Extracellular Single Fibre Recording Technique for Peripheral Nerves without Section of Nerve or Incision of Perineurium

Abstract

Two main techniques are at present in use to obtain electrophysiological data from single afferent fibres in mammalian and reptilian nerves. (1) The nerve trunk is severed and successively fractionated until the stage is reached at which a fine strand (or strands) gives a unit response. This method suffers from the disadvantage that the nerve trunk is severely damaged and only a few fibres can be investigated in each experiment—an inevitably non-representative sample of the nerve fibre (or receptor) spectrum. (2) A micro-electrode is inserted into the dorsal root or its ganglion, from which extra- or intra-cellular single unit recordings are made. In this case a representative sample of all dorsal root fibres can be taken, but it is impossible to obtain a true sample of the fibres supplying a particular area of skin. Several isolated reports also describe extracellular^1–5 and intra-cellular⁶ records made with micro-electrodes inserted blindly into nerve trunks, but no generally applicable technique has yet emerged.