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At least 19 recordsLinked to original sources
PubMed1978

Central neural pathways for angiotensin-induced thirst.

Evidence is reviewed implicating the preoptic region in angiotensin-induced thirst. The most responsive area according to results obtained with behavioral, electrophysiological, and autoradiographic mapping techniques is at the caudal border of the medial preoptic region and rostral border of the anterior hypothalamus. The neural pathway from this preoptic site for angiotensin-induced thirst extends along the medial forebrain bundle through the midlateral hypothalamus to the paramedial midbrain tegmentum and to an area ventrolateral to the central gray. Lesions of this pathway in the midlateral hypothalamus and rostral midbrain significantly attenuated drinking induced by microinjections of angiotensin II into the preoptic area but did not disrupt water intake induced by microinjections of angiotensin II into the subfornical organ or cerebral ventricles. Although the efferent pathways from angiotensin-receptive sites in the subfornical organ and cerebral ventricles are unknown, it appears from these observations that the medial forebrain bundle is not involved. Lesions of the medial forebrain bundle-lateral hypothalamus also do not disrupt drinking induced by microinjections of hypertonic saline into the preoptic region although lesions placed 1 mm further lateral do. Since fat lateral hypothalamic lesions are without effect on drinking induced by centrally administered angiotensin II, this suggests that intracellular and extracellular thirst signals are subserved by separate neural pathways in the hypothalamus.

Action Potentials↗
PubMed1992

Meal-induced jejunal absorption requires intact neural pathways.

A signal for meal-induced absorption originates from the small intestine and is transmitted to a luminally excluded segment of the proximal jejunum (Thiry-Vella [TV] fistula). Using intraluminal topical anesthesia with oxethazaine, this study assessed the role of intestinal neural pathways in basal and postprandial jejunal water and electrolyte absorption. Studies (n = 45) were performed on dogs with 25-cm proximal jejunal TV fistulae and feeding jejunostomies, using luminal perfusion with 14C-polyethylene glycol. The animals were randomized into five study groups: (1) jejunostomy oxethazaine alone, (2) jejunostomy water and jejunal meal, (3) jejunostomy oxethazaine and jejunal meal, (4) TV fistula water and jejunal meal, and (5) TV fistula oxethazaine and jejunal meal. The jejunal meal significantly increased TV fistula absorption, whereas oxethazaine significantly reduced basal absorption when administered via the TV fistula and postprandial absorption when administered via the jejunostomy (p less than 0.05). TV fistula oxethazaine did not diminish the magnitude of postprandial absorption. We conclude that intact intestinal neurotransmission is necessary for maintenance of the normal basal absorptive state of the proximal jejunum and for the generation of a normal meal-stimulated proabsorptive signal from the small intestine. A nonneural mechanism appears to be of predominant importance in transmitting the proabsorptive signal from the intact gastrointestinal tract to the TV fistula.

Anesthetics, Local↗
PubMed1978

Neural pathways of a cardiogenic hypertensive chemoreflex.

Excitation of a cardiac chemoreceptor with 5-hydroxytryptamine (serotonin) produces a complex autonomic reflex which includes hypertension, changes in heart rate and contractile force, and disturbances of AV conduction. This study examines the afferent and efferent neural pathways of this autonomic reflex in 60 anesthetized dogs. We used cooling and sectioning techniques in 40 of these, and in 20 others recorded afferent neurograms. The most common afferent pathways for the reflex were found in the left and right recurrent cardiac nerves. No preferential efferent routes to the heart were found, although the nature of the reflex cardiac response could be altered by specific nerve interruption. Cyproheptadine (1 mg/kg iv) regularly abolished both the reflex and the chemoreceptor afferent neural traffic, but injection of a 10 times higher concentration of serotonin (1 mg/ml) readily surmounted the blockade and restored the chemoreceptor neural traffic. Thus cyproheptadine interdicts the reflex at the site of its initiation.

Afferent Pathways↗
PubMed1978

Neural pathways common to vestibular and optokinetic eye movements.

To determine how vestibular and optokinetic eye movement signals share the central oculomotor neural organization, optokinetic afternystagmus was superposed on vestibular nystagmus in the monkey. To a first approximation there was algebraic additivity in the velocity domain. This result suggests that vestibular and optokinetic eye movements are integrated at a level of neural organization above the ocular motoneurons, at a level in which neural signals are coded in terms of eye movement velocity rather than eye position.

Animals↗
PubMed1978

[Neural pathway of Powassan virus spread in the central nervous system of white mice].

Electron microscopic investigation of the brains and lumbar spinal cords of adult albino mice infected with Powassan virus was carried out. Virus particles were found within all parts of neurons (perikarya, dendrites, axon), as well as within synaptic apparatus and intercellular gaps of the central nervous tissue. The possibility of the virus spread both throughout the cytoplasm of nerve cells and their processes and the extracellular spaces of the brain was confirmed. Localization of virions within neurons, synapses and myelinated fibers of the spinal cord after intracerebral inoculation suggests that virus spread in the CNS can occur through the CNS parenchyma and also through the nervous conduction pathways. The possible mechanisms of virus dissemination in the CNS of albino mice with experimental Powassan virus encephalomyelitis are discussed.

Animals↗
PubMed1975

Mapping of functional neural pathways by autoradiographic survey of local metabolic rate with (14C)deoxyglucose.

An enzymatic preparation from human brain converts tryptamine to tryptoline (9H-1,2,3,4-tetrahydropyrido(3,4-b)indole) in the presence of 5-methyltetrahydrofolic acid. Similarly, N-methyltryptamine and 5-hydroxytryptamine yield 1-methyltryptoline and 5-hydroxytryptoline, respectively. Neither in vitro nor in vivo formation of these compounds by human tissues has been described.

Animals↗
PubMed1976

Afferent neural pathway in the regulation of cardiopulmonary responses to tissue hypermetabolism.

We studied the role of neural transmission from hypermetabolic peripheral tissues in the regulation of cardiac output and pulmonary ventilation in chloralose-anesthetized dogs. Cross-circulation techniques with femoral-femoral or femoral-aortic anastomoses were used to produce a vascularly isolated, but normally innervated, hindlimb or lower half-body, 2,4-Dinitrophenol (DNP) was infused into the arterial side of the perfusion circuit to triple oxygen consumption and to increase lactate production by the cross-perfused area. After infusion of DNP, cardiac output and mean systemic arterial blood pressure increased, but neither heart rate nor pulmonary artery wedge pressure changed significantly. Pulmonary minute ventilation and arterial pH also increased, while arterial PCO2 fell. These changes were abolished when the nerve connections between the perfused limb and its parent body were severed. Normal saline, when administered in a similar manner, did not increase either ventilation or cardiac output, and simple denervation without previous infusions of DNP also had no effect. These results indicate that there are receptors sensitive to metabolic changes in the tissue, and that neural transmission is an important afferent link in regulating the cardiopulmonary responses to increased tissue metabolism.

Afferent Pathways↗
PubMed1978

Differences in reaction times and average evoked potentials as a function of direct and indirect neural pathways.

Average evoked potentials and manula response latencies were collected during a simple detection task in which brief visual stimuli were presented to the left and right visual fields. Latencies generated by the ipsilateral stimulus-hand combinations were shorter than contralateral combinations only under certain conditions, impugning the hypothesis that the reaction time difference reflects interhemispheric transfer time. Certain evoked potential components recorded contralateral to the stimulus occurred earlier than their ipsilateral counterparts, but whether this difference can be interpreted as representing interhemispheric transfer time is also questioned.

Adult↗
PubMed1975

Neural pathways from the vestibular labyrinths to the flocculus in the cat.

In decerebrate, unanesthetized cats, responses in the flocculus were evoked by electric stimulation of the vestibular nerves and by natural stimulation of horizontal head angular acceleration. Field potentials in the flocculus and intracellular recording from Purkinje cells following vestibular nerve stimulation indicated that the responses were produced by mossy fiber inputs. Field potentials evoked from the contralateral labyrinth were as large as those from the ipsilateral one. There was considerable convergence of bilateral labyrinthine mossy fiber inputs to a Purkinje cell. In view of the effects of incision at the midline of the cerebellum and the brain stem, inputs from the contralateral labyrinth were mainly conveyed through the midline of the brain stem and partly through the midline of the cerebellum. Primary vestibular afferents were involved in the transcerebellar crossed pathway. Fibers of the secondary vestibular neurons projecting to the contralateral flocculus were implicated in the brain stem-mediated pathway and, in part, presumably in the transcerebellar crossed pathway. About one-third of the axon spikes examined in the flocculus responded to horizontal head angular acceleration. Commissural inhibition was observed in more than half of the axon spikes in the flocculus which were presumed to be mono- or polysynaptically activated from the vestibular nerve.

Animals↗
PubMed1977

Neural pathway mediating somatic evoked responses in the caudate nucleus of cats.

The course of somatic afferents to caudate nucleus (CN) was investigated. In curaized cats discrete lesions in intralaminar nuclei, n. centralis medialis (NCM) affect evoked response (ER) in CN to radial nerve stimulation. NCM lesions totally abolish these somatic responses, while after subthalamic lesions ER appear only when a high stimulus intensity is used. Lesions in the specific relay nuclei, ventralis posterior lateralis (VPL) have no effect on somatic ER in CN. Barbiturates (10 mg/kg) abolish somatic ER in CN. Stimulation of the ponto-mesencephalic reticular formation (RF) in a region where visual and somatic responses are recorded shows lowest threshold values for eliciting evoked responses in NCM and CN. The potentials in CN to RF stimulation are restricted to this nucleus and disappear in the internal capsule.

Afferent Pathways↗