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

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SUMMARY1. 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.

Section: Discussionmentioning

confidence: 70%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Landgren¹,

Silfvenius²,

Wolsk³

1967

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“…It is now well established that low threshold muscle afferents (Group I of Lloyd, 1943) from the contralateral forelimb project to the cat's cerebral cortex (Amassian & Berlin, 1958;Oscarsson & Rosen, 1963 Oscarsson, Rosen & Sulg, 1966;Swett & Bourassa, 1967a; Landgren, Silfvenius & Wolsk, 1967). Several investigators have looked in vain for the equivalent hind limb projections.…”

Section: Introductionmentioning

confidence: 99%

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

Landgren¹,

Silfvenius²

1969

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135

SUMMARY1. 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-miedial 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 lb 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 I a 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 C 1-C 3 levels but disappeared after a superficial section in the dorsolateral fascicle at C 1 level. The responses were not affected by cerebellectomy. It was concluided 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 S. LANDGREN AND H. SILFVENI US 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.

“…The region of cortex involved in hopping and placing reflexes is restricted largely to the pericruciate area (Bard, 1931(Bard, , 1933. As might be expected, the pericruciate area receives connexion from proprioceptive afferent systems (Mountcastle, Covian & Harrison, 1952;Gardner & Haddad, 1953;McIntyre, 1953;Amassian & Berlin, 1958;Oscarsson & Rosen, 1963), but this region is not unique in this respect, and such input goes to the second somatosensory area (Mountcastle et al 1952;Gardner & Haddad, 1953), the region of the postcruciate dimple (Oscarsson, Rosen & Sulg, 1966) and the anterior pole of the suprasylvian gyrus (Landgren, Silfvenius & Wolsk, 1967a;Landgren & Silfvenius, 1968. The existence of these widespread cortical proprioceptive connexions has not been adequately ex-plained and may be related to hitherto unexamined cortical function in posture.…”

Section: Introductionmentioning

confidence: 99%

Cervico‐lumbar reflex interactions involving a proprioceptive receiving area of the cerebral cortex

Abrahams¹

1970

SUMMARY1. In the decerebrate cat descending cervico-lumbar reflex interactions from neck muscle nerves are absent, and those from forepaw nerves are reduced or absent.2. Lesions restricted to the anterior pole of the suprasylvian gyrus regularly abolish descending cervico-lumbar reflex interactions from neck muscle nerves. The same lesions may reduce or abolish descending cervicolumbar reflex interactions from forepaw nerves.3. The ascending cortical looping pathway utilized in descending cervicolumbar reflex interactions is crossed, and the descending pathway from the cerebral cortex is bilateral.