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S Landgren

Publications and source records attributed to S Landgren.

27 records · Page 2Linked to original sources
PubMed1969

Projection to cerebral cortex of group I muscle afferents from the cat's hind limb.

1. Muscle afferent projections from the contralateral hind limb to the postsigmoid gyrus of the cerebral cortex were investigated in cats anaesthetized with chloralose. The evoked potentials were recorded from the cortical surface or from deeper layers by penetrating micro-electrodes. Graded electrical stimulation of the nerves was used.2. Group Ia as well as Ib muscle afferents from the contralateral quadriceps, posterior biceps-semitendinosus, gastrocnemius-soleus and deep peroneal muscles projected to two different loci in the postsigmoid gyrus. One of these was located on the dorsal surface of the hemisphere 4-5 mm lateral to the mid line and 1-3 mm posterior to the cruciate sulcus, thus rostro-medial to the postcruciate dimple. The other was located on the medial surface of the hemisphere adjacent to the cruciate sulcus. There was no overlap between the two loci.3. There was no significant difference in thresholds or latencies of the Group I responses in the two loci. The latency was short and similar to that of the potential evoked by the cutaneous afferents in the somatosensory primary projection areas.4. The Group Ib path was largely independent of the Ia path, because a maximal Group I volley evoked a response, when the Ia path was made refractory by simultaneous stimulation with a maximal Ia volley at 20 per second.5. The cortical potentials evoked by the Group I muscle afferents from the contralateral hind limb did not change after transection of the dorsal columns at C1-C3 levels but disappeared after a superficial section in the dorsolateral fascicle at C1 level. The responses were not affected by cerebellectomy. It was concluded that the path travelled with the dorsal spinocerebellar tract or utilized brain stem collaterals of this tract.6. Group II muscle afferents evoked a response near the border of the Group I loci, but not in the positions where the Group I responses were maximal in amplitude.7. The receptor origin of the stimulated Group I afferents, the location of the medullary relay in the Group I path and the destination of the efferent outflow from the Group I loci were discussed.

Animals↗
PubMed1967

Somato-sensory paths to the second cortical projection area of the group I muscle afferents.

1. Cats anaesthetized with chloralose and paralysed with Flaxedil were used. The projections of muscle, joint and skin afferents to the cortical fold hidden in the anterior suprasylvian sulcus were investigated with micro-electrode recording techniques.2. Electrical stimulation of Group I muscle afferents from the contralateral forelimb evoked a negative focal potential (latency 5 msec) in a locus of 1-2 mm diameter found in the lower bank of the fold. In one experiment a response to Group I muscle afferents from the contralateral hind limb was observed. The Group I potentials disappeared after sectioning of the dorsal columns at C3.3. Groups II and III muscle afferents, low threshold skin afferents and joint afferents also evoked potentials in the Group I locus. It was concluded that the joint afferents originated mainly in the Ruffini endings of the joint capsule.4. Groups II and III muscle afferents, low threshold skin and low threshold joint afferents projected to the upper bank of the suprasylvian fold. A certain somatotopic arrangement was observed.5. The possibility of connexions between the cortex of the anterior suprasylvian fold and the primary somato-sensory projection areas was discussed, as well as the organization of the loci in the fold in terms of cell colonies with different properties.

Animals↗
PubMed1967

Vestibular, cochlear and trigeminal projections to the cortex in the anterior suprasylvian sulcus of the cat.

1. Cats anaesthetized with chloralose were used. Potentials evoked by electrical stimulation of the vestibular, cochlear, facial, trigeminal and chorda tympani nerves were recorded with micro-electrodes in the cortex in the anterior syprasylvian sulcus.2. Negative focal potentials with a latency of 3 msec were evoked by stimulation of the contralateral and ipsilateral vestibular nerves. These potentials were located in the lower and upper banks of the sulcus at a level just caudal to the projection of the Group I muscle afferents to the lower bank.3. The cochlear projections were located mainly in the lower bank partially overlapping the vestibular and the Group I fields.4. Trigeminal responses were recorded in both banks of the sulcus but were of largest amplitude and shortest latency rostrally in the upper bank. The potentials evoked by the chorda tympani had a similar distribution but were of low amplitude.5. The hypothesis is suggested, that the cortex in the anterior suprasylvian sulcus plays a role in the orientation of the body and head towards auditory stimuli.

Animals↗
PubMed1966

The thalamic relay and cortical projection of group I muscle afferents from the forelimb of the cat.

1. Stimulation of Group I muscle afferents in contralateral forelimb nerves evoked a response in nucleus ventralis posterolateralis (VPL) in the thalamus of the cat. This response was located in the rostral two-thirds of VPL in a narrow zone near the dorsomedial border of the nucleus.2. Group I afferents in nerves from more than one of the muscles in the contralateral forelimb often excited the same thalamic relay cell. In addition these cells were often discharged by skin afferents from the contralateral forelimb. They were not affected by electrical stimulation of the dorsal column-lemniscal or the spino-cervico-lemniscal paths from the contralateral hind limb.3. In experiments with peripheral conduction paths of similar length, the latency of the thalamic focal potential evoked by stimulation of Group I muscle afferents in the nerve to m. extensor carpi radialis was 3.8 S.E. +/- 0.1 msec, and that of the focal potential evoked by skin afferents (n. radialis superficialis) in the centromedial part of VPL was 4.3 +/- 0.1 msec.4. The majority of the thalamic neurones discharged by Group I muscle afferents responded with a latency shorter than 1 msec to electrical stimulation of the cerebral cortex in the region of the post-cruciate dimple. A considerable number of the thalamic Group I relay cells were also discharged with a similar short latency from another cortical focus located on either side of the anterior suprasylvian sulcus near the S II hind limb areas. These responses were considered to be antidromic in nature, and the findings were interpreted as indicating two separate cortical projection areas for the Group I path. The second projection area was assumed to be located in the cortical fold formed by the anterior suprasylvian sulcus.5. Cortical stimulation also excited the thalamic Group I relay cells trans-synaptically. Trans-synaptic excitation with short (1-2 msec) and longer (2-7 msec) latency was observed. The cortical focus near the S II area was particularly potent in evoking trans-synaptic excitation in the thalamic region where the Group I relays were located.

Animals↗