DEMONSTRATION OF A-FIBER AFFERENTS WITH OVERLAPPING RECEPTIVE-FIELDS IN HUMANS

ACCORDING to previous data peripheral nerves may lack a detailed micro anatomical 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 leas t partially organized by both modality and somatotopy it might be poss ible to demonstrate such a phenomenon electrophysiologically provided that adequate procedures are used. To address this issue we recorded a ctivity in single myelinated afferents supplying the hand with concent ric needle electrodes. A combination of electrical and/or natural stim uli applied to the area where rapidly adapting (RA) or slowly adapting type I (SAI) fibres ended demonstrated that fibres of the same functi onal class may exhibit overlapping receptive fields in the skin.