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R Schaumberg

Publications and source records attributed to R Schaumberg.

4 recordsLinked to original sources
PubMed1981

Patterns of parallel signal transmission between multiple alpha efferents and multiple Ia afferents in the cat semitendinosus muscle.

1. Certain features of signal transmission from multiple alpha-axons to multiple Ia fibres via extrafusal muscle tissue were studied by stimulating three ventral root filaments separately and simultaneously and by recording spike trains from three dorsal root filaments. 2. Post-stimulus time histograms (PSTH) revealed widely graded influences of single motor unit contractions on different muscle spindles, thus confirming results of Binder et al. (1976, 1980a). 3. In most instances, the signal transmission from a single motor unit to a single Ia fibre was disturbed to varying degrees by concomitant activity from other motor units. 4. This deterioration of signal transmission can probably be compensated for, at least in part, by correlations between discharge patterns of two or more Ia fibres induced by the "common input" of motor unit activity. 5. These correlations showed a topographical pattern such that a peak in the cross-correlogram (CCH) occurred at zero time for pairs of spindles located virtually in parallel to each other, and was shifted away from zero time as a function of the serial distance between spindles in the longitudinal muscle fibre direction. 6. Fusimotor innervation had complex effects on correlations between Ia fibre discharge patterns. It might de-correlate the latter as well as favour new correlations. 7. The possible role of topographical correlation patterns in the afferent reflex limb for tremor suppression is discussed.

Afferent Pathways↗
PubMed1981

Some methods to study information transmission through multi-channel neuronal systems.

Methods are proposed to isolate nearly simultaneous events or events with specific time relations to each other from two (or more) stimulus or spike trains. The methods can be implemented by means of a digital computer, but were implemented here with simple electronic hardware to present an alternative. The usefulness of these methods is demonstrated on data from cat experiments in which the influences of several motor units activated in parallel upon muscle spindle discharge patterns were studied by use of poststimulus time histograms (PSTHs). The contractions of one motor unit can interfere with the effects of others on muscle spindle discharges. In order to show this conditioning influence quantitatively, the integral of the PSTH is shown graphically as a function of the time interval between contractions of two motor units. These methods may help to elucidate some features of interactions between parallel neuronal channels bearing on the problem of the kind of information and how the latter is transmitted through complex multichannel systems.

Animals↗
PubMed1979

Transynaptic transport of procion yellow in the central nervous system.

Intracellular recordings were performed in slices of the lateral geniculate body, the visual cortex, and the hippocampus of guinea pigs. After recording, Procion Yellow was iontophoretically injected. During the injection period the neurones were activated antidromically and/or transynaptically. Up to 6 h after dye injection slices were fixed in a buffered formaldehyde/sucrose solution and later histologically processed. In the lateral geniculate body, after orthodromic stimulation across the optic tract, optic tract fibers were stained secondarily. Orthodromic activation across intrageniculate connections led to secondarily stained geniculate neurones. In the visual cortex orthodromic activation of the injected neurones across white matter led to secondarily stained fibres travelling in the direction to the white matter or to secondarily stained neurones in the vicinity of the injected neurone. In the hippocampus anti- and orthodromic activation across the alveus or the mossy fibre pathway led to a secondary staining of neighbouring pyramidal neurones and to a secondary staining of fibres which where afferent to the injected neurone. All slices where Procion Yellow was detected in the extracellular space were rejected. These findings led to the conclusion that Procion Yellow must have been transported across chemical synapses from the post- to the presynaptic side. The transport occurred only if the concerned synapses were activated.

Animals↗