Introduction to Electrophysiological Methods and Instrumentation (eBook)

Front cover 1
Title page 4
Copyright page 5
Table of contents 8
Preface 13
1 Electricity 16
Electrical Quantities 16
Electric Charge, Current and Potential 16
Resistance 17
Capacitance 19
Magnetism 20
Self-Inductance 20
Direct and Alternating Current Frequency
Reactance 23
Current and Voltage Sources 24
Components, Unwanted Properties 25
Unwanted Properties, Impedance 28
Cables 31
Circuits, Schematics, Kirchoff’s Laws 32
Composition of Similar Components: Attenuators 34
Practical Voltage Sources and Current Sources 37
Voltage and Current Measurement 38
Composition of Unequal Components: Filters 40
Integration and Differentiation 46
LC Filters 47
2 Electronics 49
Active Elements 49
Vacuum Tubes and Semiconductors 50
Semiconductor Devices 51
Diodes and Transistors 52
Other Semiconductor Types 55
Amplifiers, Gain, Decibels and Saturation 57
Gain 58
Bandwidth 58
Input and Output Impedances 60
Maximum Signal Strength, Distortion 61
Noise, Hum Interference and Grounding 62
Differential Amplifiers, Block Diagrams 70
Operational Amplifiers, Feedback 73
Electronic Filters 78
Electrophysiological Preamplifiers 80
Amplifier for Extracellular Recording 80
Amplifier for Intracellular Recording 81
Patch-Clamp Amplifier 83
Two-Electrode Voltage-Clamp Amplifier 86
Measurement of Membrane Capacitance in Voltage-Clamp 86
Recording of Secretory Events 87
Power Supplies and Signal Sources 90
Electronic Voltmeters 94
Electrometers 94
The Cathode Ray Oscilloscope 95
LCD Screen Oscilloscopes 97
Important Properties of Oscilloscopes 97
Digital Electronics, Logic 100
A/D and D/A Conversions 108
Computers 111
3 Electrochemistry 118
Introduction, Properties of Electrolytes 118
Electrolytes 119
The Metal/Electrolyte Interface 124
Capacitance of Polarized Electrodes 125
Faradaic Processes 126
Practical Electrodes 128
Electrochemical Cells, Measuring Electrodes 128
The Silver/Silver Chloride Electrode 129
Non-Faradaic Processes 130
Electrokinetic Processes 130
Liquid Junction Potentials 131
Membrane Potentials 133
Derivation of the Equilibrium Potential 133
The Reversal Potential 134
Ion Selectivity 136
Electrodes Sensitive to pH and Other Ions 137
Electrodes: Practical Aspects 138
The Glass Micropipette 138
Patch Electrodes 140
The Semi-Permeable Patch 141
Ground Electrodes 142
Volume Conduction: Electric Fields in Electrolyte Solutions 143
Homogeneous Electric Field 143
Monopole Field 145
Dipole Field 145
4 Signal Analysis 147
Introduction 147
Analysis of Analogue Potentials 147
Systems Analysis 147
Convolution 150
The Laplace Transform 153
The Fourier Transform 155
Odd and Even Functions 159
Linearity 159
Analogue-to-Digital and Digital-to-Analogue Conversions 161
Signal Windowing 163
Digital Signal Processing 165
Signal Averaging 165
Autocorrelation 166
Crosscorrelation 168
The Discrete Fourier Transform 170
The Detection of Signals of Known Shape 171
Digital Filters 172
Fourier Filters and Non-Causal Filters 175
Non-Linear Systems Analysis 179
The Formal Method: Wiener Kernel Analysis 179
The Informal Method: Output Shape Analysis 181
The Importance of Non-Linearity 182
Analysis of Action Potential Signals 184
Population Spike and Gross Activity 185
Recording from the Skin Surface 186
The Electrocardiogram 186
The Electroencephalogram 188
Other Surface Recording Techniques 189
Single-Unit Activity 190
Uncertainty and Ambiguity in Spike Series 191
Interval Histogram 194
Poisson Processes 195
The Gamma Distribution 197
The Mathematics of Random Point Processes 197
Markov Chains 199
Time Series Analysis: Spike Rate, Interval Series and Instantaneous Frequency 199
Spike Frequency or Rate 199
Interval Series and Instantaneous Frequency 200
Dot Display 202
Stimulus–Response Characteristics: The PSTH 203
Analysis of Nerve Membrane Data 205
Terminology: The Hodgkin and Huxley Channel 205
Analysis of Macroscopic (Whole-Cell) Currents 206
The Current to Voltage (I/V) Curve 207
Leak Subtraction by Extrapolation 208
Leak Subtraction by Prepulses: The P/N Method 209
Noise Analysis: Estimating the Single-Channel Conductance from Whole-Cell or Large Patch Recordings 209
Noise Analysis: Estimating Channel Kinetics 211
Analysis of Microscopic (Unitary) Currents 211
Estimation of the unitary current 212
Detection of opening and closing events 213
Estimation of the number of channels in the patch 214
Measurement of dwell times 216
Calculating Dwell Time Histograms from Markov Chains 219
The First Latency Distribution 219
The Closed Time Distribution 222
The Open Time Distribution 223
The Macroscopic Current 223
Example: Simulation of the Hodgkin and Huxley Voltage-Dependent Sodium Channel 223
Appendices 225
A: Symbols, Abbreviations and Codes 225
Symbols 225
Abbreviations 226
Decimal Multipliers 227
Colour Code for Resistors 227
B: Symbols for Circuit Diagrams 228
C: Electrical Safety in Electrophysiological Set-Ups 230
Regular Instruments 230
Medical Instruments 233
D: The Use of CRT Monitors in Visual Experiments 236
Image Generation in CRT Monitors 236
Frame Rates and Interlacing 237
The Video Signal 237
The Use of CRT Monitors in Electrophysiology 239
Contrast, Gamma and Other Brightness Issues 240
Colour Coding 241
Geometry 242
Timing 242
Spatial and Brightness Resolution 243
E: Complex Numbers and Complex Frequency 245
The Meaning of Complex Frequency 247
F: The Mathematics of Markov Chains 248
G: Recursive (Non-Causal) Filters 254
H: Pseudocode to Calculate the Macroscopic Current and Dwell Time Distributions from a Transition Matrix 256
I: Referred and Recommended Literature 259
Electricity and Electronics 259
Electrochemistry 259
Neurophysiology 259
Recording Methods 259
Signal Analysis 260
Mathematics 260
Index 261