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
Both external and endogenous electrical fields widely exist in the environment of cortical neurons. The effects of a weak alternating current （AC） field on a neural network model with synaptic plasticity are studied...Both external and endogenous electrical fields widely exist in the environment of cortical neurons. The effects of a weak alternating current （AC） field on a neural network model with synaptic plasticity are studied. It is found that self-sustained rhythmic firing patterns, which are closely correlated with the cognitive functions, are significantly modified due to the self-organizing of the network in the weak AC field. The activities of the neural networks are affected by the synaptic connection strength, the exterrtal stimuli, and so on. In the presence of learning rules, the synaptic connections can be modulated by the external stimuli, which will further enhance the sensitivity of the network to the external signal. The properties of the external AC stimuli can serve as control parameters in modulating the evolution of the neural network.展开更多
Amblyopia resulting from early deprivation of vision or defocus in one eye reflects an imbalance of input from the eyes to the visual cortex.We tested the hypothesis that asynchronous stimulation of the two eyes might...Amblyopia resulting from early deprivation of vision or defocus in one eye reflects an imbalance of input from the eyes to the visual cortex.We tested the hypothesis that asynchronous stimulation of the two eyes might induce synaptic plasticity and rebalance input.Experiments on normal adults showed that repetitive brief exposure of grating stimuli,with the onset of each stimulus delayed by 8.3 ms in one eye,results in a shift in perceptual eye dominance.Clinical studies(Clinical trial registration number:Chi CTR2100049130),using popular 3D movies with similar asynchrony between the two eyes(amblyopic eye stimulated first)to treat anisometropic amblyopia,established that just 10.5 h of conditioning over<3 weeks produced improvement that met criteria for successful treatment.The benefits of asynchronous conditioning accumulate over 20–3045 min sessions,and are maintained for at least 2 years.Finally,we demonstrate that asynchronous binocular treatment alone is more effective than patching only.This novel treatment is popular with children and is some 50 times more efficient than patching alone.展开更多
Multilevel resistive switching(RS)is a key property to embrace the full potential of memristive devices for non-volatile memory and neuromorphic computing applications.In this study,we employed nanoparticulated cobalt...Multilevel resistive switching(RS)is a key property to embrace the full potential of memristive devices for non-volatile memory and neuromorphic computing applications.In this study,we employed nanoparticulated cobaltite oxide(Co_(3)O_(4))as a model material to demonstrate the multilevel RS and synaptic learning capabilities because of its multiple and stable redox state properties.The Pt/Co_(3)O_(4)/Pt memristive device exhibited tunable RS properties with respect to different voltages and compliance currents(CC)without the electroforming process.That is,the device showed voltage-dependent RS at a higher CC whereas CC-dependent RS was observed at lower CC.The device showed four different resistance states during endurance and retention measurements and non-volatile memory results indicated that the CC-based measurement had less variation.Besides,we investigated the basic and complex synaptic plasticity properties using the analog current-voltage characteristics of the Pt/Co_(3)O_(4)/Pt device.In particular,we mimicked the potentiation–depression and four-spike time-dependent plasticity(STDP)rules such as asymmetric Hebbian,asymmetric anti-Hebbian,symmetric Hebbian,and symmetric antiHebbian learning rules.The results of the present work indicate that the cobaltite oxide is an excellent nanomaterial for both multilevel RS and neuromorphic computing applications.展开更多
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.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61072012, 60901035, 50907044, and 61172009)
文摘Both external and endogenous electrical fields widely exist in the environment of cortical neurons. The effects of a weak alternating current （AC） field on a neural network model with synaptic plasticity are studied. It is found that self-sustained rhythmic firing patterns, which are closely correlated with the cognitive functions, are significantly modified due to the self-organizing of the network in the weak AC field. The activities of the neural networks are affected by the synaptic connection strength, the exterrtal stimuli, and so on. In the presence of learning rules, the synaptic connections can be modulated by the external stimuli, which will further enhance the sensitivity of the network to the external signal. The properties of the external AC stimuli can serve as control parameters in modulating the evolution of the neural network.
基金supported by the National Basic Research Program of China(2011CB510206,2015CB351806)the National Natural Science Foundation of China(31170986,31571091)Beijing Municipal Science&Technology Commission(Z151100000915070)。
文摘Amblyopia resulting from early deprivation of vision or defocus in one eye reflects an imbalance of input from the eyes to the visual cortex.We tested the hypothesis that asynchronous stimulation of the two eyes might induce synaptic plasticity and rebalance input.Experiments on normal adults showed that repetitive brief exposure of grating stimuli,with the onset of each stimulus delayed by 8.3 ms in one eye,results in a shift in perceptual eye dominance.Clinical studies(Clinical trial registration number:Chi CTR2100049130),using popular 3D movies with similar asynchrony between the two eyes(amblyopic eye stimulated first)to treat anisometropic amblyopia,established that just 10.5 h of conditioning over<3 weeks produced improvement that met criteria for successful treatment.The benefits of asynchronous conditioning accumulate over 20–3045 min sessions,and are maintained for at least 2 years.Finally,we demonstrate that asynchronous binocular treatment alone is more effective than patching only.This novel treatment is popular with children and is some 50 times more efficient than patching alone.
基金the National Research Foundation of Korea(NRF)grant funded by the Korea government(No.2016R1A3B 1908249)。
文摘Multilevel resistive switching(RS)is a key property to embrace the full potential of memristive devices for non-volatile memory and neuromorphic computing applications.In this study,we employed nanoparticulated cobaltite oxide(Co_(3)O_(4))as a model material to demonstrate the multilevel RS and synaptic learning capabilities because of its multiple and stable redox state properties.The Pt/Co_(3)O_(4)/Pt memristive device exhibited tunable RS properties with respect to different voltages and compliance currents(CC)without the electroforming process.That is,the device showed voltage-dependent RS at a higher CC whereas CC-dependent RS was observed at lower CC.The device showed four different resistance states during endurance and retention measurements and non-volatile memory results indicated that the CC-based measurement had less variation.Besides,we investigated the basic and complex synaptic plasticity properties using the analog current-voltage characteristics of the Pt/Co_(3)O_(4)/Pt device.In particular,we mimicked the potentiation–depression and four-spike time-dependent plasticity(STDP)rules such as asymmetric Hebbian,asymmetric anti-Hebbian,symmetric Hebbian,and symmetric antiHebbian learning rules.The results of the present work indicate that the cobaltite oxide is an excellent nanomaterial for both multilevel RS and neuromorphic computing applications.
