Intelligent Systems Reference Library 126 Qiang Yu Huajin Tang Jun Hu Kay Chen Tan Neuromorphic Cognitive Systems A Learning and Memory Centered Approach Intelligent Systems Reference Library Volume 126 Series editors Janusz Kacprzyk, Polish Academy of Sciences, Warsaw, Poland e-mail: [email protected] Lakhmi C. Jain, University of Canberra, Canberra, Australia; Bournemouth University, UK; KES International, UK e-mail: [email protected]; [email protected]; URL: http://www.kesinternational.org/organisation.php About this Series The aim of this series is to publish a Reference Library, including novel advances and developments in all aspects of Intelligent Systems in an easily accessible and well structured form. The series includes reference works, handbooks, compendia, textbooks,well-structuredmonographs,dictionaries,andencyclopedias.Itcontains well integrated knowledge and current information in the field of Intelligent Systems. The series covers the theory, applications, and design methods of IntelligentSystems.Virtuallyalldisciplinessuchasengineering,computerscience, avionics, business, e-commerce, environment, healthcare, physics and life science are included. More information about this series at http://www.springer.com/series/8578 Qiang Yu Huajin Tang Jun Hu (cid:129) (cid:129) Kay Chen Tan Neuromorphic Cognitive Systems A Learning and Memory Centered Approach 123 QiangYu Jun Hu Institute for Infocomm Research AGI Technologies Singapore Singapore Singapore Singapore HuajinTang Kay ChenTan Collegeof Computer Science Department ofComputer Science SichuanUniversity City University of HongKong Chengdu KowloonTong China Hong Kong ISSN 1868-4394 ISSN 1868-4408 (electronic) Intelligent Systems Reference Library ISBN978-3-319-55308-5 ISBN978-3-319-55310-8 (eBook) DOI 10.1007/978-3-319-55310-8 LibraryofCongressControlNumber:2017933943 ©SpringerInternationalPublishingAG2017 Reuse of the materials of “Cheu, E.Y., Yu, J., Tan, C.H. and Tang, H. Synaptic conditions for auto-associativememorystorageandpatterncompletioninJensenetal.’smodelofhippocampalarea CA3.JournalofComputationalNeuroscience,2012,33(3):435–447”,withpermissionfromSpringer Publisher. 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Neither the publisher nor the authorsortheeditorsgiveawarranty,expressorimplied,withrespecttothematerialcontainedhereinor for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictionalclaimsinpublishedmapsandinstitutionalaffiliations. Printedonacid-freepaper ThisSpringerimprintispublishedbySpringerNature TheregisteredcompanyisSpringerInternationalPublishingAG Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland To our family, for their loves and supports. Qiang Yu Huajin Tang Jun Hu Kay Chen Tan Preface Thepowerfulandyetmysterioushumanbrainsystemattractsnumerousresearchers devoting themselves to characterizing what nervous systems do, determining how they function, and understanding why they operate in particular ways. Encompassing various studies of biology, physics, psychology, mathematics, and computer science, theoretical neuroscience provides a quantitative basis for uncoveringthegeneralprinciplesbywhichthenervous systems operate.Basedon these principles, neuromorphic cognitive systems introduce some basic mathe- matical and computational methods to describe and utilize schemes at a cognitive level. Since the mechanisms how human memory cognitively operates and how to utilize the bioinspired mechanisms to practical applications are rarely known, the study of neuromorphic cognitive systems is urgently demanded. This book presents the computational principles underlying spike-based infor- mationprocessingandcognitivecomputationwithaspecificfocusonlearningand memory. Specifically, the action potential timing is utilized for sensory neuronal representations and computation, and spiking neurons are considered as the basic information processing unit. The topics covered in this book vary from neuronal level to system level, including neural coding, learning in both single- and multi- layered networks, cognitive memory, and applied developments of information processing systems with spiking neurons. From the neuronal level, synaptic adaptation plays an important role on learning patterns. In order to perform higher level cognitive functions such as recognition and memory, spiking neurons with learningabilitiesareconsistentlyintegratedwitheachother,buildingasystemwith the functionality of encoding, learning, and decoding. All these aspects are described with details in this book. Theories, concepts, methods, and applications are provided to motivate researchers in this exciting and interdisciplinary area. Theoretical modeling and analysisaretightlyboundedwithpracticalapplications,whichwouldbepotentially vii viii Preface beneficial for readers in the area of neuromorphic computing. This book presents the computational ability of bioinspired systems and gives a better understanding of the mechanisms by which the nervous system might operate. Singapore Qiang Yu Chengdu, China Huajin Tang Singapore Jun Hu Kowloon Tong, Hong Kong Kay Chen Tan December 2016 Contents 1 Introduction.... .... .... ..... .... .... .... .... .... ..... .... 1 1.1 Background .... .... ..... .... .... .... .... .... ..... .... 1 1.2 Spiking Neurons. .... ..... .... .... .... .... .... ..... .... 2 1.2.1 Biological Background ... .... .... .... .... ..... .... 2 1.2.2 Generations of Neuron Models. .... .... .... ..... .... 3 1.2.3 Spiking Neuron Models .. .... .... .... .... ..... .... 4 1.3 Neural Codes ... .... ..... .... .... .... .... .... ..... .... 5 1.3.1 Rate Code.... ..... .... .... .... .... .... ..... .... 6 1.3.2 Temporal Code..... .... .... .... .... .... ..... .... 7 1.3.3 Temporal Code Versus Rate Code .. .... .... ..... .... 7 1.4 Cognitive Learning and Memory in the Brain ... .... ..... .... 8 1.4.1 Temporal Learning .. .... .... .... .... .... ..... .... 8 1.4.2 Cognitive Memory in the Brain .... .... .... ..... .... 11 1.5 Objectives and Contributions .... .... .... .... .... ..... .... 12 1.6 Outline of the Book .. ..... .... .... .... .... .... ..... .... 14 References.. .... .... .... ..... .... .... .... .... .... ..... .... 15 2 Rapid Feedforward Computation by Temporal Encoding and Learning with Spiking Neurons . .... .... .... .... ..... .... 19 2.1 Introduction .... .... ..... .... .... .... .... .... ..... .... 19 2.2 The Spiking Neural Network .... .... .... .... .... ..... .... 21 2.3 Single-Spike Temporal Coding... .... .... .... .... ..... .... 22 2.4 Temporal Learning Rule.... .... .... .... .... .... ..... .... 26 2.4.1 The Tempotron Rule. .... .... .... .... .... ..... .... 26 2.4.2 The ReSuMe Rule... .... .... .... .... .... ..... .... 27 2.4.3 The Tempotron-Like ReSuMe Rule . .... .... ..... .... 28 2.5 Simulation Results ... ..... .... .... .... .... .... ..... .... 29 2.5.1 The Data Set and the Classification Problem... ..... .... 29 2.5.2 Encoding Images.... .... .... .... .... .... ..... .... 30 2.5.3 Choosing Among Temporal Learning Rules... ..... .... 30 ix x Contents 2.5.4 The Properties of Tempotron Rule .. .... .... ..... .... 32 2.5.5 Recognition Performance . .... .... .... .... ..... .... 34 2.6 Discussion . .... .... ..... .... .... .... .... .... ..... .... 37 2.6.1 Encoding Benefits from Biology.... .... .... ..... .... 37 2.6.2 Types of Synapses .. .... .... .... .... .... ..... .... 37 2.6.3 Schemes of Readout . .... .... .... .... .... ..... .... 38 2.6.4 Extension of the Network for Robust Sound Recognition... ..... .... .... .... .... .... ..... .... 38 2.7 Conclusion. .... .... ..... .... .... .... .... .... ..... .... 39 References.. .... .... .... ..... .... .... .... .... .... ..... .... 39 3 A Spike-Timing Based Integrated Model for Pattern Recognition .... .... .... ..... .... .... .... .... .... ..... .... 43 3.1 Introduction .... .... ..... .... .... .... .... .... ..... .... 43 3.2 The Integrated Model. ..... .... .... .... .... .... ..... .... 45 3.2.1 Neuron Model and General Structure .... .... ..... .... 45 3.2.2 Latency-Phase Encoding.. .... .... .... .... ..... .... 46 3.2.3 Supervised Spike-Timing Based Learning. .... ..... .... 49 3.3 Numerical Simulations ..... .... .... .... .... .... ..... .... 50 3.3.1 Network Architecture and Encoding of Grayscale Images . .... .... .... .... .... ..... .... 51 3.3.2 Learning Performance.... .... .... .... .... ..... .... 52 3.3.3 Generalization Capability . .... .... .... .... ..... .... 53 3.3.4 Parameters Evaluation.... .... .... .... .... ..... .... 55 3.3.5 Capacity of the Integrated System... .... .... ..... .... 57 3.4 Related Works .. .... ..... .... .... .... .... .... ..... .... 59 3.5 Conclusions .... .... ..... .... .... .... .... .... ..... .... 60 References.. .... .... .... ..... .... .... .... .... .... ..... .... 61 4 Precise-Spike-Driven Synaptic Plasticity for Hetero Association of Spatiotemporal Spike Patterns.. .... .... ..... .... 65 4.1 Introduction .... .... ..... .... .... .... .... .... ..... .... 65 4.2 Methods... .... .... ..... .... .... .... .... .... ..... .... 67 4.2.1 Spiking Neuron Model ... .... .... .... .... ..... .... 67 4.2.2 PSD Learning Rule.. .... .... .... .... .... ..... .... 68 4.3 Results .... .... .... ..... .... .... .... .... .... ..... .... 71 4.3.1 Association of Single-Spike and Multi-spike Patterns. .... 71 4.3.2 Generality to Different Neuron Models... .... ..... .... 76 4.3.3 Robustness to Noise . .... .... .... .... .... ..... .... 77 4.3.4 Learning Capacity... .... .... .... .... .... ..... .... 79 4.3.5 Effects of Learning Parameters . .... .... .... ..... .... 81 4.3.6 Classification of Spatiotemporal Patterns.. .... ..... .... 83 4.4 Discussion and Conclusion.. .... .... .... .... .... ..... .... 84 References.. .... .... .... ..... .... .... .... .... .... ..... .... 86