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NETWORK FUNCTIONS AND PLASTICITY

NETWORK FUNCTIONSAND PLASTICITY: Perspectives From Studying Neuronal Electrical Coupling in Microcircuits

Copyright

DEDICATION

CONTENTS

LIST OF CONTRIBUTORS

PREFACE

REFERENCES

1 - Electrical Coupling in Caenorhabditis elegans Mechanosensory Circuits

1. INTRODUCTION

2. THE NOSE TOUCH CIRCUIT

3. SIMPLIFIED MATHEMATICAL MODEL OF THE NOSE TOUCH CIRCUIT

4. LATERAL FACILITATION

5. INHIBITION BY SHUNTING

6. CONCLUSIONS AND FUTURE PERSPECTIVES

OUTSTANDING QUESTIONS/FUTURE DIRECTIONS

REFERENCES

2 - Neural Circuits Underlying Escape Behavior in Drosophila: Focus on Electrical Signaling

1. INTRODUCTION

2. THE DROSOPHILA GIANT FIBER SYSTEM

2.1 GFS Cellular Elements

2.2 GFS Synaptic Connections

3. ELECTRICAL TRANSMISSION IN THE GFS: MOLECULES AND MECHANISMS

3.1 shakB: The First Invertebrate Prechordate Gap-Junction Gene

3.2 shakB Gene Transcripts Are Differentially Expressed in GFS Neurons

3.3 Some GFS Synapses Are Rectifying Junctions

4. CHEMICAL TRANSMISSION IN THE GFS: TRANSMITTERS AND RECEPTORS

5. THE GF CIRCUIT IS RESPONSIBLE FOR SHORT-MODE ESCAPE

6. SUMMARY

QUESTIONS ARISING

REFERENCES

3 - Gap Junctions Underlying Labile Memory

1. INTRODUCTION

2. GAP JUNCTIONS BETWEEN APL AND DPM NEURONS FOR LABILE MEMORY

3. DUAL ROLE OF APL NEURON IN ITM THROUGH GAP-JUNCTIONAL AND OCTOPAMINERGIC CHEMICAL NEUROTRANSMISSION

4. NONSPIKING APL AND DPM NEURAL NETWORK

5. LABILE MEMORY CIRCUIT OF PERSISTENT ACTIVITY

6. SUMMARY AND IMPLICATION

OUTSTANDING ISSUES AND FUTURE RESEARCH

ACKNOWLEDGMENTS

REFERENCES

4 - The Role of Electrical Coupling in Rhythm Generation in Small Networks

1. INTRODUCTION

2. RHYTHMOGENESIS

2.1 Tonic Spiking

2.2 Network Oscillations

2.3 Subthreshold Oscillatory Activity

3. SYNCHRONIZED OSCILLATIONS

3.1 Synchronization in Electrically Coupled Networks

3.2 Synchrony in Networks With Both Electrical Coupling and Chemical Synapses

3.3 Implications of Synchrony in Electrically Coupled Networks for Behavior

4. PATTERN GENERATION

5. NEUROMODULATION

5.1 Neuromodulators Can Alter the Sign of a Synapse by Determining the Relative Weights of Electrical and Chemical Synapses

5.2 Electrical Synapses in the Mammalian Thalamic Reticular Nucleus Can Be Modulated by Ionic Currents

5.3 Neuromodulators of Electrical Coupling can Modify Behavior

5.4 Expression of Identified Connexins in Model Systems Suggest That Gap Junctions Can Be Modulated Directly by Phosphorylation ...

6. SUMMARY

OUTSTANDING ISSUES AND FUTURE DIRECTIONS

ACKNOWLEDGMENTS

REFERENCES

5 - Network Functions of Electrical Coupling Present in Multiple and Specific Sites in Behavior-Generating Circuits

1. INTRODUCTION

2. THE FEEDING NEURAL CIRCUIT IN APLYSIA

2.1 Local Circuit—Rhythm Generation in a Multifunctional Network

2.1.1 Generation of Biphasic Rhythmic Activity (Protraction–Retraction)

2.1.2 Protraction: Electrical Coupling–Based Separation Into Two Functional Subgroups/Modules for Neurons Active in One Phase

2.1.3 Retraction: Generation of Variable Phasic Activity Within One Phase and Roles of Asymmetric Coupling

2.1.4 Opening/Closing: Different Roles of Electrical Coupling in the Control of Motoneurons Showing Different Phasic Activity in ...

2.2 Interaction With Remote Circuit Elements

2.2.1 Input Activation of the Local Circuit by CBIs

2.2.2 Output From the Local Circuit: Coordination With Remote Elements

2.2.3 Experimental Procedures Used to Establish Electrical Coupling Between Remote Circuit Elements

2.3 Summary of Electrical Coupling in the Aplysia Feeding Circuit

3. OTHER NEURAL CIRCUITS IN GASTROPOD MOLLUSCS

3.1 The Feeding Circuits in Lymnaea and Pleurobranchaea

3.2 Locomotor Networks in Gastropod Molluscs

3.3 Swimming Networks in Benthic Gastropod Molluscs

3.4 Variations of Electrical Coupling Strength Between Homologous Neurons in Different Species: Implications for Evolution

4. SUMMARY

FUTURE DIRECTIONS

ACKNOWLEDGMENTS

REFERENCES

6 - Electrical Synapses and Learning–Induced Plasticity in Motor Rhythmogenesis

1. INTRODUCTION

2. ELECTRICAL SYNAPSES IN THE ORGANIZATION OF BEHAVIORAL ACTIONS

2.1 Electrical Synapses in Rhythmic Motor Pattern Genesis

2.2 Electrical Synapses in the Organization of Motivated Behaviors

3. PLASTICITY OF ELECTRICAL SYNAPSES

3.1 Modulatory and Sensory-Induced Plasticity

3.2 Activity-Dependent Plasticity

3.3 Dopamine and Activity-Dependent Regulation of Rhythmogenesis in Aplysia

4. IMPLICATION OF ELECTRICAL SYNAPSES IN LEARNING, MEMORY, AND MOTOR RHYTHMOGENESIS IN MAMMALS

4.1 Learning and Memory

4.2 Plasticity of Electrical Synapses and the Expression of Habitual or Compulsive Behaviors

5. ROLE OF ELECTRICAL SYNAPSES IN THE INDUCTION OF COMPULSIVE-LIKE BEHAVIOR IN APLYSIA

5.1 Learning-Induced Plasticity in Motor Pattern Genesis

5.2 Respective Roles of Electrical Synapses and Neuronal Excitability in the Plasticity of Motor Rhythmogenesis

6. CONCLUSION

OUTSTANDING QUESTIONS

ACKNOWLEDGMENTS

REFERENCES

7 - Electrical Synapses and Neuroendocrine Cell Function

1. NEUROENDOCRINE CELLS

2. GAP JUNCTIONS AND ELECTRICAL COUPLING IN NEUROENDOCRINE CELLS

3. THE X-ORGAN-SINUS GLAND COMPLEX OF CRUSTACEA

4. THE PROTHORACIC GLAND AND INTRINSIC NEUROSECRETORY CELLS OF THE CORPORA CARDIACA FROM INSECTA

5. THE BETA CELLS OF THE VERTEBRATE PANCREAS

6. THE CHROMAFFIN CELLS OF THE VERTEBRATE ADRENAL MEDULLA

7. THE MAGNOCELLULAR NEUROENDOCRINE CELLS OF THE MAMMALIAN HYPOTHALAMUS

8. THE BAG CELL NEURONS OF APLYSIA AND CAUDODORSAL CELLS OF LYMNAEA

9. THE INFLUENCE OF THE EXTENT AND STRENGTH OF ELECTRICAL COUPLING ON NEUROENDOCRINE CELL FUNCTION

10. CONCLUDING REMARKS

REFERENCES

8 - Electrical Synapses in Fishes: Their Relevance to Synaptic Transmission

1. INTRODUCTION: THE DISCOVERY OF ELECTRICAL TRANSMISSION

2. SUPRAMEDULLARY NEURONS IN THE PUFFER FISH: THE FIRST EVIDENCE OF ELECTRICAL COUPLING BETWEEN VERTEBRATE NEURONS

3. ELECTRIC FISHES: CONTRIBUTION OF ELECTRICAL SYNAPSES TO SYNCHRONIZED NEURONAL ACTIVITY

4. CLUB ENDINGS IN GOLDFISH: ELECTRICAL AND CHEMICAL SYNAPSES CAN INTERACT

5. RETINA: MODULATION OF ELECTRICAL TRANSMISSION AND THE IDENTIFICATION OF NEURONAL CONNEXINS

6. ZEBRAFISH: CONNEXIN DIVERSITY AND COMMON DEVELOPMENTAL STEPS FOR CHEMICAL AND ELECTRICAL SYNAPSES

7. CONCLUSIONS

ACKNOWLEDGMENTS

REFERENCES

9 - Dynamic Properties of Electrically Coupled Retinal Networks

1. INTRODUCTION

2. OVERVIEW OF THE SYNAPTIC ARCHITECTURE OF THE RETINA

3. GAP JUNCTION COUPLING DIFFERENTIALLY MODIFIES RECEPTIVE FIELD SIZE IN DIFFERENT RETINAL CELL TYPES

4. GAP JUNCTIONS ARE REQUIRED FOR NIGHTTIME VISION

5. GAP JUNCTIONS PROMOTE SPONTANEOUS ACTIVITY DURING RETINAL DEGENERATION

6. ELECTRICAL SYNAPSES ARE IMPORTANT FOR SIGNALING VISUAL MOTION

7. FAST GAP JUNCTION SIGNALS DRIVE FINE-SCALE CORRELATED SPIKE OUTPUT

8. SUMMARY AND FUTURE DIRECTIONS

ACKNOWLEDGMENTS

REFERENCES

10 - Circadian and Light-Adaptive Control of Electrical Synaptic Plasticity in the Vertebrate Retina

1. INTRODUCTION

2. PHOTORECEPTORS

2.1 Physiological Functions of Electrical Coupling Between Photoreceptors

2.1.1 Rod–Rod Coupling

2.1.2 Rod–Cone Coupling

2.1.3 Cone–Cone Coupling

2.2 Circadian and Light-Adaptive Control of Coupling

2.3 Mechanisms of Control

3. HORIZONTAL CELLS

3.1 Horizontal Cell Coupling

3.2 Light-Adaptive Control of Horizontal Cell Coupling

3.3 Mechanisms of Control

4. AMACRINE CELLS

4.1 Light-Adaptive Control of AII Amacrine Cell Coupling

4.2 Mechanisms of Control

5. CONCLUDING REMARKS

OUTSTANDING QUESTIONS

REFERENCES

11 - Electrical Coupling in the Generation of Vertebrate Motor Rhythms

1. INTRODUCTION

2. ELECTRIC FISH

3. CHEWING

4. GAP JUNCTIONS IN THE SPINAL CORD AND LOCOMOTOR RHYTHMOGENESIS

4.1 Gap Junctions Between Spinal Motoneurons

4.2 Is Electrical Coupling Needed for Generating Pacemaker-Like Oscillations?

4.3 The Role of Gap Junctions in Locomotor Rhythmogenesis

5. INVOLVEMENT OF ELECTRICAL COUPLING IN THE NEURAL CONTROL OF BREATHING

5.1 Rhythmogenesis

5.2 Synchronization of Motoneurons

5.3 Chemosensitivity

6. CONCLUDING REMARKS

OUTSTANDING ISSUES AND FUTURE RESEARCH

REFERENCES

12 - Implications of Electrical Synapse Plasticity in the Inferior Olive

1. INTRODUCTION

2. ELECTRICAL COUPLING IN THE IO AND MOVEMENT

2.1 The Discovery of Electrical Synapses in the IO

2.2 In Vivo Estimates of Electrical Coupling Strength and Patterning in the IO

2.3 IO Electrical Synapses, Skilled Movement, and Muscle Synergies

2.4 Electrical Synapses in the IO Contribute Centisecond Precision to Muscle Synergies

3. ELECTRICAL COUPLING AND SUBTHRESHOLD OSCILLATIONS IN THE IO

3.1 Electrical Synapses Are Necessary for Subthreshold Oscillations in the IO

3.2 Direct (SLDs) and Indirect (STOs) Effects of Electrical Synapses on Synchronous Spiking Within the IO

4. ENHANCING STOS BY UPREGULATING ELECTRICAL COUPLING BY NMDA RECEPTOR ACTIVATION

4.1 NMDA Receptor Contributions to Electrical Rhythmogenesis in the IO

4.2 NMDA Receptor Activation Strengthens Neuronal Electrical Synapses

4.3 NMDA Receptor-Mediated Strengthening of Electrical Synapses in the IO Enhances Network Rhythmogenesis

5. A HYPOTHESIS OF STRENGTHENING PLASTICITY OF ELECTRICAL SYNAPSES DURING THE LEARNING OF MOTOR SYNERGIES

OUTSTANDING QUESTIONS

ACKNOWLEDGMENT

REFERENCES

13 - Gap Junctions Between Pyramidal Cells Account for a Variety of Very Fast Network Oscillations (﹥80Hz) in Corti ...

1. WHERE DID THE IDEA OF AXONAL GAP JUNCTIONS COME FROM?

2. IF AXONAL GAP JUNCTIONS EXIST, HOW MIGHT THEY ACCOUNT FOR VFO?

3. PHYSIOLOGICAL EVIDENCE FOR AXONAL GAP JUNCTIONS

4. ANATOMICAL EVIDENCE FOR AXONAL GAP JUNCTIONS

5. PREDICTIONS OF THE AXONAL GAP JUNCTION MODEL OF VFO, AND SPECIFICALLY OF RIPPLES

6. WHAT MIGHT THE GAP JUNCTION PROTEIN BE?

7. CLINICAL IMPLICATIONS

REFERENCES

14 - Lineage-Dependent Electrical Synapse Formation in the Mammalian Neocortex

1. INTRODUCTION

2. COMPOSITION OF ELECTRICAL SYNAPSES IN THE MAMMALIAN NEOCORTEX

3. LINEAGE-DEPENDENT SPECIFICITY OF ELECTRICAL SYNAPSES IN THE MOUSE NEOCORTEX

3.1 Lineage-Dependent Electrical Synapses Between Progenitor and Progeny

3.2 Lineage-Dependent Specificity of Electrical Synapses Between Excitatory Neurons in the Mouse Neocortex

4. PROGRESSIVE DEVELOPMENT OF ELECTRICAL SYNAPSES BETWEEN SISTER EXCITATORY NEURONS

5. MECHANISMS UNDERLYING LINEAGE-DEPENDENT ELECTRICAL SYNAPSE FORMATION

6. SIGNIFICANCE OF LINEAGE-DEPENDENT ELECTRICAL SYNAPSES IN NEOCORTICAL MICROCIRCUIT ASSEMBLY

7. CONCLUSIONS

OUTSTANDING QUESTIONS

ACKNOWLEDGMENTS

REFERENCES

GLOSSARY

INDEX

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D

E

F

G

H

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J

K

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M

N

O

P

R

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T

U

V

W

X

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