Rolf Ekedahl

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Thin diameter concentric needle electrodes with a small recording surface were used to explore the characteristics of neighboring fibers in sensory median nerve fascicles. Fibers which were close neighbors in the fascicle, were not randomly distributed intraneurally. Instead there was an intrafascicular segregation by modality of both myelinated and(More)
Thin concentric needle electrodes were used to explore intact median nerve fascicles in human subjects. In particular, the presence of single units, probably recorded from nodes of Ranvier, was studied in different parts of a fascicle. Single-unit activity in myelinated fibers was rarely found at numerous sites. In many other intrafascicular areas, a(More)
Concentric needle electrodes with a central core diameter of 20-30 microm were used to explore median nerve fascicles in man. Such electrodes can simultaneously monitor subtle electrophysiological and topographical features even within parts of a fascicle. Single-unit recordings from myelinated fibres were more easily obtained at some intrafascicular sites(More)
The intrafascicular organization of human peripheral nerves was studied with percutaneous microneurography in the median, radial and peroneal nerves with one-surface or two-surface thin diameter concentric needle electrodes. Data from 33 recording sites containing 47 slowly adapting type II (SAII) units were analysed. At many sites two, sometimes even(More)
 To further study the functional organisation of human peripheral nerves, the intrafascicular arrangement of afferent fibres supplying Pacinian corpuscles (PCs) was explored by percutaneous microneurography using thin-calibre, concentric needle electrodes. In normal adults, 20 PC afferents were identified in 13 recording sites. Low-amplitude (less than 30(More)
Percutaneous microneurography was performed with concentric needle electrodes to record neural activity from myelinated fibres in human peripheral nerves. Template matching techniques were used together with interspike interval analysis and studies on functional class, receptive field characteristics, conduction velocities and other single fibre properties(More)
According to previous data peripheral nerves may lack a detailed microanatomical organization. Nevertheless, stimuli within restricted skin areas might excite more than one afferent of the same modality. Since, as recently demonstrated, peripheral myelinated afferents are at least partially organized by both modality and somatotopy it might be possible to(More)
Clustered rapidly adapting (RA) or slowly adapting type I (SA I) units recorded with concentric needle electrodes from median nerves of healthy human volunteers may exhibit overlapping receptive fields in the skin as also Paccini afferents (PC units) and slowly adapting type II unitary elements (SA II units) with their much larger innervation areas.(More)
 Using standardised concentric needle electrodes 170 single units were recorded from myelinated cutaneous afferents in the human median or ulnar nerves. The unitary waveforms were of four types: single-peaked monophasic potentials (type I), double-peaked monophasic potentials (type II), biphasic potentials (type III) and triphasic potentials (type IV). Type(More)
Percutaneous microneurography is a powerful technique allowing studies of activity in single nerve fibres of conscious humans. However, the mechanisms by which single-unit recordings are achieved with this technique are not fully understood. To further elucidate these mechanisms, dual-lead recordings, using a modified concentric needle electrode with two(More)
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