A short‐latency crossed pathway from cutaneous afferents to rat hindlimb motoneurones.

Edgley, S A; Wallace, Nolan

doi:10.1113/jphysiol.1989.sp017584

Cited by 24 publications

(6 citation statements)

References 14 publications

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“…Contralateral FRAs activate those connected with extensor muscle Ia afferents. A similar result has been recently reported in the rat (Edgley & Wallace, 1989). However, the intensity of stimulation used in the present experiments is not likely to activate FRAs which are small diameter fibres requiring strong electrical stimulation to be recruited.…”

Section: Afferents Responsible For the Changes In Reciprocal Inhibitionsupporting

confidence: 91%

The influence of contralateral primary afferents on Ia inhibitory interneurones in humans.

Delwaide

Pépin

1991

The Journal of Physiology

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SUMMARY1. Contralateral influences on short latency reciprocal inhibition between wrist extensor and flexor muscles were investigated in twenty-two healthy volunteers. Reciprocal inhibition, probably mediated through the Ia inhibitory interneurone, was measured by conditioning the flexor carpi radialis (FCR) H reflex by weak stimulation of the ipsilateral radial nerve. Maximum reciprocal inhibition occurring at a precise delay between conditioning and conditioned stimulations was taken as the test level of inhibition.2. Contralateral median or radial nerves were stimulated at short intervals before the onset of reciprocal inhibition. The latter was increased by 8-6% after median nerve stimulation and decreased by 16-5 % after radial nerve stimulation.3. The contribution of sensory fibres in the two nerves to contralateral effects was investigated by stimulating purely sensory branches of the nerves. No clear modification of the contralateral reciprocal inhibition was observed. The effects produced by mixed nerve stimulation are thus likely to have been mediated by la fibres.4. In three hemiplegic patients where reciprocal inhibition was reduced unilaterally, stimulation on the spastic side produced contralateral effects similar to those observed in normal subjects. This result indicates that contralateral effects are not mediated through the la inhibitory interneurone ipsilateral to the conditioning stimulus.5. Since contralateral effects occur after short delays (2 ms, median nerve; 3 ms, radial nerve), we suggest a functional scheme in which the excitability of la inhibitory interneurones is modified by contralateral primary afferents via the interneurones activated by group I fibres, probably Ia fibres. The short delays indicate that the interneurone transmitting primary afferent influences to the contralateral side is probably excitatory.

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Section: Afferents Responsible For the Changes In Reciprocal Inhibitionsupporting

confidence: 91%

The influence of contralateral primary afferents on Ia inhibitory interneurones in humans.

Delwaide

Pépin

1991

The Journal of Physiology

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“…Convergence of input from the central pattern generator for locomotion and from sensory afferents produces reflex modulations in lower vertebrates (Sillar & Roberts, 1988, 1992. Convergence of this type has also been reported in cats (Edgley & Wallace, 1989;Shefchyk, McCrea, Kriellaars, Fortier & Jordan, 1990). Whatever the mechanisms for generating the reversal, the results reported here indicate that the control must be very specific.…”

Section: Methodological Considerationssupporting

confidence: 66%

Mechanism for reflex reversal during walking in human tibialis anterior muscle revealed by single motor unit recording.

Serres

Yang

Patrick

1995

The Journal of Physiology

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1. A reversal in the sign of a cutaneous reflex during walking was recently described in the human. Such reversals were most clearly seen in muscles that were active in two parts of the step cycle, such as the tibialis anterior (TA). The current study determined whether the reversal resulted from differential activation of a single group of motor units. 2. Single motor units were recorded from the TA muscle of healthy human subjects while they walked on a treadmill with a splint that limited motion at the ankle joint. The majority of motor units from which recordings were made (43 out of 46) were active in both the swing phase and the transition from swing to stance, indicating that the two bursts of activity from the TA muscle do not represent the activity of two separate populations of motor units.3. The firing behaviour of three motor units was observed during walking steps when stimuli were applied to the posterior tibial nerve during either the swing phase or the transition from swing to stance. The post-stimulus time histograms indicated that the same motor unit was excited during the swing phase, and inhibited during the transition from swing to stance.4. The results support the hypothesis that there are parallel excitatory and inhibitory pathways from cutaneous afferents to single motoneurones of the TA muscle. A shift in balance between the two pathways as a function of the step cycle most probably generates the reflex reversal observed.

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“…5A, E ), an area containing various groups of commissural interneurons [50] , [51] some of which have been shown to project monosynaptically to contralateral motoneurons in the rodent spinal cord [22] , [51] . Traditionally, these neurons have been implicated in mediation of crossed reflexes in the cat [52] , [53] but also in the selection of different motor patterns [50] , [51] .…”

Section: Discussionmentioning

confidence: 99%

The Use of PRV-Bartha to Define Premotor Inputs to Lumbar Motoneurons in the Neonatal Spinal Cord of the Mouse

2010

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BackgroundThe neonatal mouse has become a model system for studying the locomotor function of the lumbar spinal cord. However, information about the synaptic connectivity within the governing neural network remains scarce. A neurotropic pseudorabies virus (PRV) Bartha has been used to map neuronal connectivity in other parts of the nervous system, due to its ability to travel trans-neuronally. Its use in spinal circuits regulating locomotion has been limited and no study has defined the time course of labelling for neurons known to project monosynaptically to motoneurons.Methodology/Principal FindingsHere we investigated the ability of PRV Bartha, expressing green and/or red fluorescence, to label spinal neurons projecting monosynaptically to motoneurons of two principal hindlimb muscles, the tibialis anterior (TA) and gastrocnemius (GC). As revealed by combined immunocytochemistry and confocal microscopy, 24–32 h after the viral muscle injection the label was restricted to the motoneuron pool while at 32–40 h the fluorescence was seen in interneurons throughout the medial and lateral ventral grey matter. Two classes of ipsilateral interneurons known to project monosynaptically to motoneurons (Renshaw cells and cells of origin of C-terminals) were consistently labeled at 40 h post-injection but also a group in the ventral grey matter contralaterally. Our results suggest that the labeling of last order interneurons occurred 8–12 h after motoneuron labeling and we presume this is the time taken by the virus to cross one synapse, to travel retrogradely and to replicate in the labeled cells.Conclusions/SignificanceThe study establishes the time window for virally - labelling monosynaptic projections to lumbar motoneurons following viral injection into hindlimb muscles. Moreover, it provides a good foundation for intracellular targeting of the labeled neurons in future physiological studies and better understanding the functional organization of the lumbar neural networks.

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A short‐latency crossed pathway from cutaneous afferents to rat hindlimb motoneurones.

Cited by 24 publications

References 14 publications

The influence of contralateral primary afferents on Ia inhibitory interneurones in humans.

The influence of contralateral primary afferents on Ia inhibitory interneurones in humans.

Mechanism for reflex reversal during walking in human tibialis anterior muscle revealed by single motor unit recording.

The Use of PRV-Bartha to Define Premotor Inputs to Lumbar Motoneurons in the Neonatal Spinal Cord of the Mouse

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