Touch, pain and tickling: an electro‐physiological investigation on cutaneous sensory nerves

IN 1933 Blair and Erlanger demonstrated that the recorded spike heights of axone potentials from a phalangeal nerve preparation of the frog varied as their rate of conduction. On the assumption that the intrinsic potential is independent of fibre size the recorded spike heights vary as the diameters squared. Their result offers the possibility of computing the relative rate of axone potentials recorded from sensory nerves in response to various stimuli applied to their receptors. Such a procedure was adopted in some recent investigations on the lingual nerve [Zotterman, 1936]. The present research was started in order to study the response of the thinnest afferent fibres to various stimuli applied to the skin. When records of axone potentials from the thinnest nerve fibres had been obtained attempts were made to measure their rate of conduction directly. This was possible for fibres conducting at rates down to 10 m./ sec. Slower potentials than these, however, could not be measured. Although direct measurements of the slowest rates have not yet been made, the present data concerning the larger fibres provide some fixed points for the correlation of results from different experiments.