Unexpected features of the interaction between individual primary afferents and spinal motoneurones.

Simultaneous intracellular recording from spinal motoneurone and dorsal root fibres afferent to it in the isolated amphibian cord revealed a specific correlation between the slow spontaneous depolarizing activity in motoneurones and primary afferents.     

Inhibitory interaction between spinal reflexes to primary afferents

Zusammenfassung Die Depolarisation der Ia Nervenfasern, welche durch eine Entladung in Ia Fasern eines Flexormuskelnerven reflektorisch ausgelöst werden kann, wird durch Reizung der sensorisch-motorischen Grosshirnrinde oder der Flexor-Reflex-Afferenten gehemmt.Es wird vorausgesetzt, dass der Mechanismus dieser Hemmung präsynaptisch ist, und zwar durch eine Depolarisation der Endigungen der Interneuronen, welche die Wirkung von Ia- zu Ia-Afferenten übertragen.     

Effects from the pyramidal tract on primary afferents and on spinal reflex actions to primary afferents

Zusammenfassung Es konnte gezeigt werden, dass Überleitungen in spinalen Reflexsystemen, die für die präsynaptische Depolarisation gewisser primärer Afferenzen verantwortlich sind, von der sensorisch-motorischen Grosshirnrinde über die Pyramidenbahn gefördert werden kann.     

Postsynaptic inhibition evoked from primary afferents in spinal interneurones

Résumé L'enregistrement intracellulaire de l'activité des 81 interneurons localisés dans la corne postérieure et la région intermédiare de la moëlle épinière lombaire a été effectué chez des chats spinaux. Dans 76% de ces interneurons, on a trouvé des potentiels postsynaptiques inhibiteurs (IPSP's), provoqués le plus souvent par l'activation des afférences des réflexes de flexion, mais aussi des fibres afférentes d'origine cutanée à seuil bas et du groupe I des fibres musculaires.     

The effects of passive muscle stretching on the discharge of individual phrenic motoneurones

Conclusion From the results of the present experiments the following conclusion may be drawn: since phrenic motoneurones are activated by muscle stretching, it is possible that the involved muscle receptor afferents may influence the ventilatory control in muscular excercise.

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Zusammenfassung An narkotisierten, gelähmten und mit Sauerstoff beatmeten Hunden konnte gezeigt werden, dass passive Muskeldehnung reflektorisch die Impulsfrequenz einzelner Motoneurone desN. phrenicus erhöht und zur Rekrutierung neuer Einheiten führt.

     

Polysynaptic activation of extensor motoneurones from Group Ia fibres in the cat spinal cord

Résumé Chez le chat décérébré, les réponses unitaires des neurones moteurs sont évoquées par la stimulation répétitive des Group Ia fibres des nerfs musculaires extenseurs. Il a été montré deux types des réponses par rapport à les latences et les façons des décharges.     

Integrative pattern of reflex actions by impulses in large muscle spindle afferents on motoneurones to hip muscles

Zusammenfassung Es werden die intrazellulären Potentiale an Motoneuronen von Hüftmuskeln abgeleitet. Motoneurone des HüftstreckersSemimembranosus werden von Ia-Impulsen der Hüftstrecker und Kniebeuger erregt, Motoneurone des HüftstreckersAdductor femoris dagegen von den Hüftstreckern und Kniestreckern. Motoneurone der Hüftbeuger werden von Ia-Impulsen gehemmt, nicht nur von deren Antagonisten, sondern auch vom KniestreckerVasto Cruralis.     

Corticospinal influences on primary afferents during sleep and wakefulness

Riassunto Nel sonno desincronizzato si osserva un aumento della scarica piramidale originante dalle aree somato-sensoriali della corteccia in corrispondenza dei REM. Queste scariche piramidali depolarizzano le fibre afferenti primarie della via riflessa flessoria e verosimilmente contribuiscono alla depressione fasica dei riflessi polisinaptici che si manifesta durante i REM.

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This investigation was supported by PHS research grant NB-02990-04 from the National Institute of the Neurological Diseases and Blindness, N.I.H., Public Health Service (USA).     

In vitro primary immune response resulting from the interaction between bone marrow-derived and thymus cells

Riassunto Globuli rossi di pecora inducono in vitro, in colture miste di cellule spleniche di topi timectomizzati e timociti di topi normali, una risposta immune di tipo emolitico paragonabile a quella di cellule spleniche di topi normali. I dati indicano che la risposta immune delle colture miste risulta dall'interazione dell'antigene con timociti e cellule spleniche di origine midollare.

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Supported by CNEN-Euratom Association Contract. Publication No. 512 of the Euratom Biology Division.     

Effects of monovalent cations on the responses of motoneurones to different groups of amino acid excitants in frog and rat spinal cord

Summary Classification of excitatory amino acids into different groups, of possible value for transmitter identification, can be made on the basis of the differential effects of altered external [Na⁺] and [K⁺] on motoneurone depolarization in frog and immature rat spinal cord.Acknowledgments. We thank Mr D. J. Oakes for skilled technical assistance. This work was supported from the Medical Research Council.     

Distribution of bilateral dorsal root potentials evoked by volleys in afferents entering lumbar and sacral segments of the spinal cord

Summary Ipsilateral dorsal root potentials evoked by volleys entering lumbar and sacral segments of the cord are largest at the level of entry of afferent volleys. Contralateral potentials resulting from stimulation of any of these nerves attain maximum amplitude in lower sacral and upper caudal segments.     

Distribution of bilateral dorsal root potentials evoked by volleys in afferents entering lumbar and sacral segments of the spinal cord

Ipsilateral dorsal root potentials evoked by volleys entering lumbar and sacral segments of the cord are largest at the level of entry of afferent volleys. Contralateral potentials resulting from stimulation of any of these nerves attain maximum amplitude in lower sacral and upper caudal segments.     

Functional interaction between calsequestrin and ryanodine receptor in the heart

Evidence obtained in the last two decades indicates that calsequestrin (CSQ2), as the major Ca²⁺-binding protein in the sarcoplasmic reticulum of cardiac myocytes, communicates changes in the luminal Ca²⁺ concentration to the cardiac ryanodine receptor (RYR2) channel. This review summarizes the major aspects in the interaction between CSQ2 and the RYR2 channel. The single channel properties of RYR2 channels, discussed here in the context of structural changes in CSQ2 after Ca²⁺ binding, are particularly important. We focus on five important questions concerning: (1) the method for reliable detection of CSQ2 on the reconstituted RYR2 channel complex; (2) the power of the procedure to strip CSQ2 from the RYR2 channel complex; (3) structural changes in CSQ2 upon binding of Ca²⁺ which cause CSQ2 dissociation; (4) the potential role of CSQ2-independent regulation of the RYR2 activity by luminal Ca²⁺; and (5) the vizualization of CSQ2 dissociation from the RYR2 channel complex on the single channel level. We discuss the potential sources of the conflicting experimental results which may aid detailed understanding of the CSQ2 regulatory role. Although we mainly focus on the cardiac isoform of the proteins, some aspects of more extensive work carried out on the skeletal isoform are also discussed.     

The relationship between the flexion reflex and certain ascending spinal pathways

Zusammenfassung Vier aufsteigende Rückenmarksbahnen werden bei spinalen Katzen durch somatische Afferenzen, die den Flexorreflex auslösen, beeinflusst. Genau wie beim Flexorreflex ist die Übertragung auf diese Bahnen bei dezerebrierten Katzen stark gehemmt. Die Regulierung der supraspinalen Hemmung der Bahnen und des Flexorreflexes scheint in gleicher Weise organisiert zu sein.