Stochastic binary synapses having sigmoidal cumulative distribution functions for unsupervised learning with spike timing-dependent plasticity

Abstract Spike timing-dependent plasticity (STDP), which is widely studied as a fundamental synaptic update rule for neuromorphic hardware, requires precise control of continuous weights. From the viewpoint of hardware implementation, a simplified update rule is desirable. Although simplified STDP w...

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Autores principales: Yoshifumi Nishi, Kumiko Nomura, Takao Marukame, Koichi Mizushima
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Publicado: Nature Portfolio 2021
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Acceso en línea:https://doaj.org/article/1b42b9540ff943b4805ab44b662f914c
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spelling oai:doaj.org-article:1b42b9540ff943b4805ab44b662f914c2021-12-02T18:02:14ZStochastic binary synapses having sigmoidal cumulative distribution functions for unsupervised learning with spike timing-dependent plasticity10.1038/s41598-021-97583-y2045-2322https://doaj.org/article/1b42b9540ff943b4805ab44b662f914c2021-09-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-97583-yhttps://doaj.org/toc/2045-2322Abstract Spike timing-dependent plasticity (STDP), which is widely studied as a fundamental synaptic update rule for neuromorphic hardware, requires precise control of continuous weights. From the viewpoint of hardware implementation, a simplified update rule is desirable. Although simplified STDP with stochastic binary synapses was proposed previously, we find that it leads to degradation of memory maintenance during learning, which is unfavourable for unsupervised online learning. In this work, we propose a stochastic binary synaptic model where the cumulative probability of the weight change evolves in a sigmoidal fashion with potentiation or depression trials, which can be implemented using a pair of switching devices consisting of serially connected multiple binary memristors. As a benchmark test we perform simulations of unsupervised learning of MNIST images with a two-layer network and show that simplified STDP in combination with this model can outperform conventional rules with continuous weights not only in memory maintenance but also in recognition accuracy. Our method achieves 97.3% in recognition accuracy, which is higher than that reported with standard STDP in the same framework. We also show that the high performance of our learning rule is robust against device-to-device variability of the memristor's probabilistic behaviour.Yoshifumi NishiKumiko NomuraTakao MarukameKoichi MizushimaNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-12 (2021)
institution DOAJ
collection DOAJ
language EN
topic Medicine
R
Science
Q
spellingShingle Medicine
R
Science
Q
Yoshifumi Nishi
Kumiko Nomura
Takao Marukame
Koichi Mizushima
Stochastic binary synapses having sigmoidal cumulative distribution functions for unsupervised learning with spike timing-dependent plasticity
description Abstract Spike timing-dependent plasticity (STDP), which is widely studied as a fundamental synaptic update rule for neuromorphic hardware, requires precise control of continuous weights. From the viewpoint of hardware implementation, a simplified update rule is desirable. Although simplified STDP with stochastic binary synapses was proposed previously, we find that it leads to degradation of memory maintenance during learning, which is unfavourable for unsupervised online learning. In this work, we propose a stochastic binary synaptic model where the cumulative probability of the weight change evolves in a sigmoidal fashion with potentiation or depression trials, which can be implemented using a pair of switching devices consisting of serially connected multiple binary memristors. As a benchmark test we perform simulations of unsupervised learning of MNIST images with a two-layer network and show that simplified STDP in combination with this model can outperform conventional rules with continuous weights not only in memory maintenance but also in recognition accuracy. Our method achieves 97.3% in recognition accuracy, which is higher than that reported with standard STDP in the same framework. We also show that the high performance of our learning rule is robust against device-to-device variability of the memristor's probabilistic behaviour.
format article
author Yoshifumi Nishi
Kumiko Nomura
Takao Marukame
Koichi Mizushima
author_facet Yoshifumi Nishi
Kumiko Nomura
Takao Marukame
Koichi Mizushima
author_sort Yoshifumi Nishi
title Stochastic binary synapses having sigmoidal cumulative distribution functions for unsupervised learning with spike timing-dependent plasticity
title_short Stochastic binary synapses having sigmoidal cumulative distribution functions for unsupervised learning with spike timing-dependent plasticity
title_full Stochastic binary synapses having sigmoidal cumulative distribution functions for unsupervised learning with spike timing-dependent plasticity
title_fullStr Stochastic binary synapses having sigmoidal cumulative distribution functions for unsupervised learning with spike timing-dependent plasticity
title_full_unstemmed Stochastic binary synapses having sigmoidal cumulative distribution functions for unsupervised learning with spike timing-dependent plasticity
title_sort stochastic binary synapses having sigmoidal cumulative distribution functions for unsupervised learning with spike timing-dependent plasticity
publisher Nature Portfolio
publishDate 2021
url https://doaj.org/article/1b42b9540ff943b4805ab44b662f914c
work_keys_str_mv AT yoshifuminishi stochasticbinarysynapseshavingsigmoidalcumulativedistributionfunctionsforunsupervisedlearningwithspiketimingdependentplasticity
AT kumikonomura stochasticbinarysynapseshavingsigmoidalcumulativedistributionfunctionsforunsupervisedlearningwithspiketimingdependentplasticity
AT takaomarukame stochasticbinarysynapseshavingsigmoidalcumulativedistributionfunctionsforunsupervisedlearningwithspiketimingdependentplasticity
AT koichimizushima stochasticbinarysynapseshavingsigmoidalcumulativedistributionfunctionsforunsupervisedlearningwithspiketimingdependentplasticity
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