Field potentials generated by group II muscle afferents in the middle lumbar segments of the cat spinal cord.

Edgley, S A; Jankowska, E.

doi:10.1113/jphysiol.1987.sp016498

Cited by 126 publications

(146 citation statements)

References 31 publications

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“…A search was made in the L 3 -L 5 segments for group II activated interneurons at depths at which dorsal horn field potentials were evoked ( Fig. 1) (Edgley and Jankowska, 1987b). These were identified on the basis of monosynaptic activation after stimulation of muscle nerves at sufficient intensities to recruit group II muscle afferent fibers (five times threshold for recruitment of the most easily activated axons) and lack of antidromic activation by stimulation of the lateral fasciculi rostrally.…”

Section: Methodsmentioning

confidence: 99%

Differential Projections of Excitatory and Inhibitory Dorsal Horn Interneurons Relaying Information from Group II Muscle Afferents in the Cat Spinal Cord

Bannatyne¹,

Edgley²,

Hammar³

et al. 2006

J. Neurosci.

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Dorsal horn interneurons with input from group II muscle spindle afferents are components of networks involved in motor control. Thirteen dorsal horn interneurons with monosynaptic group II input were characterized electrophysiologically and labeled intracellularly with Neurobiotin. Their axonal projections were traced, and neurotransmitter content was established by using immunocytochemistry. Two subpopulations were identified: five interneurons had axons that contained vesicular glutamate transporter 2 and hence were glutamatergic and excitatory. Terminals of the remaining eight interneurons were immunoreactive for the glycine transporter 2 or were apposed to gephyrin but did not contain the GABA-synthesizing enzyme glutamic acid decarboxylase and were therefore glycinergic and inhibitory. Excitatory cells were located mainly in the central region of lamina IV and had relatively small somata and restricted dendritic trees. In contrast, inhibitory interneurons were located more ventrally, in lamina V and had relatively larger somata and more extensive dendritic trees. Axonal projections of the two subpopulations differed considerably. Excitatory interneurons predominantly projected ipsilaterally, whereas most inhibitory interneurons projected both ipsilaterally and contralaterally. Three inhibitory axons formed contacts with large cholinergic cells in motor nuclei, thus revealing a novel direct coupling between inhibitory dorsal horn interneurons and motoneurons. The organization of the excitatory interneurons is consistent with current knowledge of reflex pathways to motoneurons, but the existence and connections of the inhibitory subpopulation could not be predicted from previous data. Our results indicate that these latter interneurons exercise widespread inhibitory control over a variety of cell types located on both sides of the spinal cord.

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Section: Methodsmentioning

confidence: 99%

Differential Projections of Excitatory and Inhibitory Dorsal Horn Interneurons Relaying Information from Group II Muscle Afferents in the Cat Spinal Cord

Bannatyne¹,

Edgley²,

Hammar³

et al. 2006

J. Neurosci.

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“…To the extent that monoaminergic actions are involved in the effects produced by E. JANKOWT"SKA AAND OTHERS the electrical conditioning stimuli, depression of transmission from group II afferents to the intermediate zone interneurones interposed in disynaptic pathways Cavallari et al 1987) and the dorsal horn interneurones interposed in other pathways (Edgley & Jankowska, 1987a;Bras et al 1989a) is likely to be mediated by different descending systems. The differential effects of monoamines on transmission to these interneurones (Bras et al 1990), suggest that the former should be preferentially affected by noradrenergic and the latter by serotonergic pathways.…”

Section: The Site Of the Depressive Actionsmentioning

confidence: 99%

“…6 of Lundberg, Malmgren & Schomburg, 1987a). Given the delay between group I and TI volleys (see Table I of Edgley & Jankowska, 1987a) and conduction time to and from the interposed interneurones (see b Cavallari et al 1987, at least the earliest synaptic actions of group IT afferents were most likely evoked disynaptically.…”

Section: The Sample Of Pspsmentioning

confidence: 99%

Gating of transmission to motoneurones by stimuli applied in the locus coeruleus and raphe nuclei of the cat.

Jankowska

Riddell

Skoog

et al. 1993

The Journal of Physiology

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SUMMARY1. Neuronal systems activated by stimulation in the region of the locus coeruleus/subcoeruleus (LC/SC) and raphe nuclei have previously been shown to depress transmission from group II muscle afferents in regions of the midlumbar spinal segments in which premotor interneurones are located. The aim of the present investigation was to determine the extent to which such depression is paralleled by depression of the reflex actions of group II afferents on motoneurones.2. The effects of short trains of conditioning electrical stimuli applied within the LC/SC and raphe nuclei were examined on postsynaptic potentials (PSPs) evoked by group I and group II muscle afferents in hindlimb motoneurones. The effects were examined over a wide range of conditioning-test intervals but particular emphasis was placed on the effects produced at long intervals (> 100 ms) since such effects are more likely to be mediated by the descending noradrenergic and serotonergic neurones of the LC/SC and raphe nuclei which are of slow conduction velocity. In addition, conditioning stimuli alone evoked PSPs in motoneurones (with latencies of 7-15 ms and a duration of 50-80 ms) and effects evoked at short conditioning-test intervals might therefore have been secondary to changes in motoneurone membrane properties.3. At conditioning-test intervals between 100 and 350 ms synaptic actions of group II origin were strongly and consistently depressed. Both EPSPs and IPSPs were affected, two-thirds of those tested being reduced in amplitude by 50 % or more. A similar depression was exerted on PSPs evoked from the quadriceps and deep peroneal nerves mediated predominantly by interneurones located in the midlumbar segments and on PSPs evoked from the hamstring and triceps surae nerves mediated by interneurones located in more caudal segments. It is thus concluded that neuronal systems activated by stimuli applied in the LC/SC and raphe nuclei are capable of gating transmission in all those interneuronal pathways which mediate the reflex actions of group II afferents on motoneurones in anaesthetized animals.

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“…However, when differences in peripheral conduction time of group I and II afferents (1-1.5 ms) (Edgley and Jankowska, 1987a;Riddell et al, 1993Riddell et al, , 1995 are taken into account, the segmental latencies of IPSPs attributable to group II afferents, i.e., latencies from group II volleys, are comparable with the segmental latencies of IPSPs of group I origin.…”

Section: Inhibition Of Dsct Neurons From Group II Muscle Afferentsmentioning

confidence: 91%

Interneuronal Activity in Reflex Pathways from Group II Muscle Afferents Is Monitored by Dorsal Spinocerebellar Tract Neurons in the Cat

Jankowska¹,

Puczynska²

2008

J. Neurosci.

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The main aim of the study was to investigate whether group II muscle afferents contribute to the inhibition of dorsal spinocerebellar tract (DSCT) neurons and thereby modulate information provided by these neurons in the cat. In intracellular recordings, we found disynaptic IPSPs from group II afferents in the majority of DSCT neurons, most often in parallel with IPSPs evoked from group I afferents. In an attempt to identify interneurons that mediate these IPSPs, the second aim of the study, laminas IV-VII in midlumbar segments were searched for interneurons antidromically activated by stimuli applied within Clarke's column. Such interneurons were found in regions in which focal field potentials were evoked by group I and II afferents, or ventral to them, and most were coexcited by these afferents. The input to these interneurons and their location indicate that they belonged to the previously identified population of premotor interneurons in disynaptic pathways between group I and II afferents and hindlimb motoneurons. The study leads thus to the conclusion that inhibitory actions of group II afferents on DSCT neurons are collateral to actions on motoneurons and that DSCT neurons monitor inhibitory actions of group II afferents on motoneurons as closely as they monitor actions of group I afferents. The results also indicate that interneurons mediating disynaptic reflex actions from tendon organ (group Ib) afferents and those mediating disynaptic actions from secondary muscle spindle (group II) afferents to motoneurons may be parts and parcel of the same interneuronal population rather than constitute distinct interneuronal populations.

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Field potentials generated by group II muscle afferents in the middle lumbar segments of the cat spinal cord.

Cited by 126 publications

References 31 publications

Differential Projections of Excitatory and Inhibitory Dorsal Horn Interneurons Relaying Information from Group II Muscle Afferents in the Cat Spinal Cord

Differential Projections of Excitatory and Inhibitory Dorsal Horn Interneurons Relaying Information from Group II Muscle Afferents in the Cat Spinal Cord

Gating of transmission to motoneurones by stimuli applied in the locus coeruleus and raphe nuclei of the cat.

Interneuronal Activity in Reflex Pathways from Group II Muscle Afferents Is Monitored by Dorsal Spinocerebellar Tract Neurons in the Cat

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