scholarly journals Studies on the flexor reflex.-V. General conclusions

1931 ◽  
Vol 107 (754) ◽  
pp. 597-605 ◽  
Keyword(s):  
Spinal Cord ◽  
Experimental Evidence ◽  
Experimental Work ◽  
Reflex Activity ◽  
Flexor Reflex ◽  
Afferent Nerves ◽  
The Subject ◽  
Set Up ◽  
Afferent Terminals ◽  
Antidromic Volley

The experiments described in the preceding four papers bear on various problems presented by reflex activity. Their results confirm some of the inferences already drawn elsewhere from other experimental work, and they allow certain further inferences. A brief prefatory statement of all these inferences and of the experimental evidence which allows them will advantageously introduce the description of the processes set up in the ipselateral flexor centres of the spinal cord by a single centripetal volley and by a single antidromic volley. Then, finally, discussion of the theories of reflex excitation can be undertaken in the light of the present experimental observations. the statement treats of the subject in its present phase only; the references to relevant papers are therefore restricted in the main to the more recent ones. II. Inferences from Experimental Observations. 1. The convergence of Different Afferent Paths on the same Motoneurones The following evidence shows that this occurs:- (a) Histological .-Each motoneurone receives its “ boutons terminaux ” from many individual afferent terminals (Cajal, 1903). (b) Physiological .-Centripetal volleys set up in different afferent nerves excite the same motoneurones (Camis, 1909; Cooper, Denny-Brown, and Sherrington, 1926; 1927; Sherrington, 1929; Cooper and Denny-Brown, 1929 ; Eccles and Sherrington, 1930 ; 1931, a ; 1931, b ).

scholarly journals Abnormal cutaneous flexor reflex activity during controlled isometric plantarflexion in human spinal cord injury spasticity syndrome

Spinal Cord ◽  
2016 ◽  
Vol 54 (9) ◽  
pp. 687-694 ◽  
Author(s):  
J Gómez-Soriano ◽  
E Bravo-Esteban ◽  
E Pérez-Rizo ◽  
G Ávila-Martín ◽  
I Galán-Arriero ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Reflex Activity ◽  
Flexor Reflex ◽  
Human Spinal Cord ◽  
Cord Injury

scholarly journals Studies on the flexor reflex.-IV. After-discharge

1931 ◽  
Vol 107 (754) ◽  
pp. 586-596 ◽  
Keyword(s):  
Refractory Period ◽  
Afferent Nerve ◽  
Tetanic Stimulation ◽  
Flexor Reflex ◽  
General Technique ◽  
Reflex Pathway ◽  
Neon Tube ◽  
Set Up ◽  
Reflex Discharge ◽  
Antidromic Volley

In many preparations the flexor reflex elicited by the application of a moderately strong break-shock to an ipselateral afferent nerve has an after-discharge following the initial reflex discharge, even when the strength of the break-shock it such that it sets up no more than a single centripetal volley (Sherrington, 1921, a ; 1921, b ; Adrian and Forbes, 1922). The prolonged excitatory condition which must occur at some part of the central reflex pathway clearly has some affinity to the persistence of the c. e. s. which forms the basis of facilitation (Eccles and Sherrington, 1930). It is of interest therefore to investigate the effect of an antidromic volley on after-discharge. It must, however, be remembered that an antidromic volley set up during an after-discharge will be prevented from reaching some motoneurones by meeting centrifugal (reflex) impulses. Denny-Brown (1929, p. 273) observed that an antidromic volley set up during the after-discharge of either a flexor or extensor reflex (in response to a tetanic stimulation) was followed by a period of quiescence owing to a temporary lapse of the after-discharge. The duration of this period seemed to be too long for a central refractory period set up by the antidromic volley, so he suggested that there might be a temporary exhaustion of the central exciting agent (c. e. s.). II. Method. The general technique is as described previously (Eccles and Sherrington, 1931, a ). In all cases the muscle (tibialis anticus) has been completely deafferented. Tetanic stimuli have been provided by a neon-tube oscillator.

scholarly journals On the myogram of the flexor-reflex evoked by a single break-shock

1921 ◽  
Vol 92 (643) ◽  
pp. 108-117 ◽  
Keyword(s):  
Motor Nerve ◽  
Cervical Region ◽  
Thoracic Region ◽  
Similar Stimulus ◽  
Spinal Transection ◽  
Flexor Reflex ◽  
Vibration Period ◽  
Afferent Nerves ◽  
The Subject ◽  
Deep Anaesthesia

Our object has been to compare the reflex contraction of a muscle when evoked by a single induction shock with the contraction evoked from the same muscle when a similar stimulus is applied directly to the muscle’s motor nerve. The experiments extend some observations previously reported in these Proceedings (2) and in the ' Journ. of Physiology’ (6). The literature of the subject was given in those papers and for it reference may be had to them. Method . The reflex preparation employed has been the spinal cat, the muscle being tibialis anticus. Either before or after the spinal cord had been transected the animal was decerebrated. The spinal transection and the decerebration were performed under deep anæsthesia. The spinal transection was in some cases made three to ten days prior to the decerebration. The seat of spinal transection was usually at the posterior end of the thoracic region, but sometimes at the anterior end of the cervical region. All the hind-limb muscles except tibialis anticus were immobilised by nerve section, or in the case of extensores, digitorum and peronei, tenotomy. The limb was fixed by steel drills in tibia and femur, the drills being clamped to unyielding uprights on the experimental table. The tendon of tibialis anticus was attached by a short length of waxed fishing line to an isometric myograph of the torsionwire pattern. The vibration period of this recorder was somewhat less than 0.01". The afferent nerves of the limb were severed and those used for stimulation were popliteal in the ham, musculo-cutaneous on the dorsum of the foot, and internal saphenous, femoralis, and external cutaneous below the groin.

scholarly journals Studies on the flexor reflex.-III. The central effects produced by an antidromic volley

1931 ◽  
Vol 107 (754) ◽  
pp. 557-585 ◽  
Keyword(s):  
Spinal Cord ◽  
Peripheral Nerve ◽  
Nerve Cell ◽  
Motor Nerve ◽  
Ventral Root ◽  
Nerve Fibres ◽  
Flexor Reflex ◽  
Central Effects ◽  
Reflex Arc ◽  
Antidromic Volley

In 1822 Magendie demonstrated that no reflex activities were evoked by impulses passing into the spinal cord by a ventral root. This result has been confirmed and extended by other investigators who showed that no action currents can be detected in other nerves when the central end of a cut ventral root is stimulated (Mislawski, 1895; Bernstein, 1898). Attempts have been made to account for the irreversibility of conduction in the reflex arc by postulating a “dynamical polarisation” of the nerve cell so that the conduction would be solely from dendrite to axon, never the reverse (cajal, 1891; van Gehuchten, 1900). The antidromic impulses “back-fired” into a motoneurone might, however, be blocked at the synapse (sherrington, 1900, p. 798). It seems unlikely that the conduction of nerve impulses in the cell body and dendrites of a motoneurone would differ fundamentally from the conduction in peripheral nerve fibres, e. g ., that impulses passing along the dendrites would suffer an irreciprocal decrement. In the present paper it has been assumed that antidromic impulses in motor nerve fibres are blocked at the synapses of the motoneurones.

The importance of segmental and main arteries of thorachic and abdomen aorta in collateral blood supply of the spinal cord (experimental work)

2018 ◽  
Vol 60 (3) ◽  
pp. 226-232
Author(s):  
L.A. Boсkeria ◽  
V.S. Arakelyan ◽  
A.Yu. Gorodkov ◽  
V.L. Khon ◽  
V.G. Papitashvili ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Blood Supply ◽  
Experimental Work

M. V. Nadkarni. Farmer's Movements in India. New Delhi: Allied Publishers Pvt. Ltd., 1987.237 pp.,Price: (hardbound edition) Rupees (Indian) 100.00.

1988 ◽  
Vol 27 (3) ◽  
pp. 333-335
Author(s):  
Khwaja Sarmad
Keyword(s):  
Tamil Nadu ◽  
Rural Poverty ◽  
Price Policy ◽  
New Delhi ◽  
Root Cause ◽  
The Subject ◽  
The Rich ◽  
Land Holdings ◽  
Set Up ◽  
Agricultural Price

This book is a comprehensive analysis of farmers' movements in India with a focus on the movements in Tamil Nadu, Maharashtra, Punjab and Karnatka. It examines the economic, social and political aspects of the farmers' struggle for a better deal within regional and national perspectives and evaluates the potential impact of these struggles on economic development in general, and on rural development, in particular. In a most competent way the author has presented the current state of the debate on the subject. He deals exhaustively with the subject of agricultural price policy and argues against the proposition that favourable price-setting for farm products is adequate to alleviate rural poverty. A better way to tackle this problem is to improve the per capita output in the rural sector, since the root cause of the problem is not unfavourable terms of trade but the increasing proportion of land holdings, which are economically not viable. Agricultural price policy is analyzed within the context of class relations, which enables to establish a link between the economic and political demands of the farmers. This analysis leads the author to conclude, that in contrast with the peasants' movements in India, which helped to break up the feudal agrarian set-up, the recent farmers' movements, with a few exceptions, have little revolutionary content. Their leadership has been appropriated by the rich landowners, who have transformed the movements into a lobby for advancing their own interests, within the existing power structure, to the neglect of the poorer peasantry.

HUBUNGAN ANTARA JIWA WIRAUSAHA MAHASISWA DENGAN MOTIVASI, LINGKUNGAN KELUARGA DAN PENDIDIKAN PADA POLITEKNIK LP3I JAKARTA KAMPUS BEKASI

2018 ◽  
Vol 6 (2) ◽  
pp. 14
Author(s):  
Darmawan Darmawan ◽  
Jajang Setiawan
Keyword(s):  
Key Words ◽  
Family Background ◽  
Research Result ◽  
Education Institution ◽  
Education Level ◽  
Study Program ◽  
Economic Level ◽  
The Subject ◽  
Set Up

<p align="center"><strong>ABSTRACT</strong><strong></strong></p><p align="center"><strong> </strong></p><p align="justify"><em>Today, the growth of economic level begins to rise again that is generated by the increase of   different kind of product and different kind of businesses that are offered by both individual businesses that are done easly independently. To deal with all of business trends, the education institution has to prepare the students to be able to set up a business idenpendedntly through the subject of entrepeuneurship.  As it is regulated in Vision and Mision of study program and is also regulated in the curriculum of lectures. </em><em></em></p><p align="justify"><em>This research is aimed at to find out the correlation between the spirit of entrepeunership and motivation , Family background, and education level. Based on the research result, the finding showed that the spirit of entrepeneurship correlated with the motivation and family background. Based on the finding, it was also found that education level did not correlate with that the spirit of entrepeneurship. In regard with the findings, it is important to develop more the motivation of students to touch up the sperit of entrepenuership. </em><em></em></p><p align="justify"> </p><p><em>Key words: Entrepenuer, Students, Entrepeuneurship. </em></p>

scholarly journals On Kaufmann's theory of the impact of the pianoforte hammer

1920 ◽  
Vol 97 (682) ◽  
pp. 99-110 ◽  
Keyword(s):  
Initial Conditions ◽  
Practical Importance ◽  
Prima Facie ◽  
Point Of View ◽  
Infinite Length ◽  
Modes Of Vibration ◽  
Rigorous Treatment ◽  
The Subject ◽  
Set Up ◽  
The Impact

The theory of the vibrations of the pianoforte string put forward by Kaufmann in a well-known paper has figured prominently in recent discussions on the acoustics of this instrument. It proceeds on lines radically different from those adopted by Helmholtz in his classical treatment of the subject. While recognising that the elasticity of the pianoforte hammer is not a negligible factor, Kaufmann set out to simplify the mathematical analysis by ignoring its effect altogether, and treating the hammer as a particle possessing only inertia without spring. The motion of the string following the impact of the hammer is found from the initial conditions and from the functional solutions of the equation of wave-propagation on the string. On this basis he gave a rigorous treatment of two cases: (1) a particle impinging on a stretched string of infinite length, and (2) a particle impinging on the centre of a finite string, neither of which cases is of much interest from an acoustical point of view. The case of practical importance treated by him is that in which a particle impinges on the string near one end. For this case, he gave only an approximate theory from which the duration of contact, the motion of the point struck, and the form of the vibration-curves for various points of the string could be found. There can be no doubt of the importance of Kaufmann’s work, and it naturally becomes necessary to extend and revise his theory in various directions. In several respects, the theory awaits fuller development, especially as regards the harmonic analysis of the modes of vibration set up by impact, and the detailed discussion of the influence of the elasticity of the hammer and of varying velocities of impact. Apart from these points, the question arises whether the approximate method used by Kaufmann is sufficiently accurate for practical purposes, and whether it may be regarded as applicable when, as in the pianoforte, the point struck is distant one-eighth or one-ninth of the length of the string from one end. Kaufmann’s treatment is practically based on the assumption that the part of the string between the end and the point struck remains straight as long as the hammer and string remain in contact. Primâ facie , it is clear that this assumption would introduce error when the part of the string under reference is an appreciable fraction of the whole. For the effect of the impact would obviously be to excite the vibrations of this portion of the string, which continue so long as the hammer is in contact, and would also influence the mode of vibration of the string as a whole when the hammer loses contact. A mathematical theory which is not subject to this error, and which is applicable for any position of the striking point, thus seems called for.

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