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Elzbieta Jankowska - One of the best experts on this subject based on the ideXlab platform.
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Interactions between spinal interneurons and ventral Spinocerebellar Tract neurons.
The Journal of physiology, 2013Co-Authors: Elzbieta Jankowska, Ingela HammarAbstract:Recent evidence indicates that ventral Spinocerebellar Tract (VSCT) neurons do not merely receive information provided by spinal interneurons but may also modulate the activity of these interneurons. Hence, interactions between them may be mutual. However, while it is well established that spinal interneurons may provide both excitatory and inhibitory input to ascending Tract neurons, the functional consequences of the almost exclusively inhibitory input from premotor interneurons to subpopulations of VSCT neurons were only recently addressed. These are discussed in the first part of this review. The second part of the review summarizes evidence that some VSCT neurons may operate both as projection neurons and as spinal inter- neurons and play a role in spinal circuitry. It outlines the evidence that initial axon collaterals of VSCT neurons target premotor inhibitory interneurons in disynaptic reflex pathways from tendon organs and muscle spindles (group Ia, Ib and/or II muscle afferents) to motoneurons. By activating these interneurons VSCT neurons may evoke disynaptic IPSPs in motoneurons and thus facilitate inhibitory actions of contralateral muscle afferents on motoneurons. In this way they may contribute to the coordination between neuronal networks on both sides of the spinal cord in advance of modulatory actions evoked via the cerebellar control systems.
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A survey of spinal collateral actions of feline ventral Spinocerebellar Tract neurons
The European journal of neuroscience, 2012Co-Authors: Pierre Geborek, E. Nilsson, Francesco Bolzoni, Elzbieta JankowskaAbstract:The aim of this study was to identify spinal target cells of Spinocerebellar neurons, in particular the ventral Spinocerebellar Tract (VSCT) neurons, giving off axon collaterals terminating within the lumbosacral enlargement. Axons of Spinocerebellar neurons were stimulated within the cerebellum while searching for most direct synaptic actions on intracellularly recorded hindlimb motoneurons and interneurons. In motoneurons the dominating effects were inhibitory [inhibitory postsynaptic potentials (IPSPs) in 67% and excitatory postsynaptic potentials (EPSPs) in 17% of motoneurons]. Latencies of most IPSPs indicated that they were evoked disynaptically and mutual facilitation between these IPSPs and disynaptic IPSPs evoked by group Ia afferents from antagonist muscles and group Ib and II afferents from synergists indicated that they were relayed by premotor interneurons in reflex pathways from muscle afferents. Monosynaptic EPSPs from the cerebellum were accordingly found in Ia inhibitory interneurons and intermediate zone interneurons with input from group I and II afferents but only oligosynaptic EPSPs in motoneurons. Monosynaptic EPSPs following cerebellar stimulation were also found in some VSCT neurons, indicating coupling between various Spinocerebellar neurons. The results are in keeping with the previously demonstrated projections of VSCT neurons to the contralateral ventral horn, showing that VSCT neurons might contribute to motor control at a spinal level. They might thus play a role in modulating spinal activity in advance of any control exerted via the cerebellar loop.
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INHIBITORY INPUTS TO FOUR TYPES OF Spinocerebellar Tract NEURONS IN THE CAT SPINAL CORD
Neuroscience, 2012Co-Authors: S. Shakya Shrestha, Elzbieta Jankowska, Ingela Hammar, B.a. Bannatyne, E. Nilsson, David J. MaxwellAbstract:Spinocerebellar Tract neurons are inhibited by various sources of input via pathways activated by descending Tracts as well as peripheral afferents. Inhibition may be used to modulate transmission of excitatory information forwarded to the cerebellum. However it may also provide information on the degree of inhibition of motoneurons and on the operation of inhibitory premotor neurons. Our aim was to extend previous comparisons of morphological substrates of excitation of Spinocerebellar neurons to inhibitory input. Contacts formed by inhibitory axon terminals were characterised as either GABAergic, glycinergic or both GABAergic/glycinergic by using antibodies against vesicular GABA transporter, glutamic acid decarboxylase and gephyrin. Quantitative analysis revealed the presence of much higher proportions of inhibitory contacts when compared with excitatory contacts on spinal border (SB) neurons. However similar proportions of inhibitory and excitatory contacts were associated with ventral Spinocerebellar Tract (VSCT) and dorsal Spinocerebellar Tract neurons located in Clarke's column (ccDSCT) and the dorsal horn (dhDSCT). In all of the cells, the majority of inhibitory terminals were glycinergic. The density of contacts was higher on somata and proximal versus distal dendrites of SB and VSCT neurons but more evenly distributed in ccDSCT and dhDSCT neurons. Variations in the density and distribution of inhibitory contacts found in this study may reflect differences in information on inhibitory processes forwarded by subtypes of Spinocerebellar Tract neurons to the cerebellum.
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Excitatory inputs to four types of Spinocerebellar Tract neurons in the cat and the rat thoraco-lumbar spinal cord.
The Journal of physiology, 2012Co-Authors: Sony Shakya Shrestha, Elzbieta Jankowska, Ingela Hammar, B.a. Bannatyne, E. Nilsson, David J. MaxwellAbstract:The cerebellum receives information from the hindlimbs through several populations of Spinocerebellar Tract neurons. Although the role of these neurons has been established in electrophysiological experiments, the relative contribution of afferent fibres and central neurons to their excitatory input has only been estimated approximately so far. Taking advantage of differences in the immunohistochemistry of glutamatergic terminals of peripheral afferents and of central neurons (with vesicular glutamate transporters VGLUT1 or VGLUT2, respectively), we compared sources of excitatory input to four populations of Spinocerebellar neurons in the thoraco-lumbar spinal cord: dorsal Spinocerebellar Tract neurons located in Clarke's column (ccDSCT) and in the dorsal horn (dhDSCT) and ventral Spinocerebellar Tract (VSCT) neurons including spinal border (SB) neurons. This was done on 22 electrophysiologically identified intracellularly labelled neurons in cats and on 80 neurons labelled by retrograde transport of cholera toxin b subunit injected into the cerebellum of rats. In both species distribution of antibodies against VGLUT1 and VGLUT2 on SB neurons (which have dominating inhibitory input from limb muscles), revealed very few VGLUT1 contacts and remarkably high numbers of VGLUT2 contacts. In VSCT neurons with excitatory afferent input, the number of VGLUT1 contacts was relatively high although VGLUT2 contacts likewise dominated, while the proportions of VGLUT1 and VGLUT2 immunoreactive terminals were the reverse on the two populations of DSCT neurons. These findings provide morphological evidence that SB neurons principally receive excitatory inputs from central neurons and provide the cerebellum with information regarding central neuronal activity.
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Collateral Actions of Premotor Interneurons on Ventral Spinocerebellar Tract Neurons in the Cat
Journal of neurophysiology, 2010Co-Authors: Elzbieta Jankowska, Piotr Krutki, Ingela HammarAbstract:Strong evidence that premotor interneurons provide ventral Spinocerebellar Tract (VSCT) neurons with feedback information on their actions on motoneurons was previously found for Ia inhibitory inte...
Ingela Hammar - One of the best experts on this subject based on the ideXlab platform.
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Interactions between spinal interneurons and ventral Spinocerebellar Tract neurons.
The Journal of physiology, 2013Co-Authors: Elzbieta Jankowska, Ingela HammarAbstract:Recent evidence indicates that ventral Spinocerebellar Tract (VSCT) neurons do not merely receive information provided by spinal interneurons but may also modulate the activity of these interneurons. Hence, interactions between them may be mutual. However, while it is well established that spinal interneurons may provide both excitatory and inhibitory input to ascending Tract neurons, the functional consequences of the almost exclusively inhibitory input from premotor interneurons to subpopulations of VSCT neurons were only recently addressed. These are discussed in the first part of this review. The second part of the review summarizes evidence that some VSCT neurons may operate both as projection neurons and as spinal inter- neurons and play a role in spinal circuitry. It outlines the evidence that initial axon collaterals of VSCT neurons target premotor inhibitory interneurons in disynaptic reflex pathways from tendon organs and muscle spindles (group Ia, Ib and/or II muscle afferents) to motoneurons. By activating these interneurons VSCT neurons may evoke disynaptic IPSPs in motoneurons and thus facilitate inhibitory actions of contralateral muscle afferents on motoneurons. In this way they may contribute to the coordination between neuronal networks on both sides of the spinal cord in advance of modulatory actions evoked via the cerebellar control systems.
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INHIBITORY INPUTS TO FOUR TYPES OF Spinocerebellar Tract NEURONS IN THE CAT SPINAL CORD
Neuroscience, 2012Co-Authors: S. Shakya Shrestha, Elzbieta Jankowska, Ingela Hammar, B.a. Bannatyne, E. Nilsson, David J. MaxwellAbstract:Spinocerebellar Tract neurons are inhibited by various sources of input via pathways activated by descending Tracts as well as peripheral afferents. Inhibition may be used to modulate transmission of excitatory information forwarded to the cerebellum. However it may also provide information on the degree of inhibition of motoneurons and on the operation of inhibitory premotor neurons. Our aim was to extend previous comparisons of morphological substrates of excitation of Spinocerebellar neurons to inhibitory input. Contacts formed by inhibitory axon terminals were characterised as either GABAergic, glycinergic or both GABAergic/glycinergic by using antibodies against vesicular GABA transporter, glutamic acid decarboxylase and gephyrin. Quantitative analysis revealed the presence of much higher proportions of inhibitory contacts when compared with excitatory contacts on spinal border (SB) neurons. However similar proportions of inhibitory and excitatory contacts were associated with ventral Spinocerebellar Tract (VSCT) and dorsal Spinocerebellar Tract neurons located in Clarke's column (ccDSCT) and the dorsal horn (dhDSCT). In all of the cells, the majority of inhibitory terminals were glycinergic. The density of contacts was higher on somata and proximal versus distal dendrites of SB and VSCT neurons but more evenly distributed in ccDSCT and dhDSCT neurons. Variations in the density and distribution of inhibitory contacts found in this study may reflect differences in information on inhibitory processes forwarded by subtypes of Spinocerebellar Tract neurons to the cerebellum.
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Excitatory inputs to four types of Spinocerebellar Tract neurons in the cat and the rat thoraco-lumbar spinal cord.
The Journal of physiology, 2012Co-Authors: Sony Shakya Shrestha, Elzbieta Jankowska, Ingela Hammar, B.a. Bannatyne, E. Nilsson, David J. MaxwellAbstract:The cerebellum receives information from the hindlimbs through several populations of Spinocerebellar Tract neurons. Although the role of these neurons has been established in electrophysiological experiments, the relative contribution of afferent fibres and central neurons to their excitatory input has only been estimated approximately so far. Taking advantage of differences in the immunohistochemistry of glutamatergic terminals of peripheral afferents and of central neurons (with vesicular glutamate transporters VGLUT1 or VGLUT2, respectively), we compared sources of excitatory input to four populations of Spinocerebellar neurons in the thoraco-lumbar spinal cord: dorsal Spinocerebellar Tract neurons located in Clarke's column (ccDSCT) and in the dorsal horn (dhDSCT) and ventral Spinocerebellar Tract (VSCT) neurons including spinal border (SB) neurons. This was done on 22 electrophysiologically identified intracellularly labelled neurons in cats and on 80 neurons labelled by retrograde transport of cholera toxin b subunit injected into the cerebellum of rats. In both species distribution of antibodies against VGLUT1 and VGLUT2 on SB neurons (which have dominating inhibitory input from limb muscles), revealed very few VGLUT1 contacts and remarkably high numbers of VGLUT2 contacts. In VSCT neurons with excitatory afferent input, the number of VGLUT1 contacts was relatively high although VGLUT2 contacts likewise dominated, while the proportions of VGLUT1 and VGLUT2 immunoreactive terminals were the reverse on the two populations of DSCT neurons. These findings provide morphological evidence that SB neurons principally receive excitatory inputs from central neurons and provide the cerebellum with information regarding central neuronal activity.
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Collateral Actions of Premotor Interneurons on Ventral Spinocerebellar Tract Neurons in the Cat
Journal of neurophysiology, 2010Co-Authors: Elzbieta Jankowska, Piotr Krutki, Ingela HammarAbstract:Strong evidence that premotor interneurons provide ventral Spinocerebellar Tract (VSCT) neurons with feedback information on their actions on motoneurons was previously found for Ia inhibitory inte...
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Modulation of responses of feline ventral Spinocerebellar Tract neurons by monoamines.
The Journal of comparative neurology, 2002Co-Authors: Ingela Hammar, Barbara Chojnicka, Elzbieta JankowskaAbstract:Ventral Spinocerebellar Tract neurons located in laminae V–VII of cat lumbar spinal cord were tested for the effects of ionophoretically applied monoamines and receptor selective agonists. Extracellularly recorded responses, monosynaptically evoked by group I afferents in a muscle nerve, were compared before, during, and after ionophoresis. They were analyzed with respect to changes in the number of evoked spikes and in the latency. Both serotonin (5-HT) and noradrenaline (NA) were found to facilitate responses of all neurons tested. Ionophoresis of three serotonin subtype receptor agonists (5-carboxamidotryptamine maleate, 5 methoxytryptamine HCl, and alpha-methyl 5-hydroxytryptamine) and of two NA receptor agonists (phenylephrine and isoproterenol) likewise had a facilitatory effect. However, three other 5-HT receptor agonists (8-hydroxy-dipropylaminotetraline hydrobromide), 2-methyl 5-hydroxytryptamine, and 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl and two NA receptor agonists (tizanidine and clonidine) had the opposite effect because they depressed responses of the tested neurons. These results show that information forwarded by means of the ventral Spinocerebellar Tract may be modulated by monoamines and that several receptor subtypes, located pre- or postsynaptically, may be involved. The results also demonstrate that transmission by means of group I muscle afferents may not only be facilitated by monoamines but also depressed by selective receptor subtype activation. J. Comp. Neurol. 443:298–309, 2002. © 2002 Wiley-Liss, Inc.
David J. Maxwell - One of the best experts on this subject based on the ideXlab platform.
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INHIBITORY INPUTS TO FOUR TYPES OF Spinocerebellar Tract NEURONS IN THE CAT SPINAL CORD
Neuroscience, 2012Co-Authors: S. Shakya Shrestha, Elzbieta Jankowska, Ingela Hammar, B.a. Bannatyne, E. Nilsson, David J. MaxwellAbstract:Spinocerebellar Tract neurons are inhibited by various sources of input via pathways activated by descending Tracts as well as peripheral afferents. Inhibition may be used to modulate transmission of excitatory information forwarded to the cerebellum. However it may also provide information on the degree of inhibition of motoneurons and on the operation of inhibitory premotor neurons. Our aim was to extend previous comparisons of morphological substrates of excitation of Spinocerebellar neurons to inhibitory input. Contacts formed by inhibitory axon terminals were characterised as either GABAergic, glycinergic or both GABAergic/glycinergic by using antibodies against vesicular GABA transporter, glutamic acid decarboxylase and gephyrin. Quantitative analysis revealed the presence of much higher proportions of inhibitory contacts when compared with excitatory contacts on spinal border (SB) neurons. However similar proportions of inhibitory and excitatory contacts were associated with ventral Spinocerebellar Tract (VSCT) and dorsal Spinocerebellar Tract neurons located in Clarke's column (ccDSCT) and the dorsal horn (dhDSCT). In all of the cells, the majority of inhibitory terminals were glycinergic. The density of contacts was higher on somata and proximal versus distal dendrites of SB and VSCT neurons but more evenly distributed in ccDSCT and dhDSCT neurons. Variations in the density and distribution of inhibitory contacts found in this study may reflect differences in information on inhibitory processes forwarded by subtypes of Spinocerebellar Tract neurons to the cerebellum.
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Excitatory inputs to four types of Spinocerebellar Tract neurons in the cat and the rat thoraco-lumbar spinal cord.
The Journal of physiology, 2012Co-Authors: Sony Shakya Shrestha, Elzbieta Jankowska, Ingela Hammar, B.a. Bannatyne, E. Nilsson, David J. MaxwellAbstract:The cerebellum receives information from the hindlimbs through several populations of Spinocerebellar Tract neurons. Although the role of these neurons has been established in electrophysiological experiments, the relative contribution of afferent fibres and central neurons to their excitatory input has only been estimated approximately so far. Taking advantage of differences in the immunohistochemistry of glutamatergic terminals of peripheral afferents and of central neurons (with vesicular glutamate transporters VGLUT1 or VGLUT2, respectively), we compared sources of excitatory input to four populations of Spinocerebellar neurons in the thoraco-lumbar spinal cord: dorsal Spinocerebellar Tract neurons located in Clarke's column (ccDSCT) and in the dorsal horn (dhDSCT) and ventral Spinocerebellar Tract (VSCT) neurons including spinal border (SB) neurons. This was done on 22 electrophysiologically identified intracellularly labelled neurons in cats and on 80 neurons labelled by retrograde transport of cholera toxin b subunit injected into the cerebellum of rats. In both species distribution of antibodies against VGLUT1 and VGLUT2 on SB neurons (which have dominating inhibitory input from limb muscles), revealed very few VGLUT1 contacts and remarkably high numbers of VGLUT2 contacts. In VSCT neurons with excitatory afferent input, the number of VGLUT1 contacts was relatively high although VGLUT2 contacts likewise dominated, while the proportions of VGLUT1 and VGLUT2 immunoreactive terminals were the reverse on the two populations of DSCT neurons. These findings provide morphological evidence that SB neurons principally receive excitatory inputs from central neurons and provide the cerebellum with information regarding central neuronal activity.
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Serotoninergic and noradrenergic axons make contacts with neurons of the ventral Spinocerebellar Tract in the cat
The Journal of comparative neurology, 2002Co-Authors: Ingela Hammar, David J. MaxwellAbstract:Contacts between monoaminergic fibers and electrophysiologically identified neurons of the ventral Spinocerebellar Tract were investigated in the cat. Five neurons were labeled intracellularly with rhodamine dextran, and monoaminergic fibers were revealed with antibodies against serotonin and dopamine beta-hydroxylase. The distribution of appositions between monoaminergic varicosities and the soma and the whole length of dendrites of these neurons was examined by using a three-channel confocal microscope. The analysis showed that close appositions between monoaminergic fibers and labeled processes occurred over the whole surface of the neurons. The highest percentage of such appositions was found on proximal dendrites, for both serotonin (37%) and noradrenaline (57%). The total number of serotoninergic contacts (66–134 per neuron) by far exceeded that of noradrenergic contacts (3–36 per neuron). Contacts between serotoninergic fibers and two neurons were analyzed by using electron microscopy. These neurons were labeled intracellularly with horseradish peroxidase, and serotoninergic varicosities were identified by immunocytochemistry. Six of 10 serially analyzed boutons in apposition to proximal dendrites were found to form morphologic synapses. The identification of the remaining four was inconclusive. These results indicate that many of the appositions seen in confocal microscopy may represent direct synaptic contacts. They also indicate that monoaminergic neurons may modulate activity of neurons of the ventral Spinocerebellar Tract by direct postsynaptic actions in addition to any effects evoked by means of volume transmission. J. Comp. Neurol. 443:310–319, 2002. © 2002 Wiley-Liss, Inc.
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Synaptic relationships between serotonin-immunoreactive axons and dorsal horn Spinocerebellar Tract cells in the cat spinal cord
Neuroscience, 1996Co-Authors: David J. Maxwell, Elzbieta JankowskaAbstract:Dorsal horn Spinocerebellar Tract cells were identified according to electrophysiological criteria in adult cats and labelled intracellularly with horseradish peroxidase. Sections containing labelled neurons were processed to reveal serotonin immunoreactivity and examined with light and electron microscopy. Numerous contacts were observed on cell bodies, and on proximal and intermediate parts of dendrites. Electron microscopic examination of contacts revealed that synaptic junctions were usually present at the region of apposition. It is concluded that serotonin has a postsynaptic action on dorsal horn Spinocerebellar Tract cells and that this action is mediated through conventional synapses.
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Contacts between serotoninergic fibres and dorsal horn Spinocerebellar Tract neurons in the cat and rat: A confocal microscopic study
Neuroscience, 1995Co-Authors: Elzbieta Jankowska, Piotr Krutki, David J. Maxwell, S. Dolk, P.v. Belichenko, A. DahlströmAbstract:Contacts between serotoninergic nerve fibres and dorsal horn dorsal Spinocerebellar Tract neurons were analysed in order to investigate the morphological basis of actions of serotonin upon dorsal Spinocerebellar Tract neurons. In a series of experiments dorsal Spinocerebellar Tract neurons were labelled with intracellularly injected rhodamine-dextran in the cat. The neurons were monosynaptically excited by group II muscle afferents and cutaneous afferents and were identified by antidromic activation following stimuli applied in the cerebellum. In the second series of experiments dorsal Spinocerebellar Tract neurons were labelled by retrograde transport of Fluorogold injected into the cerebellum in the rat. In both series, serotoninergic fibres were labelled by using a specific anti-serotonin antiserum and were revealed by immunofluorescence. Appositions between the serotoninergic fibres and the cells were inspected with a dual channel confocal microscope. The merged images obtained with the two channels of the microscope were viewed in single optical planes 2 microns apart and in rotated three-dimensional reconstructions. Serotoninergic nerve fibres were found in apposition to cell bodies of all feline dorsal Spinocerebellar Tract neurons (n = 7) and of 75% of rat dorsal Spinocerebellar Tract neurons (n = 90). The numbers of putative contacts on cell bodies varied between less than 100 and nearly 300 (mean 160) in the cat and between about five and 30 in the rat. Contacts with dendrites of feline neurons were seen on 96% of 72 dendrites within 300 microns from soma and on 91% of 23 dendrites at distances of 300-500 microns. The number of such contacts varied from less than five to 150 on a single dendrite within these ranges of distances. Their total number within 100 microns from the soma was comparable or exceeded the number of contacts on the soma.
Peter J. Soja - One of the best experts on this subject based on the ideXlab platform.
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State-dependent GABAergic inhibition of sciatic nerve-evoked responses of dorsal Spinocerebellar Tract neurons.
Journal of neurophysiology, 2004Co-Authors: Niwat Taepavarapruk, Shelly A. Mcerlane, Angela Chan, Sylvia Chow, Lizbeth Fabian, Peter J. SojaAbstract:Peripheral nerve-evoked potentials recorded in the cerebellum 35 yr ago inferred that sensory transmission via the dorsal Spinocerebellar Tract (DSCT) is reduced occasionally and only during eye mo...
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On the reduction of spontaneous and glutamate-driven Spinocerebellar and spinoreticular Tract neuronal activity during active sleep.
Neuroscience, 2001Co-Authors: Peter J. Soja, Niwat Taepavarapruk, B E Cairns, Walton Pang, Shelly A. McerlaneAbstract:AbsTract The present study was performed to provide evidence that dynamic neural processes underlie the reduction in dorsal Spinocerebellar Tract and spinoreticular Tract neuron activity that occurs during active sleep. To ascertain the effect of local inhibition on the spontaneous and glutamate-evoked spike discharge of sensory Tract neurons, preliminary control tests were performed during the state of quiet wakefulness, where GABA or glycine was co-administered in a sustained fashion during pulsatile release of glutamate to dorsal Spinocerebellar Tract ( n =3) or spinoreticular Tract ( n =2) neurons. Co-administration of GABA or glycine also resulted in a significant marked suppression of spontaneous spike activity and glutamate-evoked responses of these cells. Extracellular recording experiments combined with juxtacellular application of glutamate were then performed on 20 antidromically identified dorsal Spinocerebellar Tract and spinoreticular Tract neurons in the chronic intact cat as a function of sleep and wakefulness. The glutamate-evoked activity of a group of 10 sensory Tract neurons (seven dorsal Spinocerebellar Tract, three spinoreticular Tract), which exhibited a significant decrease in their spontaneous spike activity during active sleep, was examined. Glutamate-evoked activity in these cells was significantly attenuated during active sleep compared with wakefulness. In contrast, the glutamate-evoked activity of a second group of eight sensory Tract neurons (four dorsal Spinocerebellar Tract, four spinoreticular Tract), which exhibited a significant increase in their spontaneous spike activity during active sleep, was not significantly altered in a state-dependent manner. These data indicate that, during natural active sleep, a dynamic neural process is engaged onto certain dorsal Spinocerebellar Tract and spinoreticular Tract neurons, which in turn dampens sensory throughput to higher brain centers.
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Dorsal Spinocerebellar Tract neurons in the chronic intact cat during wakefulness and sleep: analysis of spontaneous spike activity
The Journal of neuroscience : the official journal of the Society for Neuroscience, 1996Co-Authors: Peter J. Soja, M C Fragoso, B E Cairns, Wg JiaAbstract:Relatively little is known about the transmission of ascending sensory information from lumbar levels across the behavioral states of sleep and wakefulness. The present study used extracellular recording methods in chronically instrumented intact behaving cats to monitor the activity of lumbar dorsal Spinocerebellar Tract (DSCT) neurons within Clarke's column during the states of wakefulness, quiet sleep, and active sleep. Clarke's column DSCT neurons were identified using antidromic identification and retrograde labeling techniques. The spontaneous spike rate and interspike interval data of DSCT neurons were quantified as a function of behavioral state. During wakefulness and quiet sleep, the spike rate of DSCT neurons was stable, and interspike interval histograms (ISIH) indicated a relatively high degree of regularity in DSCT neuronal spike train patterns. In contrast, during active sleep there was a marked reduction in the ongoing spike rate in a vast majority of cells tested. The magnitude of change in ISIHs and interspike interval data during active sleep depended in part on whether the reduction in cell firing was maintained or periodic throughout active sleep. Further suppression of spontaneous activity also was observed during intense rapid-eye-movement episodes of active sleep that were associated with clustered pontogeniculo-occipital wave and muscular twitches and jerks. After re-awakening, spontaneous spike activity of Clarke's column DSCT neurons resembled that recorded during previous episodes of wakefulness. These data provide evidence that ascending proprioceptive and exteroceptive sensory transmission through Clarke's column is diminished during the behavioral state of active sleep.
Naoki Hirai - One of the best experts on this subject based on the ideXlab platform.
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Physiological studies of thoracic Spinocerebellar Tract neurons in relation to respiratory movement.
Neuroscience research, 1994Co-Authors: Yuji Tanaka, Naoki HiraiAbstract:AbsTract The differential roles of thoracic Spinocerebellar Tract (SCT) neurons with axons ascending in ipsi- (uncrossed) and contralaterally (crossed) spinal cord and their activities during respiratory movement were examined by extracellular recordings in the T 9 –T 12 spinal segments of the anaesthetized cat. A total of 36 uncrossed and 7 crossed SCT neurons showed rhythmic discharges in relation to either spontaneous or artificial respiration. Uncrossed neurons were located in and around Clarke's column and thus are cells of origin of the dorsal Spinocerebellar Tract (DSCT). Crossed neurons were located in laminae VII and VIII. Almost all DSCT neurons were modulated during artificial respiration. Nineteen DSCT neurons showed high-frequency discharges during chest expansion and 15 DSCT neurons showed high-frequency discharges during the chest reTraction phase of artificial respiration. Their respiration-related activity maintained the same phase relation and firing patterns after vagotomy. The phase relationship of neural rhythmicity to chest movement during artificial respiration and spontaneous breathing was the same in 14 neurons examined. Artificially induced pneumothorax caused a marked decrease of respiration-related modulation, and severing of a single nerve to the appropriate muscle caused a marked decrease of modulation, suggesting that respiration-related rhythmic activity of DSCT neurons is induced by the extension of respiratory muscles in the chest wall during both spontaneous and artificial respiration. Crossed SCT neurons showed rhythmic activity in phase with the central respiratory rhythm as indexed by phrenic nerve activity. Two neurons received an excitatory influence and five an inhibitory influence in the inspiratory phase from the centre. Four neurons in the latter group also received excitatory inputs from the periphery during chest expansion. Since inspiration brings chest expansion during spontaneous breathing, the central and peripheral inputs seem antagonistic in function. These neurons seemed to signal a discrepancy between the chest wall movement and the central respiratory rhythm. Functional differences between uncrossed and crossed SCTs in the lower thoracic segments in regard to the central and peripheral inputs as observed here are similar to those observed in the lumbar SCTs during locomotion.
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Activity of crossed Spinocerebellar Tract neurones in the thoracic spinal cord in relation to the central respiratory rhythm
Brain research, 1990Co-Authors: Yuji Tanaka, Dilshat Abla, Naoki HiraiAbstract:AbsTract Correlation between respiratory movement and neural discharges of antidromically identified 20 crossed Spinocerebellar Tract (SCT) neurones in the T8–11 segments was examined in the anaesthetized, paralysed cat. Activity of 11 neurones of them was related to phrenic nerve activity; 7 neurons increased and 4 decreased their activity during the active phase of the phrenic nerve. Their rhythmic activity remained even after artificial ventilation was turned off, indicating the central genesis of their rhytmic activity. By comparing discharge patterns with the ventilator on and off, it is suggested that half of these crossed SCT neurones appear to receive additional inputs from the periphery. Neurones which increased their firing rate during phrenic nerve activity tend to respond with decrease discharge to passive chest inflation, and vice versa.
