Manipulating the expression of synaptic plasticity of neuromorphic devices provides fascinating opportunities to develop hardware platforms for artifi-cial intelligence.However,great efforts have been devoted to explo...Manipulating the expression of synaptic plasticity of neuromorphic devices provides fascinating opportunities to develop hardware platforms for artifi-cial intelligence.However,great efforts have been devoted to exploring biomimetic mechanisms of plasticity simulation in the last few years.Recent progress in various plasticity modulation techniques has pushed the research of synaptic electronics from static plasticity simulation to dynamic plasticity modulation,improving the accuracy of neuromorphic computing and providing strategies for implementing neuromorphic sensing functions.Herein,several fascinating strategies for synap-tic plasticity modulation through chemical techniques,device structure design,and physical signal sensing are reviewed.For chemical techniques,the underly-ing mechanisms for the modification of functional materials were clarified and its effect on the expression of synaptic plasticity was also highlighted.Based on device structure design,the reconfigurable operation of neuromorphic devices was well demonstrated to achieve programmable neuromorphic functions.Besides,integrating the sensory units with neuromorphic processing circuits paved a new way to achieve human-like intelligent perception under the modulation of physical signals such as light,strain,and temperature.Finally,considering that the relevant technology is still in the basic exploration stage,some prospects or development suggestions are put forward to promote the development of neuromorphic devices.展开更多
Synaptic plasticity can greatly affect the firing behavior of neural networks,and it specifically refers to changes in the strength,morphology,and function of synaptic connections.In this paper,a novel memristor model...Synaptic plasticity can greatly affect the firing behavior of neural networks,and it specifically refers to changes in the strength,morphology,and function of synaptic connections.In this paper,a novel memristor model,which can be configured as a volatile and nonvolatile memristor by adjusting its internal parameter,is proposed to mimic the short-term and long-term synaptic plasticity.Then,a bi-neuron network model,with the proposed memristor serving as a coupling synapse and the external electromagnetic radiation being emulated by the flux-controlled memristors,is established to elucidate the effects of short-term and long-term synaptic plasticity on firing activity of the neuron network.The resultant seven-dimensional(7D)neuron network has no equilibrium point and its hidden dynamical behavior is revealed by phase diagram,time series,bifurcation diagram,Lyapunov exponent spectrum,and two-dimensional(2D)dynamic map.Our results show the short-term and long-term plasticity can induce different bifurcation scenarios when the coupling strength increases.In addition,memristor synaptic plasticity has a great influence on the distribution of firing patterns in the parameter space.More interestingly,when exploring the synchronous firing behavior of two neurons,the two neurons can gradually achieve phase synchronization as the coupling strength increases along the opposite directions under two different memory attributes.Finally,a microcontroller-based hardware system is implemented to verify the numerical simulation results.展开更多
Anelasticity, as an intrinsic property of amorphous solids, plays a significant role in understanding their relaxation and deformation mechanism. However, due to the lack of long-range order in amorphous solids, the s...Anelasticity, as an intrinsic property of amorphous solids, plays a significant role in understanding their relaxation and deformation mechanism. However, due to the lack of long-range order in amorphous solids, the structural origin of anelasticity and its distinction from plasticity remain elusive. In this work, using frozen matrix method, we study the transition from anelasticity to plasticity in a two-dimensional model glass. Three distinct mechanical behaviors, namely,elasticity, anelasticity, and plasticity, are identified with control parameters in the amorphous solid. Through the study of finite size effects on these mechanical behaviors, it is revealed that anelasticity can be distinguished from plasticity.Anelasticity serves as an intrinsic bridge connecting the elasticity and plasticity of amorphous solids. Additionally, it is observed that anelastic events are localized, while plastic events are subextensive. The transition from anelasticity to plasticity is found to resemble the entanglement of long-range interactions between element excitations. This study sheds light on the fundamental nature of anelasticity as a key property of element excitations in amorphous solids.展开更多
Background The neurophysiological differences in cortical plasticity and cholinergic system function due to ageing and their correlation with cognitive function remain poorly understood.Aims To reveal the differences ...Background The neurophysiological differences in cortical plasticity and cholinergic system function due to ageing and their correlation with cognitive function remain poorly understood.Aims To reveal the differences in long-term potentiation(LTP)-like plasticity and short-latency afferent inhibition(SAl)between older and younger individuals,alongside their correlation with cognitive function using transcranial magnetic stimulation(TMS).Methods The cross-sectional study involved 31 younger adults aged 18-30 and 46 older adults aged 60-80.All participants underwent comprehensive cognitive assessments and a neurophysiological evaluation based on TMS.Cognitive function assessments included evaluations of global cognitive function,language,memory and executive function.The neurophysiological assessment included LTP-like plasticity and SAl.Results The findings of this study revealed a decline in LTP among the older adults compared with the younger adults(wald χ^(2)=3.98,p=0.046).Subgroup analysis further demonstrated a significant reduction in SAl level among individuals aged 70-80 years in comparison to both the younger adults(SAI(N20)):(t=-3.37,p=0.018);SAl(N20+4):(t=-3.13,p=0.038)and those aged 60-70(SAl(N20)):(t=3.26,p=0.025);SAl(N20+4):(t=-3.69,p=0.006).Conversely,there was no notable difference in SAl level between those aged 60-70 years and the younger group.Furthermore,after employing the Bonferroni correction,the correlation analysis revealed that only the positive correlation between LTP-like plasticity and language function(r=0.61,p<0.001)in the younger group remained statistically significant.Conclusions During the normal ageing process,a decline in synaptic plasticity may precede cholinergic system dysfunction.In individuals over 60 years of age,there is a reduction in LTP-like plasticity,while a decline in cholinergic system function is observed in those over 70.Thus,the cholinergic system may play a vital role in preventing cognitive decline during normal ageing.In younger individuals,LTP-like plasticity might represent a potential neurophysiological marker for language function.展开更多
Current-induced multilevel magnetization switching in ferrimagnetic spintronic devices is highly pursued for the application in neuromorphic computing.In this work,we demonstrate the switching plasticity in Co/Gd ferr...Current-induced multilevel magnetization switching in ferrimagnetic spintronic devices is highly pursued for the application in neuromorphic computing.In this work,we demonstrate the switching plasticity in Co/Gd ferrimagnetic multilayers where the binary states magnetization switching induced by spin–orbit toque can be tuned into a multistate one as decreasing the domain nucleation barrier.Therefore,the switching plasticity can be tuned by the perpendicular magnetic anisotropy of the multilayers and the in-plane magnetic field.Moreover,we used the switching plasticity of Co/Gd multilayers for demonstrating spike timing-dependent plasticity and sigmoid-like activation behavior.This work gives useful guidance to design multilevel spintronic devices which could be applied in high-performance neuromorphic computing.展开更多
A new nonlocal plasticity model,which is based on the integral-type nonlocal model and the cubic representative volumetric element（RVE）,is proposed to simulate shear band localization in geotechnical materials such ...A new nonlocal plasticity model,which is based on the integral-type nonlocal model and the cubic representative volumetric element（RVE）,is proposed to simulate shear band localization in geotechnical materials such as soils and rocks.An algorithm is developed to solve the resulting nonlinear system of equations.In this algorithm,the nonlocal averaging of plastic strain over the RVE is evaluated using C0 elements instead of using C1 elements to solve the second-order gradient of plastic strains.To obtain the average plastic strain,a set of special elements,called the nonlocal elements,are constructed to approximate the RVE.The updating of average stresses of the local element is based on the nonlocal plastic strain of the corresponding nonlocal elements.Numerical examples show that meshindependent results can be achieved using the proposed model and the algorithm,and the thickness of the shear band is insensitive to the mesh refinement.展开更多
Neuronal networks,especially those in the central nervous system(CNS),evolved to support extensive functional capabilities while ensuring stability.Several physiological"brakes"that maintain the stability of...Neuronal networks,especially those in the central nervous system(CNS),evolved to support extensive functional capabilities while ensuring stability.Several physiological"brakes"that maintain the stability of the neuronal networks in a healthy state quickly become a hinderance postinjury.These"brakes"include inhibition from the extracellular environment,intrinsic factors of neurons and the control of neuronal plasticity.There are distinct differences between the neuronal networks in the peripheral nervous system(PNS)and the CNS.Underpinning these differences is the trade-off between reduced functional capabilities with increased adaptability through the formation of new connections and new neurons.The PNS has"facilitators"that stimulate neuroregeneration and plasticity,while the CNS has"brakes"that limit them.By studying how these"facilitators"and"brakes"work and identifying the key processes and molecules involved,we can attempt to apply these theories to the neuronal networks of the CNS to increase its adaptability.The difference in adaptability between the CNS and PNS leads to a difference in neuroregenerative properties and plasticity.Plasticity ensures quick functional recovery of abilities in the short and medium term.Neuroregeneration involves synthesizing new neurons and connections,providing extra resources in the long term to replace those damaged by the injury,and achieving a lasting functional recovery.Therefore,by understanding the factors that affect neuroregeneration and plasticity,we can combine their advantages and develop rehabilitation techniques.Rehabilitation training methods,coordinated with pharmacological interventions and/or electrical stimulation,contributes to a precise,holistic treatment plan that achieves functional recovery from nervous system injuries.Furthermore,these techniques are not limited to limb movement,as other functions lost as a result of brain injury,such as speech,can also be recovered with an appropriate training program.展开更多
With key roles in essential brain functions ranging from the long-term potentiation(LTP) to synaptic plasticity,the N-methyl-D-aspartic acid receptor(NMDAR) can be considered as one of the fundamental glutamate recept...With key roles in essential brain functions ranging from the long-term potentiation(LTP) to synaptic plasticity,the N-methyl-D-aspartic acid receptor(NMDAR) can be considered as one of the fundamental glutamate receptors in the central nervous system.The role of NMDA R was first identified in synaptic plasticity and has been extensively studied.Some molecules,such as Ca^(2+),postsynaptic density 95(PSD-95),calcium/calmodulin-dependent protein kinase II(Ca MK II),protein kinase A(PKA),mitogen-activated protein kinase(MAPK) and cyclic adenosine monophosphate(c AMP) responsive element binding protein(CREB),are of special importance in learning and memory.This review mainly focused on the new research of key molecules connected with learning and memory,which played important roles in the NMDAR signaling pathway.展开更多
Objective To investigate whether there is endogenous neural stem cell proliferation and whether these proliferated neural stem cells represent neural plasticity in the adult rats after cerebral infarction. Methods Cer...Objective To investigate whether there is endogenous neural stem cell proliferation and whether these proliferated neural stem cells represent neural plasticity in the adult rats after cerebral infarction. Methods Cerebral infarction models of rats were established and the dynamic expression of bromodeoxyuridine （BrdU）, BrdU/polysialylated neural cell adhesion molecule （PSA-NCAM） were determined by immunohistochemistry and immunofluorescence staining. BrdU was used to mark dividing neural stem cells. PSA-NCAM was used to mark the plasticity of neural stem cells. Results Compared with controls, the number of BrdU-positive cells in the subventricular zone （SVZ） and hippocampus increased significantly at 1st day after cerebral infarction （P 〈 0. 05 ）, reached maximum at 7th day, decreased markedly at 14th day, but it was still elevated compared with that of the controls （ P 〈 0. 05 ）. The number of BrdU-labeled with PSA-NCAM-positive cells increased significantly at 7th day （ P 〈 0. 05 ）, reached maximum at 14th day, markedly decreased at 28th day, but it was still elevated compared with that of the controls （P 〈 0. 05 ）. It was equal to 60% of the number of BrdU-positive cells in the same period. Conclusion Cerebral infarction may stimulate the proliferation of endogenous neural stem cells in situ and most proliferated neural stem cells represent neural plasticity.展开更多
The need to develop armour systems to protect against attacks from various sources is increasingly a matter of personal,social and national security.To develop innovative armour systems it is necessary to monitor deve...The need to develop armour systems to protect against attacks from various sources is increasingly a matter of personal,social and national security.To develop innovative armour systems it is necessary to monitor developments being made on the type,technology and performance of the threats(weapons,projectiles,explosives,etc.) Specifically,the use of high protection level helmets on the battlefield is essential.The development of evaluation methods that can predict injuries and trauma is therefore of major importance.However,the risk of injuries or trauma that can arise from induced accelerations is an additional consideration.To develop new materials and layouts for helmets it is necessary to study the effects caused by ballistic impacts in the human head on various scenarios.The use of numerical simulation is a fundamental tool in this process.The work here presented focuses on the use of numerical simulation(finite elements analysis) to predict the consequences of bullet impacts on military helmets on human injuries.The main objectives are to assess the level and probability of head trauma using the Head Injury Criterion,caused by the impact of a 9 mm NATO projectile on a PASGT helmet and to quantify the relevance of projectile plasticity on the whole modelling process.The accelerations derived from the impact phenomenon and the deformations caused on the helmet are evaluated using fully three-dimensional models of the helmet,head,neck and projectile.Impact studies are done at impact angles ranging from 0 to 75°.Results are presented and discussed in terms of HIC and probability of acceleration induced trauma levels.Thorough comparison analyses are done using a rigid and a deformable projectile and it is observed that plastic deformation of the projectile is a significant energy dissipation mechanism in the whole impact process.展开更多
Bruguiera sexangula(Lour.)Poir is an exclusive evergreen mangrove species to the Sundarbans of Bangladesh.It grows well in moderate saline zones with full sunlight.This study presents leaf morphological plasticity in ...Bruguiera sexangula(Lour.)Poir is an exclusive evergreen mangrove species to the Sundarbans of Bangladesh.It grows well in moderate saline zones with full sunlight.This study presents leaf morphological plasticity in B.sexangula to saline zones.Leaves were sampled from different saline zones and various morphological traits were measured.The results exposed a wide deviations of leaf size parameters:leaf length varied 6.6–17.3 cm;width 2.7–7.8 cm;upper quarter width 2.2–6.5 cm;down quarter width 2.5–7.3 cm;and petiole length 0.17–1.43 cm.Leaf length was significantly larger in fresh water than in other salinity zones,whereas,leaf width,upper and lower leaf quarters were significantly larger in medium saline zone.Leaf shape parameters showed a large variation among saline zones.Leaf base angle was significantly larger in both medium and strong salinity zones.Tip angle was significantly greater in medium salinity zone.Leaf perimeter was significantly larger in fresh water but leaf area was significantly bigger in medium saline zone.Leaf index and specific leaf area were maximum in moderate saline zone.Plasticity index was the highest in moderate saline for almost all the parameters presented.The ordination(PCA)showed clusters of leaf samples although there were some overlap among them which suggested a salt-stress relationship among salinity zones.The results indicate that B.sexangula had a plasticity strategy on leaf morphological parameters to salinity in the Sundarbans.This study will provide basic information of leaf plasticity of this species among saline zones which will help for site selection of coastal planting and will also provide information for policy makers to take necessary steps for its conservation.展开更多
Phase transitions widely exist in nature and occur when some control parameters are changed. In neural systems, their macroscopic states are represented by the activity states of neuron populations, and phase transiti...Phase transitions widely exist in nature and occur when some control parameters are changed. In neural systems, their macroscopic states are represented by the activity states of neuron populations, and phase transitions between different activity states are closely related to corresponding functions in the brain. In particular, phase transitions to some rhythmic synchronous firing states play significant roles on diverse brain functions and disfunctions, such as encoding rhythmical external stimuli, epileptic seizure, etc. However, in previous studies, phase transitions in neuronal networks are almost driven by network parameters （e.g., external stimuli）, and there has been no investigation about the transitions between typical activity states of neuronal networks in a self-organized way by applying plastic connection weights. In this paper, we discuss phase transitions in electrically coupled and lattice-based small-world neuronal networks （LBSW networks） under spike-timing-dependent plasticity （STDP）. By applying STDP on all electrical synapses, various known and novel phase transitions could emerge in LBSW networks, particularly, the phenomenon of self-organized phase transitions （SOPTs）： repeated transitions between synchronous and asynchronous firing states. We further explore the mechanics generating SOPTs on the basis of synaptic weight dynamics.展开更多
The most critical issue in the steel catenary riser design is to evaluate the fatigue damage in the touchdown zone accurately. Appropriate modeling of the riser-soil resistance in the touchdown zone can lead to signif...The most critical issue in the steel catenary riser design is to evaluate the fatigue damage in the touchdown zone accurately. Appropriate modeling of the riser-soil resistance in the touchdown zone can lead to significant cost reduction by optimizing design. This paper presents a plasticity model that can be applied to numerically simulate riser-soil interaction and evaluate dynamic responses and the fatigue damage of a steel catenary riser in the touchdown zone. Utilizing the model, numerous riser-soil elements are attached to the steel catenary riser finite elements, in which each simulates local foundation restraint along the riser touchdown zone. The riser-soil interaction plasticity model accounts for the behavior within an allowable combined loading surface. The model will be represented in this paper, allowing simple numerical implementation. More importantly, it can be incorporated within the structural analysis of a steel catenary riser with the finite element method. The applicability of the model is interpreted theoretically and the results are shown through application to an offshore 8.625 steel catenary riser example. The fatigue analysis results of the liner elastic riser-soil model are also shown. According to the comparison results of the two models, the fatigue life analysis results of the plasticity framework are reasonable and the horizontal effects of the riser-soil interaction can be included.展开更多
Visual deprivation leads to structural neuroplasticity in the blind subjects,including gray matter(GM)and white matter(WM)atrophy and alterations in structural connectivity.The rat model of binocular enucleation(BE)is...Visual deprivation leads to structural neuroplasticity in the blind subjects,including gray matter(GM)and white matter(WM)atrophy and alterations in structural connectivity.The rat model of binocular enucleation(BE)is a frequently used animal model for studying brain plasticity induced by early blindness.Yet few neuroimaging studies have been performed on this model to investigate whether or not the BE rats have image phenotypes similar to or comparable to,those observed in the early blind subjects.The current study aimed to assess brain structural plasticity in BE rats using anatomical magnetic resonance imaging(MRI)and diffusion tensor imaging(DTI).The results demonstrated that early BE at postnatal day 4(P4)caused almost complete degeneration of optic nerve(ON)and optic chiasma(OCH),atrophy in a number of visual and non-visual structures,including optic tract(OT),dorsal lateral geniculate nucleus(DLG)and corpus callosum(CC).The BE rats also exhibited impairments of WM microstructural integrity in the OT,and reduction of structural connectivity between the normal-appearing visual cortex(VC)and somatosensory/motor cortices at 4 months of age,likely as manifestations of deafferentationinduced maldevelopment.The structural neuroplasticity in BE rats observable to structural MRI parallels largely with what has been reported in blind subjects,suggesting that longitudinal neuroimaging studies on animal models of sensory deprivation can provide insights into how the brain changes its wiring and function during development/adaption in response to the lack of sensory stimuli.展开更多
Using molecular dynamics simulations,the plastic deformation behavior of nanocrytalline Ti has been investigated under tension and compression normal to the{0001},{1010},and{1210}planes.The results indicate that the p...Using molecular dynamics simulations,the plastic deformation behavior of nanocrytalline Ti has been investigated under tension and compression normal to the{0001},{1010},and{1210}planes.The results indicate that the plastic deformation strongly depends on crystal orientation and loading directions.Under tension normal to basal plane,the deformation mechanism is mainly the grain reorientation and the subsequent deformation twinning.Under compression,the transformation of hexagonal-close packed(HCP)-Ti to face-centered cubic(FCC)-Ti dominates the deformation.When loading is normal to the prismatic planes(both{1010}and{1210}),the deformation mechanism is primarily the phase transformation among HCP,body-centered cubic(BCC),and FCC structures,regardless of loading mode.The orientation relations(OR)of{0001}HCP||{111}FCC and<1210>HCP||<110>FCC,and{1010}HCP||{110}FCC and<0001>HCP||<010>FCC between the HCP and FCC phases have been observed in the present work.For the transformation of HCP→BCC→HCP,the OR is{0001}α1||{110}β||{1010}α2(HCP phase before the critical strain is defined as α1-Ti,BCC phase is defined as β-Ti,and the HCP phase after the critical strain is defined as α2-Ti).Energy evolution during the various loading processes further shows the plastic anisotropy of nanocrystalline Ti is determined by the stacking order of the atoms.The results in the present work will promote the in-depth study of the plastic deformation mechanism of HCP materials.展开更多
Background:Plasticity in response to environmental drivers can help trees cope with droughts.However,our understanding of the importance of plasticity and physiological adjustments in trees under global change is limi...Background:Plasticity in response to environmental drivers can help trees cope with droughts.However,our understanding of the importance of plasticity and physiological adjustments in trees under global change is limited.Methods:We used the International Tree-Ring Data Bank(ITRDB)to examine 20th century growth responses in conifer trees during(resistance)and following(resilience)years of severe soil and atmospheric droughts occurring in isolation or as compound events.Growth resilience indices were calculated using observed growth divided by expected growth to avoid spurious correlations,in which the expected values were obtained by the autoregressive moving average(ARIMA)model.We used high atmospheric vapour pressure deficit(VPD)to select years of atmospheric drought and low annual values of the Standardized Precipitation-Evapotranspiration Index(SPEI)to select years with soil drought.We acquired the sensitivities(i.e.,the slopes of the relationships)by fitting the resilience indices as a function of environmental drivers,and assessed how these sensitivities changed over time for different types of drought events using linear mixed models.We also checked whether plasticity in growth responses was sufficient to prevent long-term trends of growth reductions during or after severe droughts.We acknowledge that by focusing on the response of surviving trees from the ITRDB we are potentially biasing our results towards higher resilience,as stand level responses(e.g.,mortality)may result in lowered competition after the disturbance event.Results:Sensitivities of resilience to VPD and SPEI changed throughout the 20th century,with the directions of these changes often reversing in the second half of the century.For the 1961–2010 period,changing sensitivities had positive effects on resilience,especially following years of high-VPD and compound events,avoiding growth losses that would have occurred if sensitivities had remained constant.Despite sensitivity changes,resilience was still lower at the end of the 20th century compared to the beginning of the century.Conclusions:Future adjustments to low-SPEI and high-VPD events are likely to continue to compensate for the trends in climate only partially,leading to further generalized reductions in tree growth of conifers.An improved understanding of these plastic adjustments and their limits,as well as potential compensatory processes at the stand level,is needed to project forest responses to climate change.展开更多
Indenter size effect on the reversible incipient plasticity of Al(001) surface is studied by quasicontinuum simulations.Results show that the incipient plasticity under small indenter, the radius of which is less than...Indenter size effect on the reversible incipient plasticity of Al(001) surface is studied by quasicontinuum simulations.Results show that the incipient plasticity under small indenter, the radius of which is less than ten nanometers, is dominated by a simple planar fault defect that can be fully removed after withdrawal of the indenter; otherwise, irreversible incipient plastic deformation driven by a complex dislocation activity is preferred, and the debris of deformation twins, dislocations,and stacking fault ribbons still remain beneath the surface when the indenter has been completely retracted. Based on stress distributions calculated at an atomic level, the reason why the dislocation burst instead of a simple fault ribbon is observed under a large indenter is the release of the intensely accumulated shear stress. Finally, the critical load analysis implies that there exists a reversible-irreversible transition of incipient plasticity induced by indenter size. Our findings provide a further insight into the incipient surface plasticity of face-centered-cubic metals in nano-sized contact issues.展开更多
The lack of the long-range order in the atomic structure challenges the identification of the structural defects,akin to dislocations in crystals,which are responsible for predicting plastic events and mechanical fail...The lack of the long-range order in the atomic structure challenges the identification of the structural defects,akin to dislocations in crystals,which are responsible for predicting plastic events and mechanical failure in metallic glasses(MGs).Although vast structural indicators have been proposed to identify the structural defects,quantitatively gauging the correlations between these proposed indicators based on the undeformed configuration and the plasticity of MGs upon external loads is still lacking.Here,we systematically analyze the ability of these indicators to predict plastic events in a representative MG model using machine learning method.Moreover,we evaluate the influences of coarse graining method and medium-range order on the predictive power.We demonstrate that indicators relevant to the low-frequency vibrational modes reveal the intrinsic structural characteristics of plastic rearrangements.Our work makes an important step towards quantitative assessments of given indicators,and thereby an effective identification of the structural defects in MGs.展开更多
The way in which persistent firing activity and synaptic plasticity are orchestrated to underlie working memory in recurrent neural networks is not fully understood. Here, we build a continuous attractor network of py...The way in which persistent firing activity and synaptic plasticity are orchestrated to underlie working memory in recurrent neural networks is not fully understood. Here, we build a continuous attractor network of pyramidal cells and interneurons to simulate an oculomotor delayed response task. Both short-term facilitation(STF) and short-term depression(STD) manifest at synapses between pyramidal cells. The efficacy of individual synapses depends on the time constants of STF and STD as well as the presynaptic firing rate. Self-sustained firing activity(i.e., a bump attractor) during the delay period encodes the cue position. The bump attractor becomes more robust against random drifts and distractions with enhancing STF or reducing STD. Keeping STF and STD at appropriate levels is crucial for optimizing network performance. Our results suggest that, besides slow recurrent excitation and strong global inhibition, short-term plasticity plays a prominent role in facilitating mnemonic behavior.展开更多
Emulation of synaptic function by ionic/electronic hybrid device is crucial for brain-like computing and neuromorphic systems.Electric-double-layer(EDL)transistors with proton conducting electrolytes as the gate diele...Emulation of synaptic function by ionic/electronic hybrid device is crucial for brain-like computing and neuromorphic systems.Electric-double-layer(EDL)transistors with proton conducting electrolytes as the gate dielectrics provide a prospective approach for such application.Here,artificial synapses based on indium-tungsten-oxide(IWO)-based EDL transistors are proposed,and some important synaptic functions(excitatory post-synaptic current,paired-pulse facilitation,filtering)are emulated.Two types of spike-timing-dependent plasticity(Hebbian STDP and anti-Hebbian STDP)learning rules and multistore memory(sensory memory,short-term memory,and long-term memory)are also mimicked.At last,classical conditioning is successfully demonstrated.Our results indicate that IWO-based neuromorphic transistors are interesting for neuromorphic applications.展开更多
基金financial support from the National Natural Science Foundation of China(Nos.62104017 and 52072204)Beijing Institute of Technology Research Fund Program for Young Scholars.
文摘Manipulating the expression of synaptic plasticity of neuromorphic devices provides fascinating opportunities to develop hardware platforms for artifi-cial intelligence.However,great efforts have been devoted to exploring biomimetic mechanisms of plasticity simulation in the last few years.Recent progress in various plasticity modulation techniques has pushed the research of synaptic electronics from static plasticity simulation to dynamic plasticity modulation,improving the accuracy of neuromorphic computing and providing strategies for implementing neuromorphic sensing functions.Herein,several fascinating strategies for synap-tic plasticity modulation through chemical techniques,device structure design,and physical signal sensing are reviewed.For chemical techniques,the underly-ing mechanisms for the modification of functional materials were clarified and its effect on the expression of synaptic plasticity was also highlighted.Based on device structure design,the reconfigurable operation of neuromorphic devices was well demonstrated to achieve programmable neuromorphic functions.Besides,integrating the sensory units with neuromorphic processing circuits paved a new way to achieve human-like intelligent perception under the modulation of physical signals such as light,strain,and temperature.Finally,considering that the relevant technology is still in the basic exploration stage,some prospects or development suggestions are put forward to promote the development of neuromorphic devices.
基金Project supported by the National Natural Science Foundations of China(Grant Nos.62171401 and 62071411)。
文摘Synaptic plasticity can greatly affect the firing behavior of neural networks,and it specifically refers to changes in the strength,morphology,and function of synaptic connections.In this paper,a novel memristor model,which can be configured as a volatile and nonvolatile memristor by adjusting its internal parameter,is proposed to mimic the short-term and long-term synaptic plasticity.Then,a bi-neuron network model,with the proposed memristor serving as a coupling synapse and the external electromagnetic radiation being emulated by the flux-controlled memristors,is established to elucidate the effects of short-term and long-term synaptic plasticity on firing activity of the neuron network.The resultant seven-dimensional(7D)neuron network has no equilibrium point and its hidden dynamical behavior is revealed by phase diagram,time series,bifurcation diagram,Lyapunov exponent spectrum,and two-dimensional(2D)dynamic map.Our results show the short-term and long-term plasticity can induce different bifurcation scenarios when the coupling strength increases.In addition,memristor synaptic plasticity has a great influence on the distribution of firing patterns in the parameter space.More interestingly,when exploring the synchronous firing behavior of two neurons,the two neurons can gradually achieve phase synchronization as the coupling strength increases along the opposite directions under two different memory attributes.Finally,a microcontroller-based hardware system is implemented to verify the numerical simulation results.
基金Project supported by Guangdong Major Project of Basic and Applied Basic Research,China (Grant No.2019B030302010)the National Natural Science Foundation of China (Grant No.52130108)+1 种基金Guangdong Basic and Applied Basic Research,China (Grant No.2021B1515140005)Pearl River Talent Recruitment Program (Grant No.2021QN02C04)。
文摘Anelasticity, as an intrinsic property of amorphous solids, plays a significant role in understanding their relaxation and deformation mechanism. However, due to the lack of long-range order in amorphous solids, the structural origin of anelasticity and its distinction from plasticity remain elusive. In this work, using frozen matrix method, we study the transition from anelasticity to plasticity in a two-dimensional model glass. Three distinct mechanical behaviors, namely,elasticity, anelasticity, and plasticity, are identified with control parameters in the amorphous solid. Through the study of finite size effects on these mechanical behaviors, it is revealed that anelasticity can be distinguished from plasticity.Anelasticity serves as an intrinsic bridge connecting the elasticity and plasticity of amorphous solids. Additionally, it is observed that anelastic events are localized, while plastic events are subextensive. The transition from anelasticity to plasticity is found to resemble the entanglement of long-range interactions between element excitations. This study sheds light on the fundamental nature of anelasticity as a key property of element excitations in amorphous solids.
基金the National Key Research and Development Program of China(2022YFC2009700)the National Science Foundation of China(82372582)+1 种基金the Medical Applications Basic Research Project of Suzhou Science and Technology Bureau(SKY2023033)the Wujiang District Science,Education,Health and Promotion Project(WWK202021).
文摘Background The neurophysiological differences in cortical plasticity and cholinergic system function due to ageing and their correlation with cognitive function remain poorly understood.Aims To reveal the differences in long-term potentiation(LTP)-like plasticity and short-latency afferent inhibition(SAl)between older and younger individuals,alongside their correlation with cognitive function using transcranial magnetic stimulation(TMS).Methods The cross-sectional study involved 31 younger adults aged 18-30 and 46 older adults aged 60-80.All participants underwent comprehensive cognitive assessments and a neurophysiological evaluation based on TMS.Cognitive function assessments included evaluations of global cognitive function,language,memory and executive function.The neurophysiological assessment included LTP-like plasticity and SAl.Results The findings of this study revealed a decline in LTP among the older adults compared with the younger adults(wald χ^(2)=3.98,p=0.046).Subgroup analysis further demonstrated a significant reduction in SAl level among individuals aged 70-80 years in comparison to both the younger adults(SAI(N20)):(t=-3.37,p=0.018);SAl(N20+4):(t=-3.13,p=0.038)and those aged 60-70(SAl(N20)):(t=3.26,p=0.025);SAl(N20+4):(t=-3.69,p=0.006).Conversely,there was no notable difference in SAl level between those aged 60-70 years and the younger group.Furthermore,after employing the Bonferroni correction,the correlation analysis revealed that only the positive correlation between LTP-like plasticity and language function(r=0.61,p<0.001)in the younger group remained statistically significant.Conclusions During the normal ageing process,a decline in synaptic plasticity may precede cholinergic system dysfunction.In individuals over 60 years of age,there is a reduction in LTP-like plasticity,while a decline in cholinergic system function is observed in those over 70.Thus,the cholinergic system may play a vital role in preventing cognitive decline during normal ageing.In younger individuals,LTP-like plasticity might represent a potential neurophysiological marker for language function.
基金supported by Beijing Natural Science Foundation Key Program(Grant No.Z190007)Beijing Natural Science Foundation(Grant No.2212048)+1 种基金the National Natural Science Foundation of China(Grant Nos.11474272,61774144,and 12004212)the Chinese Academy of Sciences(Grant Nos.QYZDY-SSW-JSC020,XDB28000000,and XDB44000000)。
文摘Current-induced multilevel magnetization switching in ferrimagnetic spintronic devices is highly pursued for the application in neuromorphic computing.In this work,we demonstrate the switching plasticity in Co/Gd ferrimagnetic multilayers where the binary states magnetization switching induced by spin–orbit toque can be tuned into a multistate one as decreasing the domain nucleation barrier.Therefore,the switching plasticity can be tuned by the perpendicular magnetic anisotropy of the multilayers and the in-plane magnetic field.Moreover,we used the switching plasticity of Co/Gd multilayers for demonstrating spike timing-dependent plasticity and sigmoid-like activation behavior.This work gives useful guidance to design multilevel spintronic devices which could be applied in high-performance neuromorphic computing.
基金support for this work provided by Louisiana Board of Regents (RCS and Pfund)high performance grid computing resources (HPC) provided by LONI (Louisiana Optical Network Initiative)
文摘A new nonlocal plasticity model,which is based on the integral-type nonlocal model and the cubic representative volumetric element（RVE）,is proposed to simulate shear band localization in geotechnical materials such as soils and rocks.An algorithm is developed to solve the resulting nonlinear system of equations.In this algorithm,the nonlocal averaging of plastic strain over the RVE is evaluated using C0 elements instead of using C1 elements to solve the second-order gradient of plastic strains.To obtain the average plastic strain,a set of special elements,called the nonlocal elements,are constructed to approximate the RVE.The updating of average stresses of the local element is based on the nonlocal plastic strain of the corresponding nonlocal elements.Numerical examples show that meshindependent results can be achieved using the proposed model and the algorithm,and the thickness of the shear band is insensitive to the mesh refinement.
文摘Neuronal networks,especially those in the central nervous system(CNS),evolved to support extensive functional capabilities while ensuring stability.Several physiological"brakes"that maintain the stability of the neuronal networks in a healthy state quickly become a hinderance postinjury.These"brakes"include inhibition from the extracellular environment,intrinsic factors of neurons and the control of neuronal plasticity.There are distinct differences between the neuronal networks in the peripheral nervous system(PNS)and the CNS.Underpinning these differences is the trade-off between reduced functional capabilities with increased adaptability through the formation of new connections and new neurons.The PNS has"facilitators"that stimulate neuroregeneration and plasticity,while the CNS has"brakes"that limit them.By studying how these"facilitators"and"brakes"work and identifying the key processes and molecules involved,we can attempt to apply these theories to the neuronal networks of the CNS to increase its adaptability.The difference in adaptability between the CNS and PNS leads to a difference in neuroregenerative properties and plasticity.Plasticity ensures quick functional recovery of abilities in the short and medium term.Neuroregeneration involves synthesizing new neurons and connections,providing extra resources in the long term to replace those damaged by the injury,and achieving a lasting functional recovery.Therefore,by understanding the factors that affect neuroregeneration and plasticity,we can combine their advantages and develop rehabilitation techniques.Rehabilitation training methods,coordinated with pharmacological interventions and/or electrical stimulation,contributes to a precise,holistic treatment plan that achieves functional recovery from nervous system injuries.Furthermore,these techniques are not limited to limb movement,as other functions lost as a result of brain injury,such as speech,can also be recovered with an appropriate training program.
基金supported by the National Natural Science Foundation of China(61401497)
文摘With key roles in essential brain functions ranging from the long-term potentiation(LTP) to synaptic plasticity,the N-methyl-D-aspartic acid receptor(NMDAR) can be considered as one of the fundamental glutamate receptors in the central nervous system.The role of NMDA R was first identified in synaptic plasticity and has been extensively studied.Some molecules,such as Ca^(2+),postsynaptic density 95(PSD-95),calcium/calmodulin-dependent protein kinase II(Ca MK II),protein kinase A(PKA),mitogen-activated protein kinase(MAPK) and cyclic adenosine monophosphate(c AMP) responsive element binding protein(CREB),are of special importance in learning and memory.This review mainly focused on the new research of key molecules connected with learning and memory,which played important roles in the NMDAR signaling pathway.
基金Supportedby the Early-stage Special FundforImportant Basis Research Projectfrom the Technology Department of China(2002CCAO4400)
文摘Objective To investigate whether there is endogenous neural stem cell proliferation and whether these proliferated neural stem cells represent neural plasticity in the adult rats after cerebral infarction. Methods Cerebral infarction models of rats were established and the dynamic expression of bromodeoxyuridine （BrdU）, BrdU/polysialylated neural cell adhesion molecule （PSA-NCAM） were determined by immunohistochemistry and immunofluorescence staining. BrdU was used to mark dividing neural stem cells. PSA-NCAM was used to mark the plasticity of neural stem cells. Results Compared with controls, the number of BrdU-positive cells in the subventricular zone （SVZ） and hippocampus increased significantly at 1st day after cerebral infarction （P 〈 0. 05 ）, reached maximum at 7th day, decreased markedly at 14th day, but it was still elevated compared with that of the controls （ P 〈 0. 05 ）. The number of BrdU-labeled with PSA-NCAM-positive cells increased significantly at 7th day （ P 〈 0. 05 ）, reached maximum at 14th day, markedly decreased at 28th day, but it was still elevated compared with that of the controls （P 〈 0. 05 ）. It was equal to 60% of the number of BrdU-positive cells in the same period. Conclusion Cerebral infarction may stimulate the proliferation of endogenous neural stem cells in situ and most proliferated neural stem cells represent neural plasticity.
文摘The need to develop armour systems to protect against attacks from various sources is increasingly a matter of personal,social and national security.To develop innovative armour systems it is necessary to monitor developments being made on the type,technology and performance of the threats(weapons,projectiles,explosives,etc.) Specifically,the use of high protection level helmets on the battlefield is essential.The development of evaluation methods that can predict injuries and trauma is therefore of major importance.However,the risk of injuries or trauma that can arise from induced accelerations is an additional consideration.To develop new materials and layouts for helmets it is necessary to study the effects caused by ballistic impacts in the human head on various scenarios.The use of numerical simulation is a fundamental tool in this process.The work here presented focuses on the use of numerical simulation(finite elements analysis) to predict the consequences of bullet impacts on military helmets on human injuries.The main objectives are to assess the level and probability of head trauma using the Head Injury Criterion,caused by the impact of a 9 mm NATO projectile on a PASGT helmet and to quantify the relevance of projectile plasticity on the whole modelling process.The accelerations derived from the impact phenomenon and the deformations caused on the helmet are evaluated using fully three-dimensional models of the helmet,head,neck and projectile.Impact studies are done at impact angles ranging from 0 to 75°.Results are presented and discussed in terms of HIC and probability of acceleration induced trauma levels.Thorough comparison analyses are done using a rigid and a deformable projectile and it is observed that plastic deformation of the projectile is a significant energy dissipation mechanism in the whole impact process.
基金supported by JSPS RONPAKU Program FY2018,Japan(R11810)Bangladesh University Grants Commission(UGC/SciTech/Agri(Crop-47)-26/2017/4915)。
文摘Bruguiera sexangula(Lour.)Poir is an exclusive evergreen mangrove species to the Sundarbans of Bangladesh.It grows well in moderate saline zones with full sunlight.This study presents leaf morphological plasticity in B.sexangula to saline zones.Leaves were sampled from different saline zones and various morphological traits were measured.The results exposed a wide deviations of leaf size parameters:leaf length varied 6.6–17.3 cm;width 2.7–7.8 cm;upper quarter width 2.2–6.5 cm;down quarter width 2.5–7.3 cm;and petiole length 0.17–1.43 cm.Leaf length was significantly larger in fresh water than in other salinity zones,whereas,leaf width,upper and lower leaf quarters were significantly larger in medium saline zone.Leaf shape parameters showed a large variation among saline zones.Leaf base angle was significantly larger in both medium and strong salinity zones.Tip angle was significantly greater in medium salinity zone.Leaf perimeter was significantly larger in fresh water but leaf area was significantly bigger in medium saline zone.Leaf index and specific leaf area were maximum in moderate saline zone.Plasticity index was the highest in moderate saline for almost all the parameters presented.The ordination(PCA)showed clusters of leaf samples although there were some overlap among them which suggested a salt-stress relationship among salinity zones.The results indicate that B.sexangula had a plasticity strategy on leaf morphological parameters to salinity in the Sundarbans.This study will provide basic information of leaf plasticity of this species among saline zones which will help for site selection of coastal planting and will also provide information for policy makers to take necessary steps for its conservation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11135001 and 11174034)
文摘Phase transitions widely exist in nature and occur when some control parameters are changed. In neural systems, their macroscopic states are represented by the activity states of neuron populations, and phase transitions between different activity states are closely related to corresponding functions in the brain. In particular, phase transitions to some rhythmic synchronous firing states play significant roles on diverse brain functions and disfunctions, such as encoding rhythmical external stimuli, epileptic seizure, etc. However, in previous studies, phase transitions in neuronal networks are almost driven by network parameters （e.g., external stimuli）, and there has been no investigation about the transitions between typical activity states of neuronal networks in a self-organized way by applying plastic connection weights. In this paper, we discuss phase transitions in electrically coupled and lattice-based small-world neuronal networks （LBSW networks） under spike-timing-dependent plasticity （STDP）. By applying STDP on all electrical synapses, various known and novel phase transitions could emerge in LBSW networks, particularly, the phenomenon of self-organized phase transitions （SOPTs）： repeated transitions between synchronous and asynchronous firing states. We further explore the mechanics generating SOPTs on the basis of synaptic weight dynamics.
文摘The most critical issue in the steel catenary riser design is to evaluate the fatigue damage in the touchdown zone accurately. Appropriate modeling of the riser-soil resistance in the touchdown zone can lead to significant cost reduction by optimizing design. This paper presents a plasticity model that can be applied to numerically simulate riser-soil interaction and evaluate dynamic responses and the fatigue damage of a steel catenary riser in the touchdown zone. Utilizing the model, numerous riser-soil elements are attached to the steel catenary riser finite elements, in which each simulates local foundation restraint along the riser touchdown zone. The riser-soil interaction plasticity model accounts for the behavior within an allowable combined loading surface. The model will be represented in this paper, allowing simple numerical implementation. More importantly, it can be incorporated within the structural analysis of a steel catenary riser with the finite element method. The applicability of the model is interpreted theoretically and the results are shown through application to an offshore 8.625 steel catenary riser example. The fatigue analysis results of the liner elastic riser-soil model are also shown. According to the comparison results of the two models, the fatigue life analysis results of the plasticity framework are reasonable and the horizontal effects of the riser-soil interaction can be included.
基金the the National Natural Science Foundation of China(Nos.81000598).
文摘Visual deprivation leads to structural neuroplasticity in the blind subjects,including gray matter(GM)and white matter(WM)atrophy and alterations in structural connectivity.The rat model of binocular enucleation(BE)is a frequently used animal model for studying brain plasticity induced by early blindness.Yet few neuroimaging studies have been performed on this model to investigate whether or not the BE rats have image phenotypes similar to or comparable to,those observed in the early blind subjects.The current study aimed to assess brain structural plasticity in BE rats using anatomical magnetic resonance imaging(MRI)and diffusion tensor imaging(DTI).The results demonstrated that early BE at postnatal day 4(P4)caused almost complete degeneration of optic nerve(ON)and optic chiasma(OCH),atrophy in a number of visual and non-visual structures,including optic tract(OT),dorsal lateral geniculate nucleus(DLG)and corpus callosum(CC).The BE rats also exhibited impairments of WM microstructural integrity in the OT,and reduction of structural connectivity between the normal-appearing visual cortex(VC)and somatosensory/motor cortices at 4 months of age,likely as manifestations of deafferentationinduced maldevelopment.The structural neuroplasticity in BE rats observable to structural MRI parallels largely with what has been reported in blind subjects,suggesting that longitudinal neuroimaging studies on animal models of sensory deprivation can provide insights into how the brain changes its wiring and function during development/adaption in response to the lack of sensory stimuli.
基金Project supported by the National Natural Science Foundation of China(Grant No.11572259)the Natural Science Foundation of Shaanxi Province,China(Grant Nos.2019JQ-827,2018JM1013,and 2018JQ5108)the Scientific Research Program Funded by Shaanxi Provincial Education Department,China(Grant No.19JK0672)。
文摘Using molecular dynamics simulations,the plastic deformation behavior of nanocrytalline Ti has been investigated under tension and compression normal to the{0001},{1010},and{1210}planes.The results indicate that the plastic deformation strongly depends on crystal orientation and loading directions.Under tension normal to basal plane,the deformation mechanism is mainly the grain reorientation and the subsequent deformation twinning.Under compression,the transformation of hexagonal-close packed(HCP)-Ti to face-centered cubic(FCC)-Ti dominates the deformation.When loading is normal to the prismatic planes(both{1010}and{1210}),the deformation mechanism is primarily the phase transformation among HCP,body-centered cubic(BCC),and FCC structures,regardless of loading mode.The orientation relations(OR)of{0001}HCP||{111}FCC and<1210>HCP||<110>FCC,and{1010}HCP||{110}FCC and<0001>HCP||<010>FCC between the HCP and FCC phases have been observed in the present work.For the transformation of HCP→BCC→HCP,the OR is{0001}α1||{110}β||{1010}α2(HCP phase before the critical strain is defined as α1-Ti,BCC phase is defined as β-Ti,and the HCP phase after the critical strain is defined as α2-Ti).Energy evolution during the various loading processes further shows the plastic anisotropy of nanocrystalline Ti is determined by the stacking order of the atoms.The results in the present work will promote the in-depth study of the plastic deformation mechanism of HCP materials.
基金TZ acknowledges contribution from the China Scholarship Council(CSC)MM and JM-V received support from the Spanish Ministry of Science and Innovation(MICINN)via competitive grant CGL2017-89149-C2-1-RAG and JJC were supported by the FUNDIVER project of the Spanish Ministry of Science and Innovation(CGL2015-69186-C2-1-R).
文摘Background:Plasticity in response to environmental drivers can help trees cope with droughts.However,our understanding of the importance of plasticity and physiological adjustments in trees under global change is limited.Methods:We used the International Tree-Ring Data Bank(ITRDB)to examine 20th century growth responses in conifer trees during(resistance)and following(resilience)years of severe soil and atmospheric droughts occurring in isolation or as compound events.Growth resilience indices were calculated using observed growth divided by expected growth to avoid spurious correlations,in which the expected values were obtained by the autoregressive moving average(ARIMA)model.We used high atmospheric vapour pressure deficit(VPD)to select years of atmospheric drought and low annual values of the Standardized Precipitation-Evapotranspiration Index(SPEI)to select years with soil drought.We acquired the sensitivities(i.e.,the slopes of the relationships)by fitting the resilience indices as a function of environmental drivers,and assessed how these sensitivities changed over time for different types of drought events using linear mixed models.We also checked whether plasticity in growth responses was sufficient to prevent long-term trends of growth reductions during or after severe droughts.We acknowledge that by focusing on the response of surviving trees from the ITRDB we are potentially biasing our results towards higher resilience,as stand level responses(e.g.,mortality)may result in lowered competition after the disturbance event.Results:Sensitivities of resilience to VPD and SPEI changed throughout the 20th century,with the directions of these changes often reversing in the second half of the century.For the 1961–2010 period,changing sensitivities had positive effects on resilience,especially following years of high-VPD and compound events,avoiding growth losses that would have occurred if sensitivities had remained constant.Despite sensitivity changes,resilience was still lower at the end of the 20th century compared to the beginning of the century.Conclusions:Future adjustments to low-SPEI and high-VPD events are likely to continue to compensate for the trends in climate only partially,leading to further generalized reductions in tree growth of conifers.An improved understanding of these plastic adjustments and their limits,as well as potential compensatory processes at the stand level,is needed to project forest responses to climate change.
基金supported by the National Natural Science Foundation of China(Grant No.51172040)the National Basic Research Program of China(Grant No.2011CB606403)the General Project of Scientific Research from Liaoning Educational Committee,China(Grant No.L2014135)
文摘Indenter size effect on the reversible incipient plasticity of Al(001) surface is studied by quasicontinuum simulations.Results show that the incipient plasticity under small indenter, the radius of which is less than ten nanometers, is dominated by a simple planar fault defect that can be fully removed after withdrawal of the indenter; otherwise, irreversible incipient plastic deformation driven by a complex dislocation activity is preferred, and the debris of deformation twins, dislocations,and stacking fault ribbons still remain beneath the surface when the indenter has been completely retracted. Based on stress distributions calculated at an atomic level, the reason why the dislocation burst instead of a simple fault ribbon is observed under a large indenter is the release of the intensely accumulated shear stress. Finally, the critical load analysis implies that there exists a reversible-irreversible transition of incipient plasticity induced by indenter size. Our findings provide a further insight into the incipient surface plasticity of face-centered-cubic metals in nano-sized contact issues.
基金the Science Challenge Project(Grant No.TZ2018004)the NSAF Joint Program(Grant No.U1930402)+1 种基金the National Natural Science Foundation of China(Grant No.51801230)the National Key Research and Development Program of China(Grant No.2018YFA0703601).
文摘The lack of the long-range order in the atomic structure challenges the identification of the structural defects,akin to dislocations in crystals,which are responsible for predicting plastic events and mechanical failure in metallic glasses(MGs).Although vast structural indicators have been proposed to identify the structural defects,quantitatively gauging the correlations between these proposed indicators based on the undeformed configuration and the plasticity of MGs upon external loads is still lacking.Here,we systematically analyze the ability of these indicators to predict plastic events in a representative MG model using machine learning method.Moreover,we evaluate the influences of coarse graining method and medium-range order on the predictive power.We demonstrate that indicators relevant to the low-frequency vibrational modes reveal the intrinsic structural characteristics of plastic rearrangements.Our work makes an important step towards quantitative assessments of given indicators,and thereby an effective identification of the structural defects in MGs.
基金supported by STI 2030-Major Projects 2021ZD0201300。
文摘The way in which persistent firing activity and synaptic plasticity are orchestrated to underlie working memory in recurrent neural networks is not fully understood. Here, we build a continuous attractor network of pyramidal cells and interneurons to simulate an oculomotor delayed response task. Both short-term facilitation(STF) and short-term depression(STD) manifest at synapses between pyramidal cells. The efficacy of individual synapses depends on the time constants of STF and STD as well as the presynaptic firing rate. Self-sustained firing activity(i.e., a bump attractor) during the delay period encodes the cue position. The bump attractor becomes more robust against random drifts and distractions with enhancing STF or reducing STD. Keeping STF and STD at appropriate levels is crucial for optimizing network performance. Our results suggest that, besides slow recurrent excitation and strong global inhibition, short-term plasticity plays a prominent role in facilitating mnemonic behavior.
基金the National Natural Science Foundation of China(Grant Nos.11674162 and 61834001)the National Key R&D Program of China(Grant Nos.2018YFA0305800 and 2019YFB2205400).
文摘Emulation of synaptic function by ionic/electronic hybrid device is crucial for brain-like computing and neuromorphic systems.Electric-double-layer(EDL)transistors with proton conducting electrolytes as the gate dielectrics provide a prospective approach for such application.Here,artificial synapses based on indium-tungsten-oxide(IWO)-based EDL transistors are proposed,and some important synaptic functions(excitatory post-synaptic current,paired-pulse facilitation,filtering)are emulated.Two types of spike-timing-dependent plasticity(Hebbian STDP and anti-Hebbian STDP)learning rules and multistore memory(sensory memory,short-term memory,and long-term memory)are also mimicked.At last,classical conditioning is successfully demonstrated.Our results indicate that IWO-based neuromorphic transistors are interesting for neuromorphic applications.
