Relationship between EPSP shape and cross-correlation profile explored by computer simulation for studies on human motoneurons

Ashby, Peter; Zilm, Duane H.

doi:10.1007/bf00235883

Cited by 99 publications

(56 citation statements)

References 18 publications

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“…2E-H) following a stimulation of the posterior tibial nerve (0 7 x motor threshold (MT)), when the units were activated either during isolated plantarflexion ( Fig. 2A (Ashby & Zilm, 1982), it was ensured that the investigated units fired regularly and that the mean interspike intervals and their standard deviation were the same in the two situations. Furthermore, the number of counts within the window of analysis was the same in the two situations.…”

Section: Resultsmentioning

confidence: 99%

The regulation of presynaptic inhibition during co‐contraction of antagonistic muscles in man.

Nielsen¹,

Kagamihara²

1993

The Journal of Physiology

215

144

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SUMMARY1. The size of the soleus, tibialis anterior and medial gastrocnemius H reflexes were measured at different levels of EMG activity in ankle plantar-and dorsiflexors. At similar levels of EMG activity in the agonist muscle, the soleus and tibialis anterior H reflexes were found to be smaller during co-contraction than during an isolated agonist contraction. In contrast to this, the medial gastrocnemius H reflex had the same size during co-contraction as during an isolated plantarflexion at comparable EMG levels.2. Peaks occurred at monosynaptic reflex latency in the post-stimulus time histogram (PSTH) of firing of soleus and tibialis anterior motor units following stimulation of their respective motor nerves. These homonymous Ia peaks were found to be smaller during co-contraction than during isolated agonist contraction, whereas that of medial gastrocnemius motor units was unchanged. As the monosynaptic peak in the PSTH may give an indirect measure of the size of the monosynaptic EPSP in the motoneurone, it is suggested that these findings reflect a differential control of presynaptic inhibition of soleus and tibialis anterior motor units with respect to medial gastrocnemius motor units.3. The monosynaptic Ia facilitation of the soleus H reflex evoked by a stimulation of the femoral nerve, was also found to be smaller during cocontraction of tibialis anterior and soleus than during isolated plantarflexion. This suggests that presynaptic inhibition of heteronymous I a fibres from the quadriceps muscle projecting to soleus motoneurones is regulated in the same way as presynaptic inhibition of homonymous I a fibres during co-contraction.4. The femoral nerve-induced monosynaptic facilitation of the soleus H reflex was found to decrease with increasing tonic levels of both co-contraction and isolated dorsi-and plantarflexion. The amount of facilitation decreased to the same degree with increasing levels of dorsiflexion and co-contraction. For the same level of EMG in the dorsiflexors there was thus no difference in the amount of facilitation whether the dorsiflexors were activated separately or in a co-contraction.

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Section: Resultsmentioning

confidence: 99%

The regulation of presynaptic inhibition during co‐contraction of antagonistic muscles in man.

Nielsen¹,

Kagamihara²

1993

The Journal of Physiology

215

144

View full text Add to dashboard Cite

show abstract

“…The second-order product density at lag , ,isdefined as (4) which may be interpreted as shown in (5) at bottom of page. The second-order product densities and are defined as in (4) by making the appropriate changes in the subscripts.…”

Section: Synchronization Indices Defined As Point Process Parametersmentioning

confidence: 99%

“…This can be defined and estimated as (18) The synchronization index referred to as the "common input synchronization" or was introduced in [35]. This index is also based on the cross-correlation histogram, and in addition, depends on a model for a rhythmically discharging motoneurone [4], [5]. In its final form is estimated by where is the number of counts in the cross-correlation histogram peak exceeding those expected by chance alone, and is the duration of the record in seconds.…”

Section: Synchronization Indices Defined As Point Process Parametersmentioning

confidence: 99%

Neural Spike Train Synchronization Indices: Definitions, Interpretations, and Applications

Halliday

Rosenberg

Breeze

et al. 2006

IEEE Trans. Biomed. Eng.

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Article:Halliday, D.M. orcid.org/0000-0001-9957-0983, Rosenberg, J.R., Breeze, P. et ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Abstract-A comparison of previously defined spike train syncrhonization indices is undertaken within a stochastic point process framework. The second-order cumulant density (covariance density) is shown to be common to all the indices. Simulation studies were used to investigate the sampling variability of a single index based on the second-order cumulant. The simulations used a paired motoneurone model and a paired regular spiking cortical neurone model. The sampling variability of spike trains generated under identical conditions from the paired motoneurone model varied from 50% to 160% of the estimated value. On theoretical grounds, and on the basis of simulated data a rate dependence is present in all synchronization indices. The application of coherence and pooled coherence estimates to the issue of synchronization indices is considered. This alternative frequency domain approach allows an arbitrary number of spike train pairs to be evaluated for statistically significant differences, and combined into a single population measure. The pooled coherence framework allows pooled time domain measures to be derived, application of this to the simulated data is illustrated. Data from the cortical neurone model is generated over a wide range of firing rates (1-250 spikes/s). The pooled coherence framework correctly characterizes the sampling variability as not significant over this wide operating range. The broader applicability of this approach to multielectrode array data is briefly discussed.

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“…A different approach to the estimation of postsynaptic potentials was based on a simple computer model of the membrane potential of a tonically-active motor neuron (Ashby & Zilm 1982). In this model, the membrane potential approaches the firing threshold of the motor neuron with a linear trajectory during the interspike interval.…”

Section: Estimation Of Post-synaptic Potentials In Human Motor Neuronsmentioning

confidence: 99%

The Control of Human Motor Units

Miles

1994

Clin Exp Pharma Physio

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SUMMARY1. The motor unit, consisting of a single motor neuron and the skeletal muscle fibres that it innervates, is the final output pathway of the motor system. 2.Much is now known about the way that human motor neurons are recruited and controlled during voluntary and reflex movements. This review briefly summarizes some of the recent experimental data that has contributed to our present understanding. The review is largely limited to data obtained in human experiments. While much of what we know about the organization of the nervous system has come from studies of the anatomy and physiology of experimental animals, there are some questions that cannot be addressed in reduced animal preparations. The development of new techniques has made it possible to investigate the human nervous system at a level of detail that has not hitherto been possible. Key words: motoneuron, motor neuron, motor unit, reflex.The human neuromuscular system can play the piano, run, walk, smile, speak, wheel a barrow and ride a bike. Moreover, it can do these things with a minimum of voluntary intervention. The purpose of this review is to give an overview of some of the mechanisms that enable these remarkable motor feats to be achieved. This review will concentrate particularly on evidence from human subjects, and on the information that has been obtained by recordings from single motor units.The first point is the most obvious, but bears restating. That is, that the skeletal muscles are essentially the only means that we have to communicate with the external environment. The motor system is the final output pathway from the 1013 or so neurons that constitute the human CNS. The smallest functional component of this final output path is the

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Relationship between EPSP shape and cross-correlation profile explored by computer simulation for studies on human motoneurons

Cited by 99 publications

References 18 publications

The regulation of presynaptic inhibition during co‐contraction of antagonistic muscles in man.

The regulation of presynaptic inhibition during co‐contraction of antagonistic muscles in man.

Neural Spike Train Synchronization Indices: Definitions, Interpretations, and Applications

The Control of Human Motor Units

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