-periodic structures. Simulations using the handwritten digit recognition classification achieve the highest accuracy of 94.38%. These attributes suggest that the devices hold considerable promise for application in data storage and neuromorphic computing, offering a platform for high-density neural circuits in intelligent electronic devices.

PICK1 links KIBRA and AMPA receptor subunit GluA2 in coiled-coil-driven supramolecular complexes

The human memory-associated protein KIBRA regulates synaptic plasticity and trafficking of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors, and is implicated in multiple neuropsychiatric and cognitive disorders. How KIBRA forms complexes with and regulates AMPA receptors remains unclear. Here, we show that KIBRA does not interact directly with the AMPA receptor subunit GluA2, but that protein interacting with C kinase 1 (PICK1), a key regulator of AMPA receptor trafficking, can serve as a bridge between KIBRA and GluA2. In contrast, KIBRA can form a complex with GluA1 independent of PICK1. We identified structural determinants of KIBRA-PICK1-AMPAR complexes by investigating interactions and cellular expression patterns of different combinations of KIBRA and PICK1 domain mutants. We find that the PICK1 BAR domain, a coiled-coil structure, is sufficient for interaction with KIBRA, whereas mutation of the PICK1 BAR domain disrupts KIBRA-PICK1-GluA2 complex formation. In addition, KIBRA recruits PICK1 into large supramolecular complexes, a process which requires KIBRA coiled-coil domains. These findings reveal molecular mechanisms by which KIBRA can organize key synaptic signaling complexes.

Breath-hold diving as a tool to harness a beneficial increase in cardiac vagal tone

Here we review central mechanisms that mediate the diving bradycardia and propose that breath-hold diving (BH-D) is a powerful therapeutic tool to improve cardiac vagal tone (CVT). Physiological fluctuations in CVT are known as the respiratory heart rate variability (respirHRV) and involve two respiratory-related brainstem mechanisms. During inspiration pre-Bötzinger complex (pre-BötC) neurons inhibit cardiac vagal motor neurons to increase heart rate and subsequently cardiac vagal disinhibition and a decrease in heart rate is associated with a Kölliker-Fuse (KF) nucleus-mediated partial glottal constriction during early expiration. Both KF and pre-BötC receive direct descending cortical inputs that could mediate volitional glottal closure as critical anatomical framework to volitionally target brainstem circuits that generate CVT during BH-D. Accordingly we show that volitional and reflex glottal closure during BH-D appropriates the respirHRV core network to mediate the diving bradycardia via converging trigeminal afferents inputs from the nose and forehead. Additional sensory inputs linked to prolonged BH-D after regular training further increase CVT during the acute dive and can yield a long-term increase in CVT. Centrally, evidence of Hebbian plasticity within respirHRV/BH-D core circuit further support the notion that regular BH-D exercise can yield a permanent increase in CVT specifically via a sensitization of synapse involved in the generation of the respirHRV. Contrary to other regular physical activity, BH-D reportedly does not cause structural remodeling of the heart and therefore we suggest that regular BH-D exercise could be employed as a save and non-invasive approach to treat sympathetic hyperactivity, particularly in elderly patients with cardio-vascular predispositions.

Neuroplasticity and psychedelics: A comprehensive examination of classic and non-classic compounds in pre and clinical models

Neuroplasticity, the ability of the nervous system to adapt throughout an organism's lifespan, offers potential as both a biomarker and treatment target for neuropsychiatric conditions. Psychedelics, a burgeoning category of drugs, are increasingly prominent in psychiatric research, prompting inquiries into their mechanisms of action. Distinguishing themselves from traditional medications, psychedelics demonstrate rapid and enduring therapeutic effects after a single or few administrations, believed to stem from their neuroplasticity-enhancing properties. This review examines how classic psychedelics (e.g., LSD, psilocybin, N,N-DMT) and non-classic psychedelics (e.g., ketamine, MDMA) influence neuroplasticity. Drawing from preclinical and clinical studies, we explore the molecular, structural, and functional changes triggered by these agents. Animal studies suggest psychedelics induce heightened sensitivity of the nervous system to environmental stimuli (meta-plasticity), re-opening developmental windows for long-term structural changes (hyper-plasticity), with implications for mood and behavior. Translating these findings to humans faces challenges due to limitations in current imaging techniques. Nonetheless, promising new directions for human research are emerging, including the employment of novel positron-emission tomography (PET) radioligands, non-invasive brain stimulation methods, and multimodal approaches. By elucidating the interplay between psychedelics and neuroplasticity, this review informs the development of targeted interventions for neuropsychiatric disorders and advances understanding of psychedelics' therapeutic potential.

Acute Treatment with Fucoidan Ameliorates Traumatic Brain Injury-Induced Neurological Damages and Memory Deficits in Rats: Role of BBB Integrity, Microglial Activity, Neuroinflammation, and Oxidative Stress

There is no acquiesced remedy for the treatment of traumatic brain injury (TBI)-associated impairment, especially cognitive decline. The first 24 h after TBI is a golden time for preventing the progress of the impairments. The present study aimed to examine the acute effects of fucoidan on neurological outcomes and memory performance and investigate its potential mechanisms in rats with TBI. Fucoidan (25, 50, and 100 mg/kg, i.p.) was injected immediately after TBI induction. Veterinary coma scale (VCS), brain edema, blood-brain barrier (BBB) integrity, passive avoidance memory and spatial memory, neuroplasticity, myeloperoxidase (MPO) activity, oxidative stress, and histological alteration were evaluated after TBI induction and fucoidan treatment. The findings revealed that TBI resulted in an enhancement in brain water content and BBB permeability and diminished the performance of passive avoidance memory and spatial memory. These were accompanied by long-term potentiation (LTP) suppression in the hippocampus and the prevention of activities of SOD, catalase, and GPx and enhancement of MPO activity, TNF-α, IL-6, and lipid peroxidation levels in the hippocampus as well as hippocampal neuronal loss. Fascinatingly, acute treatment of TBI rats with fucoidan especially in the higher doses (50 and 100 mg/kg) significantly ameliorated (p < 0.05) neurological outcomes of VCS, cerebral edema, BBB integrity, passive avoidance memory, spatial memory, LTP impairment, and oxidative-antioxidative balance. Also, fucoidan significantly ameliorated hippocampal neuronal loss, TNF-α and IL-6 levels, and MPO activity as an indicator of microglial activation. These outcomes imply that fucoidan can be a hopeful remedy for TBI-associated neuronal impairments. However, further research is necessary to endorse this issue.

A novel role of Arp2/3 complex in the forgetting behavior of Caenorhabditis elegans to Pseudomonas aeruginosa PA14

Forgetting behavior is a common phenomenon that has been widely studied in various model organisms, including Caenorhabditis elegans (C. elegans), Drosophila, and mammals such as mice and humans. Understanding the mechanisms underlying forgetting can provide valuable insights into potential treatments for memory-related disorders. In this study, C. elegans was used as a model organism to establish a forgetting model based on the PA14 pathogen. A proteomic analysis of signaling pathways involved in forgetting revealed the role of the Arp2/3 complex in regulating pathogen-induced forgetting. Manipulation of genes encoding the components of the Arp2/3 complex (arx-1, arx-2, arx-3, arx-5, and arx-7) led to a reduction in the duration of pathogen-induced forgetting. Additionally, one hour after pathogen removal, a significant decrease in the mRNA levels of arx-5 and arx-7 was observed, along with a reduction in arx-2::mCherry fluorescence in specific tissues of C. elegans. This study demonstrates that C. elegans exhibits forgetting behavior towards PA14, with a forgetting duration of approximately 2 hours. Pathogen-induced forgetting is associated with an increase in heterogeneous proteins localized to the cytoskeleton. Moreover, the expression levels of genes related to the Arp2/3 complex (arx-1, arx-2, arx-3, arx-5, and arx-7) are reduced, inhibiting cytoskeleton nucleation in cells. This inhibition may contribute to the observed pathogen-induced forgetting in C. elegans in response to PA14.

MicroRNA-138-5p suppresses excitatory synaptic strength at the cerebellar input layer

MicroRNAs are small, highly conserved non-coding RNAs that negatively regulate mRNA translation and stability. In the brain, miRNAs contribute to neuronal development, synaptogenesis, and synaptic plasticity. MicroRNA 138-5p (miR-138-5p) controls inhibitory synaptic transmission in the hippocampus and is highly expressed in cerebellar excitatory neurons. However, its specific role in cerebellar synaptic transmission remains unknown. Here, we investigated excitatory transmission in the cerebellum of mice expressing a sponge construct that sequesters endogenous miR-138-5p. Mossy fibre stimulation-evoked EPSCs in granule cells were ∼40% larger in miR-138-5p sponge mice compared to controls. Furthermore, we observed larger miniature EPSC amplitudes, suggesting an increased number of functional postsynaptic AMPA receptors. High-frequency train stimulation revealed enhanced short-term depression following miR-138-5p downregulation. Together with computational modelling, this suggests a negative regulation of presynaptic release probability. Overall, our results demonstrate that miR-138-5p suppresses synaptic strength through pre- and postsynaptic mechanisms, providing a potentially powerful mechanism for tuning excitatory synaptic input into the cerebellum. KEY POINTS: MicroRNAs are powerful regulators of mRNA translation and control key cell biological processes including synaptic transmission, but their role in regulating synaptic function in the cerebellum has remained elusive. In this study, we investigated how microRNA-138-5p (miR-138-5p) modulates excitatory transmission at adult murine cerebellar mossy fibre to granule cell synapses. Downregulation of miR-138-5p enhances excitatory synaptic strength at the cerebellar input layer and increases short-term depression. miR-138-5p exerts its regulatory function through both pre- and postsynaptic mechanisms by negatively regulating release probability at mossy fibre boutons, as well as functional AMPA receptor numbers in granule cells. These findings provide insights into the role of miR-138-5p in the cerebellum and expand our understanding of microRNA-dependent control of excitatory synaptic transmission and short-term plasticity.

Astrocytic EphB3 receptors regulate d-serine-gated synaptic plasticity and memory

The activation of classical NMDA receptors (NMDARs) requires the binding of a co-agonist in addition to glutamate. Whereas astrocytic-derived d-serine was shown to play such a role at CA3-CA1 hippocampal synapses, the exact mechanism by which neurons interact with neighboring astrocytes to regulate synaptic d-serine availability remains to be fully elucidated. Considering the close anatomical apposition of astrocytic and neuronal elements at synapses, the aforementioned process is likely to involve cells adhesion molecules. One very likely candidate could be the astrocytic EphB3 receptor and its neuronal partner, ephrinB3. Here, we first showed in acute hippocampal slices from adult mice that stimulation of EphB3 receptors with exogenous ephrinB3 increased d-serine availability at CA3-CA1 synapses, resulting in an increased NMDAR activity. Conversely, inhibiting endogenous EphB3 receptors caused an impairment of both synaptic NMDAR activity and NMDAR-dependent long-term synaptic potentiation (LTP), effects that could be rescued by exogenous d-serine. Most interestingly, knocking down EphB3 receptors specifically in astrocytes yielded a similar impairment in hippocampal plasticity and, most importantly, caused a deficit in novel object recognition memory. Altogether, our data thus indicate that EphB3 receptors in hippocampal astrocytes play a key role in regulating synaptic NMDAR function, activity-dependent plasticity and memory.

Inhibition of NMDA receptors and other ion channel types by membrane-associated drugs

N-methyl-D-aspartate receptors (NMDARs) are ligand-gated ion channels present at most excitatory synapses in the brain that play essential roles in cognitive functions including learning and memory consolidation. However, NMDAR dysregulation is implicated in many nervous system disorders. Diseases that involve pathological hyperactivity of NMDARs can be treated clinically through inhibition by channel blocking drugs. NMDAR channel block can occur via two known mechanisms. First, in traditional block, charged drug molecules can enter the channel directly from the extracellular solution after NMDAR activation and channel opening. Second, uncharged molecules of channel blocking drug can enter the hydrophobic plasma membrane, and upon NMDAR activation the membrane-associated drug can transit into the channel through a fenestration within the NMDAR. This membrane-associated mechanism of action is called membrane to channel inhibition (MCI) and is not well understood despite the clinical importance of NMDAR channel blocking drugs. Intriguingly, a hydrophobic route of access for drugs is not unique to NMDARs. Our review will address inhibition of NMDARs and other ion channels by membrane-associated drugs and consider how the path of access may affect a drug's therapeutic potential.

Significance of NMDA receptor-targeting compounds in neuropsychological disorders: An in-depth review

N-methyl-D-aspartate receptors (NMDARs), a subclass of glutamate-gated ion channels, play an integral role in the maintenance of synaptic plasticity and excitation-inhibition balance within the central nervous system (CNS). Any irregularities in NMDAR functions, whether hypo-activation or over-activation, can destabilize neural networks and impair CNS function. Several decades of experimental and clinical investigations have demonstrated that NMDAR dysfunction is implicated in the pathophysiology of various neurological disorders. Despite designing a long list of compounds that differentially modulate NMDARs, success in developing drugs that can selectively and effectively regulate various NMDAR subtypes while showing encouraging efficacy in clinical settings remains limited. A better understanding of the basic mechanism of NMDAR function, particularly its selective regulation in pathological conditions, could aid in designing effective drugs for the treatment of neurological conditions. Here, we reviewed the experimental and clinical investigations that studied the effects of available NMDAR modulators in various neurological disorders and weighed up the pros and cons of the use of these substances on the improvement of functional outcomes of these disorders. Despite numerous efforts to develop NMDAR modulatory drugs that did not produce the desired outcomes, NMDARs remain a significant target for advancing novel drugs to treat neurological disorders. This article reviews the complexity of NMDAR signaling dysfunction in different neurological diseases, the efforts taken to examine designed compounds targeting specific subtypes of NMDARs, including challenges associated with using these substances, and the potential enhancements in drug discovery for NMDAR modulatory compounds by innovative technologies.

From Obesity to Mitochondrial Dysfunction in Peripheral Tissues and in the Central Nervous System

Obesity is a condition of chronic low-grade inflammation affecting peripheral organs of the body, as well as the central nervous system. The adipose tissue dysfunction occurring under conditions of obesity is a key factor in the onset and progression of a variety of diseases, including neurodegenerative disorders. Mitochondria, key organelles in the production of cellular energy, play an important role in this tissue dysfunction. Numerous studies highlight the close link between obesity and adipocyte mitochondrial dysfunction, resulting in excessive ROS production and adipose tissue inflammation. This inflammation is transmitted systemically, leading to metabolic disorders that also impact the central nervous system, where pro-inflammatory cytokines impair mitochondrial and cellular functions in different areas of the brain, leading to neurodegenerative diseases. To date, several bioactive compounds are able to prevent and/or slow down neurogenerative processes by acting on mitochondrial functions. Among these, some molecules present in the Mediterranean diet, such as polyphenols, carotenoids, and omega-3 PUFAs, exert a protective action due to their antioxidant and anti-inflammatory ability. The aim of this review is to provide an overview of the involvement of adipose tissue dysfunction in the development of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and multiple sclerosis, emphasizing the central role played by mitochondria, the main actors in the cross-talk between adipose tissue and the central nervous system.

Nutritional interventions to counteract the detrimental consequences of early-life stress

Exposure to stress during sensitive developmental periods comes with long term consequences for neurobehavioral outcomes and increases vulnerability to psychopathology later in life. While we have advanced our understanding of the mechanisms underlying the programming effects of early-life stress (ES), these are not yet fully understood and often hard to target, making the development of effective interventions challenging. In recent years, we and others have suggested that nutrition might be instrumental in modulating and possibly combatting the ES-induced increased risk to psychopathologies and neurobehavioral impairments. Nutritional strategies are very promising as they might be relatively safe, cheap and easy to implement. Here, we set out to comprehensively review the existing literature on nutritional interventions aimed at counteracting the effects of ES on neurobehavioral outcomes in preclinical and clinical settings. We identified eighty six rodent and ten human studies investigating a nutritional intervention to ameliorate ES-induced impairments. The human evidence to date, is too few and heterogeneous in terms of interventions, thus not allowing hard conclusions, however the preclinical studies, despite their heterogeneity in terms of designs, interventions used, and outcomes measured, showed nutritional interventions to be promising in combatting ES-induced impairments. Furthermore, we discuss the possible mechanisms involved in the beneficial effects of nutrition on the brain after ES, including neuroinflammation, oxidative stress, hypothalamus-pituitary-adrenal axis regulation and the microbiome-gut-brain axis. Lastly, we highlight the critical gaps in our current knowledge and make recommendations for future research to move the field forward.

SFRP1 upregulation causes hippocampal synaptic dysfunction and memory impairment

Impaired neuronal and synaptic function are hallmarks of early Alzheimer's disease (AD), preceding other neuropathological traits and cognitive decline. We previously showed that SFRP1, a glial-derived protein elevated in AD brains from preclinical stages, contributes to disease progression, implicating glial factors in early pathogenesis. Here, we generate and analyze transgenic mice overexpressing astrocytic SFRP1. SFRP1 accumulation causes early dendritic and synaptic defects in adult mice, followed by impaired synaptic long-term potentiation and cognitive decline, evident only when the animals age, thereby mimicking AD's structural-functional temporal distinction. This phenotype correlates with proteomic changes, including increased structural synaptic proteins like neurexin, which localizes in close proximity with SFRP1 in cultured hippocampal neurons. We conclude that excessive SFRP1 hinders synaptic protein turnover, reducing synaptic plasticity-a mechanism that may underlie the synaptopathy observed in the brains of prodromal AD patients.

Distributed Synaptic Connection Strength Changes Dynamics in a Population Firing Rate Model in Response to Continuous External Stimuli

Neural network complexity allows for diverse neuronal population dynamics and realizes higherorder brain functions such as cognition and memory. Complexity is enhanced through chemical synapses with exponentially decaying conductance and greater variation in the neuronal connection strength due to synaptic plasticity. However, in the macroscopic neuronal population model, synaptic connections are often described by spike connections, and connection strengths within the population are assumed to be uniform. Thus, the effects of synaptic connections variation on network synchronization remain unclear. Based on recent advances in mean field theory for the quadratic integrate-and-fire neuronal network model, we introduce synaptic conductance and variation of connection strength into the excitatory and inhibitory neuronal population model and derive the macroscopic firing rate equations for faithful modeling. We then introduce a heuristic switching rule of the dynamic system with respect to the mean membrane potentials to avoid divergences in the computation caused by variations in the neuronal connection strength. We show that the switching rule agrees with the numerical computation of the microscopic level model. In the derived model, variations in synaptic conductance and connection strength strongly alter the stability of the solutions to the equations, which is related to the mechanism of synchronous firing. When we apply physiologically plausible values from layer 4 of the mammalian primary visual cortex to the derived model, we observe event-related desynchronization at the alpha and beta frequencies and event-related synchronization at the gamma frequency over a wide range of balanced external currents. Our results show that the introduction of complex synaptic connections and physiologically valid numerical values into the low-dimensional mean field equations reproduces dynamic changes such as eventrelated (de)synchronization, and provides a unique mathematical insight into the relationship between synaptic strength variation and oscillatory mechanism.

Habituation to novel stimuli alters hippocampal plasticity associated with morphine tolerance in male Wistar rats

Chronic morphine exposure affects neuroplasticity in the hippocampus, a key area for learning and memory. Since, novelty exploration influence rodent hippocampal plasticity, the aim of this study was to investigate the effects of habituation to novel contexts and odors on hippocampal plasticity in morphine-tolerant rats. For this purpose, neurogenesis markers, dendritic spine density and mRNA levels for various genes encoding neurotrophic factors were evaluated in the hippocampus tissue (ventral, vH vs. dorsal, dH) of male rats. Habituation to the new environment was established using animal models of morphine tolerance. Following multiple exposures to a novel context (open field habituation, OFH) or a series of novel odors (odor habituation, OH), markers (Ki67 or DCX) associated with neurogenesis were found to be lower in the morphine-tolerant rats that underwent habituation than the non-habituated morphine-tolerant rats, with specific regions (dH, vH), being differently influenced by specific type of habituation (OFH, OH, respectively). Further results showed subregion and habituation specific effects on the number of dendritic spines per spine type or levels of neurotropic factors including BDNF and TrkB mRNA levels in the dH and vH in morphine-tolerant rats that underwent habituation as compared to the non-habituated morphine-tolerant rats. We provide new evidence that habituation to novel contexts and novel odors appears to affect hippocampal plasticity in morphine-tolerant rats and that pro-plasticity molecules appear to mediate habituation effects on morphine tolerance plasticity.

Unravelling the role of protein kinase R (PKR) in neurodegenerative disease: a review

Protein Kinase R is an essential regulator of many cell activities and belongs to one of the largest and most functionally complex gene families. These are found all over the body, and by adding phosphate groups to the substrate proteins, they regulate their activity and coordinate the action of almost all cellular processes. Recent research has illuminated the involvement of PKR in the pathogenesis of neurodegenerative disorders (NDs), thereby expanding our understanding of intricate molecular mechanisms underlying disease progression. Through their inhibition or activation, they hold potential therapeutic targets for the pathogenesis or protection of NDs. In the case of AD (AD), PKR contributes to the protection or elevation of Aβ accumulation, neuroinflammation, synaptic plasticity alterations, and neuronal excitability. Similarly, in Parkinson's disease (PD), PKR again has a dual role in dopaminergic neuronal loss, gene mutations, and mitochondrial dysfunction via various pathways. Notably, neuronal excitotoxicity, as well as genetic mutations, have been linked to ALS. In Huntington's disease (HD), PKR is associated with decreased or increased mutated genes, striatal neuron degeneration, neuroinflammation, and excitotoxicity. This review emphasizes strategies that target PKR for the treatment of neurodegenerative disorders. Doing so offers valuable insights that can guide future research endeavors and the development of innovative therapeutic approaches.

A Wireless Cortical Surface Implant for Diagnosing and Alleviating Parkinson's Disease Symptoms in Freely Moving Animals

Parkinson's disease (PD), one of the most common neurodegenerative diseases, is involved in motor abnormality, primarily arising from the degeneration of dopaminergic neurons. Previous studies have examined the electrotherapeutic effects of PD using various methodological contexts, including live conditions, wireless control, diagnostic/therapeutic aspects, removable interfaces, or biocompatible materials, each of which is separately utilized for testing the diagnosis or alleviation of various brain diseases. Here, a cortical surface implant designed to improve motor function in freely moving PD animals is presented. This implant, a minimally invasive system equipped with a graphene electrode array, is the first integrated system to exhibit biocompatibility, wearability, removability, target specificity, and wireless control. The implant positioned at the motor cortical surface activates the motor cortex to maximize therapeutic effects and minimize off-target effects while monitoring motor activities. In PD animals, cortical motor surface stimulation restores motor function and brain waves, which corresponds to potentiated synaptic responses. Furthermore, these changes are associated with the upregulation of metabotropic glutamate receptor 5 (mGluR5, Grm5) and D5 dopamine receptor (D5R, Drd5) genes in the glutamatergic synapse. The newly designed wireless neural implant demonstrates capabilities in both real-time diagnostics and targeted therapeutics, suggesting its potential as a wireless system for biomedical devices for patients with PD and other neurodegenerative diseases.

Electrical Nerve Stimulation Induces Synaptic Plasticity in the Brain and the Spinal Cord: A Systematic Review

OBJECTIVES

This review aimed to compile the literature on synaptic plasticity induced by electrical nerve stimulation (ENS) in nociceptive and somatosensory circuits within the central nervous system, with a particular focus on its effects on both the brain and spinal cord. Understanding the mechanisms underlying synaptic changes, enhances our comprehension of how ENS contributes to both pain relief and the development of experimental pain models.

MATERIALS AND METHODS

We conducted a systematic search of PubMed, Scopus, PEDro, SciELO, and Cochrane databases, adhering to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, and evaluated the quality of evidence using SYRCLE's risk of bias tool. The inclusion criteria were application of ENS to peripheral nerves, reporting of a detailed methodology, providing direct physiological measurements of synaptic activity (eg, field potentials or intracellular recordings), and publication in English or Spanish. From 8094 results, 85 studies met the inclusion criteria.

RESULTS

ENS was found to induce synaptic potentiation in 70 studies, depression in 7, and both effects in 8. These outcomes were determined by specific stimulation parameters and individual characteristics, with distinct molecular mechanisms involved in each case. Notably, most research focused on long-term potentiation in nociceptive pathways to create experimental pain models, with most studies conducted in the spinal cord. Few studies explored the link between ENS-induced synaptic plasticity and its analgesic effects or the role of plasticity in supraspinal brain regions, suggesting promising areas for future research.

CONCLUSIONS

ENS-induced synaptic plasticity presents a valuable opportunity for both pain management and the development of experimental pain models. Further research is needed to explore the connections between plasticity, analgesia, and higher brain regions.

Relationships and representations of brain structures, connectivity, dynamics and functions

The review explores the complex interplay between brain structures and their associated functions, presenting a diversity of hierarchical models that enhances our understanding of these relationships. Central to this approach are structure-function flow diagrams, which offer a visual representation of how specific neuroanatomical structures are linked to their functional roles. These diagrams are instrumental in mapping the intricate connections between different brain regions, providing a clearer understanding of how functions emerge from the underlying neural architecture. The study details innovative attempts to develop new functional hierarchies that integrate structural and functional data. These efforts leverage recent advancements in neuroimaging techniques such as fMRI, EEG, MEG, and PET, as well as computational models that simulate neural dynamics. By combining these approaches, the study seeks to create a more refined and dynamic hierarchy that can accommodate the brain's complexity, including its capacity for plasticity and adaptation. A significant focus is placed on the overlap of structures and functions within the brain. The manuscript acknowledges that many brain regions are multifunctional, contributing to different cognitive and behavioral processes depending on the context. This overlap highlights the need for a flexible, non-linear hierarchy that can capture the brain's intricate functional landscape. Moreover, the study examines the interdependence of these functions, emphasizing how the loss or impairment of one function can impact others. Another crucial aspect discussed is the brain's ability to compensate for functional deficits following neurological diseases or injuries. The investigation explores how the brain reorganizes itself, often through the recruitment of alternative neural pathways or the enhancement of existing ones, to maintain functionality despite structural damage. This compensatory mechanism underscores the brain's remarkable plasticity, demonstrating its ability to adapt and reconfigure itself in response to injury, thereby ensuring the continuation of essential functions. In conclusion, the study presents a system of brain functions that integrates structural, functional, and dynamic perspectives. It offers a robust framework for understanding how the brain's complex network of structures supports a wide range of cognitive and behavioral functions, with significant implications for both basic neuroscience and clinical applications.

Sex-dependent effects of stress on aIC-NAc circuit neuroplasticity: Role of the endocannabinoid system

Stress is a major risk factor for psychiatric disorders and affects neuroplasticity in brain areas like the nucleus accumbens core (NAcC) and the insular cortex (IC). This study examined neuroplasticity changes in the aIC-NAcC circuit after restraint stress in male and female rats, and explored the role of the endocannabinoid system. Male and female rats underwent 2 h of acute restraint stress. Behavioral tests and in vivo electrophysiological recordings were performed immediately and 24 h after stress exposure. cFos was performed immediately after stress. Since stress effects were observed only in males, we evaluated the systemic and intra-NAc blockade of CB1 receptors in male rats. We found increased c-Fos expression in the hypothalamus but not in the IC in both sexes after acute restraint stress, along with heightened anxiety and reduced exploratory behavior. Males and females exhibited different neuronal plasticity in the aIC-NAcC pathway. Under basal conditions, males showed equal proportions of long-term potentiation (LTP) and long-term depression (LTD), whereas females predominantly exhibited LTP. Stress disrupted synaptic plasticity in males by eliminating LTD in the aIC-NAcC pathway 24 h after exposure. This effect was reversed by systemic and local CB1 receptor blockade. These findings suggest that integration of aIC information into NAcC differs by sex, with stress-induced neuroplasticity changes occurring only in males, dependent on the endocannabinoid system. This study provides insight into sex differences in stress reactivity, which may relate to stress-related psychiatric disorders.

Mechanistic insights into the interaction between epilepsy and sleep

Epidemiological evidence has demonstrated associations between sleep and epilepsy, but we lack a mechanistic understanding of these associations. If sleep affects the pathophysiology of epilepsy and the risk of seizures, as suggested by correlative evidence, then understanding these effects could provide crucial insight into the basic mechanisms that underlie the development of epilepsy and the generation of seizures. In this Review, we provide in-depth discussion of the associations between epilepsy and sleep at the cellular, network and system levels and consider the mechanistic underpinnings of these associations. We also discuss the clinical relevance of these associations, highlighting how they could contribute to improvements in the management of epilepsy. A better understanding of the mechanisms that govern the interactions between epilepsy and sleep could guide further research and the development of novel approaches to the management of epilepsy.

The synaptic availability of GluA1 is reduced in hippocampal neurons of a murine model of dynamin-2 linked autosomal dominant centronuclear myopathy

ObjectiveAutosomal dominant centronuclear myopathy (AD-CNM) is a neuromuscular congenital disease caused by mutations in the DNM2 gene that encodes dynamin-2 (DNM2). The main clinical features of AD-CNM are progressive weakness and atrophy of skeletal muscles. However, cognitive defects have also been reported, suggesting that AD-CNM-causing mutations in DNM2 might also affect central nervous system (CNS). We recently demonstrated that defects in excitatory synaptic transmission occur in the brain of transgenic knock-in (KI) mice harboring the DNM2 p.R465W mutation, the most common causing AD-CNM. As DNM2 regulates the trafficking of glutamate-AMPA receptors (AMPARs), major mediators of excitatory synaptic transmission in mammals, it is feasible that the synaptic availability of AMPAR is affected in the context of AD-CNM. The main objective of this work was to evaluate the impact of the p.R465W DNM2 mutation on the GluA1-AMPAR-subunit synaptic availability in the brain of KI mice.MethodsWe addressed an experimental quantitative study. By using subcellular fractionation and western blot we quantified the expression of GluA1 and synaptic proteins in hippocampal total homogenates and postsynaptic densities (PSDs) in the brain of WT and KI mice. By total internal reflection microscopy (TIRFM) we also analyzed the arrival and residence time of GluA1 into the plasma membrane of hippocampal cultured neurons.ResultsAlthough we did not observe significant differences in the GluA1 expression in hippocampal total homogenates, it was significantly reduced in the PSDs of KI compared to wild-type (WT) brains. Moreover, the residence time of GluA1 in the surface membranes of KI hippocampal neurons was significantly reduced compared to WT neurons.ConclusionThese data strongly suggest that the p.R465W mutation in DNM2 perturbs synaptic GluA1-availability in hippocampal neurons, likely leading to defects in excitatory synaptic transmission.

An Adaptive Solid-State Synapse with Bi-Directional Relaxation for Multimodal Recognition and Spatio-Temporal Learning

The brain's unique processing power, such as perception, understanding, and interaction with the multimodal world, is achieved through diverse synaptic functionalities, which include varied temporal responses and adaptation. Although specific functions in brain-like computing have been successfully realized, emulating multimodal recognition and spatio-temporal learning remain significant challenges due to the difficulties in achieving multimodal signal processing and adaptive long-term plasticity in a single electronic synapse. Here, a purely electrically-modulated ferroelectric tunnel junction (FTJ) memristive synapse which realizes multimodal recognition and spatio-temporal pattern identification, through the integration of oxygen vacancies migration and ferroelectric polarization switching mechanisms, providing bi-directional relaxation and adaptive long-term plasticity simultaneously in the isolated device. The bi-directional relaxation enables multimodal recognition in the purely electrically-modulated FTJ device by encoding distinct sensory signals with different electrical polarities. The multimodal perception task is implemented with a multimodal computing system combining visual and speech pattern recognition. Moreover, the adaptive long-term plasticity allows spatio-temporal pattern recognition, which is demonstrated by identifying object orientation and direction of motion with a neural network incorporating the arrayed synapses. This work provides a feasible approach for designing bio-realistic electronic synapses and achieving highly intelligent neuromorphic computing.

Risk Factors, Pathological Changes, and Potential Treatment of Diabetes-Associated Cognitive Dysfunction

BACKGROUND

Diabetes is a prevalent public health issue worldwide, and the cognitive dysfunction and subsequent dementia caused by it seriously affect the quality of life of patients.

METHODS

Recent studies were reviewed to provide a comprehensive summary of the risk factors, pathogenesis, pathological changes and potential drug treatments for diabetes-related cognitive dysfunction (DACD).

RESULTS

Several risk factors contribute to DACD, including hyperglycemia, hypoglycemia, blood sugar fluctuations, hyperinsulinemia, aging, and others. Among them, modifiable risk factors for DACD include blood glucose control, physical activity, diet, smoking, and hypertension management, while non-modifiable risk factors include age, genetic predisposition, sex, and duration of diabetes. At the present, the pathogenesis of DACD mainly includes insulin resistance, neuroinflammation, vascular disorders, oxidative stress, and neurotransmitter disorders.

CONCLUSIONS

In this review, we provide a comprehensive summary of the risk factors, pathogenesis, pathological changes and potential drug treatments for DACD, providing information from multiple perspectives for its prevention and management.

Review on pathogenesis and treatment of Alzheimer's disease

The rising incidence of Alzheimer's disease (AD) and the associated economic impacts has prompted a global focus in the field. In recent years, there has been a growing understanding of the pathogenic mechanisms of AD, including the aggregation of β-amyloid, hyperphosphorylated tau, and neuroinflammation. These processes collectively lead to neurodegeneration and cognitive decline, which ultimately results in the loss of autonomy in patients. Currently, there are three main types of AD treatments: clinical tools, pharmacological treatment, and material interventions. This review provides a comprehensive analysis of the underlying etiology and pathogenesis of AD, as well as an overview of the current prevalence of AD treatments. We believe this article can help deepen our understanding of the AD mechanism, and facilitate the clinical translation of scientific research or therapies, to address this global problem of AD.

Brief early-life motor training induces behavioral changes and alters neuromuscular development in mice

In this study, we aimed to determine the impact of an increase in motor activity during the highly plastic period of development of the motor spinal cord and hindlimb muscles in newborn mice. A swim training regimen, consisting of two sessions per day for two days, was conducted in 1 and 2-day-old (P1, P2) pups. P3-trained pups showed a faster acquisition of a four-limb swimming pattern, accompanied by dysregulated gene expression in the lateral motor column, alterations in the intrinsic membrane properties of motoneurons (MNs) and synaptic plasticity, as well as increased axonal myelination in motor regions of the spinal cord. Network-level changes were also observed, as synaptic events in MNs and spinal noradrenaline and serotonin contents were modified by training. At the muscular level, slight changes in neuromuscular junction morphology and myosin subtype expression in hindlimb muscles were observed in trained animals. Furthermore, the temporal sequence of acquiring the adult-like swimming pattern and postural development in trained pups showed differences persisting until almost the second postnatal week. A very short motor training performed just after birth is thus able to induce functional adaptation in the developing neuromuscular system that could persist several days. This highlights the vulnerability of the neuromuscular apparatus during development and the need to evaluate carefully the impact of any given sensorimotor procedure when considering its application to improve motor development or in rehabilitation strategies.

Biological physics to uncover cell signaling

In this report, I describe some of the subjects and problems that we have addressed over the last 25 years in the area of cell signaling using the tools of biological physics. The report covers part of our work on intracellular Ca2 + signals, pattern formation, transport of messengers in the interior of cells, quantification of biophysical parameters from experiments, and information transmission. The description includes both our modeling and experimental work highlighting how the tools of physics can give useful insights into the workings of biological systems.

Exploring Male-Specific Synaptic Plasticity in Major Depressive Disorder: A Single-Nucleus Transcriptomic Analysis Using Bioinformatics Methods

Major depressive disorder (MDD) is a complex psychiatric illness, with synaptic plasticity playing a key role in its pathology. Our study aims to investigate the molecular basis of MDD by analyzing synaptic plasticity-related gene expression at the single-cell level. Utilizing a published snRNA-seq dataset (GSE144136), we identified Excitatory.neurons_1 as the cell cluster most associated with MDD and synaptic plasticity through cell clustering, gene set enrichment analysis (GSEA), and pseudotime analysis. Integrating the bulk RNA-seq data (GSE38206), we identified CASKIN1 and CSTB as hub genes via differential expression analysis and machine learning methods. Further exploration of the relevant mechanisms was performed via cell-cell communication and ligand-receptor interaction analysis, functional enrichment analysis, and the construction of molecular regulatory networks, highlighting miR-21-5p as a key biomarker. We propose that elevated miR-21-5p in MDD downregulates CASKIN1 in Excitatory.neurons_1 cells, resulting in decreased neural connectivity and altered synaptic plasticity. As our analyzed snRNA-seq dataset consists solely of male samples, these findings may be male-specific. Our findings shed light on potential mechanisms underlying synaptic plasticity in MDD, offering novel insights into the disorder's cellular and molecular dynamics.