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Die Reflexfunktionen des Zentralnervensystems mit besonderer Berücksichtigung der rhythmischen Tätigkeiten beim Säugetier

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... The idea that rhythmic motor patterns are under neural control of what today is commonly referred to as central pattern generator (CPG) can be traced back to the work of Thomas Graham Brown (for historical accounts, see Stuart & Hultborn, 2008;Zupanc, 2019). While working in the laboratory of Charles Scott Sherrington at the University of Liverpool, Brown had obtained experimental evidence for the existence of a spinal cord network whose autonomous | 7 ZUPANC activity is able to generate the basic rhythm of locomotor activity (Brown, 1911(Brown, , 1914(Brown, , 1916. This idea contradicted the then prevailing model proposed by Sherrington that motor activity is solely under neural control of a chain of reflexes. ...
Article
Central pattern generators play a critical role in the neural control of rhythmic behaviors. One of their characteristic features is the ability to modulate the oscillatory output. An important yet little studied type of modulation involves the generation of oscillations that are sexually dimorphic in frequency. In the weakly electric fish Apteronotus leptorhynchus, the pacemaker nucleus serves as a central pattern generator that drives the electric organ discharge of the fish in a one‐to‐one fashion. Males discharge at higher frequencies than females — a sexual dimorphism that develops under the influence of steroid hormones. The two principal neurons that constitute the oscillatory network of the pacemaker nucleus are the pacemaker and relay cells. Whereas the number and size of the pacemaker and relay cells are sexually monomorphic, pronounced sex‐dependent differences exist in the morphology and subcellular properties of astrocytes, which form a syncytium closely associated with these neurons. In females, compared to males, the astrocytic syncytium covers a larger area surrounding the pacemaker and relay cells and exhibits higher levels of expression of connexin‐43 expression. The latter indicates a strong gap‐junction coupling of the individual cells within the syncytium. It is hypothesized that these sex‐specific differences result in an increased capacity for buffering of extracellular potassium ions, thereby lowering the potassium equilibrium potential, which, in turn, leads to a decrease in the oscillation frequency. This hypothesis has received strong support from simulations based on computational models of individual neurons and the whole neural network of the pacemaker nucleus.
Article
Einige Medusenarten besitzen breite muskelfreie Felder, welche erregbar sind und auch bei starker Verschmlerung Erregungen von einem Muskelfelde auf das andere bertragen knnen. Dadurch wird bewiesen, da die Erregungsleitung bei diesen Tieren nicht myogener Natur ist, sondern dem Nervennetz zuzuschreiben ist.Nach Anlegung einer schmalen, erregungsleitendes Gewebe enthaltenden Brcke zwischen zwei Schirmteilen tritt wie beim Herzen zunchst totaler Block auf. Tritt Wiederherstellung der Erregungsleitung ein, so ist die Leitung wie dort anfangs stark verzgert und hufig nur in einer Richtung mglich (irreziproke Leitung). Die Wiederherstellung der Erregungsleitung in der anderen Richtung kann durch hufige Wiederholung der Reizung in der durchlssigen Richtung beschleunigt werden (Bahnung). Ist die Brcke berhaupt durchgngig, so bertrgt sich die Erregung auf alle angeschlossenen Teile (Auxomerie).Wird die Subumbrella mit zunehmender Frequenz knstlich gereizt, so erhlt man hufig alle bergnge von 11-Vollrhythmus durch 11-Alternans undWenckebachsche Perioden zu 21-Vollrhythmus und weiterhin durch 21-Alternans zu 31-Rhythmen usw. Diese Effekte sind sowohl bei Reizung von Muskelfeldern, wie bei Reizung muskelfreier Felder zu erzielen. Hieraus und aus anderen Tatsachen wird geschlossen, da die Rhythmusbildung im Nervennetz zustande kommt.Werden bei diesen Versuchen die Bewegungen zweier Muskeln registriert, so zeigen sich an beiden der Zeit und Gre nach bereinstimmende Vernderungen sowohl beim Alternans wie bei den komplizierteren Perioden. Hieraus wird geschlossen, da der Alternans auf totaler, rhythmisch wechselnder Hypodynamie beruht.Aus der Feststellung, da die Reizstrke von wesentlichem Einflu auf diese Phnomene ist, wird geschlossen, da das sogenannte Allesoder-Nichts-Gesetz im hypodynamen Zustand seine Gltigkeit verliert.
Article
A cinematographic analysis of the unrestrained walking, trotting, galloping, jumping and landing movements of 11 adult cats was undertaken to provide previously unavailable information concerning the demands imposed on the nervous system for the control of low and high speed movements and the demands imposed by such natural movements on muscle performance and proprioceptive response. With due regard for the swing (F and E1) and stance (E2 and E3) phases of the step cycle of an individual limb, single frame analysis of the film permitted measurement of instantaneous angles of the lower spine, hip, knee, ankle and metatarsophalangeal joints. Appropriate lever arm measurements were also made on 50 freshly dispatched cats and 25 cadavers such that the Law of Cosines could be used to calculate instantaneous lengths of select hind limb muscles that would apply to the natural movements of adult cats of small (1.5–2.5 Kg), intermediate (2.6–3.5 Kg) and large (3.6–4.5 Kg) size. Muscle displacements were analyzed relative to maximum and minimus in situ lengths and the lengths associated with quiet standing. Use was also made of a previous electromyographic analysis of hind limb muscles during unrestrained locomotion (Engberg and Lundberg, '69). The sequential relations between the four phases of the step cycle are maintained as forward speed increases from walking ( < 2 mph) to high speed galloping ( > 16 mph). There are significant differences in the time consumed by each phase, however, with a greater reduction in the E3 phase, little reduction in the E2 and E1 phases and virtually no reduction in the F phase. When each phase is expressed as a relative percentage of the duration of the total step cycle, the greatest reduction is again in E3 with little change in the E2 phase. In contrast F and E1 phases increase in the percent of time they occur in each cycle, with the greatest increase in the F phase. For all speeds, analysis of the phase relations between movements of various sections of the hind limb revealed a remarkable unity of knee and ankle joint movement. The hip joint is largely out of phase with the knee and ankle during E1 and E2, all three joints being in phase in F and E3. The digits are essentially out of phase with the other joints except in the stance phase of the gallop. Rates and extents of muscle displacement during natural movements are greater than might be anticipated when expressed in absolute mm's and mm/sec but not when considered in relation to maximum and minimum in situ length and the length associated with quiet standing (Ls). During stepping a progressive increase in forward speed results in: (a) a greater usage of muscles at lengths between Ls and maximum in situ length; (b) for knee and ankle extensors, pronounced increase in the lengthening contraction associated with the E2 (yield) phase of step; and, (c) for both flexor and extensor muscles, an increased active phase of lengthening or near isometric contraction immediately prior to periods of active shortening. In contrast to these changes in active muscle status, the change from walking to galloping has little effect on the extent and rate of passive muscle displacements, particularly the F phase stretch of extensors. For the soleus muscle, calculations were made of the relation between changes in overall muscle length during natural movements and the length of the average muscle fiber and the tendon of insertion. These measurements revealed that the increases in fiber length when passive and decreases in length during active shortening are less than would be anticipated from the extensive liteature on extirpated fibers. In contrast, the increase in fiber length when active is greater than would be expected from the admittedly sparse literature on this subject. The results of this study are discussed largely in relation to two points of neurophysiological interest: the physiological range of muscle stretch as it pertains to the responsiveness of muscle spindles and tendon organs; and those mechanical aspects of lengthening contractions that give insight into the neural control of stepping. For exciting both spindles and tendon organs passive muscle stretch and shortening contractions are shown to be relatively ineffective and lengthening and isometric contractions particularly effective movements. It is suggested that, just as recent literature has emphasized the co-activation of efferent alpha and gamma motoneurons as a muscle becomes active, so too is there a synchronous activation of afferents, particularly the Ia and group II endings of muscle spindles and Ib endings of tendon organs. Finally the thesis is advanced that, while it has been convenient to separate E2 from E3 in the description of the stance phase of the step cycle, extensor muscles are actually undergoing a single mechanical event: an active stretch-shorten cycle for knee and ankle extensors and an active isometric-shorten cycle for hip extensors. This hypothesis has significant implications for the neural control program that regulates the stepping sequence in that it emphasizes the extent to which appropriate changes must be preprogrammed in the mechanical properties of muscles for the smooth execution of stepping.
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Thomas Graham Brown undertook seminal experiments on the neural control of locomotion between 1910 and 1915. Although elected to the Royal Society in 1927, his locomotion research was largely ignored until the 1960s when it was championed and extended by the distinguished neuroscientist, Anders Lundberg. Puzzlingly, Graham Brown's published research stopped in the 1920s and he became renowned as a mountaineer. In this article, we review his life and multifaceted career, including his active neurological service in WWI. We outline events behind the scenes during his tenure at Cardiff's Institute of Physiology in Wales, UK, including an interview with his technician, Terrence J. Surman, who worked in this institute for over half a century.
Article
Thomas Graham Brown (1882–1965) undertook experiments on the neural control of stepping in the University of Liverpool laboratory of Charles Sherrington (1857–1952) in 1910–13 and his own laboratory in 1913–15 at the University of Manchester. His results revealed the intrinsic capability of the spinal cord in the guinea pig and cat to generate a stepping output pattern whose timing did not depend upon descending or sensory inputs. This idea was then revolutionary because the prevailing viewpoint was that the stepping rhythm was generated by spinal reflexes. Sadly, Graham Brown's GBR peers gave little credence to this seminal accomplishment, except perhaps Sherrington, who waxed but largely waned on the potential significance of the work. It remained for the Swedish neuroscientist, Anders Lundberg (1920–), to rescue Graham Brown's concepts from obscurity: in seminars presented in several countries between 1957 and 1980, and in widely read articles and reviews (1965–1981). Graham Brown had proposed mutually inhibitory connections between a pair of intrinsically active flexor and extensor “half-centers” on each side of the spinal cord, with the rhythmic output modulated by sensory proprioceptive input. Lundberg, Elzbieta Jankowska (1930–), and their colleagues provided seminal, compelling evidence for spinal half-center interneuronal circuitry implicated in the control of stepping and Lundberg and Ingemar Engberg (1935–2005) made behavioral EMG observations on unrestrained cats that supported a central generation of the rhythm. Subsequently, models of the spinal pattern generators for mammalian locomotion have become progressively more complex but they mostly still include a half-center component.
Article
In this paper a model capable of predicting individual muscle forces in the right lower limb is formulated. The approach developed is a physiological hierarchical model the lowest level of which concerns itself with the data necessary to define the musculoskeletal system. These include the muscle's moment arms, lengths, and velocities. Data describing the muscle anatomy and bone structure are also included. The middle level, the muscle model, defines the force-length-velocity-activation relationship of a single muscle unit. These data, with those from the anatomical model, are used to estimate the maximum and minimum force a muscle can exert given its previous force history, current kinematics, and previous stimulation level. The stimulation needed to generate any intermediate force is also defined. At the top of the hierarchy the control model provides a singular solution of the muscle forces, within the constraints defined in the muscle and anatomical models, by stimulating the muscles. The control model selects the muscle stimuli, based on a simple neurophysiological model of pattern generators, to satisfy the measured net muscle moments about those axes for which a large range of movement exist. It is assumed that one pattern generator exists for each major degree of freedom in the lower extremity. The discussion is focused upon the limitations of the model.
Article
An examination of the literature on walking stick insects shows: sensory influences on the transition from stance to swing phase (timing influences) also influence the shape of the stance phase motor output, as far as this was tested. Therefore, the distinction between timing and shaping influences seems to be artificial in this case. The results suggest that the walking pattern generator is a relaxation oscillator.
Article
Die Haut des Goldfisches besitzt eine hohe Empfindlichkeit gegen Wasserstrmung. Nach Rckenmarkdurchschneidung in der Gegend zwischen dem 16. und dem 6. letzten Wirbel ist die Reizbarkeit dieses Hautstromsinnes im Hintertier oft hher als die des intakten Seitenliniensystems im gleichen Vordertier. Der Hautsinn wird nur durch rasche Stromste erregt; gleichmige, beliebig hoch anschwellende Stromreize bleiben unbeantwortet. (Also keine Rheotaxis mit Hilfe dieses Sinnes!)Der Rckenmarksfisch zeigt folgende Reflexe : Reizung der ventralen Partie bewirkt je nach dem Reizort Zusammenlegen der Bauchflossen, der Afterflosse, Hochzucken der Schwanzflosse. Strmungsreiz dorsal hinter der Rckenflosse erregt den Propellerreflex, eine rhythmische Schwingbewegung der Schwanzflosse, ferner den Wedelreflex, ein schnelles Hin- und Herbewegen des Hinterrandes von Rcken- und Afterflosse. Seitliche Bestrmung erregt den Rumpfschlagreflex, einen krftigen Schlag nach der gereizten Seite hin.Der Propellerreflex folgt der xkllschen Dehnungsregel, der Rumpfschlagreflex nicht. Die Frequenz des Propellerreflexes wird beeinflut von der Reizstrke.Der Rumpfschlagreflex wurde mittels einer Apparatur, die gestattet, den Stromreiz und den Reflex selbst nach Form und Gre messend zu registrieren, nher untersucht; er zeigt folgende Eigenschaften: die Strke des Reflexausschlages hngt streng von der Reizstrke ab. Nach lngerer Reizung zeigen sich (scheinbar spontane) Nachentladungen. Ermdung bleibt auf die gereizte Seite beschrnkt. Unterschwellige Reize werden summiert. Die Reizbarkeit ist dorsalwrts am grten, nimmt nach ventral und nach hinten hin allmhlich ab.Der Rumpfschlagreflex stellt eine halbe (einseitige) Lokomotionswelle dar, die vom jeweiligen Reizort nach hinten wandert. Es gelingt aber nicht, durch rhythmische oder kontinuierliche Strmungsreizung Lokomotionsbewegung zu erzielen.Bei Durchschneidung des Rckenmarks in Krpermitte oder weiter hinten bewirkt Wasserstromreiz einen einmaligen Gegenschlag; liegt der Rckenmarkquerschnitt weiter vorne, so zeigen sich kleine Rckschlge; diese werden strker, sind von kleinen rhythmischen Bewegungen gefolgt (Schnitt in der Gegend des berganges zur Medulla); weiter vorne nehmen die Rhythmen zu, der erste Gegenschlag wird kleiner ; bei Durchschneidung der Medulla in Hhe der vorderen Vaguswurzel oder weiter vorne bewirkt Reizung einer Anzahl rhythmischer Schlge; solche Tiere neigen sehr zu ausdauernden Schwimmbewegungen ; Wasserstromreiz bewirkt dann eine momentane Erhhung von Amplitude und Frequenz mit nachfolgender Herabminderung beider.Die Rhythmik der Atem-, Schwanz- und Brustflossenbewegungen ist im intakten Tier ungleichmig und die drei Bewegungen hngen nicht miteinander zusammen. In Urethannarkose werden die drei Bewegungen sehr gleichmig und fallen zusammen, indem sie alle drei streng den gleichen Takt einhalten. In diesem Narkosestadium sind die hheren Hirnzentren gelhmt, die Aufnahme peripherer Erregung auf ein Minimum reduziert.Daraus wird hypothetisch geschlossen, da sich im ganzen vorderen Bereich des Rckenmarks ein automatisch-rhythmischer (Adrian) Vorgang abspielt, der die gemeinsame Grundlage von Atem-, Brustflossen- und Schwanzbewegung darstellt; an Stelle anatomisch streng umschriebener Zentren fr diese drei Bewegungen wird ein nur physiologisch, durch die Ttigkeit der jeder der drei Bewegungen zugeordneten und sie gesondert mit Erregung versehenen Rezeptoren aufgeteiltes Gebiet mit labilen Grenzen angenommen.Diese Hypothese wird durch weitere, teils eigene, teils frhere Befunde anderer Forscher belegt.
Chapter
This critique focuses on the need for detailed kinesiological studies of locomotion in general, and phase-dependent reflexes in particular. It is further emphasised that agreement is needed on the definition of reflex reactions during stepping and that the selective activation issue should be taken into account when ascribing reflex effects to the input of a single afferent species.
Article
The analysis is attempted of the nervous mechanisms underlying certain innate behaviour patterns of young kittens. The rhythmical sideways swinging movement of the head, searching for the teat, is shown to be dependent upon an endogenous automatism. As long as the kitten is awake, the movement is performed continuously. It is stopped, however, by sleep and by the sign-stimuli emanating from the areola mammilae. The stimulation of the innate realising mechanism here effects the blocking of an instinctive activity, instead of removing the block as in most other known cases. In a state when the internuntial neurons are inhibited by myanesin, there is no appreciable influence upon this movement.
Chapter
Im Ablauf der menschlichen Selbstbewegung kann eine stehende Haltung entweder eine Endphase oder einen Ausgangspunkt darstellen, das Resultat einer Handlung : erreichtes Ziel beim Aufstehen oder Anhalten, oder eine Ausgangslage als erste Phase einer neuen Tätigkeit. Doch in beiden Fällen zeigt sich das Stehen von der beendeten oder zu beginnenden Handlung abhängig.
Chapter
Eine Darstellung der Tätigkeit des Nervensystems muß von den physiologischen und anatomischen Tatsachen und Gesetzmäßigkeiten ausgehen, die am besten gesichert sind. Theorien und Hypothesen sind dabei nicht ganz zu entbehren, aber reine Spekulationen ohne experimentelle Grundlage können unberücksichtigt bleiben.
Chapter
Die Bezeichnung Tetanie wurde von L. Corvisart für ein damals immer häufiger zur Beobachtung gelangendes Krankheitsbild geprägt, das durch das Auftreten folgender Erscheinungen gekennzeichnet war: Im allgemeinen gesunde, zumeist jugendliche Personen wurden nach uncharakteristischen Prodromen von Kribbeln und späterem Taubheitsgefühl in den Händen befallen, das alsbald in eine zunehmende Steifigkeit der Finger und schließlich in einen ausgeprägten, mehr oder minder schmerzhaftem Krampfzustand überging, in dem die Finger gestreckt und unter Einziehung des Daumens konusförmig zusammengezogen wurden. Dieser Krampf griff im weiteren Verlaufe auch auf die Arme, die Brust und die Beine über, wobei die Arme in den Ellbogen abgewinkelt und an den Rumpf gepreßt, die Beine hingegen gestreckt und die Füße nach innen gedreht wurden und die Kranken so allmählich in einen recht qualvollen Zustand gerieten, in dem das Bewußtsein eigenartigerweise fast immer ungetrübt blieb. Nach kürzerem oder längerem Bestehen verschwanden diese Krampferscheinungen stets in der umgekehrten Reihenfolge ihres Auftretens, stellten sich jedoch nach einer kürzeren oder längeren Pause eines Tages in der gleichen Weise wieder ein, weshalb das Leiden auch als „intermittierender Tetanus“ bezeichnet worden war Dance). Im Intervall zwischen diesen Attacken waren die Betroffenen mehr oder weniger beschwerdefrei, keinesfalls jedoch augenscheinlich krank.
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Neural mechanisms that integrate posture with movement are widespread throughout the central nervous system (CNS), and they are recruited in patterns that are both task- and context-dependent. Scientists from several countries who were born in the 19th century provided essential groundwork for these modern-day concepts. Here, the focus is on three of this group with each selected for a somewhat different reason. Charles Sherrington (1857-1952) had innumerable contributions that were certainly needed in the subsequent study of posture and movement: inhibition as an active coordinative mechanism, the functional anatomy of spinal cord-muscle connectivity, and helping set the stage for modern work on the sensorimotor cortex and the corticospinal tract. Sadly, however, by not championing the work of his trainee and collaborator, Thomas Graham Brown (1882-1965), he delayed progress on two key motor control mechanisms: central programming and pattern generation. Walter Hess (1881-1973), a self-taught experimentalist, is now best known for his work on CNS coordination of autonomic (visceral) and emotional behavior. His contributions to posture and movement, however, were also far-reaching: the coordination of eye movements and integration of goal-directed and "framework" (anticipatory set) motor behavior. Nikolai Bernstein (1896-1966), the quintessence of an interdisciplinary, self-taught movement neuroscientist, made far-reaching contributions that were barely recognized by Western workers prior to the 1960s. Today, he is widely praised for showing that the CNS's hierarchy of control mechanisms for posture and movement is organized hand-in-hand with distributed and parallel processing, with all three subject to evolutionary pressures. He also made important observations, like those of several previous workers, on the goal focus of voluntary movements. The contributions of Sherrington, Hess, and Bernstein are enduring. They prompt thought on the philosophical axioms that appear to have driven their research, and the continual need for emphasis on interdisciplinary, comparative, and transnational approaches to advance movement neuroscience.
The available evidence from phase contrast, polarization optical, and electron microscopic studies on vertebrate skeletal muscle, insect skeletal muscle, and dipteran flight muscle is interpreted as favoring the following general structure of striated muscle. A continuous array of filaments (actin) runs through all bands of the sarcomere. These are linked by an axially periodic system of transverse filamentous bridges. Myosin (and probably other substances) are localized in the A bands. The system of transverse bridges compensates the birefringence of actin and is thus responsible for the isotropy of the I band. Myosin is responsible for the birefringence of the A bands. On strong contraction, A band material migrates to the Z bands to form contraction bands. It is not yet certain whether this migration involves myosin or another A band component.
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This paper is in continuation of one brought before the Society in 1892, and published in ‘Phil. Trans.,’ B, vol. 184. In that communication the peripheral distribution of the sensory nerve-roots of the sacro-lumbar and the thoracic regions was examined. In the present the examination is extended to the cervical and brachial sensory roots, and to the skin distribution of the cranial nerves.
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After an introduction, in which the author sets forth the present state of knowledge with reference to the electromotive properties of the electrical organ of Torpedo, he gives an account of his own experimental investigations in three sections.
Article
The method of investigation employed by the author is as follows:— The heart with the vagus nerve intact having been removed from the body together with a portion of the oesophagus, a thread is tied to the very apex of the ventricle and another to the loose flap which is dis­closed at the junction of the two auricles when the two aortic trunks are cut away. The piece of the oesophagus removed with the heart is held firmly in a suitable holder and the heart suspended between two horizontal levers by means of the two threads which are attached to the auricles and ventricle. Between the two levers a clamp is placed, the edges of which can be approximated to any degree by means of a fine micrometer screw j the two limbs of this clamp are placed one on each side of the suspended heart, and by means of the micrometer screw, the tissue between the two edges can be simply held firm or compressed to any extent required. In this way, with the clamp in the auriculo-ven­tricular groove, the beats of both auricles and ventricle are registered simultaneously and separately; the contractions of the auricles pull the upper lever downwards, those of the ventricle the lower lever upwards. Similarly by varying the position of the clamp the con­tractions of any two adjacent portions of the heart can be studied, as for example, sinus and 'auricles, base and apex of the ventricle, &c.; heat, cold, and poisons can be applied to the tissue on the one side of the clamp and not on the other; and under all these various condi­tions the effects of stimulation of the vagus can be observed.
Article
In the present memoir the author details the results of further observations as to the electromotive properties of the electrical organ of Torpedo, the experiments being carried out in October, 1887, at the laboratory of the Société Scientifique d'Arcachon. I. The first part of the work deals entirely with the phenomena of “irreciprocal conduction” in the organ of Torpedo, as described by du Bois-Reymond. From du Bois-Reymond’s experiments it would appear that the organ possesses the remarkable property of conducting an intense current of short duration, led lengthwise through its columns, better when the current is directed from its ventral to its dorsal surface than when directed the reverse way.
The following paper contains an account of observations upon Rana temporaria, Bufo vulgaris, Triton tœniatus, Triton cristatus,and Coluber natrix . In these animals I have examined the structure of the resting stomach and noted the alterations which occur in it during secretion. I have also estimated the relative amounts of pepsin contained by different portions of the stomach, and the amount of pepsin contained by a definite weight of the gastric mucous membrane in the resting and in the active state. I have further attempted to ascertain whether pepsin exists as such, or in a combined form, in the gland-cells. I do not propose to give a complete account of the structure of the resting stomach in each animal, although certain points in which my observations differ from or extend those of previous observers I may have to treat somewhat fully.
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In the spring of the year 1895, Dr. II. O. Forbes, the Director of the Corporation Museum at Liverpool, obtained several living specimens of Malapterurus electricus , which were brought from the mouth of the river Senegal by Mr. A. Ridyard (s.s. “Niger”), and through the liberality of the Museum Committee four of these were placed at our disposal. The fish remained in excellent health for a period of over six months; they were kept in tanks placed in a warm room at a temperature of 80° Fahrenheit and were fed with small worms or pieces of m eat; the specimens were from 5 to 6 inches long and gave powerful shocks to the hand when touched.
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Zusammenfassung Als direkte Folgen der einseitigen Labyrinthexstirpation lassen sich beim Hunde nachweisen:
Article
1. Bei normalen intakten Kaninchen mit unverletztem Grosshirn kann man den Einfluss der Kopfstellung auf den Tonus der Krpermuskulatur nachweisen. 2. Dabei kann man sowohl den Einfluss der frher geschilderten Labyrinth- wie der Halsreflexe erkennen. 3. Durch nderung der Stellung des Kopfes zum Rumpfe (Halsreflexe) lsst sich nicht nur der Tonus der Extremittenmuskeln, sondern auch der Rumpfmuskeln (besonders an der Lendenwirbelsule) beeinflussen. 4. Die Labyrinthe knnen also die Krperstellung entweder direkt beeinflussen oder indirekt, indem sie auf die Stellung des Halses einwirken.
Article
1. Die tonischen Erregungen und Hemmungen der Gliedermuskeln, welche durch nderung der Kopfstellung reflektorisch hervorgerufen werden knnen, lassen sich in deutlichster Weise auch an einem einzelnen Gliederstreckmuskel nachweisen, der von den Einflssen seiner Antagonisten befreit ist. 2) Selbst durch solche Strychnindosen, welche heftige Krmpfe hervorrufen, lassen sich die hierbei auftretenden Hemmungen nicht in Erregungen umkehren.
Article
Durch Versuche am Hinterbeine von Rückenmarkshunden wurde gezeigt, dass die in der I. Mitteilung beschriebenen Schaltungs- und Umkehrreaktionen nach Fortfall der Haut- und Gelenksensibilität noch unverändert bestehen bleiben. Bei diesen Reaktionen wurde die Richtung der Reflexbewegung, welche auf einen kontralateralen Reiz eintrat, bestimmt durch die Lage und Stellung, welche dem Gliede vor Auflösung des Reflexes gegeben war. Einerlei, ob nur die Gelenke allein, oder ob nur die Haut allein, oder beide zusammen asensibel gemacht waren, einerlei ferner, ob nur die Reaktion des für diese Schaltungen wichtigsten Gelenkes, des Hüftgelenkes, oder ob die Reaktion des ganzen Beines mit allen drei Gelenken untersucht wurde, das Resultat war stets das gleiche: die Schaltungsreaktionen blieben unverändert erhalten. Im Anfang dieser Arbeit wurde nun in einer Reihe von Versuchen an Hunden und Katzen gezeigt, dass die Schaltungsreaktionen endgültig aufgehoben werden, wenn alle sensiblen Nervenbahnen von dem betreffenden Gliede nach dem Zentralnervensystem durchgeschnitten worden sind. Daraus folgt, dass in den zuletzt geschilderten Experimenten die Schaltung im Zentralorgan bewirkt sein muss durch Vermittlung derjenigen sensiblen Bahnen, welche nach Ausschaltung der Haut und Gelenksensibilität noch von der betr. Extremität zum Rückenmark ziehen. Das können nur die afferenten Bahnen von den Muskeln (einschliesslich derer von den Sehnen und Faszien) sein. In den ersten beiden Mitteilungen wurde ferner gezeigt, dass die bisher beschriebenen Fälle von Schaltung der von v. Uexküll bei Wirbellosen aufgestellten Regel folgen, nach welcher in einem diffusen Nervensystem eine Erregung immer mit besonderer Leichtigkeit den Zentren derjenigen Muskeln zufliesst, welche sich im Zustand der grössten Dehnung befinden. Auch bei unseren bisher beschriebenen Schaltungen floss im Rückenmark die Erregung bei allen möglichen Reflexen mit besonderer Vorliebe den Zentren der gedehnten Muskeln zu. Die in der vorliegenden Arbeit beschriebenen Experimente liefern nun, soweit wenigstens der Warmblüter in Frage kommt, die Erklärung für dieses Verhalten. Es handelt sich bei den besprochenen Schaltungen eben um Reflexe, welche von den Muskeln selber ausgelöst und auf dem Wege der sensiblen Muskelnerven dem Zentralorgan übermittelt werden 1). Solange diese Bahnen funktionsfähig sind, so lange ist die Schaltung in den bisher beschriebenen Fällen möglich. Werden sie durchtrennt, so hört das geschilderte Phänomen auf.