scholarly journals THE NERVOUS MECHANISM OF COORDINATION IN THE CRINOID, ANTEDON ROSACEUS

1924 ◽  
Vol 6 (3) ◽  
pp. 281-288 ◽  
Author(s):  
A. R. Moore
Keyword(s):  
Ventral Side ◽  
Ventral Surface ◽  
Reciprocal Inhibition ◽  
The Other ◽  
Dynamic Symmetry ◽  
Other Hand ◽  
Stimulation Of

1. Stimulation causes Antedon to swim by means of alternate oral bending and dorsal stroke of the arms. Two arms of a given ray move alternately so that while one is executing the aboral stroke its mate is flexing ventrally. This implies reciprocal inhibition. 2. Recriprocal inhibition between the two arms of an isolated ray can be abolished by the use of either strychnine or nicotine. 3. Coordination between the rays is referable to the conducting properties of the nervous pentagon which connects the five rays. In this system an impulse loses in effectiveness as it passes from the point of origin. 4. When Antedon is made to rest oral face down on the floor of an aquarium, oral flexion of all the rays, swimming movements, and righting result. Antedon is therefore negatively stereotropic with reference to its ventral side. 5. Excitation of the dorsal cirri results in aboral bending of all the rays. Stimulation of the cirri inhibits ventral flexion to the extent of preventing righting movements while on the other hand stimulation of the ventral surface inhibits the grasp reflex of the cirri. Thus oral and aboral sides of Antedon exhibit dynamic symmetry although structurally dissimilar.

EFFECT OF ACTINOMYCIN D ON TSH-INDUCED STIMULATION OF THYROIDAL PROTEIN SYNTHESIS IN THE RAT

1974 ◽  
Vol 77 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Gustav Wägar
Keyword(s):  
Protein Synthesis ◽  
Actinomycin D ◽  
The Other ◽  
Leucine Incorporation ◽  
Short Term ◽  
Other Hand ◽  
Thyroid Glands ◽  
Translational Level ◽  
Stimulation Of

ABSTRACT Whether the short-term regulation of thyroidal protein synthesis by TSH occurs at the transcriptional or the translational level was tested by measuring the effect of actinomycin D (act D) on the TSH-induced stimulation of L-14C-leucine incorporation into the thyroidal proteins of rats. TSH was injected 6 h before the rats were killed. The thyroid glands were then removed and incubated in vitro in the presence of L-14C-leucine for 2 h. The pronounced stimulation of leucine incorporation in the TSH-treated animals was depressed as compared with controls but still significant even when the animals had been pre-treated with 100 μg act D 24 and 7 h before sacrifice. On the other hand, act D strongly decreased incorporation of 3H-uridine into RNA. Short-term regulation of thyroidal protein synthesis by TSH appears to be partly but not wholly dependent on neosynthesis of RNA. Hence regulation may partly occur at the translation level of protein synthesis.

On Research and Other Matters

1922 ◽  
Vol 26 (140) ◽  
pp. 325-330
Author(s):  
S. Heckstall Smith
Keyword(s):  
British Empire ◽  
Air Force ◽  
The Other ◽  
Other Hand ◽  
Secretary Of State ◽  
The Press ◽  
The Subject ◽  
Stimulation Of

If the thought of another war troubles you, then don't read this article. If you would rather say to yourself as the Secretary of State said to the Air Conference, “ There won't be another war for ten years, so why worry? ” then no doubt you will think with him that it is better to let other nations have alk the bother and expense of trying to advance; after all, we are jolly fine fellows and can soon pick up. If, on the other hand, you have imagination which gives you a nasty queasy sensation when you think of what might be, then perhaps the following notes, albeit disjointed and mostly stale, may at least conjure up in you thoughts of your own on the subject. This is all that is needed to help, our advancement in the air–the stimulation of spoken and written thoughts by the British nation, for if every taxpayer in the British Empire says “ Air Force,” then the Press and Parliament will say it too.

Localization of Spontaneous Respiratory Neuronal Activities in the Medulla Oblongata of the Cat: A New Location of the Expiratory Center

1957 ◽  
Vol 190 (2) ◽  
pp. 350-355 ◽  
Author(s):  
Edgar Haber ◽  
Kurt W. Kohn ◽  
S. H. Ngai ◽  
D. A. Holaday ◽  
S. C. Wang
Keyword(s):  
Vagus Nerve ◽  
Reticular Formation ◽  
Medulla Oblongata ◽  
Electric Stimulation ◽  
The Other ◽  
Drug Induced ◽  
Other Hand ◽  
Twin Beam ◽  
New Location ◽  
Stimulation Of

Medulla oblongata of 80 vagotomized cats was explored with microelectrodes. Spontaneous respiratory neuronal activities and chest movements were recorded simultaneously with a twin beam cathode ray oscilloscope. It was found that inspiratory discharges are concentrated in the reticular formation between 3 mm rostral and 1 mm caudal to the level of the obex, which corresponds approximately to the inspiratory region of Pitts, Magoun and Ranson. On the other hand, expiratory discharges are not obtained in Pitts' expiratory area, but are found in a circumscribed region in the reticular formation from the level of the obex to 3 mm caudally. Electric stimulation of this region has been found recently by Ngai and Wang to yield marked expiratory spasm. It is concluded that the expiratory center is located caudally to the inspiratory center in the cat. The spontaneous respiratory neuronal discharges continue with no alterations of pattern of firing during drug-induced respiratory paralysis, and are increased both in number and in frequency during CO2 inhalation. Stimulation of the vagus nerve with 50 shocks/sec. reduces inspiratory discharges and prolongs the duration of expiratory discharges.

Saccadic eye movements evoked by microstimulation of the fastigial nucleus of macaque monkeys

1988 ◽  
Vol 60 (3) ◽  
pp. 1036-1052 ◽  
Author(s):  
H. Noda ◽  
S. Murakami ◽  
J. Yamada ◽  
J. Tamada ◽  
Y. Tamaki ◽  
...  
Keyword(s):  
Eye Movements ◽  
White Matter ◽  
Purkinje Cells ◽  
Saccadic Eye Movements ◽  
The Other ◽  
Fastigial Nucleus ◽  
Threshold Region ◽  
Other Hand ◽  
Low Threshold ◽  
Stimulation Of

1. Systematic exploration throughout the deep cerebellar nuclei and white matter disclosed that the region from which saccadic eye movements (saccades) were evoked with weak currents (less than 10 microA) was confined to the fastigial nucleus and the adjacent white matter. 2. When an electrode for stimulation was advanced in the cerebellum, saccades were evoked in the direction of the stimulated side (ipsilateral saccades) as it entered the low-threshold region. In some tracks, particularly when the electrode was advanced in the medial portion of the fastigial nucleus, the direction of the evoked saccades changed from the ipsilateral to the contralateral. 3. The mappings with microstimulation disclosed that the ipsilateral saccades were elicited from a relatively wide region that included almost the full extent of the fastigial nucleus. The low-threshold region continued in the white matter caudally into vermal lobule VII and rostrally into the dorsal aspect of the brachium conjunctivum. On the other hand, the contralateral saccades were evoked from a relatively circumscribed region in the ventromedial portion of the fastigial nucleus. 4. The reversal in the direction of the horizontal component occurred always in a narrow zone in the core of the fastigial nucleus. The caudal part of this zone coincided with an ellipsoidal region where anterogradely labeled axons of the Purkinje cells terminated when HRP was injected into vermal lobule VII. 5. When bicuculline (0.2-1 microgram) was injected in the ellipsoidal region, the ipsilateral saccades evoked from the dorsocaudal aspect of the region were suppressed for several hours. On the other hand, the contralateral saccades evoked from the ventromedial portion of the fastigial nucleus were either unchanged or enhanced. 6. Because the ipsilateral saccades were suppressed by bicuculline, they were most probably evoked by stimulation of the presynaptic component of gamma-amino-butyric acid-(GABA) mediated synapses, namely the axons of Purkinje cells. 7. Because stimulation of the presynaptic component of the inhibitory synapses evoked ipsilateral saccades, activation of the postsynaptic component would evoke contralateral saccades. In fact, the distribution of the fastigial sites yielding contralateral saccades coincided with the course of axons of fastigial neurons arising in the ellipsoidal region. It is most likely, therefore, that the contralateral saccades were evoked by stimulation of fastigial neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

CORTICOID PRODUCTION IN VITRO AS A TEST OF ADRENOCORTICAL FUNCTION IN RATS

1960 ◽  
Vol XXXIII (I) ◽  
pp. 59-66 ◽  
Author(s):  
J. van der Vies
Keyword(s):  
Adrenal Cortex ◽  
Adrenal Function ◽  
The Other ◽  
Adrenocortical Function ◽  
Experimental Conditions ◽  
Adrenal System ◽  
Other Hand ◽  
Stimulation Of

ABSTRACT Adrenal function in rats under various experimental conditions was studied by incubating the adrenals in vitro and determining the corticosteroid output during one hour. This in vitro corticoid production was reduced after hypophysectomy, hypothalamus-lesioning and treatment with hydrocortisone or with Nembutal and morphine. On the other hand, an increased production was observed following stimulation of the pituitary-adrenal system by exogenous histamine or corticotrophin. From these experiments it is concluded that the corticoid production in vitro reflects the activity of the adrenal cortex in vivo and hence can be used for the study of the latter function.

A Report of Further Impedance Studies of the Acoustic Reflex

1967 ◽  
Vol 10 (3) ◽  
pp. 616-622 ◽  
Author(s):  
Alan S. Feldman
Keyword(s):  
Muscle Contraction ◽  
Middle Ear ◽  
Surgical Intervention ◽  
Acoustic Stimulation ◽  
Bell’S Palsy ◽  
The Other ◽  
Acoustic Reflex ◽  
Stapedius Muscle ◽  
Other Hand ◽  
Stimulation Of

The result of acoustic stimulation of the middle ear muscles was studied using subjects in whom one or the other muscle contraction was known to be ineffective. Otosclerosis presented a condition of an intact pair of muscles but a stapes unresponsive to the contraction of the stapedius muscle. Bell’s Palsy represented a condition of a paralyzed stapedius muscle but an otherwise normal middle ear system. Through surgical intervention the ears of otosclerotic patients were altered by sectioning of the stapedius muscle and insertion of a prosthesis, while in other patients an exploratory tympanotomy verified that the middle ear was without pathology and then one or the other of the middle ear muscles was sectioned. All except one of these instances would eliminate the response of the stapedius muscle only, while the other would only eliminate the tensor tympani response. In each instance of restriction of response of the stapedius muscle the acoustic reflex could not be elicited. On the other hand, when the remainder of the system was intact and only the tensor tympani sectioned, the acoustic reflex appeared normal. These observations would strongly support the contention that the tensor tympani is not responsive to acoustic stimulation.

scholarly journals DRUG ACTION IN GALVANOTROPIC RESPONSES

1928 ◽  
Vol 11 (5) ◽  
pp. 507-513 ◽  
Author(s):  
E. F. B. Fries
Keyword(s):  
Reciprocal Inhibition ◽  
Drug Action ◽  
The Other ◽  
Other Hand ◽  
Abnormal Posture ◽  
Central Synapses ◽  
Longitudinal Muscles

Under strychninization involving reversal of reciprocal inhibition of the circular and longitudinal muscles, planarians and earthworms show reversed, i.e., anodal, galvanotropic responses, which neither nicotine nor atropine induce (in planarians). The results strengthen the conclusion (Crozier, 1926–27) that in causing reversal of inhibition strychnine acts primarily on central synapses or on homologous elements. Like other arthropods, on the other hand, Asellus is little affected by strychnine; no reversal occurs. Caffeine and atropine are even less effective. Nicotine evokes abnormal posture and movements, perhaps reversed, but no alteration of anodal galvanotropism.

scholarly journals Modulation ofβ-Cell Ouabain-SensitiveR86b+Influx (Na+/k+Pump) by D-Glucose, Glibenclamide or Diazoxide

2000 ◽  
Vol 1 (4) ◽  
pp. 265-274 ◽  
Author(s):  
Adrian Elmi ◽  
Lars-ÅKe Idahl ◽  
Janove Sehlin
Keyword(s):  
Atpase Activity ◽  
Direct Effect ◽  
Mechanism Of Action ◽  
The Other ◽  
Pump Function ◽  
Other Hand ◽  
Insulin Secretagogues ◽  
Pre Treatment ◽  
Effect Of Glucose ◽  
Stimulation Of

The activity of theβ-cellNa+/k+pump was studied by using ouabain-sensitive (lmM ouabain)R86b+influx inβ-cell-rich islets of Umeå-ob/obmice as an indicator of the pump function. The present results show that the stimulatory effect of glucose on ouabain-sensitiveR86b+influx reached its approximate maximum at 5mM glucose. Pre-treatment of the islets with 20mM glucose for 60 min strongly reduced the glucose-induced stimulation of theNa+/k+pump. Pre-treatment (60 or 180 min) of islets at 0mM glucose, on the other hand, did not affect the magnitude of the glucose-induced stimulation ofR86b+influx dunng the subsequent 5-min incubation. Glibenclamide stimulated the ouabain-sensitiveR86b+uptake in the same manner as glucose. The stimulatory effect, showed its apparent maximum at 0.5μM. Pre-treatment (60 min) of islets with 1μM glibenclamide did not reduce the subsequent stimulation of the ouabain-sensitiveR86b+influx. The stimulatory effect of glibenclamide and D-glucose were not .additive, suggesting that they may have the same mechanism of action. No direct effect of glibenclamide (0.01-1μM) was observed on theNa+/k+ATPase activity in homogenates of islets. Diazoxide (0.4mM) inhibited theNa+/k+pump. This effect was sustained even after 60 min of pre-treatment of islets with 0.4mM diazoxide. The stimulatory effect of glibenclamide and D-glucose were abolished by diazoxide. It is concluded that nutrient as well as non-nutrient insulin secretagogues activate theNa+/k+pump, probably as part of the membrane repolarisation process.

Two forms of inhibition of spinothalamic tract neurons produced by stimulation of the periaqueductal gray and the cerebral cortex

1991 ◽  
Vol 65 (6) ◽  
pp. 1567-1579 ◽  
Author(s):  
D. X. Zhang ◽  
C. M. Owens ◽  
W. D. Willis
Keyword(s):  
Cerebral Cortex ◽  
Sural Nerve ◽  
Background Activity ◽  
Periaqueductal Gray ◽  
Afferent Input ◽  
The Other ◽  
Inhibitory Effects ◽  
Spinothalamic Tract ◽  
Other Hand ◽  
Stimulation Of

1. Recordings were made from the lumbosacral spinal cord in anesthetized macaque monkeys. The inhibitory effects of electrical stimulation of the periaqueductal gray (PAG) and the cerebral cortex or cerebral peduncle (CP) were tested and compared by recording 1) cord dorsum potentials evoked by stimulation of the sural nerve, 2) discharges recorded extracellularly, and 3) membrane potentials recorded intracellularly from spinothalamic tract (STT) neurons at rest (background activity) or in response to stimulation of the sural nerve. 2. Stimulation of the cortex or in the CP preferentially reduced the amplitude of the N1 and N2 waves of the cord dorsum potential evoked by stimulation of the sural nerve, without affecting the N3 wave. Stimulation of the PAG, on the other hand, reduced the amplitude of the N3 wave with little effect on the N1 and N2 waves. 3. The activity of 62 STT neurons was recorded extracellularly. Stimulation of the PAG or the cortex/CP inhibited nonpreferentially the responses of the neurons in the superficial laminae to all afferent inputs. On the other hand, stimulation of the PAG or the cortex/CP inhibited preferentially the responses of most STT neurons in deep layers of the dorsal horn to the small or large afferent input, respectively. 4. Thirty-five neurons were recorded intracellularly. The membrane potential of the neurons averaged -45.5 +/- 10.1 (SD) mV. All neurons were recorded in laminae III-VI; the neurons were of the wide-dynamic-range (WDR) type and had background activity. 5. The inhibitory effects of stimulation of the PAG were tested on all 35 neurons. In 32 of the neurons, stimulation of the PAG evoked a hyperpolarization. The background activity of the neurons was reduced (generally it completely ceased) by the hyperpolarization. In three neurons stimulation of the PAG did not evoke a hyperpolarization and the background activity of the neurons did not change. Nevertheless, the responses of these three neurons to afferent input were inhibited by stimulation in the PAG. 6. The inhibitory effects of stimulating the cortex and/or the CP were tested in 26 of the 35 neurons. Stimulation of the cortex and/or the CP evoked a hyperpolarization in all the neurons, although, in 10 of the 26 neurons, stimulation of the CP also evoked a depolarization. The hyperpolarization generally blocked the background activity of the neurons. 7. The effective stimuli in the PAG and the cortex/CP to evoke a hyperpolarization in STT neurons were short, high-frequency trains of pulses.(ABSTRACT TRUNCATED AT 400 WORDS)

Ongoing and Stimulus-Evoked Activity of Sympathetically Correlated Neurons in the Intermediate Zone and Dorsal Horn of Acutely Spinalized Rats

2000 ◽  
Vol 83 (5) ◽  
pp. 2699-2707 ◽  
Author(s):  
David Chau ◽  
Devin G. Johns ◽  
Lawrence P. Schramm
Keyword(s):  
Dorsal Horn ◽  
Intermediate Zone ◽  
The Other ◽  
Noxious Stimulation ◽  
Renal Sympathetic Nerve Activity ◽  
Other Hand ◽  
Evoked Activity ◽  
Processing Properties ◽  
Injured Patients ◽  
Stimulation Of

We have shown previously that in the acutely spinalized anesthetized rat the activities of many dorsal horn interneurons (DHN) at the T10 level are correlated positively with both ongoing and stimulus-evoked renal sympathetic nerve activity (RSNA) and therefore may belong to networks generating RSNA after acute, cervical, spinal transection. In the present study, we recorded from both DHN and interneurons in the intermediate zone (IZN) of the T10spinal segment in acutely C1-transected, chloralose-anesthetized, artificially respired rats. The activities of a similar percentage of IZN and DHN were correlated positively with ongoing RSNA, but the peaks of spike-triggered averages of RSNA based on the activity of IZN were larger, relative to dummy averages, than spike-triggered averages of RSNA based on the activity of DHN. Sympathetically correlated DHN and IZN differed in their responses to noxious somatic stimuli. Most correlated DHN had relatively simple somatic fields; they were excited by noxious stimulation of the T10 and nearby dermatomes and inhibited by stimulation of more distal dermatomes. As we have shown previously, the excitatory and inhibitory fields of these neurons were very similar to fields that, respectively, excited and inhibited RSNA. On the other hand, the somatic fields of 50% of sympathetically correlated IZN were significantly more complex, indicating a difference between either the inputs or the processing properties of IZN and DHN. Sympathetically correlated IZN and DHN also differed in their responses to colorectal distension (CRD), a noxious visceral stimulus. CRD increased RSNA in 11/15 rats and increased the activity of most sympathetically correlated T10 IZN. On the other hand, CRD decreased the activity of a majority of sympathetically correlated T10 DHN. These observations suggest that the same stimulus may differentially affect separate, putative, sympathoexcitatory pathways, exciting one and inhibiting the other. Thus the magnitude and even the polarity of responses to a given stimulus may be determined by the modality and location of the stimulus, the degree to which multiple pathways are affected by the stimulus, and the ongoing activity of presympathetic neurons, at multiple rostrocaudal levels, before stimulation. A multipathway system may explain the variability in autonomic responses to visceral and somatic stimuli exhibited in spinally injured patients.

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