1991 Fiscal Year Final Research Report Summary
A Study of Rostrocaudal Distribution and Functional Localization of Spinal Interneurones Contributing to Motor Control of the Cat Forelimb.
| Project/Area Number |
02454120
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Neurophysiology and muscle physiology
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| Research Institution | University of Tokyo |
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Principal Investigator |
HONGO Toshinori Dept. Neurophysiol., Inst. Brain Research, Faculty of Medicine, University of Tokyo, Professor, 医学部(医), 教授 (60013843)
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| Project Period (FY) |
1990 – 1991
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| Keywords | spinal cord / interneurone / premotor nevrone / primary afferents / dorsal column / pyramidal tract / rubrospinal tract / cat |
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| Research Abstract |
Analyses were made of interneurone pathways to cat forelimb motoneurones. The following results were obtained.
1. Segmental distribution of premotor neurones : Studies of premotor neurones using preparations of isolated spinal segments revealed the followings.
(1) Motoneurones of biceps and triceps brachii and ulnar hand muscles all received inputs from premotor neurones located in each of C4-Tl segments. (2) The rostrocaudal distribution of excitatory and inhibitory premotor neurones varied with the motoneurone species (muscles) to which they projected. (3) Synaptic linkages of primary afferent and pyramidal tract fibres with premotor neurones varied with the segments. Namely, premotor neurones in the rostral cervical segments received inputs monosynaptically and those in the caudal cervical segments mono- and disynaptically from both afferent and descending fibres. This applied to the motor nuclei of all three species.
2. Input patterns of C6-C8 premotor neurones, as analysed by motoneu
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rone PSPS : Experiments using preparation of isolated C6-C8 segments and the technique of spatial facilitation revealed the following properties of C6-C8 premotor neurones projecting to Tl. (1) Premotor neurones mediating disynaptic group I inhibition received convergent-disynaptic excitation from skin, pyramidal and rubrospinal tract fibres. (2) Interneurones mediating skin reflex effects. received mono- and disynaptic excitation from pyramidal and rubrospinal tract fibres. (3) Premotor neurones mediating disynaptic pyramidal and rubrospinal effects received mono- and disynaptic excitation from cutaneous afferents.
3. C6-C8 premotor neurones projecting to Tl : Input patterns were investigated of C6-C8 premotor and candidate premotor neurones projecting to Tl motor nucleus by directly recording from these neurones. Thus revealed patterns of inputs converging from skin and muscle afferent, pyramidal and rubrospinal tract fibres and their axonal conduction time well explained the spatially facilitated PSPs of motoneurones in the study 2.
4. Multiplicity of premotor pathways : Studied premotor neurones showed varieties of input patterns and laminar locations, indicating the presence of multiple premotor pathways. It is suggested that they are used in different aspects of motor functions. Less
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