Frog Neurobiology

In review, the amount of information available on the morphological and func­ tional properties of the frog nervous system is very extensive indeed and in certain areas is the only available source of information in vertebrates. Further­ more, much of the now classical knowledge in neurobiology was originally ob­ tained and elaborated in depth in this vertebrate. To cite only a few examples, studies of nerve conduction, neuromuscular transmission, neuronal integration, sense organs, development, and locomotion have been developed with great detail in the frog and in conjunction provide the most complete holistic descrip­ tion of any nervous system. Added to the above considerations, the ease with which these animals may be maintained (both as adults and during development) and the advantage of their lower cost as compared with other vertebrate forms make the frog one of the most important laboratory animals in neurobiology. With these thoughts in mind, we decided to compile this volume. Our goal in doing so was to assemble as much as possible of the information available on frog neurobiology and to have the different topics covered by authorities in each of the fields represented. To keep the handbook restricted to one volume, we found it necessary to omit the large field of amphibian muscle neurobiology, which has already been summarized in various other publications.

Section 1. Peripheral Systems.- 1. Electrophysiology of the Peripheral Myelinated Nerve.- 1 Preparation, Morphology, and Excitation of Single Myelinated Fibers.- 2 Biophysics of Ionic Permeability Mechanisms at the Node of Ranvier.- 3 Conclusion.- 4 Summary.- 2. Neuromuscular Transmission.- 1 Introduction.- 2 Structure and Functional Localizations.- 3 Biochemistry.- 4 Physiology.- 5 Pharmacology.- 6 Summary.- 3. Morphology of the Autonomic Nervous Systems.- 1 Anatomy.- 2 The Ganglia.- 3 The Peripheral Autonomic Innervation.- 4 Summary.- 4. Physiology of the Autonomic Nervous System.- 1 Introduction.- 2 The Periphery.- 3 Autonomic Ganglionic Transmission.- 4 Summary.- 5. Structure and Function of the Epidermis.- 1 Why is Frog Skin Interesting?.- 2 Structure of the Epidermis.- 3 Structure of the Corium.- 4 Transmural Uptake of NaCl.- 5 Inside the Black Box.- 6 Regulation and Mechanism of Water Transport.- 7 Transport Effects of Hormones and Transmitters.- Section II. Sensory Systems.- Olfaction.- 6. Structure of the Olfactory and Accessory Olfactory Systems.- 1 Introduction.- 2 The Peripheral Olfactory System.- 3 Structure of the Olfactory Bulb and Accessory Olfactory Bulb.- 4 General Structure of the Telencephalon.- 5 Experimental Analysis of the Central Olfactory and Accessory Olfactory Pathways.- 6 Summary.- 7. Physiology of Olfactory Reception.- 1 Introduction.- 2 Olfactory and Vomeronasal Receptor Organ Anatomy.- 3 Olfactory Behavior.- 4 Dynamic Morphology of Olfactory Receptor Cells.- 5 Olfactory Organ Electrophysiology.- 6 Action Potentials in Olfactory Receptor Neurons.- 7 Summary.- Vision.- 8. Visual Pigments and Photoreceptor Function.- 1 The Visual Cells.- 2 The Properties and Spectral Characteristics of the Visual Pigments.- 3 Spectral Properties of the Electroretinogram and the Ganglion Cell Discharge.- 4 The Bleaching and Regeneration of the Visual Pigment.- 5 Excitation and Adaptation of the Receptors in Relation to Bleaching and Regeneration of the Visual Pigment.- 6 Summary.- 9. Physiology and Morphology of the Retina.- 1 Introduction.- 2 Light Microscopy.- 3 Electron Microscopy.- 4 Synaptic Pathways.- 5 Intraretinal Recording.- 6 A Model of the Synaptic Organization of the Mudpuppy Retina.- 7 Summary.- 10. Neurophysiology of the Anuran Visual System.- 1 Introduction.- 2 Eyes, Visual Field and Eye Movements.- 3 Classes of Retinal Ganglion Cells.- 4 Quantitative Investigations of Retinal Neuron Responses.- 5 Comparative Studies of Anuran Retinal Ganglion Cell Responses.- 6 The Neurophysiology of the Tectum Opticum.- 7 Visually Activated Neurons in the Diencephalon.- 8 Visual Neuronal Responses of the Telencephalon.- 9 Visual Responses in the Vestibular Nuclei and Cerebellum.- 10 Correlations between Neuronal Responses and Behavioral Patterns.- 11 Models and Concepts.- 11. The Optic Pathway of the Frog: Nuclear Organization and Connections.- 1 Introduction.- 2 The Optic Pathway.- 3 Terminal Neuropil and Cell-Masses in the Optic Pathway.- 4 Further Connections within the Visual System.- 5 Development of the Optic Pathway.- 6 Summary.- 12. Cellular and Synaptic Architecture of the Optic Tectum.- 1 Introduction.- 2 Histology of the Optic Tectum.- 3 Synaptology of the Optic Tectum.- 4 The Tectal Circuitry.- 5 Summary.- 13. Behavioral Correlates of Central Visual Function in Anurans.- 1 Introduction.- 2 Retinal Encoding of the Visual Image.- 3 Analysis of the Prey-Detection System.- 4 Plasticity in Prey-Catching Behavior.- 5 Releasers of Avoidance.- 6 Detection of Stationary Objects.- 7 Orientation toward Maximal Light Intensity.- 8 The Accessory Optic System and Optokinetic Nystagmus.- 9 Binocular Vision.- 10 Telencephalic Visual System.- 11 Summary.- Vestibular and Lateral Systems.- 14. Morphology of Peripheral and Central Vestibular Systems.- 1 Introduction.- 2 Bony Labyrinth.- 3 Membranous Labyrinth.- 4 Perilymphatic Space.- 5 Vestibular Nerve Branching.- 6 Receptor Areas.- 7 Receptor Epithelium.- 8 Primary Afferent System.- 9 Efferent Vestibular System.- 10 Efferent Projections of the Vestibular Nuclei.- 11 Afferents to Vestibular Nuclei.- 12 Summary.- 15. Physiology of the Peripheral and Central Vestibular Systems.- 1 Introduction.- 2 Vestibular Receptors.- 3 Responses of Primary Vestibular Neurons.- 4 Efferent Vestibular System.- 5 Responses of Neurons in the Vestibular Nuclei.- 6 Vestibulo-Ocular Relationship.- 7 Vestibulo-Spinal Relationship.- 8 Summary.- 16. Amphibian Lateral Line Receptors.- 1 Introduction.- 2 Gross Morphology and Distribution of the Lateral Line.- 3 Function of the Lateral Line.- 4 The Ultra Structure of the Lateral Line.- 5 Development of Lateral Line Organs.- 6 Regression and Regeneration of Lateral Line Organs.- 7 The Physiology of Lateral Line Organs.- 8 Functional Significance of the Responses of Afferent Fibers to Water Displacements.- 9 Organization of Lateral Line Input to the Central Nervous System.- 10 The Afferent Control of the Lateral Line System.- 11 Summary.- Auditory System.- 17. Morphology and Physiology of the Auditory System.- 1 Introduction.- 2 External and Middle Ear.- 3 Inner Ear.- 4 Auditory Nervous System.- 5 Summary.- Gustatory System.- 18. Physiology of the Gustatory System.- 1 Structure and Innervation of Gustatory Organs.- 2 Lingual Nerve Response to Chemical Stimuli.- 3 Events at the Taste Cell and Cell-Axon Junction.- 4 Efferent Control of Gustatory Organs.- 5 Summary.- 19. Morphology of Gustatory Organs.- 1 Introduction.- 2 General Aspects of Gustatory Organs.- 3 Papillary Gustatory Organs.- 4 Non-Papillary Gustatory Organs.- 5 Concluding Remarks.- 6 Summary.- Cutaneous Receptors.- 20. Pain and Temperature Receptors of Anurans.- 1 Introduction.- 2 Anatomy of Frog Cutaneous Nerve Endings and Their Afferent Fibers.- 3 Pain Receptors in Frog Skin.- 4 Anuran Thermoreceptors.- 5 Summary.- 21. Cutaneous Mechanoreceptors.- 1 Cutaneous Innervation in Frog and Toad.- 2 Categories of Frog and Toad Skin Mechanoreceptors.- 3 Receptor Fields.- 4 Receptor Thresholds.- 5 Response Latencies.- 6 Excitability Changes under Subliminal Stimulation.- 7 Responses to Ramp-and-Plateau Stimulation.- 8 Receptor Fatigue.- 9 Receptor Adaptation.- 10 Effects of Sympathetic Stimulation and of Catecholamines.- 11 Summary.- Muscle Spindles.- 22. Morphology and Physiology of Muscle Spindles.- 1 The Structure of the Spindle.- 2 Functions of the Spindle.- 3 Concluding Remarks.- Section III. Nervous System Spinal Cord.- 23. Morphology of the Spinal Cord.- 1 General Introduction.- 2 The Basic Organization.- 3 Spinal Afferents.- 4 Ascending Spinal Systems.- 5 Transmitters in the Ranid Spinal Cord.- 6 Neurophysiological Correlates.- 7 Concluding Remarks and Summary.- 24. Ultrastructural Features of the Spinal Cord.- 1 Introduction.- 2 Materials and Methods.- 3 Ultrastructural Observations.- 4 Summary.- 25. Functional Synaptology of the Spinal Cord.- 1 Introduction.- 2 The Two Motor Systems of Anurans.- 3 Motoneurons and Primary Afferent Inputs.- 4 Dorsal Root Potentials and Primary Afferent Inputs.- 5 The Descending Lateral Column Pathway.- 6 Motoneuron Activation as an Input.- 7 Summary.- 26. Electrical Properties of Spinal Motoneurons.- 1 Introduction.- 2 Subthreshold Behavior.- 3 Antidromic Spike Components.- 4 Afterpotential Components.- 5 Rhythmic Firing Behavior.- 6 Accommodation Properties.- 7 Electrotonic Coupling between Motoneurons.- 8 Summary.- 27. Organization of Locomotion.- 1 Introduction.- 2 Locomotory Patterns in Amphibians.- 3 The Organization of the Spinal Motor Column.- 4 Spinal Control of Limb Movement.- 5 Conclusions.- 6 Summary.- 28. Spinal Reflexes with Altered Periphery.- 1 Introduction.- 2 Supernumerary Limbs.- 3 Wipe Reflexes in Rana pipiens with Trunk Skin Rotations.- 4 Excision of Lumbar Ganglia.- 5 General Discussion.- 6 Summary.- Brain Stem.- 29. Structure of the Brain Stem.- 1 Introduction.- 2 Gross Morphology.- 3 Cranial Nerves.- 4 The Overall Histological Pattern.- 5 Nuclei and Fiber Tracts.- 6 Conclusions and Comments.- 30. Metamorphic Changes in the Brain and Spinal Cord.- 1 Introduction.- 2 Endocrine Control through the Hypothalamus, Pituitary and Thyroid.- 3 Behavioral Events at Metamorphosis.- 4 Changes in Size and Shape of the Brain.- 5 The Mauthner Neurons.- 6 The Mesencephalic Nucleus of V.- 7 The Spinal Cord.- 8 The Tail Cord and Nerves.- 9 The Cerebellum and the Lateral Line System.- 10 Concluding Remarks.- 11 Summary.- Cerebellum.- 31. Morphology of the Cerebellar Cortex.- 1 Introduction.- 2 Morphology of Neuronal Elements.- 3 Neuronal Circuits.- 4 Some Comparative Aspects of the Cerebellar Circuits of the Frog.- 5 Summary.- 32. Cerebellar Physiology.- 1 Introduction.- 2 Ablation Experiments.- 3 Electrical Stimulation.- 4 General Electrophysiology of the Neuronal System in the Cerebellar Cortex.- 5 In vitro Preparations.- 6 Computer Simulation of Frog Cerebellar Cortex.- 7 Summary.- Development.- 33. Development of the Prosencephalon.- 1 Normal Development of the Prosencephalon.- 2 Morphogenetic Influences.- 3 The Concept of Morphogenetic Field in the Forebrain.- 4 Conclusions.- 5 Summary.- Nonolfactory Corte.- 34. Organization of the “Nonolfactory” Telencephalon.- 1 General Introduction.- 2 Nuclear Groups in the Telencephalon of Rana.- 3 Afferent, Efferent and Intrinsic Connections of the Ranid Telencephalon.- 4 Histochemistry of the Ranid Telencephalon.- 5 Function of the “Nonolfactory” Telencephalon of Anurans.- 6 Concluding Remarks.- 7 Summary.- Section IV. Neuroendocrinology.- 35. Neuroendocrinology.- 1 Introduction.- 2 Structures of the Neuroendocrinological Active Areas of the Brain.- 3 Functional Aspects of Hormone Production in the Hypothalamus and the Hypophysis.- 4 Summary.- Section V. General Techniques.- 36. The Frog as an Experimental Animal.- 1 Introduction.- 2 Habitat.- 3 Maintenance.- 4 Common Diseases.- 5 Physiology.- 6 Influence of Temperature.- 7 Seasonal Changes.- 8 Experimental Procedures.- 9 Summary.