Pflugers Archiv-european Journal of Physiology, 1977
Compound action potentials evoked by electrical stimulation in the brainstem of anaesthetized, pa... more Compound action potentials evoked by electrical stimulation in the brainstem of anaesthetized, paralyzed cats and rabbits were recorded distally in the carotid sinus nerve. The latencies of the components of the responses were indicative of fibres with conduction velocities between 0.5 and 32 m/s. These include both myelinated and unmyelinated fibres. Using histological reconstructions of the ‘responsive sites’, the termination of the primary afferent fibres of the sinus nerve within the medulla was mapped. In both cat and rabbit these responsive sites were restricted to thedorsomedial medulla in the vicinity of the NTS 0–3 mm rostral to the obex. Although in the cat the fast conducting myelinated fibres (conduction velocities >12.5 m/s) were discretely localized to the ventrolateral area of the NTS, the slower conducting myelinated and unmyelinated fibres were found more diffusely, spreading into areas dorsal and medial to the NTS. In the rabbit the terminals of all types of fibre were mainly confined to the NTS although some C fibres appeared to be grouped in the juxta-alar region. Responses were never evoked from the medial reticular formation or nucleus ambiguus in either cats or rabbits. The organization of the sinus nerve input to the medulla is discussed in the light of these results.
This review explores the fundamental neuranatomical and functional bases for integration of the r... more 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.
We present an easy to survey constructive method using only basic mathematics which allows us to ... more We present an easy to survey constructive method using only basic mathematics which allows us to define a homeomorphism between any compact real algebraic variety and some components of the configuration space of a mechanical linkage. The aim is to imitate addition and multiplication in the framework of weighted graphs in the euclidean plane that permit a ``mechanical description'' of polynomial functions, and thus of varieties.
Pflugers Archiv-european Journal of Physiology, 1977
Compound action potentials evoked by electrical stimulation in the brainstem of anaesthetized, pa... more Compound action potentials evoked by electrical stimulation in the brainstem of anaesthetized, paralyzed cats and rabbits were recorded distally in the carotid sinus nerve. The latencies of the components of the responses were indicative of fibres with conduction velocities between 0.5 and 32 m/s. These include both myelinated and unmyelinated fibres. Using histological reconstructions of the ‘responsive sites’, the termination of the primary afferent fibres of the sinus nerve within the medulla was mapped. In both cat and rabbit these responsive sites were restricted to thedorsomedial medulla in the vicinity of the NTS 0–3 mm rostral to the obex. Although in the cat the fast conducting myelinated fibres (conduction velocities >12.5 m/s) were discretely localized to the ventrolateral area of the NTS, the slower conducting myelinated and unmyelinated fibres were found more diffusely, spreading into areas dorsal and medial to the NTS. In the rabbit the terminals of all types of fibre were mainly confined to the NTS although some C fibres appeared to be grouped in the juxta-alar region. Responses were never evoked from the medial reticular formation or nucleus ambiguus in either cats or rabbits. The organization of the sinus nerve input to the medulla is discussed in the light of these results.
This review explores the fundamental neuranatomical and functional bases for integration of the r... more 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.
We present an easy to survey constructive method using only basic mathematics which allows us to ... more We present an easy to survey constructive method using only basic mathematics which allows us to define a homeomorphism between any compact real algebraic variety and some components of the configuration space of a mechanical linkage. The aim is to imitate addition and multiplication in the framework of weighted graphs in the euclidean plane that permit a ``mechanical description'' of polynomial functions, and thus of varieties.
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Papers by David Jordan