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Biomedical subjects

H Silfvenius

Publications and source records attributed to H Silfvenius.

66 records · Page 4Linked 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↗
PubMedDate not supplied

Cerebral hemisphere memory for manual object handling: an intracarotid Amytal study.

The memory capacity of the cerebral hemisphere for manual object handling was studied during preoperative, intracarotid Amytal testing for hemisphere speech and memory in 32 patients with intractable partial epilepsy. The tactile stereognostic memory was tested non-visually before and after amobarbital injection. Two common objects, one in each hand, were given to the patient with the request to identify each by manipulation, but not to name it. Before injection, object handling was carried out correctly by both hands. After injection, while the patient was hemiplegic, the dominant hemisphere executed the object handling correctly; the non-dominant hemisphere, however, did it less properly. Free verbal recall of the object presented before the injection was correct in 85%. The free verbal recall of the postinjection objects was much lower; 22% for the speech-dominant, and only 3% for the non-dominant hemisphere. Tactile, non-visual recognition gave a memory score of 41% for the speech-dominant, and 13% for the opposite hemisphere. An epileptic lesion in the dominant hemisphere impaired the memory performance of that hemisphere compared to the non-lesioned group.

Adolescent↗
PubMedDate not supplied

Amino acids in the neuronal microenvironment of focal human epileptic lesions.

Extracellular fluid was topically sampled with a dialysis probe during electrocorticography from the exposed cerebral cortex in 23 patients undergoing epilepsy surgery. Sampling was done in parallel from epileptiform regions and from non-epileptic areas. The former were classified according to the histopathology, into neoplastic, non-tumoral or 'special cases'. The epileptiform regions had significantly higher extracellular concentrations of alanine, glycine and phosphoethanolamine in the majority of the cases. The excised epileptic lesions were analyzed to provide the corresponding intracellular concentrations of amino acids. Several of the non-tumoral group showed high concentrations of GABA, ethanolamine and alanine. The intra- to extracellular concentration ratio for amino acids was low for phosphoethanolamine, glycine, serine and glutamine in most of the samples of epileptiform cortex, while the intracellular accumulative ability for ethanolamine apparently was stronger in epileptiform than in normal cortex.

Adolescent↗
PubMedDate not supplied

Disability pensions for epilepsy with or without mental retardation: a 15-year Swedish survey.

The disability pensions of the Swedish National Social Insurance Board to persons with epilepsy from January 1, 1971 to December 31, 1985 were studied. On the latter date 6,658 individuals in the register were receiving disability pensions. This corresponds to an age-specific prevalence (16-64 years) of 1.2 per 1,000. Female and male patients were about equally represented. Four diagnostic categories were specified: I: 34% with epilepsy as the main diagnosis; II: 43% with epilepsy as a complementary diagnosis; III: 4% with epilepsy as a main and mental retardation (MR) as a complementary diagnosis; and IV: 19% with MR as a main and epilepsy as a complementary diagnosis. Overall 43% had both epilepsy and MR. The crude prevalence per county ranged from 0.25 to 1.23 per 1,000. Age on entry was 1.8-63.8 (mean, 36.7) years, and pension duration was 0.1-15 (mean, 7.4) years. Mean age on prevalence day was 43.9 years. During the 15-year period annual pension costs were 20-380 million Swedish kronor (SEK) ($3-60 million), and the total costs were 2,370 million SEK ($365 million). Adjusted to 1989, the costs would be 84-463 million SEK ($13-71 million) and 4,258 million SEK ($655 million), respectively.

Adolescent↗
PubMedDate not supplied

An improved optical eye movement detector for visual half-field studies of cerebral hemisphere memory.

An instrument for the evaluation of cerebral hemisphere memory using the visual half-field (VHF) technique is described. The object was to improve the existing VHF-techniques by means of an infra-red eye movement detector to control visual fixation, and to automatically control the presentation of visual stimuli. The instrument consists of four functional parts; visual presentation; optical eye movement control; electronic programming; and reaction time measuring. The instrument has been used on normal controls and in neuropsychological pre- and post-operative investigations on patients with drug resistant partial epilepsy. It has proved easy to use and reveals valuable information about hemisphere memory function. The use of an optical eye movement detector together with electronic logic has improved the accuracy and reliability of the VHF-test. A schematic outline of the instrument and a brief description of electronic circuitry are given.

Brain↗