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Journal ArticleDOI

Medullary cells of origin of vagal cardioinhibitory fibers in the pigeon. I. Anatomical studies of peripheral vagus nerve and the dorsal motor nucleus.

TL;DR: The branches which mediate cardiodeceleration are found to arise from a localized segment of the vagal trunk below the thoracic ganglion, and above the level where the left and right vagi join.
Abstract: The organization to the dorsal motor nucleus of the vagus in the pigeon was studied in an attempt to localize the cells of origin of vagal cardioinhibitory fibers. The course of the peripheral vagus nerve is described form the intracranial rootlets to abdominal levels. Using combined microdissection and electrical stimulation techniques, the branches which mediate cardiodeceleration are found to arise from a localized segment of the vagal trunk below the thoracic ganglion, and above the level where the left and right vagi join. The dorsal motor nucleus, its cytoarchitectonic divisions, and other structures connected with vagal rootlets are described on the basis of normal material. Utilizing the above findings a series of retrograde degeneration experiments was undertaken. The distribution of chromatolytic neurons following cervical vagotomy was described to indicate the extent of the dorsal motor nucleus. Selective nerve sections (abdominal vagotomy, cardiac vagotomy, recurrent laryngeal neurotomy, or pneumonectomy) then indicated that there is an incompletely inverted topographic representation of the vagus nerve in the dorsal motor nucleus, including a representation of the recurrent laryngeal nerve; no evidence was found for the existence of a nucleus ambiguus. The vagal cardioinhibitory fibers appear to be represented throughout the rostral half of the nucleus, but they are most concentrated in the ventral portion of the nucleus, approximately three-quarters of a millimeter rostral to the obex.
Citations
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Journal ArticleDOI
TL;DR: This chapter focuses on learning and memory and its neural bases and examines the ways in which temporal, logical, and qualitative relationships between stimuli (CS and US) influence learning.
Abstract: Publisher Summary This chapter focuses on learning and memory and its neural bases. Learning and memory is a major topic in the field of psychology. Here also, both descriptive mechanical models and formal mathematical models have been developed. In the past, psychologists studying learning have generated a rich data base from behavioral experimentation. For example, much of the research in the Pavlovian conditioning has been designed to determine the ways in which temporal, logical, and qualitative relationships between stimuli (CS and US) influence learning. From this body of empirical knowledge, they have developed very successful models, in the form of sets of abstract learning rules that are able to account for many of the experimental findings. The strength of this approach has been that the theoretical models are able to integrate and deduce a wide range of learning phenomena and make predictions that lead to new experiments. A weakness of this approach, from the perspective of a neurobiologist, is that these psychological models do not make contact with the biological systems that underlie the behavioral phenomena.

865 citations

Journal ArticleDOI
TL;DR: This review explores the fundamental neuranatomical and functional bases for integration of the respiratory and cardiovascular systems in vertebrates and traces their evolution through the vertebrate groups, from primarily water-breathing fish and larval amphibians to facultative air-Breathers such as lungfish and some adult amphibians and finally obligate air-b breathehers among the reptiles, birds, and mammals.
Abstract: This review explores the fundamental neuranatomical and functional bases for integration of the respiratory and cardiovascular systems in vertebrates and traces their evolution through the vertebrate groups, from primarily water-breathing fish and larval amphibians to facultative air-breathers such as lungfish and some adult amphibians and finally obligate air-breathers among the reptiles, birds, and mammals. A comparative account of respiratory rhythm generation leads to consideration of the changing roles in cardiorespiratory integration for central and peripheral chemoreceptors and mechanoreceptors and their central projections. We review evidence of a developing role in the control of cardiorespiratory interactions for the partial relocation from the dorsal motor nucleus of the vagus into the nucleus ambiguus of vagal preganglionic neurons, and in particular those innervating the heart, and for the existence of a functional topography of specific groups of sympathetic preganglionic neurons in the spinal cord. Finally, we consider the mechanisms generating temporal modulation of heart rate, vasomotor tone, and control of the airways in mammals; cardiorespiratory synchrony in fish; and integration of the cardiorespiratory system during intermittent breathing in amphibians, reptiles, and diving birds. Concluding comments suggest areas for further productive research.

353 citations

Journal ArticleDOI
TL;DR: In chloralose‐urethane anesthetized spinal rats, electrical stimulation of systematically chosen points over the entire caudal brain stem area was carried out to explore the site(s) responsible for vagally mediated bradycardia to find cells of origin of vagal cardioinhibitory fibers within the brain stem.
Abstract: In chloralose-urethane anesthetized spinal rats, electrical stimulation of systematically chosen points over the entire caudal brain stem area was carried out to explore the site(s) responsible for vagally mediated bradycardia. A dorsomedial locus including the nucleus dorsalis and the adjacent structures, the nucleus tractus solitarius, the nucleus commissuralis and the area postrema, and a ventrolateral locus around the nucleus ambiguus were found to elicit bradycardia with low threshold and high responsiveness. In another series of experiments, horseradish peroxidase (HRP) was iontophoretically administered through a glass capillary microelectrode into the identified cardiac branch of the vagus nerve of rats in order to localize more precisely the cells of origin of vagal cardioinhibitory fibers within the brain stem. Distribution of the HRP-labeled cells was not confined to one area, but these cells were found within the nucleus dorsalis, the reticular formation surrounding the nucleus ambiguus and an intermediary zone between the two nuclei. Such a pattern of distribution of vagal cardioinhibitory preganglionic cells is discussed in relation to phylogenetic and ontogenetic development of the vagal motor nuclei.

225 citations

Journal ArticleDOI
TL;DR: Using interspecific grafting of neural crest between quail and chick embryos, it was determined that the cardiac ganglia originate from the cranial region (somites 1-2) of the vagal neural crest, and neuronal uptake in 8-day chick atrium was decreased.

174 citations

References
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Book
01 Jan 1967
TL;DR: The stereotaxic atlas of the pigeon brain by Karten and Hodos as discussed by the authors is a source of promise and expectation, and has also become a most useful source of general orientation in the organization of the avian brain.
Abstract: FOREWORD The problems of evolution rank among mankind's most enduring interests, and it is therefore not surprising that virtually every branch of biology and medicine has ramified in the direction of comparative studies. Although in neurology this search traditionally has been an intensive one, a lack of adequately refined techniques has long held comparative neurology confined largely within the limits of normal anatomical description. The technological scene has changed rapidly over the last few decades, and the contemporary neurologist finds an instrumentarium of unprecedented refinement available: microelectrode recording techniques, sensitive quantitative chemical methods, greatly improved techniques for both normal descriptive and experimental anatomical studies, histochemical and embryological techniques hardly dreamed of by earlier generations of neurobiologists. In the monumental writings of Edinger, the Herricks, Cajal, Ariens Kappers, Huber, Crosby and their colleagues he will find a rich store of anatomical information on the vertebrate brain, but it will not take him long to identify the great problems of interphyletic homology, both in structure and function, that have remained unresolved. Almost certainly, new insights in these problems are in store for all who venture a fresh approach by the aid of modern methods. Brain research over the years has drawn huge profits not only from a progressive refinement of physiological, chemical, and histological techniques. It owes an important part of its success to the development of accurate stereotaxic methods, spatial guides without which only few deep-lying brain structures could have been explored adequately. The appearance of this stereotaxic atlas of the pigeon brain by Drs. Karten and Hodos is therefore a source of promise and expectation. The authors, as the user will find, have succeeded in achieving standards of accuracy that match those of the best atlases used in research on the mammalian brain. Their thorough search of the available literature has extended the value of this work well beyond its primary purpose of being a practical guide in experimental research. It has also become a most useful source of general orientation in the organization of the avian brain. But no matter what its present virtues, one cannot wish this work a better fate than that of future revisions in which the currently widely accepted but unavoidably neutral labels that identify so many structures, especially in the forebrain, can be replaced or augmented by ever more meaningful indications of structure and function. ACKNOWLEDGMENTS The authors wish to gratefully acknowledge the assistance, …

945 citations

Journal ArticleDOI

127 citations