scholarly journals Reversal of the reflex effect of an afferent nerve by altering the character of the electrical stimulus applied

1911 ◽  
Vol 83 (566) ◽  
pp. 435-446 ◽  
Keyword(s):  
Hind Limb ◽  
Electrical Stimulus ◽  
Afferent Nerve ◽  
Afferent Limb ◽  
Afferent Nerves ◽  
Reflex Effect ◽  
Extensor Muscles ◽  
Central Inhibition ◽  
Reflex Stimulation ◽  
Stimulation Of

Stimulation of an afferent limb-nerve in the decerebrate or decapitate mammal (cat, dog) gives as its reflex result flexion of that limb; during this flexion the pure extensor muscles of the limb relax under central inhibition. In the hind limb this reflex effect is observable in the isolated vasto-crureus, the main extensor muscle of the knee; that muscle if engaged in contraction relaxes when the afferent nerve is stimulated. Its elongation is the sign of the central inhibition which takes place. If the reflex stimulation be strong the muscle relaxes quickly and greatly; if the stimulation be weak the relaxation is slower and less ample. These results are easily demonstrable by using as a stimulus either faradism or mechanical stimulation such as ligation of the central stump of the afferent nerve. Usual and uniform as this result is, we find it possible in the decerebrate preparation under certain conditions to obtain reflex contraction of vastocrureus as well as reflex inhibition, and to elicit the contraction through the same afferent nerves as under other conditions so regularly elicit inhibition. The condition influencing the nature of the reflex result in this respect are (1) the strength and (2) the form of the electrical stimulus applied to the afferent nerve, and (3) the reflex state obtaining in the preparation at the time.

scholarly journals The rhythmic discharge of motoneurones

1932 ◽  
Vol 110 (768) ◽  
pp. 483-514 ◽  
Keyword(s):  
Experimental Work ◽  
Repetitive Stimulation ◽  
Afferent Nerve ◽  
Reflex Response ◽  
Direct Relation ◽  
Extensor Muscles ◽  
Preliminary Account ◽  
Rhythmic Discharge ◽  
Reflex Discharge ◽  
Stimulation Of

Denny-Brown (1929) and Adrian and Bronk (1929) have described rhythmic discharges from the single motoneurones of extensor muscles during repetitive stimulation of a contralateral afferent nerve. When the stimulation is not too infrequent, e. g. , when more than 10 a second, the rhythm of this reflex discharge bears no direct relation to the rhythm of the stimulation, but within limits it varies with the intensity of the reflex stimulus, which in turn is dependent on both the rate and the strength of the stimulation. Somewhere in the reflex centre the reflex stimulus gives rise to the rhythmic discharge characteristic of the reflex response. This paper describes an investigation into conditions underlying the production of such a rhythmic discharge from a motoneurone. A preliminary account of some of the experimental work has already been published (Eccles and Hoff, 1931).

scholarly journals Nervous rhythm arising from rivalry of antagonistic reflexes: Reflex stepping as outcome of double reciprocal innervation

1913 ◽  
Vol 86 (587) ◽  
pp. 233-261 ◽  
Keyword(s):  
Afferent Nerve ◽  
The Other ◽  
Present Communication ◽  
Simultaneous Stimulation ◽  
Afferent Nerves ◽  
Wide Range ◽  
Contralateral Muscle ◽  
Stimulation Of

The observations with which the present communication deals were met with in experiments continuing those on reciprocal innervation of symmetrical muscles. In my previous paper on that subject it had been reported that in regard to symmetrical extensors of the knee the ratio borne by intensity of the ipsilateral inhibition to the contralateral excitation is such that with equal stimuli to right and left symmetrical afferent nerves there is inhibitory suppression of contraction in both the muscles. In other words, under double reciprocal innervation the ipsilateral inhibition by each nerve completely overcomes the contralateral excitation of the other. It was shown that this mutual suppression holds over a wide range of the scale of intensities of stimulation. It was also shown that with quite weak stimuli a simultaneous stimulation of both nerves, stimuli being equal in intensity, often results in concurrent contraction of both muscles. Indeed, with quite weak stimuli, the effect of stimulation of each afferent nerve by itself is, in the decerebrate preparation, usually contraction of the ipsilateral as well as of the contralateral muscle. This being so, it is evident that at some point in the scale of intensities of stimulation there should be a place below which contralateral excitation is stronger than ipsilateral inhibition, whereas above it ipsilateral inhibition is stronger than contralateral excitation.

Inhibition of spinal afferent nerve-mediated gastric hyperemia by nicotine: role of ganglionic blockade

1993 ◽  
Vol 264 (4) ◽  
pp. H1087-H1092
Author(s):  
F. W. Leung
Keyword(s):  
Blood Flow ◽  
Afferent Nerve ◽  
Gastric Blood Flow ◽  
Doppler Flowmetry ◽  
Afferent Nerves ◽  
Vasodilatory Effect ◽  
Blocking Property ◽  
Intravenous Nicotine ◽  
Ganglionic Blocking ◽  
Stimulation Of

The hypothesis that intravenous nicotine modulates gastric spinal afferent nerve function by its ganglionic-blocking property is tested. Stimulation of the gastric spinal afferent nerves in anesthetized rats is accomplished by intragastric capsaicin irrigation. Gastric blood flow is monitored by laser-Doppler flowmetry. The increase in gastric blood flow during intragastric capsaicin irrigation is significantly reduced by 4 and 40 micrograms.kg-1.min-1 of intravenous nicotine. The inhibition appears to be specific for the spinal afferent nerves as the increase in gastric blood flow induced by electrical stimulation of the vagal afferent nerves is unaltered by these doses of intravenous nicotine. A ganglionic-blocking dose (10 mg/kg) of intraperitoneal hexamethonium also significantly attenuates the gastric vasodilatory effect of intragastric capsaicin. Intravenous nicotine (40 micrograms.kg-1.min-1) combined with intraperitoneal hexamethonium (10 mg/kg) completely abolishes the gastric vasodilatory effect of intragastric capsaicin. These data suggest that intravenous nicotine offers a specific inhibition of the gastric spinal afferent nerve-mediated hyperemia, possibly as a consequence of its ganglionic-blocking property.

Interaction between primary afferent nerves in the elicitation of reflex swallowing

1980 ◽  
Vol 239 (5) ◽  
pp. R407-R414 ◽  
Author(s):  
A. Weerasuriya ◽  
D. Bieger ◽  
C. H. Hockman
Keyword(s):  
Contralateral Side ◽  
Afferent Nerve ◽  
Reflex Response ◽  
Solitary Tract ◽  
Primary Afferent ◽  
Afferent Nerves ◽  
Primary Afferent Nerves ◽  
Adult Cats ◽  
Primary Afferent Nerve ◽  
Stimulation Of

In adult cats anesthetized with urethan, a number of observations were made that support the concept that some control over the rate of reflexly induced swallowing occurs in the intermediate network at the level of the nucleus of the solitary tract. It was shown that different nerves, e.g., the two superior laryngeal and glossopharyngeal nerves, when activated in sequence interact in such a manner as to facilitate reflex swallowing. It was also shown that the decrement in the reflex response observed to continuous stimulation of a primary afferent nerve, e.g., one superior laryngeal, can be reversed by switching the stimulation to another nerve either on the same or contralateral side. And finally, following discrete medullary lesions, it was observed that that portion of the nucleus of the solitary tract located 2 mm or more rostral to the rostralmost point of the dorsal medial sulcus appears to contain an integral component of the intermediate network that governs reflexly induced swallowing, whereas lesions restricted to the ventrolateral portion of the nucleus of the solitary tract have no effect on the reflex response.

Fos induction in rat brain neurons after stimulation of the hepatoportal Na-sensitive mechanism

1997 ◽  
Vol 272 (3) ◽  
pp. R913-R923 ◽  
Author(s):  
H. Morita ◽  
Y. Yamashita ◽  
Y. Nishida ◽  
M. Tokuda ◽  
O. Hatase ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Area Postrema ◽  
Vena Cava ◽  
Plasma Osmolality ◽  
Systemic Circulation ◽  
Afferent Nerve ◽  
Hypothalamic Nucleus ◽  
Nerve Activity ◽  
Afferent Nerves ◽  
Stimulation Of

Responses of hepatic afferent nerves to intraportal bolus injection of hypertonic solutions were examined in anesthetized rats. Hepatic afferent nerve activity increased in response to an intraportal injection of 0.75 M NaCl or NaHCO3 but did not respond to a similar injection of 1.5 M mannitol, 0.75 M LiCl, or 0.15 M NaCl, implying that nerves in the hepatoportal area are sensitive to increases in Na concentrations and that this leads to stimulation of hepatic afferent nerve activity. To study central activation in response to stimulation of the hepatic Na-sensitive mechanism, c-fos induction was monitored. After electrical stimulation of hepatic afferent nerves, neurons containing Fos-like immunoreactivity (Fos-li) were found in the area postrema, nucleus of the solitary tract, paraventricular hypothalamic nucleus, and supraoptic nucleus at 90 min after stimulation. Induction of Fos-li was also studied after simultaneous infusion of 0.45 M NaCl into the portal vein and distilled water into the inferior vena cava in conscious rats so as to keep the total amount of solution introduced into the systemic circulation isotonic, thus avoiding changes in mean arterial pressure, plasma osmolality, and plasma NaCl concentrations. Fos-li-containing neurons were found in the same regions in which they were found after electrical stimulation. However, few, if any, Fos-li-containing cells were found if the rats were hepatically denervated or if they received an intraportal infusion of hypertonic LiCl or mannitol. These data provide evidence for involvement of the brain stem and forebrain structures in NaCl regulatory functions induced by stimulation of the hepatoportal Na-sensitive mechanism. However, stimulation of the hepatoportal osmosensitive mechanism does not activate these central structures.

Cardiovascular effects of thoracic afferent nerve stimulation in conscious dogs

1982 ◽  
Vol 60 (9) ◽  
pp. 1193-1199 ◽  
Author(s):  
J. A. Armour ◽  
J. B. Pace
Keyword(s):  
Nerve Stimulation ◽  
Cardiovascular Effects ◽  
Afferent Nerve ◽  
Conscious Dogs ◽  
Autonomic Nerve ◽  
Cardiovascular Reflexes ◽  
Force Of Contraction ◽  
Afferent Nerves ◽  
Pressure Changes ◽  
Stimulation Of

Afferent stimulation of a severed thoracic autonomic nerve in 18 conscious dogs produced in 13 instances hypertension and in 5 instances hypotension. Reflex hypertension was usually accompanied by augmented atrial and ventricular force of contraction. The hypertension could be maintained for over 5-min duration by constant stimulation. Inotropic changes accompanying this hypertension were accentuated following atropine administration and abolished by propranolol. Blood pressure changes following atropinization were initially augmented. On the other hand reflex hypotension was accompanied by bradycardia and decreased atrial contractility. These changes were essentially abolished by atropine. Afferent nerve stimulation with frequencies as low as 1 Hz initiated reflex changes. Maximal responses were obtained by stimulation frequencies of 10–15 Hz. It is concluded that significant and relatively sustained cardiovascular reflexes can be generated by stimulation of cardiac afferent nerves in conscious dogs.

scholarly journals On the effects of constant galvanic currents upon the mammalian nerve-muscle and reflex preparations

1921 ◽  
Vol 92 (648) ◽  
pp. 341-355 ◽  
Keyword(s):  
Peripheral Nerve ◽  
Hind Limb ◽  
Afferent Nerve ◽  
Flexor Reflex ◽  
Afferent Nerves ◽  
Exact Data ◽  
Accurate Knowledge ◽  
Nerve Muscle ◽  
Continuous Excitation ◽  
Mammalian Nerve

My experiments were to study the reflex effects resulting from stimulation by constant galvanic currents applied to an afferent nerve of the hind limb. The main points of enquiry have been: (1) the relation between reflex excitation and inhibition of the decerebrate tonus of the vasto-crureus; (2) whether the “excitation formula” (Pflüger’s law) holds good in mammalian afferent nerves; and (3) whether there is continuous excitation during the passage of the current through an afferent nerve. The reflex effects thus produced in the extensor muscle are complex and various, and are difficult to analyse without accurate knowledge of the results obtainable in the peripheral nerve-muscle and in the flexor reflex preparation. A few experiments were therefore made with these preparations, since the exact data required could not be obtained from the literature.

THE EFFECT OF GONADECTOMY ON THE RESPONSE OF THE PITUITARY I. C. S. H.-CONTENT TO STEROID SEX HORMONES

1960 ◽  
Vol XXXV (II) ◽  
pp. 245-252 ◽  
Author(s):  
G. P. van Rees ◽  
F. J. A. Paesi
Keyword(s):  
Sex Hormones ◽  
Sex Steroids ◽  
Low Dose ◽  
Testosterone Propionate ◽  
Preceding Paper ◽  
Direct Consequence ◽  
Two Factors ◽  
Reflex Stimulation ◽  
Steroid Sex Hormones ◽  
Stimulation Of

ABSTRACT In the experiments reported in this paper the hypothesis that the decrease in the pituitary I. C. S. H.-content, which occurs after administration of steroid sex hormones in gonadectomized animals, is counteracted by a reflex stimulation of the hypophysis initiated by the operation has been investigated. If treatment with a low dose of testosterone propionate (100 μg) was started immediately after castration, the resulting decrease in the pituitary I. C. S. H.-content became more marked if the reflex stimulation of the hypophysis had been prevented. If, however, two months were allowed to elapse before the beginning of treatment, the presence or absence of this reflex was no longer of importance for the effect of testosterone propionate on the pituitary I. C. S. H.-content. And yet, in this case too, the decrease in the pituitary I. C. S. H.-content by testosterone propionate was less than in intact animals (see preceding paper). Hence this decrease appears to be counteracted by two factors: one rapidly occurring and short lasting, resulting from a reflex elicited by gonadectomy; the other gradually increasing in potency and possibly a direct consequence of the continued absence of pituitary inhibiting sex steroids.

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