The Crustacean Stomatogastric System: A Model for the Study of Central Nervous Systems

Table of Contents

1 Functional Anatomy and Behavior.- 1.1 Functional Anatomy.- 1.1.1 Ossicles.- 1.1.2 Musculature.- 1.1.3 Nervous System.- 1.1.4 Ultrastructure and Neuronal Morphology.- 1.2 Behavior.- 1.2.1 Cardiac Sac.- 1.2.2 Gastric Mill.- 1.2.3 Control of the Cardio-Pyloric Valve.- 1.2.4 Pylorus.- 2 Neuromuscular Organization and Pharmacology.- 2.1 Neuromuscular Organization.- 2.1.1 Muscle Fibers.- 2.1.2 Motoneurons.- 2.1.3 Neuromuscular Synapses.- 2.2 Neuromuscular Pharmacology.- 2.2.1 Neuromuscular Transmitters.- 2.2.2 Modulatory Effects.- 2.3 Conclusion.- Appendix: Conditional Regenerative Properties in the Pyloric Dilator Muscle: Their Functional Implications.- 3 Neural Circuits.- 3.1 Circuits of the Stomatogastric Ganglion.- 3.1.1 Pyloric Circuit.- 3.1.2 Gastric Circuit.- 3.1.3 Synapses Between Neurons of the Gastric and Pyloric Circuits.- 3.2 COG Neurons and the STG Circuits.- 3.3 Descending Inputs to the STG Circuits.- 3.4 Other Stomatogastric Circuits.- 3.4.1 Cardiac Circuit.- 3.4.2 Oesophageal Circuit.- 3.5 Evidence for Monosynaptic Nature of STG Synapses.- 3.5.1 Constant Latency Test.- 3.5.2 High Ca2+ Test.- 3.5.3 TEA Test.- 3.5.4 Controls: Electrical Synapses.- 3.6 Significance of Circuit Analyses.- Appendix: PY Cell Types in the Stomatogastric Ganglion of Panulirus.- 4 Cellular and Synaptic Properties.- 4.1 Passive Electrotonic Properties and Neuronal Geometry.- 4.2 Repetitive Firing and Rebound.- 4.3 Graded Synaptic Transmission.- 4.3.1 Input-Output Properties of Graded Transmission.- 4.3.1.1 Cells Studied.- 4.3.1.2 Waveform.- 4.3.1.3 Release Threshold.- 4.3.1.4 Rebound.- 4.3.1.5 Conditioning.- 4.3.1.6 Inferences from Input-Output Properties.- 4.3.2 GST and the Oscillation Cycle.- 4.3.2.1 Current-induced Cycling Under TTX.- 4.3.2.2 Drug-induced Cycling Under TTX.- 4.3.2.3 Focal TTX Block.- 4.3.2.4 Intact Spiking Ganglia.- 4.3.3 Conclusion.- 4.4 Plateau Potentials.- 4.4.1 Criteria for Regenerative Plateaus.- 4.4.2 Cell Types Exhibiting Plateaus.- 4.4.3 Functional Roles of Regenerative Plateaus.- 4.5 Synaptic Modulation of Neuronal Properties.- 4.5.1 Synaptic Induction of Regenerative Plateaus.- 4.5.2 Plateau Induction by Identified Inputs.- 4.5.2.1 Dopaminergic Inputs.- 4.5.2.2 APM.- 4.5.2.3 Multiaction Synapses from ivn TF.- 4.6 Pacemaker Neurons.- 4.6.1 Conditional Bursters.- 4.6.2 AB Cell.- 4.6.3 LP Cell.- 4.6.4 DG (CP) Cell.- 4.7 Analysis of Membrane Currents.- 4.7.1 Pyloric Pacemaker Neurons.- 4.7.2 Inward Current.- 4.7.3 Outward Current.- 4.7.4 Modulation by Transmitters.- 4.7.5 Implications of Modulation for Studies on Ionic Mechanisms.- 4.8 Conclusions.- Appendix: Ionic Basis of Pacemaker Activity in Stomatogastric Neurons.- 5 Pyloric Mechanisms.- 5.1 Characteristics of the In Vitro Pyloric Motor Pattern.- 5.2 Why Do Pyloric Cells Fire in Bursts?.- 5.2.1 Intrinsic Mechanisms for Burst Generation.- 5.2.2 Network Mechanisms for Burst Generation.- 5.2.3 Intrinsic BPPs and Network “Burstiness”: Relative Contributions.- 5.3 What Mechanisms Determine the Phase Relationships of the Bursts Within the Pyloric Pattern?.- 5.3.1 Roles of Inhibitory Chemical Synapses.- 5.3.2 Roles of Electrotonic Coupling.- 5.3.3 Roles of Excitatory Chemical Synapses.- 5.4 What Mechanisms Determine the Overall Frequency of the Pyloric Pattern?.- 5.4.1 Intrinsic and Synaptic Mechanisms for Frequency Control.- 5.4.2 Control of Pattern Frequency by Extrinsic Inputs.- 5.5 The Pyloric Pattern: a Mechanistic Explanation.- 5.6 Concluding Remarks.- Appendix A: Pyloric Pattern Generation in Panulirus interruptus Is Terminated by Blockade of Activity Through the Stomatogastric Nerve.- Appendix B: The Pyloric Pacemakers of the Crayfish Stomatogastric Ganglion Are Conditional Burster Neurons.- 6 Gastric Mill Mechanisms.- 6.1 Introduction.- 6.2 Behavior.- 6.2.1 Semi-intact Preparations.- 6.2.2 EMG and Other Studies on Intact Animals.- 6.2.3 Endoscopic Studies In Vivo.- 6.3 Motor Patterns Recorded In Vitro.- 6.4 Building Block Concept and Modulation.- 6.4.1 Cellular Properties.- 6.4.1.1 Bursting Pacemaker Potentials (BPPs).- 6.4.1.2 Plateau Potentials.- 6.4.2 Synaptic Properties.- 6.4.2.1 Synaptic Strength.- 6.4.2.2 Delayed EPSPs.- 6.4.3 Inputs to the Gastric System.- 6.4.4 Gastric Circuits.- 6.4.4.1 Monosynaptic Connections.- 6.4.4.2 Functional Connections.- 6.4.4.3 Total Circuit.- 6.4.4.4 Simplified Lumped Circuit.- 6.5 Generation of the Gastric Pattern.- 6.5.1 Hypothesis.- 6.5.2 Testing the Hypothesis.- 6.5.2.1 Perturbing the System: Single Cell Hyperpolarization.- 6.5.2.2 Resetting Experiments.- 6.5.2.3 Killing Cells.- 6.5.3 Current Status of the Gastric System.- 6.5.3.1 Source of Bursts.- 6.5.3.2 Source of Pattern.- 6.6 Conclusion and Prognosis.- Appendix A: How Many Generators in the Gastric Mill System?.- Appendix B: Spontaneous and Proctolin-Induced Modes of Operation of the Isolated Gastric Oscillator and of the Gastric Mill in the Intact Animal.- 7 Modeling Stomatogastric Ganglion.- 7.1 Dendritic Tree Models.- 7.2 Network Models.- 7.3 Theoretical Network Models.- 7.4 Physiological Models.- 7.5 Parameter-fitted Models: The Gastric System.- 7.5.1 PABLO.- 7.5.2 SYNETSIM 1.1.- 7.5.3 Friesen-Lewis Neuromime Model.- 7.5.4 Thompson-Little Model.- 7.5.5 Conclusion...- 7.6 Parameter-measured Models: The Pyloric System.- 7.6.1 SYNETSIM 1.2.- 7.6.2 SYNETSIM 2.2.- 7.6.3 SYNETSIM 2.3.- 7.6.4 Raper’s Chemotonic Model.- 7.6.5 SYNETSIM 2.4.- 7.6.6 Voltage-clamp Modeling.- 7.6.7 Conclusions.- Appendix: Electrical Structure and Synaptic Integration: A Multicompartment Model of a Stomatogastric Neuron.- 8 Extrinsic Inputs.- 8.1 Introduction.- 8.2 Potentialities for Flexibility Built into the Stomatogastric CPGs.- 8.2.1 Conditional Oscillations in Pyloric and Gastric Neurons.- 8.2.2 Nonlinear Input-Output Relations of Stomatogastric Oscillators.- 8.3 Modulatory Inputs.- 8.3.1 The Anterior Pyloric Modulator (APM).- 8.3.1.1 Induction of Burstiness in Pyloric Neurons.- 8.3.1.2 Modulation of Burstiness in Pyloric Neurons.- 8.3.1.3 Gastric Activation.- 8.3.2 The ivn Through Fibers.- 8.3.3 The ion Fibers.- 8.4 Rhythmic Inputs.- 8.4.1 Rhythmic Control of the Pyloric Network.- 8.4.1.1 The Commissural Pyloric Oscillator (CPO).- 8.4.1.2 The P Cells.- 8.4.2 Rhythmic Control of the Gastric Network.- 8.4.2.1 The Commissural Gastric Oscillator (CGO).- 8.4.2.2 The E Cells.- 8.4.2.3 Other Inputs.- 8.5 ivn Through Fibers.- 8.6 Sensory Inputs.- 8.6.1 The Posterior Stomach Receptors (PSRs).- 8.6.1.1 Rhythmic Discharge of the PSRs.- 8.6.1.2 Long-lasting Activation of the Gastric and Pyloric CPGs.- 8.6.1.3 Triggering of Rhythmic Activity of the Gastric CPG.- 8.6.1.4 Entrainment of Gastric and Pyloric Rhythms.- 8.6.1.5 Functional Significance.- 8.6.2 The Anterior Gastric Receptor (AGR).- 8.6.3 Other Inputs.- 8.7 Conclusion.- 8.7.1 Control of Intracycle Pattern Generation.- 8.7.2 Control of Rhythm Generation.- Appendix A: Cellular Integration in a Gastric Proprioceptive Pathway.- Appendix B: Chronic Effects of De-afferentation on the Stomatogastric Ganglion of Panulirus.- Appendix C: Contingent Effects of Synaptic Input to the Pyloric Oscillator.- 9 Neurotransmitters and Neuromodulators.- 9.1 Introduction.- 9.2 Identification of Neurotransmitters Used by STG Neurons.- 9.2.1 Neuromuscular Junctions.- 9.2.1.1 Identification of Cholinergic Motoneurons.- 9.2.1.2 Pharmacological Properties and Characteristics of ACh Synaptic Sites and Receptors.- 9.2.1.3 Identification of Glutamatergic Motoneurons.- 9.2.1.4 Pharmacological Properties and Characteristics of Glutamate Synaptic Sites and Receptors.- 9.2.1.5 Extrajunctional ACh, Glutamate, and GABA Receptors.- 9.2.1.6 Peptide and Amine Modulation of Neuromuscular Junctions.- 9.2.1.7 Species Differences in Neurotransmitters and Neuromodulators Active at Neuromuscular Junctions.- 9.2.2 Neurotransmitters Released by STG Neurons at Central Synapses.- 9.2.2.1 Pharmacology of ACh Responses of STG Neurons.- 9.2.2.2 Inhibitory Cholinergic Synapses.- 9.2.2.3 Pharmacology of Glutamate Responses on STG Neurons.- 9.2.2.4 Inhibitory Glutamatergic Synapses.- 9.2.2.5 Electrically Coupled Neurons Release Different Neurotransmitters.- 9.3 Identification of Neurotransmitters and Modulators Found in Inputs to the STG.- 9.3.1 ivnTF-Histamine.- 9.3.2 APM-ACh.- 9.3.3 Dopamine.- 9.3.4 Serotonin.- 9.3.5 Octopamine.- 9.3.6 GABA.- 9.3.7 Proctolin.- 9.3.8 FMRFamide-like Peptides.- 9.3.9 Substance P-like Peptide.- 9.3.10 Other Peptides.- 9.3.11 Species Differences in Input Fibers.- 9.4 Conclusions.- 9.4.1 Why This Transmitter Organization?.- 9.4.2 Why So Many Different Neurotransmitters in Input Fibers?.- 9.4.3 Which STG Neurons Are Influenced by the Modulatory Inputs?.- 9.4.4 Mechanisms of Action of Modulators.- 9.4.4.1 Single vs Multiple Classes of Receptors and Physiological Responses.- 9.4.4.2 Biochemical and Biophysical Mechanisms.- 9.4.4.3 Modification of Synaptic Strength and Efficacy.- 9.4.5 Interactions Among Modulators and Modulatory Neurons.- 9.4.6 Colocalization of Neurotransmitters.- 9.4.7 Future Vistas.- Appendix A: Dopaminergic Modulation of the Lobster Pyloric Pacemaker Potential Is Enhanced by Concurrent Inhibition of Cyclic Nucleotide Phosphodiesterase.- Appendix B: Cocaine Activates the Motor Output of the Stomatogastric Ganglion.- 10 Comparison with Other Systems.- 10.1 Introduction.- 10.2 Well-known Oscillatory Networks.- 10.2.1 Tritonia Swim Generator.- 10.2.2 Lobster Cardiac Ganglion.- 10.2.3 Mixed Oscillators.- 10.2.3.1 Leech Heartbeat Oscillator.- 10.2.3.2 Snail Feeding CPG.- 10.3 Some Generalities.- References.