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- Frisén, Lars, 1939
(författare)
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Forced motion attachment for the Goldmann perimeter.
- 1972
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Ingår i: Ophthalmologica. Journal international d'ophtalmologie. International journal of ophthalmology. Zeitschrift fur Augenheilkunde. - 0030-3755. ; 165:5, s. 482-8
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Tidskriftsartikel (refereegranskat)
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- 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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- 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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- Jankowska, Elzbieta, et al.
(författare)
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An electrophysiological demonstration of the axonal projections of single spinal interneurones in the cat
- 1972
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Ingår i: The Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 222, s. 597-622
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Tidskriftsartikel (refereegranskat)abstract
- 1. Single interneurones excited from group Ia afferents and located in the ventral horn of the spinal cord in the cat were activated antidromically by stimulation of their axons with one micro‐electrode while recording extracellularly close to their somas with a second micro‐electrode. The interneurones studied were those which, according to previous indirect evidence, should mediate the reciprocal Ia inhibition of motoneurones. 2. Two subgroups of these interneurones were studied: those excited from group Ia afferents in the quadriceps (Q) and posterior bicepssemitendinosus (PBSt) nerves. Most of them could be activated from a number of separate loci in the PBSt and Q motor nuclei respectively and from the ventral or lateral funiculi. 3. The location of the axonal branches and the extent of their branching in the motor nuclei were reconstructed by comparing the latencies of the responses and the thresholds (0·1–5 μA) for antidromic activation of single interneurones from different electrode positions in a number of tracks, having previously established the relation between the threshold and the distance from the stimulated fibres. For the main branches in the white matter the conduction velocity was found to be about 70 m/sec. 4. The axonal projections of the investigated interneurones were found to be fully consistent with the hypothesis that they mediate reciprocal inhibition of motoneurones. © 1972 The Physiological Society
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- Jankowska, Elzbieta, et al.
(författare)
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Morphology of interneurones mediating Ia reciprocal inhibition of motoneurones in the spinal cord of the cat
- 1972
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Ingår i: The Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 226, s. 805-823
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Tidskriftsartikel (refereegranskat)abstract
- 1. Interneurones identified by physiological criteria (Hultborn, Jankowska & Lindström, 1971b) to mediate Ia reciprocal inhibition of motoneurones in the spinal cord of the cat were stained by intracellular injection of a fluorescent dye (Procion Yellow). 2. The somas of the stained cells were found in Rexed's lamina VII, just dorsal or dorsomedial to the motor nuclei. Their size was about 30 × 20 μm. The cells had four to five slender, weakly branching dendrites. The total extension of their dendritic trees was about 600 μm dorsoventrally, 400 μm mediolaterally and 300 μm rostrocaudally. 3. The axons originated from a separate axon hillock or from the base of a dendrite. They were myelinated with external diameter of about 6–14 μm and projected to either the ipsilateral ventral or lateral funiculi. Early collaterals were found only exceptionally. Some axons bifurcated into an ascending and a descending branch within the funiculi. 4. The possibility of identifying the Ia inhibitory interneurones on purely morphological grounds is discussed. © 1972 The Physiological Society
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- Jankowska, Elzbieta, et al.
(författare)
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Synaptic actions of single interneurones mediating reciprocal Ia inhibition of motoneurones
- 1972
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Ingår i: The Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 222, s. 623-642
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Tidskriftsartikel (refereegranskat)abstract
- 1. The investigation was aimed at defining the function of the interneurones which, according to indirect evidence, mediate the reciprocal Ia inhibition of motoneurones (Hultborn, Jankowska & Lindstrom, 1971 b) by studying their direct synaptic actions. These actions were tested by recording post‐synaptic potentials in motoneurones following spike activity of single interneurones activated by iontophoretic application of glutamate. The interneurones were found to produce unitary monosynaptic IPSPs in those motoneurones in which disynaptic IPSPs are evoked by the group Ia afferents which monosynaptically excite the interneurones. 2. Unitary IPSPs were found in more than 80% of the motoneurones impaled in the immediate vicinity of the axonal branches of the investigated Q interneurones in the PBSt motor nucleus. It is estimated that each interneurone might inhibit about every fifth PBSt motoneurone. The amplitudes of the unitary IPSPs ranged between 8 and 220 μV and were 10–200 times smaller than the maximal Ia IPSPs evoked in the same motoneurones. 3. The synaptic delay in the generation of unitary IPSPs was measured in relation to the spike potentials recorded from the terminal branches of interneurones in the immediate vicinity of the impaled motoneurones. The synaptic delays ranged between 0·28 and 0·42 msec. 4. From chloride reversal tests and an analysis of the time course of the unitary IPSPs it was concluded that the terminals of the investigated interneurones make synaptic contact predominantly on the soma and/or on the proximal parts of the dendrites of the motoneurones, their distribution being, however, not quite uniform. © 1972 The Physiological Society
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