Synaptic Modifications and Memory: An Electrophysiological Analysis: Studies of Brain Function, cartea 19

1 Hippocampal Long-Term Potentiation and Its Characteristics.- 1.1 Brief Overview of the Structure of the Hippocampus.- 1.2 Electrical Responses of the Hippocampus.- 1.3 Initial Experiments on Long-Term Potentiation.- 1.4 Working Hypothesis and Early Results.- 1.5 Methods.- 1.6 Long-Term Potentiation of Field Potentials in the CA3 and CAI Regions.- 1.7 Low-Frequency Depression and Self-Restoration of the Potentiated Response.- 1.8 Specificity of Long-Term Potentiation for the Tetanized Input.- 1.9 Involvement of Reinforcing Systems During Tetanization.- 1.10 Discussion.- 1.11 Summary.- 2 Unitary and Minimal Postsynaptic Potentials (Literature Review).- 2.1 Introduction.- 2.2 Methods Related to Unitary and Minimal PSP Recording.- 2.2.1 Intracellular Stimulation of the Afferent Unit.- 2.2.2 Macrostimulation of Afferent Fibres.- 2.2.3 Intracerebral Microstimulation.- 2.2.4 Recording of “Minimal” PSPs.- 2.2.5 Additional Procedures for the Detection of Single UPSPs.- 2.2.6 Measurements of UPSPs and MPSPs Amplitudes and PSCs.- 2.2.7 Mono- and Polysynaptic UPSPs.- 2.3 Unitary Field Potentials — “EEG Quanta”.- 2.4 Applications of Unitary and Minimal PSP Recordings.- 2.4.1 Organization of Neuronal Connections.- 2.4.2 Electrical and Chemical Synapses in the CNS.- 2.4.3 Spatial Organization of Synapses on the Somadendritic Membrane.- 2.5 Studies of Synaptic Plasticity in the CNS.- 2.5.1 Introductory Remarks.- 2.5.2 Habituation and Sensitization in Invertebrate CNSs.- 2.5.3 Conditioning Mechanisms in the Aplysia CNS.- 2.5.4 LFD in the Vertebrate CNS.- 2.6 Conclusions.- 2.7 Summary.- 3 “Minimal” Field Potentials of the Hippocampus and Their Post-Tetanic Changes.- 3.1 Introduction.- 3.2 Methods.- 3.3 Field Potentials Correlated with Neuronal Discharges from theContralateral Hippocampus.- 3.4 Field Activity After Spikes of the Schaffer Collaterals.- 3.5 Minimal Field Potentials.- 3.6 Post-Tetanic Changes of Minimal FPs.- 3.7 Discussion.- 3.8 Summary.- 4 Excitatory Postsynaptic Potentials of Hippocampal Neurones and Their Low-Frequency Depression.- 4.1 Introduction.- 4.2 Methods.- 4.3 Responses to Single Stimuli.- 4.4 Responses to Paired Stimuli of Different Amplitudes.- 4.5 Changes of EPSPs During Low-Frequency Stimulation.- 4.6 Changes of IPSPs During Low-Frequency Stimulation.- 4.7 Discussion.- 4.8 Summary.- 5 Responses of Hippocampal Neurones During Long-Term Potentiation.- 5.1 Introduction.- 5.2 Methods.- 5.3 General Description of Neuronal Responses.- 5.4 Short-Term Post-Tetanic Changes.- 5.5 Long-Term Changes in Spike Responses after Tetanization.- 5.6 Post-Tetanic Changes of Postsynaptic Potentials.- 5.7 Post-Tetanic Changes in Excitability and Resting Membrane Potential.- 5.8 Discussion.- 5.9 Summary.- 6 Changes in Acetylcholine Sensitivity During Long-Term Potentiation.- 6.1 Introduction.- 6.2 Effects of Acetylcholine Iontophoresis on Cellular and Field Responses.- 6.3 Changes in ACh Sensitivity During LTP.- 6.4 Discussion.- 6.5 Summary.- 7 Quantal Analysis of Postsynaptic Potentials (Literature Review).- 7.1 Introduction.- 7.2 Principles of the Quantum Hypothesis.- 7.3 Methods of Determination of the Mean Quantal Content.- 7.3.1 Direct Counting of Quantal Contents of Single PSPs.- 7.3.2 The Method of “Miniatures”.- 7.3.3 Histogram Method.- 7.3.4 Method of Failures.- 7.3.5 Method of the Coefficient of Variation.- 7.3.6 Analysis of Dispersions.- 7.3.7 Deconvolution Technique.- 7.3.8 Other Methods.- 7.4 Corrections for the Methods of Estimating m.- 7.4.1 Non-Linear Summation.- 7.4.2 Control of Steady State.- 7.4.3“Non-Specific” Activity.- 7.4.4 Multicomponent Miniature PSPs.- 7.4.5 Additional Remarks.- 7.5 Poisson and Binomial Distributions of PSP Amplitudes.- 7.6 Methods of Estimating Binomial Parameter p.- 7.6.1 Variance of Quantal Distribution.- 7.6.2 Variances of Amplitudes of PSPs and mPSPs.- 7.6.3 Division of Amplitude Histogram According to µ.- 7.6.4 Automatic Computation when v Is Known.- 7.6.5 Automatic Analysis of Amplitude Distributions.- 7.6.6 Combination of Variance and Failures Methods.- 7.6.7 Other Methods.- 7.7 Additional Explanations to Methods of Computing Quantal Parameters.- 7.7.1 Non-Stationarity and Non-Uniformity.- 7.7.2 Models with Non-Uniform p.- 7.7.3 Other Modifications.- 7.8 Basic Quantal Parameters for Various Junctions.- 7.8.1 Neuromuscular Junctions and Autonomic Ganglia.- 7.8.2 Invertebrate CNS.- 7.8.3 Spinal Cord.- 7.8.4 Cerebrum.- 7.8.5 Hippocampus.- 7.9 Binomial Parameters n and p for Various Junctions.- 7.9.1 Neuromuscular Junctions and Autonomic Ganglia.- 7.9.2 Invertebrate CNS.- 7.9.3 Spinal Cord.- 7.9.4 Cerebrum.- 7.10 Quantal Analysis of Synaptic Plasticity.- 7.10.1 Various Applications of Quantal Analysis.- 7.10.2 Frequency Facilitation (FF).- 7.10.3 Frequency Depression (FD).- 7.10.4 Post-Tetanic Potentiation (PTP) and Heterosynaptic Facilitation (HSF).- 7.10.5 Long-Term Facilitation (LTF).- 7.11 Conclusions.- 7.12 Summary.- 8 Application of Quantal Analysis to Central Synapses.- 8.1 Introduction.- 8.2 Methods.- 8.3 Consideration of Known Methods of Determination of Quantal Parameters.- 8.4 The Histogram Method.- 8.5 Method Based on the Ratio of the Mean to Maximal Amplitude.- 8.6 Quantal Parameters of Unitary EPSPs of Snail CNS.- 8.7 Theoretical Distributions of PSP Amplitudes.- 8.8 Discussion.- 8.9 Summary.- 9 Models ofTransmitter Depletion and Their Application to Analysis of Synaptic Plasticity (Literature Review).- 9.1 Introduction.- 9.2 Basic Model Parameters and Recording Conditions.- 9.3 Model of Transmitter Depletion Without Mobilization.- 9.3.1 Method of Paired Stimulation.- 9.3.2 Method of Amplitude Dependence on Serial Stimulus Number During Frequency Stimulation.- 9.3.3 Method of Relationship Between Amplitude and Sum of Amplitudes of Previous Responses.- 9.4 Model of Transmitter Depletion with Mobilization.- 9.4.1 Restoration after Stimulation Method of Paired Stimulation.- 9.4.2 Frequency Stimulation. “Continuous” Model.- 9.4.3 Approximate Estimates of Parameters of the Continuous Model.- 9.4.4 Frequency Stimulation. “Discrete” Model.- 9.5 Modifications of the Depletion Model for Variable F.- 9.5.1 Model of “Partial Depletion”.- 9.5.2 “Partial Depletion” with Paired Stimulation.- 9.6 Transmitter Mobilization and Parameters of the Store Pool.- 9.6.1 Relationship Between Mobilization and Stimulus Frequency.- 9.6.2 Dependence of Mobilization on Time.- 9.6.3 Total Transmitter Store.- 9.7 Depletion Model in Studies of Synaptic Plasticity.- 9.7.1 Applications of the Depletion Model and Simple Synaptic Plasticities.- 9.7.2 Frequency Depression and Postactivation Depression.- 9.7.3 Postactivation Facilitation.- 9.7.4 Frequency Facilitation.- 9.7.5 Post-Tetanic Potentiation.- 9.8 Conclusion.- 9.9 Summary.- 10 Parameters of Transmitter Depletion Model for Snail Central Synapses and Comparison of Depletion and Quantal Models.- 10.1 Introduction.- 10.2 Discrete Model of “Partial” Transmitter Depletion.- 10.3 Discrete Model with Arbitrary Changes in F.- 10.4 EPSP Changes During Stimulation.- 10.5 Calculation of Parameters by Basic Methods of the Depletion Model.-10.6 Calculation of Parameters by Method 10.3.- 10.7 Comparison of Parameters of Depletion and Quantal Models.- 10.8 Discussion.- 10.9 Summary.- 11 Quantal Analysis of Short-Term Plasticities at Central Synapses.- 11.1 Introduction.- 11.2 Paired-Pulse Facilitation of Hippocampal Responses.- 11.3 Low-Frequency Depression of Hippocampal Responses.- 11.4 Low-Frequency Depression at Snail Central Synapses.- 11.5 Paired-Pulse Facilitation in Hippocampal Slices.- 11.6 Discussion.- 11.7 Summary.- 12 Quantal Analysis of Hippocampal Long-Term Potentiation in Vivo.- 12.1 Introduction.- 12.2 Methods.- 12.3 Unitary Postsynaptic Potentials of Hippocampal Neurones.- 12.4 Post-Tetanic Changes in Postsynaptic Potentials Evoked by Microstimulation.- 12.5 Statistical Analysis of Minimal EPSPs Evoked by Microstimulation.- 12.6 Changes in Quantal Parameters After Tetanization.- 12.7 Discussion.- 12.8 Summary.- 13 Quantal Analysis of Minimal Postsynaptic Potentials in Hippocampal Slices: Binomial Model.- 13.1 Introduction.- 13.2 Methods.- 13.3 Results of Computer Simulations.- 13.3.1 Testing Different Methods.- 13.3.2 Testing Methods of p Determination.- 13.3.3 Testing “Objective” Method of Failures Determination.- 13.4 Results of Physiological Experiments.- 13.4.1 General Description.- 13.4.2 Testing EPSP Amplitude Stability.- 13.4.3 Comparison of Parameters Calculated from Different Samples.- 13.4.4 Objective vs. Subjective Method of Failures Determination.- 13.4.5 Comparison of Different Methods.- 13.4.6 Optimization of Noise Standard Deviation.- 13.4.7 Mean Quantal Parameters of Hippocampal Synapses.- 13.5 Discussion.- 13.5.1 Simulation Experiments.- 13.5.2 EPSP Measurements and Noise Reduction.- 13.5.3 Testing Procedures and Sample Sizes.- 13.5.4 Applicability of the QuantumHypothesis and Simple Binomial Model.- 13.5.5 Noise Reduction During EPSP.- 13.5.6 Quantal Parameters of Hippocampal Synapses.- 13.6 Summary.- 14 Binomial Analysis of Long-Term Potentiation of Minimal EPSPs in Hippocampal Slices.- 14.1 Introduction.- 14.2 Methods.- 14.3 Results.- 14.3.1 Long-Term Potentiation of Minimal EPSPs.- 14.3.2 Estimates of Quantal Parameters.- 14.3.3 Post-Tetanic Changes in Mean Quantal Content.- 14.3.4 Post-Tetanic Changes in Quantal Size.- 14.3.5 Post-Tetanic Changes in Binomial Parameters.- 14.3.6 Differential Changes in m and v for Different LTP Magnitudes.- 14.4 Discussion.- 14.5 Summary.- 15 Analysis of Fluctuations of Minimal EPSPs in Vitro: Quantal Model.- 15.1 Introduction.- 15.2 Methods.- 15.3 Results of Simulation Experiments.- 15.4 Results of Physiological Experiments.- 15.5 Discussion.- 15.5.1 Reliability of the Deconvolution Procedure.- 15.5.2 Post-Tetanic Changes in Quantal Parameters.- 15.5.3 Differential Changes in Quantal Parameters at Different LTP Magnitudes.- 15.5.4 Two Types of Synaptic Mechanisms of LTP Maintenance.- 15.6 Summary.- General Conclusions.- References.