Chapter 22 Distribution of recurrent inhibition in the cat forelimb

Illert, M.; Wietelmann, Detlef

doi:10.1016/s0079-6123(08)62221-9

Cited by 30 publications

(12 citation statements)

References 12 publications

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“…The anatomical and physiological characterization of the circuitry of V1 R interneurons is consistent with physiological descriptions in cat of a reduced degree of recurrent inhibition for motor neurons that innervate distal compared to proximal limb musculature (Illert and Wietelmann, 1989; McCurdy and Hamm, 1992). Thus, recurrent inhibition is not implemented uniformly across motor pools.…”

Section: Discussionsupporting

confidence: 80%

Spinal Inhibitory Interneuron Diversity Delineates Variant Motor Microcircuits

Bikoff

Gabitto

Rivard

et al. 2016

Cell

243

281

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SUMMARY Animals generate movement by engaging spinal circuits that direct precise sequences of muscle contraction, but the identity and organizational logic of local interneurons that lie at the core of these circuits remain unresolved. Here we show that V1 interneurons, a major inhibitory population that controls motor output, fractionate into highly diverse subsets on the basis of the expression of nineteen transcription factors. Transcriptionally defined V1 subsets exhibit distinct physiological signatures and highly structured spatial distributions with mediolateral and dorsoventral positional biases. These positional distinctions constrain patterns of input from sensory and motor neurons, arguing that interneuron position is a determinant of microcircuit organization. Moreover, V1 diversity indicates that different inhibitory microcircuits exist for motor pools controlling hip, ankle, and foot muscles, revealing a variable circuit architecture for interneurons that control limb movement.

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Section: Discussionsupporting

confidence: 80%

Spinal Inhibitory Interneuron Diversity Delineates Variant Motor Microcircuits

Bikoff

Gabitto

Rivard

et al. 2016

Cell

243

281

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“…Recurrent inhibition could of course produce troughs such as these in cross-correlograms. In a recent study Illert & Wietelmann (1988) Another explanation is that troughs either side of the central cross-correlogram peak reflect the autocorrelation functions of those inputs responsible for the primary feature in the histogram. This mechanism would account for the observed relationship between the central peak and these secondary phenomena but does not on its own explain why the position of a unilateral trough to one side or other of the central peak can be predicted by examining the autocorrelation functions of the output cells.…”

Section: Discussionmentioning

confidence: 99%

Correlation between the discharges of motor units recorded from the same and from different finger muscles in man.

Bremner¹,

Baker²,

Stephens³

1991

The Journal of Physiology

109

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SUMMARY1. Cross-correlation analysis of the discharges of individual motor units recorded from various different finger muscles has been performed during weak, isometric, voluntary contractions in man.2. The dominant feature in 88 % of the cross-correlograms studied was a narrow, central peak, the area of which significantly exceeded that expected for independent processes (P < 0-001). The highest bin counts in these central peaks were mostly within 5 ms of time zero in the histograms, and the base of these peaks extended between 5 and 31 ms (modal value = 13 ms with 90% of the values lying between 8 and 18 ms). The width and displacement of the central cross-correlogram peaks were similar irrespective of whether the contributory spike trains were recorded from motor units active in the same finger muscle or recorded from motor units in different, co-activated finger muscles.3. The time course of the central peaks in this study was found to be consistent with the hypothesis that it is generated by the joint occurrence of EPSPs evoked in motoneurones by branches of common stem presynaptic fibres using the theoretical model developed by Kirkwood (Kirkwood & Sears, 1978). The model parameters providing the best fit with our experimental data imply that synaptic contacts on motoneurones, made by these common inputs lie on average peripherally in the dendritic tree and generate small (< 300 isV) EPSPs superimposed on a high level of background synaptic noise.4. Minima (troughs) were found either side of the central peak in 27 % of the crosscorrelograms studied, and their appearance was invariably associated with a large central peak. These secondary features could not be modelled with the same operator parameters that describe the central peaks. Their presence was particularly noticed in association with very regular discharges from the output motoneurones.5. Smaller and broader secondary peaks symmetrically displaced 30-55 ms either side of the large, narrow central peak were observed in 7 % of the cross-correlograms studied. We suggest that these secondary features which were found at lags shorter than the interspike interval of the contributory motor unit spike trains reflect the autocorrelation functions of the spike trains of common input fibres. On this basis the

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“…However, before reaching this conclusion one must be sure: (i) that activation of FCR and ECR motoneurones was followed by activation of Renshaw cells; and (ii) that the conditioning reflex discharge was sufficient to activate them. In relation to the first point, Illert & Wietelmann (1989) have recently demonstrated the presence of homonymous recurrent inhibitory postsynaptic potentials (RIPSPs) in ECR and FCR motoneurones in the cat. In man, Katz et al (1993), using the paired H reflex technique described by Bussel & Pierrot-Deseilligny (1977) coupled with a pharmacological study (Mazzocchio & Rossi, 1989), demonstrated the presence of homonymous recurrent inhibition in both FCR and ECR motoneurones.…”

Section: Discussionmentioning

confidence: 99%

“…It must be pointed out, however, that the characterization of I a and I b interneurones has been performed in the cat lumbar spinal cord. Illert & Wietelmann (1989) summarized the knowledge about the cat cervical spinal cord. They indicated that, although there is no real information about the reflex connections, in the cat distal forelimb no direct evidence has been presented up to now for the presence of a disynaptic I a inhibitory pathway from motor nuclei to distal forelimb muscles.…”

Section: Discussionmentioning

confidence: 99%

Reciprocal inhibition between wrist flexors and extensors in man: a new set of interneurones?

Aymard

Chia

Katz

et al. 1995

The Journal of Physiology

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1. Interneurones mediating reciprocal inhibition between wrist flexors and extensors in man are characterized using both Renshaw cells and transarticular group I afferent activation. 2. Renshaw cells were activated by reflex discharges evoked by a tendon tap. The tendon tap was applied to the tendon of the muscles from which the Ia fibres responsible for the reciprocal inhibition originated. Contrary to what was observed both in the cat hindlimb and in human elbow muscles, this Renshaw cell activation never resulted in a long depression of the reciprocal inhibition between wrist flexors and extensors. 3. Convergence from group I elbow muscle afferents and antagonistic group I afferents onto interneurones mediating reciprocal inhibition between wrist muscles was revealed in post‐stimulus time histogram (PSTH) experiments using the technique of spatial facilitation. 4. The characteristics of the interneurones mediating reciprocal inhibition between wrist flexors and extensors could therefore be summarized as follows: (a) they are fed by antagonistic group I afferents and group I afferents originating from both flexor and extensor elbow muscles; (b) they are not inhibited by Renshaw cells; (c) they are not excited by low threshold cutaneous afferents; and (d) they are probably interposed in a disynaptic pathway. 5. It is therefore concluded that interneurones mediating reciprocal inhibition between wrist flexors and extensors in man differ both from Ia interneurones and from interneurones interposed in the Ib reflex pathways and these characteristics are related to the complex circumduction movements developed in the wrist.

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Chapter 22 Distribution of recurrent inhibition in the cat forelimb

Cited by 30 publications

References 12 publications

Spinal Inhibitory Interneuron Diversity Delineates Variant Motor Microcircuits

Spinal Inhibitory Interneuron Diversity Delineates Variant Motor Microcircuits

Correlation between the discharges of motor units recorded from the same and from different finger muscles in man.

Reciprocal inhibition between wrist flexors and extensors in man: a new set of interneurones?

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