| 1. |
- Hammar, Ingela, 1964, et al.
(författare)
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A trans-spinal loop between neurones in the reticular formation and in the cerebellum.
- 2011
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Ingår i: The Journal of physiology. - : Wiley. - 1469-7793 .- 0022-3751. ; 589:Pt 3, s. 653-65
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Tidskriftsartikel (refereegranskat)abstract
- Voluntary limb movements are initiated in the brain but the neurones responsible for activating the muscles (motoneurones and interneurones) are located in the spinal cord. The spinal cord also contains neurones that provide the brain, and especially the cerebellum, with continuous information on effects of the descending commands. We show that one population of such neurones provide the cerebellum with information on how likely the brain's commands (mediated by descending reticulospinal neurones) are to be executed as planned, depending on the degree of inhibition of motoneurones. They may therefore play an important role in preventing errors in activation of motoneurones and thereby help the brain to correct its signals to the spinal cord before such errors have been committed.
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| 2. |
- Jankowska, Elzbieta, et al.
(författare)
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Collateral actions of premotor interneurons on ventral spinocerebellar tract neurons in the cat.
- 2010
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Ingår i: Journal of neurophysiology. - : American Physiological Society. - 1522-1598 .- 0022-3077. ; 104:4, s. 1872-83
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Tidskriftsartikel (refereegranskat)abstract
- 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 interneurons and Renshaw cells, while indications for similar actions of other premotor interneurons were weaker and indirect. Therefore the aim of the present study was to reexamine this possibility with respect to interneurons relaying actions of group Ib afferents from tendon organs and group II afferents from muscle spindles. In all, 133 VSCT neurons in the L3-L5 segments (including 41 spinal border neurons) were recorded from intracellularly in deeply anesthetized cats to verify that stimuli applied in motor nuclei evoked monosynaptic inhibitory postsynaptic potentials (IPSPs) attributable to stimulation of axon collaterals of premotor interneurons. IPSPs were found in over two thirds of the investigated neurons. When intraspinal stimuli were preceded by stimuli applied to a muscle nerve at critical intervals, IPSPs evoked from motor nuclei were considerably reduced, indicating a collision of nerve volleys in axons of interneurons activated by group I and group II afferents. In individual VSCT neurons monosynaptic IPSPs were evoked from both biceps-semitendinosus and gastrocnemius-soleus motor nuclei, in parallel with disynaptic IPSPs from group Ib and group II as well as group Ia afferents. These observations indicate that individual VSCT neurons may monitor the degree of inhibition of both flexor and extensor motoneurons by premotor interneurons in inhibitory pathways from group Ib and group II afferents to motoneurons. They may thus be providing the cerebellum with feedback information on actions of these premotor interneurons on motoneurons.
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