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| 24. |
- Hongo, T., et al.
(författare)
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Convergence of excitatory and inhibitory action on interneurones in the lumbosacral cord
- 1966
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Ingår i: Experimental Brain Research. - 0014-4819 .- 1432-1106. ; 1, s. 338-358
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Tidskriftsartikel (refereegranskat)abstract
- Intracellular recording has been made in spinal cats from more than 100 interneurones in the dorsal horn and intermediary region of the lumbosacral spinal cord. The majority of interneurones receive not only EPSPs but also IPSPs from primary afferents. The IPSPs are evoked from three different systems, group I muscle afferents (probably Ib), low threshold cutaneous afferents and the FRA. The shortest central latency of the IPSPs indicates a disynaptic linkage from primary afferents. Interneurones with monosynaptic EPSPs from group I muscle afferents may receive IPSPs from all the above mentioned afferent systems. Interneurones with monosynaptic EPSPs from cutaneous afferents receive their inhibition from the two latter afferent systems. Convergence of EPSPs and IPSPs from the FRA may occur on the same interneurone. The results are discussed mainly with respect to inhibitory interaction between spinal reflex pathways. © 1966 Springer-Verlag.
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| 25. |
- Hongo, T., et al.
(författare)
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Effects from the sensorimotor cortex on the spinal cord in cats with transected pyramids
- 1967
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Ingår i: Experimental Brain Research. - 0014-4819 .- 1432-1106. ; 3, s. 117-134
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Tidskriftsartikel (refereegranskat)abstract
- Effects of stimulation of the sensorimotor cortex on activity of the lumbosacral cord were studied in pyramidotomized cats. The following actions initiated by corticofugal volleys were found: 1. postsynaptic effects on motoneurones, mainly excitatory in flexor motoneurones and inhibitory or excitatory in extensor motoneurones, 2. facilitation of spinal reflexes to motoneurones at an interneuronal level, 3. depolarization of presynaptic terminals of group Ib and cutaneous fibres. The latencies of the earliest cortical effects on motoneurones as indicated by modification of monosynaptic reflexes or PSPs were 9-12 msec. Experiments with lesions of different spinal tracts suggest that the effects on motoneurones are mediated mainly by pathways in the ventral part of the lateral funiculus (probably reticulospinal), the facilitation of reflex transmission by pathways in the dorsal part of the lateral funiculus (probably rubrospinal) and primary afferent depolarization by both the former and the latter pathways. The strongest cortical effects were evoked by stimulation of an area around the postcruciate dimple. © 1967 Springer-Verlag.
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| 26. |
- Hongo, T., et al.
(författare)
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Post‐synaptic excitation and inhibition from primary afferents in neurones of the spinocervical tract
- 1968
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Ingår i: The Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 199, s. 569-592
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Tidskriftsartikel (refereegranskat)abstract
- 1. Intra‐ and extracellular recordings were made from cells of the spinocervical tract in the lumbosacral spinal cord. A convergence of monosynaptic excitatory post‐synaptic potentials (EPSPs) and disynaptic inhibitory post‐synaptic potentials (IPSPs) was a general pattern of effects from the low threshold cutaneous fibres. Unitary IPSPs, probably mediated via the same disynaptic path, were evoked by light touch of hairs, which was also the adequate stimulus for exciting the cells. The receptive field for unitary IPSPs was closely related to the excitatory receptive field but was eccentric, not of a surround type. 2. EPSPs, IPSPs, or both, were evoked from the flexor reflex afferents in the great majority of neurones. Disynaptic IPSPs may be evoked from the interosseous nerve. No effects were produced by volleys in group I muscle afferents. 3. It is suggested, on the basis of the spatial organization of the excitatory and inhibitory receptive skin fields, that the spinocervical tract may give information regarding the direction of tactile stimuli. © 1968 The Physiological Society
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| 28. |
- Hongo, T., et al.
(författare)
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The rubrospinal tract. I. Effects on alpha-motoneurones innervating hindlimb muscles in cats
- 1969
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Ingår i: Experimental Brain Research. - 0014-4819 .- 1432-1106. ; 7, s. 344-364
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Tidskriftsartikel (refereegranskat)abstract
- 1. The effect of stimulation of the red nucleus on lumbosacral motoneurones was investigated in cats with conditioning of monosynaptic test reflexes and intracellular recording. 2. Experimental procedures were adopted to assure that the effect of stimulation was mediated by the rubrospinal tract. 3. Excitation of flexor and inhibition of extensor motoneurones is common but a mixture of EPSPs and IPSPs is found in many motoneurones. In some extensor (particularly toe extensor) motor nuclei there is dominating excitation. 4. Differential effects are found in motor nuclei innervating fast and slow muscles, excitation being more prevalent in the former and inhibition in the latter. 5. For both EPSPs and IPSPs the minimal synaptic linkage is disynaptic but in one exceptional case a monosynaptic EPSP was observed. 6. The results are discussed in relation to other findings regarding the interneuronal organization in the spinal cord. © 1969 Springer Verlag.
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| 29. |
- Hongo, T., et al.
(författare)
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The rubrospinal tract. II. Facilitation of interneuronal transmission in reflex paths to motoneurones
- 1969
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Ingår i: Experimental Brain Research. - 0014-4819 .- 1432-1106. ; 7, s. 365-391
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Tidskriftsartikel (refereegranskat)abstract
- 1. The effect of stimulation of the red nucleus on transmission of synaptic actions from different systems of primary afferents to alpha motoneurones has been investigated in cats, mainly with intracellular recording from motoneurones. 2. The dominating effect is facilitation, presumably caused by excitatory action exerted from the rubrospinal tract on interneurones of reflex arcs. The time course of facilitation suggests that the minimal linkage from the rubrospinal tract to these interneurones is monosynaptic. 3. Interneuronal transmission in reflex pathways from the following afferent systems is facilitated: a) Ia inhibitory between flexors and extensors. Rubrospinal facilitation did not reveal Ia inhibitory pathways between adductors and abductors at the hip. b) Ib excitatory and inhibitory. There is marked facilitation of the reciprocal effects evoked by Ib afferents from extensors but also of other Ib pathways, for example inhibitory from extensors to flexor nuclei and from flexors to extensor nuclei and excitatory from flexors to extensor nuclei. c) Low threshold joint, inhibitory and excitatory, presumably from afferents with Ruffini endings. d) Low threshold cutaneous, excitatory and inhibitory. Since transmission from these afferents could be facilitated under conditions when there was no effect on transmission from high threshold muscle afferents it is postulated that the effect is exerted on pathways which are not part of the common pathways from the flexor reflex afferents. e) Plexor reflex afferents, excitatory and inhibitory. Facilitation of these pathways is not found regularly, in some cases there was no effect and in others inhibition. 4. The effects are discussed in relation to the complex effects evoked from the rubrospinal tract in motoneurones and to supraspinal regulation of proprioceptive reflexes. 5. It is postulated that in complex movements alternative Ib patterns may be mobilized, whereas flexion-extension movements are subserved by the Ib pattern found in the spinal cat. 6. Facilitation of the Ia inhibitory pathway is taken to indicate "α-γ-linkage" in reciprocal inhibition. It is pointed out that convergence from Ia and descending impulses on a common inhibitory interneurone may play an important role in the regulation of α-γ-linked flexion-extension movements. © 1969 Springer Verlag.
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