Inhibition of dorsal spinocerebellar tract cells by interneurones in upper and lower lumbar segments in the cat.

Hongo, Tetsuro; Jankowska, E.; Ohno, Tadao; Sasaki, Seiko; Yamashita, Masayuki; Yoshida, Kaoru

doi:10.1113/jphysiol.1983.sp014844

Cited by 46 publications

(45 citation statements)

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“…6 might be expected to decline, as was the case in motoneurons, because transmission from Ib terminals is inhibited presynaptically during contraction (Lafleur et al 1992;Zytnicki & L'Hote, 1993). Other categories of lower and upper lumbar interneurons might also contribute to contraction-induced inhibition of DSCT neurons (see Hongo et al 1983a). A 'copy' of the contraction-induced autogenetic inhibition of motoneurons appears to be forwarded to some DSCT neurons via Ib interneuron collaterals.…”

mentioning

confidence: 99%

Heterogeneity of contraction‐induced effects in neurons of the cat dorsal spinocerebellar tract.

Zytnicki

Lafleur

Kouchtir

et al. 1995

The Journal of Physiology

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1. Clarke's column neurons of the dorsal spinocerebellar tract (DSCT) were recorded intracellularly in anaesthetized cats during weak sustained contractions of triceps surae (TS) produced by direct electrical stimulation of the muscle. 2. Of 145 DSCT neurons, 77 (53%) were contraction sensitive suggesting that information about weak contraction of a limited number of muscles is widely distributed among DSCT neurons. Four types of effects were observed in individual neurons during TS contractions. 3. In the first group of 11 DSCT neurons (14% of the contraction-sensitive cells), the effect was excitation persisting throughout the duration of contractions. These responses were ascribed to actions of afferents from contraction-activated tendon organs. 4. In a second group of 15 neurons (20% of the contraction-sensitive cells), quickly declining excitatory potentials were recorded during sustained TS contractions. By analogy with previous observations of contraction-induced effects in motoneurons, the decline of excitation might be explained by contraction-induced presynaptic inhibition of group I afferents in Clarke's column. 5. Declining inhibitions, resembling those previously observed in homonymous and synergic motoneurons, were recorded in 49 % of contraction-sensitive DSCT neurons. This appears in keeping with the fact that interneurons mediating I b inhibition to motoneurons project axon collaterals to DSCT neurons. Presynaptic inhibition of I b fibres might therefore cause parallel reductions of inhibitory potentials in motoneurons and in DSCT neurons. 6. In a final group of 13 neurons, mixed excitatory and inhibitory effects were observed during TS contractions. Such DSCT neurons might monitor the excitability of Ib interneurons by integration of information about input to and output from these neurons. 7. The non-uniform patterns of DSCT responses to TS contractions suggest complex processing of information on ankle extensor activity in cerebellum. Phasic signalling of contraction onset is observed in many DSCT neurons while others carry messages about duration and strength of contraction.

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mentioning

confidence: 99%

Heterogeneity of contraction‐induced effects in neurons of the cat dorsal spinocerebellar tract.

Zytnicki

Lafleur

Kouchtir

et al. 1995

The Journal of Physiology

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“…3A) that fell within the range (1.54 -2.62 ms) reported previously for IPSPs of group I origin (Hongo et al, 1983a). Only such IPSPs were found in 16 of 82 (19.5%) tests in which IPSPs were induced by stimulation of any of the muscle nerves.…”

Section: Ipsps Evoked In Dsct Neuronsmentioning

confidence: 70%

“…The origin of IPSPs evoked from group I afferents in individual DSCT neurons was as diversified as in the sample of Hongo et al (1983a, their Table 1), and these IPSPs were similarly evoked from several nerves, most frequently from Q and GS or from Q and FDL. The origin of IPSPs evoked from group II afferents likewise varied, but they were most frequently evoked from other combinations of afferents: Q, Sart, and DP; Q, FDL, and DP; Q and Sart; or Q and DP.…”

Section: Ipsps Evoked In Dsct Neuronsmentioning

confidence: 80%

“…Group I-activated interneurons projecting to Clarke's column appeared previously to be primarily, if not exclusively, inhibitory because any interneuronally mediated EPSPs from group I afferents were seen in DSCT neurons only if transection of the dorsal columns caudal to Clarke's column was incomplete (Hongo et al, 1983a). In addition, only IPSPs were evoked in hindlimb mo- .…”

Section: Interneurons Projecting To Clarke's Columnmentioning

confidence: 99%

“…As a search stimulus, we used 50 A (with the estimated current spread within 0.2-0.3 mm radius from the electrode tip) (Gustafsson and Jankowska, 1976). Assuming that IPSPs from group I and/or II afferents are evoked in DSCT neurons located within a length of ϳ10 mm of Clarke's column, that these IPSPs are evoked by a few interneurons (Hongo et al, 1983a), and that at least some interneurons form synaptic contacts at more than one location, we estimated that at least 10 -20% of interneurons projecting to Clarke's column would be activated by such stationary electrodes and that we might find 7-15 of ϳ75 interneurons in the L5 segment estimated to project to Clarke's column (Hongo et al, 1983a) and a similar number in the L4 segment. The search for interneurons was made in several electrode tracks 50 -100 m apart.…”

Section: Interneurons Projecting To Clarke's Columnmentioning

confidence: 99%

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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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Development of projection‐specific interneurons and projection neurons in the embryonic mouse and rat spinal cord

Nissen

Mochida

Glover

2005

J of Comparative Neurology

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Interneurons and projection neurons in the lumbar spinal cord of mouse and rat embryos were labeled retrogradely with fluorescent dextran amines from a distance of one segment from the segment of origin [lumbar segment (L) 2]. Six classes with specific axonal projections (ipsilateral ascending, descending, and bifurcating, and commissural ascending, descending, and bifurcating) were identified by differential labeling in both species and followed from embryonic day (E)12 to birth in the mouse. Neurons with shorter projections (intrasegmental interneurons) were not studied. We show that the four nonbifurcating neuron classes occupy characteristic, partially overlapping domains in the transverse plane, indicating a systematic pattern of migration and settlement related to axon trajectories. The number of neurons in each of the nonbifurcating classes increased steadily during development. Bifurcating neurons represented a minor fraction of the total throughout development and had relatively scattered positions within the ipsilateral and commissural neuron domains. Combination of retrograde tracing and immunohistochemistry for the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) showed that none of the spinal neurons in the six projection-specific classes was GABA positive, suggesting that all GABA-positive spinal neurons, including previously described GABA-positive commissural neurons, are unlikely to have projections exceeding one or two segments in either direction.

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Inhibition of dorsal spinocerebellar tract cells by interneurones in upper and lower lumbar segments in the cat.

Cited by 46 publications

References 42 publications

Heterogeneity of contraction‐induced effects in neurons of the cat dorsal spinocerebellar tract.

Heterogeneity of contraction‐induced effects in neurons of the cat dorsal spinocerebellar tract.

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

Development of projection‐specific interneurons and projection neurons in the embryonic mouse and rat spinal cord

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