Responses of cells in the brain stem of the cat to stimulation of the sinus, glossopharyngeal, aortic and superior laryngeal nerves
TL;DR: The distribution and properties of 146 brain stem units whose activity was influenced by electrical stimulation of sinus, glossopharyngeal, aortic and superior laryngeAL nerves were studied in cats.
Abstract: 1. The distribution and properties of 146 brain stem units whose activity was influenced by electrical stimulation of sinus, glossopharyngeal, aortic and superior laryngeal nerves were studied in cats.2. Cells excited by electrical stimulation of one or more of the nerves were distributed throughout the brain stem in an area extending rostrocaudally from Horsley-Clarke co-ordinates P 7.5 to P 16.5 and laterally between 1.5 and 5 mm from the mid line.3. Most of the units excited (n = 129) or inhibited (n = 17) by nerve stimulation were localized in the nucleus reticularis gigantocellularis and nucleus reticularis parvocellularis.4. The latencies of activation varied from as short as 1.5 msec to as long as 35-40 msec. A high degree of convergence was observed.5. Evoked responses varied from single spikes to bursts of impulses, the frequencies of which were sometimes as high as 1000/sec following a single shock to the nerve.6. Spontaneously active cells inhibited (seventeen) by nerve stimulation were located primarily in NRG and NRP. None of the cells was inhibited by stimulation of one nerve and excited by stimulation of the others.7. The responses of cells to a sudden rise in carotid sinus pressure were similar in kind to the responses to electrical stimulation of the nerves.
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TL;DR: The neuronal circuitry, the cellular properties of neurons, and the neurotransmitters possibly involved, as well as the peripheral and central inputs which shape the output of the network appropriately so that the swallowing movements correspond to the bolus to be swallowed are analyzed.
Abstract: Swallowing movements are produced by a central pattern generator located in the medulla oblongata. It has been established on the basis of microelectrode recordings that the swallowing network includes two main groups of neurons. One group is located within the dorsal medulla and contains the generator neurons involved in triggering, shaping, and timing the sequential or rhythmic swallowing pattern. Interestingly, these generator neurons are situated within a primary sensory relay, that is, the nucleus tractus solitarii. The second group is located in the ventrolateral medulla and contains switching neurons, which distribute the swallowing drive to the various pools of motoneurons involved in swallowing. This review focuses on the brain stem mechanisms underlying the generation of sequential and rhythmic swallowing movements. It analyzes the neuronal circuitry, the cellular properties of neurons, and the neurotransmitters possibly involved, as well as the peripheral and central inputs which shape the output of the network appropriately so that the swallowing movements correspond to the bolus to be swallowed. The mechanisms possibly involved in pattern generation and the possible flexibility of the swallowing central pattern generator are discussed.
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TL;DR: The existence of such an extensive projection system connecting these specific regions is significant evidence in support to its potential for participation in the amygdaloid expression of cardiovascular influences and has important implications for the cellular analysis of the functional role of these influences.
Abstract: Although the amygdala complex has long been known to exert a profound influence on cardiovascular activity, the neuronal and connectional substrate mediating these influences remains unclear. This paper describes a direct amygdaloid projection to medullary sensory and motor structures involved in cardiovascular regulation, the nucleus of the solitary tract (NTS) and the dorsal motor nucleus (DVN), by the use of autoradiographic anterograde transport and retrograde horseradish peroxidase (HRP) techniques in rabbits. Since all of these structures are highly heterogeneous structurally and functionally, details of the specific areas of the neuronal origin and efferent distribution of the projection were examined in relation to these features and with reference to a cytoarchitecture description of the relevant forebrain regions in the rabbit. Amygdaloid projections to the NTS and DVN, as determined from HRP experiments, arise from an extensive population of neurons concentrated exclusively within the ipsilateral central nucleus and confined to and distributed throughout a large medial subdivision of this nucleus. Projection neurons, however, also distribute without apparent interruption beyond the amygdala dorsomedially into the sublenticular substantia innominata and the lateral part of the bed nucleus of the stria terminalis and thus delineate a single entity of possible anatomical unity across all three structures, extending rostrocaudally within the basal forebrain as a diagonal band. Descending central nucleus connections, based upon autoradiographic experiments, project heavily and extensively to both the NTS and the DVN. Within both nuclei, the projections have a highly specific distribution pattern, appearing to correspond largely to structural subdivisions, including the dorsomedial, medial, ventrolateral, ventral, and commissural NTS, and to cell group “a,” a caudally located dorsomedial region, and peripheral regions of the DVN, some of which appear to be involved in cardiovascular regulation. The existence of such an extensive projection system connecting these specific regions is significant evidence in support to its potential for participation in the amygdaloid expression of cardiovascular influences and has important implications for the cellular analysis of the functional role of these influences.
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TL;DR: The chapter outlines the possible interrelationship between the modulatory biogenic amine-containing neurones and the baroreceptor reflex arc and discusses the possible site of these modulatory centers in the hypothalamus and in the brain stem.
Abstract: Publisher Summary In this chapter, the neuroanatomy of the baroreceptor reflex arc is reviewed and relevant new data are presented. The baroreceptor reflex arc consists of a multisynaptic neuronal chain. Primary neurones have perikarya in the nodose ganglion, and they connect the peripheral baroreceptor sites with the nucleus tractus solitarii (NTS) via fibres in the 9th and 10th cranial nerves. The first synapse in the baroreceptor reflex arc and also the origin of the secondary neurones are located in the caudal and partly in the commissural parts of the NTS. Neuroanatomical topography of the NTS and neighboring medullary nuclei in the rat is presented and detailed. The fibres of the secondary neurones terminate in various medullary nuclei and probably reach—directly or by multisynaptic pathways—the higher regions that may modulate the baroreceptor reflex arc. The chapter presents a discussion on the possible site of these modulatory centers in the hypothalamus and in the brain stem and of the loop of the descending fibres from these regions to the medullary and spinal baroreceptor neurones. The efferent preganglionic neurones of the baroreceptor reflex arc are located in the medulla oblongata and in the intermedio-lateral nucleus of the spinal cord. The chapter outlines the possible interrelationship between the modulatory biogenic amine-containing neurones and the baroreceptor reflex arc.
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TL;DR: The central distributions of primary afferent axons in cranial nerves V, VII, IX, and X have been re‐examined autoradiographically after 3H‐proline injections into their peripheral ganglia to suggest that trigeminal fibers of the ophthalmic and mandibular branches enter the ventrolateral part of the nucleus of the solitary tract (NST).
Abstract: The central distributions of primary afferent axons in cranial nerves V, VII, IX, and X have been re-examined autoradiographically after 3H-proline injections into their peripheral ganglia. Fiber-labeling after subtotal injections of the trigeminal ganglion, besides confirming earlier classical descriptions, suggests that trigeminal fibers of the ophthalmic and mandibular (but not maxillary) branches enter the ventrolateral part of the nucleus of the solitary tract (NST). Injection of VII's geniculate ganglion labels fibers which both ascend and descend upon reaching NST. The ascending fibers distribute in a compact and circumscribed zone immediately dorsal to the spinal V nucleus as far rostral as the caudal pole of the principal trigeminal nucleus. The descending fibers distribute to the lateral NST rostral to the level at which X joins the solitary tract. For a short distance caudal to this level, sparse label is confined to a small part of lateral NST ventral to the solitary tract, which corresponds to the zone receiving direct trigeminal afferents. Fiber-labeling after injections of the ganglia of nerves IX and X suggest the following. Although, upon reaching NST, a few fibers of either IX or X ascend as far rostrally as had those of VII, both have a much larger descending component which distributes to more caudal levels of NST. Most of IX's axons appear to end in the lateral NST; only a few travel as far as the obex. Fibers of X, on the other hand, are abundant in the medial and commissural parts of NST. Moreover, only X appears to have a crossed projection in the commissural nucleus and caudal portion of the contralateral NST. A few fibers of vagal origin also appear to enter the area postrema. Whereas fibers of X appear to constitute the solitary tract, few if any fibers of VII or IX travel within that fascicle. A significant descending components of labeled fibers appears in the spinal V tract when the superior ganglion of either IX or X is injected. These fibers distribute mainly in the pars caudalis of the spinal V nucleus and, to a lesser degree, the cuneate nucleus.
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References
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Book•
01 Jan 1964
TL;DR: This chapter discusses the development of ideas on the synapse, the ionic mechanism generating the inhibitory postsynaptic potential, and the trophic and plastic properties of synapses.
Abstract: I. The development of ideas on the synapse.- II. Structural features of chemically transmitting synapses.- III. Physiological properties of chemically transmitting synapses in the resting state.- IV. Excitatory postsynaptic responses to presynaptic impulses.- V. Excitatory transmitter substances.- VI. The release of transmitter by presynaptic impulses.- VII. The generation of impulses by the excitatory postsynaptic potential and the endplate potential.- VIII. The presynaptic terminals of chemically transmitting synapses.- IX. Excitatory synapses operating by electrical transmission.- X. The postsynaptic electrical events produced by chemically transmitting inhibitory synapses.- XI. The ionic mechanism generating the inhibitory postsynaptic potential.- XII. Inhibitory transmitter substances.- XIII. Pathways responsible for postsynaptic inhibitory action.- XIV. Inhibitory synapses operating by electrical transmission.- XV. Presynaptic inhibition.- XVI. The trophic and plastic properties of synapses.- Epilogue.- References.
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TL;DR: It is concluded that myelinated CSN fibers terminate in both the intermediate portion of the nucleus tractus solitarii (NTS) and on large neurons of the paramedial reticular formation of the medulla, that integration of CSN activity occurs in the intermediate portions of the NTS, and that specific reticular nuclei receive multisynaptic CSN projections.
Abstract: MIURA, MITSUHIKO, AND DONALD J, REXS. Tmmktzb~ and secondary projections of carotid sinus nerve in the cat brain stem. Am. J. Physiol. 217(I): 142-153. 1969.-Field responses and unit activity evoked by electrical stimulation of the carotid sinus nerve (CSN) were recorded with microelectrodes in the medulla and pons of anesthetized, paralyzed cats. A short-latency (0.7-I .4 msec), monosynaptic, “early” response, triggered by myelinated CSN fibers, was found in the intermediate portion of the nucleus tractus solitarii (NTS) and in the paramedial reticular formation of the medulla, especially in n, paramedian reticularis; a paucisynaptic “intermediate” response (1.7 msec mean latency) was localized within the intermediate portion of the NTS; and polysynaptic “late” responses (peak > 5 msec) were found in specific subnuclei of the medullary and pontine reticular formation. We conclude that myelinated CSN fibers terminate in both the intermediate portion of the NTS and on large neurons of the paramedial reticular formation of the medulla, that integration of CSN activity occurs in the intermediate portion of the NTS, and that specific reticular nuclei receive multisynaptic CSN projections.
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