Size Perception and Localisation of Sensations from Single Mechanoreceptive Units in Man

Abstract

In assessing the functional role played by individual mecha-noreceptive unit types in sensation, it is not sufficient to study the organisation and physiology of their cutaneous endings. Such characteristics as receptor response properties and unit innervation density define the quality and quantity of the raw inflow from cutaneous mechanoreceptors. But all perceptual experience is the result of cortical processing of afferent signals, and central rather than peripheral factors may determine which signals are given priority. Some inputs may be enhanced at successive relay stations, some may be inhibited and some may be entirely prevented from reaching consciousness, while still playing a role e.g. in proprioception. Psychophysical methods in combination with microneurography are therefore necessary in order to establish how the human brain deals with single unit somatic inputs: whether, for instance, signals from all mechanoreceptor types and from all skin regions are given equal treatmen.t