BIOELECTRONIC VISION: Retina Models, Evaluation Metrics and System Design (Series on Bioengineering & Biomedical Engineering)

Cover......Page 1
Frontmatter......Page 2
Title page......Page 4
Copyright © 2009......Page 5
Preface......Page 8
Acknowledgments......Page 12
Contents......Page 14
List of Figures......Page 18
List of Tables......Page 22
List of Acronyms......Page 24
1. Introduction to Bioelectronic Vision......Page 26
1.1 Main Causes of Blindness......Page 27
1.2 Main Components of a Bioelectronic Vision System......Page 30
1.3 Classification of Visual Prostheses......Page 35
1.3.1 Retinal Neuroprosthesis......Page 37
1.3.2 Cortical Visual Neuroprosthesis......Page 39
1.4 Conclusions and Further Reading......Page 40
Exercises......Page 42
2.1 Introduction......Page 46
2.2.1 Neuron Anatomy......Page 47
2.2.2 Neuron Dynamics......Page 48
2.2.2.1 Neural Communication through Chemical Synapses......Page 51
2.2.2.2 Neural Communication through Electrical Synapses......Page 52
2.3 The Human Visual System......Page 53
2.3.1 The Eye......Page 54
2.3.2 The Retina......Page 56
2.3.3 How the Retina Operates......Page 62
2.3.4 The Visual Pathway......Page 69
2.3.4.1 Optic Nerve and Tract......Page 70
2.3.4.2 Subcortical structures......Page 71
2.3.4.3 Visual Cortex......Page 73
2.4.1 The Retina Neural Code......Page 74
2.4.2 Classification of Retina Models......Page 77
2.4.2.2 Structural Models......Page 78
Exercises......Page 79
3.1 Introduction......Page 82
3.2 Spikes: The Essence of the Neural Code......Page 83
3.2.1 Retina Stimulation and Responses Recording......Page 85
3.2.2 Spike Trains and Firing Rates......Page 96
3.2.3 Spike Triggered Average......Page 108
3.2.4 Spike Train Autocorrelation Function......Page 112
3.2.5 The Spike Triggered Covariance......Page 114
3.3 Stimulus and Response Statistics, and Firing Probabilities......Page 115
3.3.1 Spike Train Statistics......Page 117
3.3.2 Homogeneous Poisson Model of Spike Trains......Page 118
3.3.2.1 Spike Count Distribution......Page 119
3.3.2.2 Interspike Interval Distribution......Page 123
3.3.3 Inhomogeneous Poisson Model of Spike Trains......Page 125
3.3.4 Spike-Count Statistics......Page 127
3.4 Spiking Mechanisms......Page 128
3.4.1 Generation of Poisson Spike Trains......Page 129
3.4.2 Integrate-and-Fire Spike Generation......Page 130
3.5 Conclusions and Further Reading......Page 132
Exercises......Page 133
4.2 Classification of Retina Models......Page 138
4.3.1 The Integrate and Fire Model......Page 140
4.3.2 The Leaky Integrate-and-Fire Model......Page 143
4.4 Functional Models......Page 148
4.4.1 Deterministic Models......Page 149
4.4.2 Stochastic Models......Page 154
4.4.3 White Noise based Models......Page 163
4.5 Conclusions and Further Reading......Page 170
Exercises......Page 171
5.2 The Metric Definition......Page 180
5.3.1 Mean Squared Error......Page 181
5.3.2 Normalized Mean Squared Error......Page 182
5.3.3 Percent Variance Accounted For......Page 183
5.3.4 Analysis of the Firing Rate Metrics......Page 184
5.4 Spike Train Metrics......Page 185
5.4.1 Spike Time Metric......Page 186
5.4.2 Interspike Interval Metric......Page 191
5.4.3 Spike Train Distance Metric......Page 195
5.4.4 Spike Train Metrics Analysis......Page 199
5.5 Spike Events Metrics......Page 202
5.5.1 Spike Events Metric Analysis......Page 212
5.6 Tuning and Assessment of Retina Models......Page 213
5.6.1 Deterministic Model......Page 214
5.6.3 White Noise Model......Page 216
5.7 Conclusions and Further Reading......Page 218
Exercises......Page 221
6.1 Retinal Prostheses......Page 224
6.1.1 Epiretinal Implants......Page 225
6.1.2 Subretinal Implants......Page 227
6.2 Retinal Bioelectronic Vision System Design......Page 229
6.3 Cortical Visual Prostheses......Page 233
6.4 Cortical Bioelectronic Vision System Design......Page 237
6.4.1 Early Layers......Page 238
6.4.2 Neuromorphic Pulse Coding......Page 242
6.4.3 Spike Multiplexing......Page 243
6.4.4 Serial Communication Link......Page 246
6.5 Vision Prosthesis Prototype......Page 248
6.6 Conclusions and Further Reading......Page 251
Exercises......Page 254
Bibliography......Page 258
Index......Page 266