| 1. |
- Asanuma, H., et al.
(författare)
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Projection of individual pyramidal tract neurons to lumbar motor nuclei of the monkey
- 1979
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Ingår i: Experimental Brain Research. - 0014-4819 .- 1432-1106. ; 34, s. 73-89
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Tidskriftsartikel (refereegranskat)abstract
- The projection of individual pyramidal tract (PT) neurons from the hindlimb area in the precentral gyrus of the cerebral cortex to the lumbar spinal cord was studied in the monkey by systematically searching for sites within identified regions of the spinal gray from which the PT neurons could be antidromically activated by local stimulation. All investigated neurons belonged to the fast conducting fraction of PT neurons. The following results were obtained. 1. Each PT neuron could be activated from more than one region of the spinal gray matter, including identified spinal motor nuclei and areas dorsomedial to these nuclei, but not the intermediate nucleus or regions dorsal to it. "Passage areas" and "termination areas" were defined. 2. Half of the PT neurons with termination areas within motor nuclei had these areas in more than one nucleus. There were thus strong suggestions for synaptic contacts of some PT neurons with motoneurons of more than one muscle. 3. Four groups of three or four neurons were recorded simultaneously by the same cortical electrode. Comparisons of passage and termination areas within groups revealed both similarities and differences in projections of neighboring neurons. Every neuron was activated from some region(s) where others of the group were not. Common passage areas, or passage and termination areas, for two or three neurons of a group within at least one motor nucleus were found for all groups. Termination areas in the same motor nucleus have been found for the majority of the neurons of only one group. These common projection areas are compatible with, but do not prove, that a group of adjacent PT neurons has common target cells in the spinal cord. © 1979 Springer-Verlag.
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| 2. |
- Bjursten, Lars Magnus, et al.
(författare)
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Behavioural repertory of cats without cerebral cortex from infancy
- 1976
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Ingår i: Experimental Brain Research. - 0014-4819. ; 25:2, s. 115-130
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Tidskriftsartikel (refereegranskat)abstract
- Bilateral removal of the cerebral cortex was made in cats neonatally. Spontaneous and imposed behaviour was studied while they were growing up and after they had become adult. Special emphasis was put on the utilization of visual cues and on learning. The cats ate, drank and groomed themselves adequately. Adequate maternal and female sexual behaviour was observed. They utilized the visual and haptic senses with respect to external space. Two cats were trained to perform visual discrimination if a T-maze. The adequacy of the behaviour of these cats is compared to that of animals with similar lesions made at maturity.
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| 3. |
- Hongo, T., et al.
(författare)
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The rubrospinal tract. III. Effects on primary afferent terminals
- 1972
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Ingår i: Experimental Brain Research. - 0014-4819 .- 1432-1106. ; 15, s. 39-53
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Tidskriftsartikel (refereegranskat)abstract
- 1. Effects evoked by stimulation of the red nucleus on primary afferent terminals in the lower lumbar segments of cats have been investigated by recording dorsal root potentials (DRPs) and by recording (intracellularly and by excitability measurements) the primary afferent depolarization (PAD) evoked in terminals of different afferent systems. Control experiments suggest that the effects are mediated by the rubrospinal tract. 2. Stimulation of the red nucleus evoked a large DRP and correspondingly there was a pronounced PAD in Ib and low threshold cutaneous afferents. A dual effect was found in Ia afferent terminals; sometimes a weak PAD was detected while in other cases there was dominating primary afferent hyperpolarization (PAH). 3. Rubrospinal volleys are found to facilitate transmission of DRPs evoked from Ia, Ib, cutaneous and high threshold muscle afferents, presumably by exerting an excitatory action on the interneurones mediating the effect from these afferents. Stimulation of the red nucleus may also inhibit transmission in the pathway mediating depolarization of Ia afferent terminals from Ia afferents, probably by activating a segmental pathway from the flexor reflex afferents from which the same effect is evoked. It is postulated that the PAH evoked in Ia afferents from the red nucleus is due to this inhibitory effect and caused by a removal of a tonic PAD in them. 4. The possible role in motor regulation of the rubral effects on primary afferent terminals is discussed in relation to the rubrospinal effects on reflex pathways to motoneurones. This work was supported by the Swedish Medical Research Council (Project No. 14X-94-07C). © 1972 Springer-Verlag.
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| 4. |
- Hongo, T., et al.
(författare)
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The rubrospinal tract. IV. Effects on interneurones
- 1972
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Ingår i: Experimental Brain Research. - 0014-4819 .- 1432-1106. ; 15, s. 54-78
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Tidskriftsartikel (refereegranskat)abstract
- 1. The effect of stimulation of the red nucleus on interneurones in the dorsal horn and intermediate region in the lower lumbar spinal cord has been investigated in cats. It has been ascertained that the effects are mediated by the rubrospinal tract. 2. Extracellular monosynaptic focal potentials evoked by single volleys in the rubrospinal tract were recorded in Rexed's layer VI and VII from a region partly overlapping with that in which focal potentials from group I muscle afferents are evoked, but extending more ventrally. 3. Monosynaptic excitatory action from the rubrospinal tract (recorded in 60 of 340 interneurones) was found in two main categories of interneurones: a) cells monosynaptically activated or disynaptically inhibited from group I muscle afferents and b) cells di- or polysynaptically activated from the flexor reflex afferents or exclusively from cutaneous afferents. The cells under a) are located more dorsally than those under b) but both within the region in which rubral focal monosynaptic potentials are recorded. There was no evidence suggesting that rubrospinal fibres have monosynaptic connexions with interneurones not influenced from primary afferents. 4. Many of the group I interneurones in the intermediate region are without monosynaptic connexions from the rubrospinal tract as are the dorsal horn cells monosynaptically activated from cutaneous afferents and dorsally located cells which do not receive monosynaptic connexions from primary afferents but are polysynaptically activated from the FRA. 5. Late (di- or polysynaptic) excitatory, inhibitory or mixed postsynaptic rubral effects are common and were found in interneurones with or without monosynaptic connexions from primary afferents but receiving similar effects from the FRA. The occurrence of spatial facilitation between peripheral nerves and the rubrospinal tract in evoking late PSPs suggests that the late rubral PSPs are evoked by activation of interneurones transmitting actions from primary afferents. 6. Some consequences of the conjoint control of interneurones from primary afferents and the rubrospinal tract are discussed. The monosynaptic effects from the rubrospinal tract are considered in relation to the rubral control of Ib reflex pathways and to the disynaptic rubromotoneuronal PSPs evoked by monosynaptic activation of last order interneurones of polysynaptic reflex pathways from primary afferents. The late rubral effects on interneurones are discussed in relation to interactive mechanisms between segmental interneuronal pathways. Rubrospinal and corticospinal effects are compared. This work was supported by the Swedish Medical Research Council (Project No. 14X-9407C). © 1972 Springer-Verlag.
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| 5. |
- Jankowska, Elzbieta, et al.
(författare)
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A long propriospinal system with direct effect on motoneurones and on interneurones in the cat lumbosacral cord
- 1974
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Ingår i: Experimental Brain Research. - 0014-4819 .- 1432-1106. ; 21, s. 169-194
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Tidskriftsartikel (refereegranskat)abstract
- Stimulation of the lateral funicle was performed at different segmenta levels in the cat in order to investigate the connecxions of long propriospinal neurones with ipsilateral lumbosacral motoneurones and interneurones projecting directly to them. In one series of experiments the propriospinal contribution was assessed from the difference between the effect of maximal stimulation in C 1 (activating supraspinal descending fibres) and in more caudal segments (activating supraspinal and propriospinal fibres). In another series on cats with chronic hemisection in C 3 pure propriospinal effects were evoked by stimulation of the thoracic spinal cord. In both series it was shown that volleys in long propriospinal neurones evoke monosynaptic EPSPs and disynaptic EPSP and/or IPSP in many flexor and extensor motoneurones; an extracellular monosynaptic focal synaptic potential was recorded in lamina VII of Rexed. The effects evoked by stimulation of the Th 11 segment after chronic C 3 hemisection were not found after chronic Th 10 hemisection. It is therefore tentatively suggested that they were due to stimulation of long descending propriospinal neurones originating in the lower cervical and upper thoracic segments, their axon trajectory being in the middle of the lateral funiculus and conduct at velocity 100 m/sec. Other effects evoked by stimulation of Th 11 after chronic Th 10 hemisection are ascribed to antidromic activation of axons of ascending neurones. © 1974 Springer-Verlag.
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| 6. |
- Liedgren, Christer, et al.
(författare)
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Projection of thalamic neurons to cat primary vestibular cortical fields studied by means of retrograde axonal transport of horseradish peroxidase
- 1976
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Ingår i: Experimental Brain Research. - : Springer. - 0014-4819 .- 1432-1106. ; 24:3, s. 237-243
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Tidskriftsartikel (refereegranskat)abstract
- The two vestibular cortical projection areas in the anterior suprasylvian sulcus and post-cruciate dimple regions were defined by evoked potential technique in anaesthetized cats. The thalamic location of neurons with axon terminals in these fields was determined using the method of retrograde axonal transport of horseradish peroxidase. The ascending vestibular pathway appeared to be separated also at the thalamic level, where cells in the ventro-posterolateral nucleus were found to project to the post cruciate dimple and cells in the posterior nuclear group to the anterior suprasylvian vestibular cortical fields.
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| 7. |
- Ödkvist, Lars, et al.
(författare)
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Vestibular and somatosensory inflow to the vestibular projection area in the post cruciate dimple region of the gat cerebral cortex
- 1975
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Ingår i: Experimental Brain Research. - : Springer. - 0014-4819 .- 1432-1106. ; 22:2, s. 185-196
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Tidskriftsartikel (refereegranskat)abstract
- In anesthetized cats 251 cells within the cortical vestibular projection area, adjacent to the post-cruciate dimple, were analyzed as to their input characteristics employing extracellular recording techniques. The post cruciate dimple vestibular field, which is located in area 3a, has a high degree of convergence between vestibular and peripheral somatosensory input. The latter is not restricted to muscle afferents but includes cutaneous modalities. The functional significance of this vestibular cortical projection field is discussed.
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