The Cutaneous Receptor and the Concept of “Specificity”

Abstract

The general concept of “specificity” of cutaneous receptors has evolved from the views expressed by Johannes Müller as early as 1826.⁸⁹ In their essence these views have come to be known as the “law of specific nerve energies.” Müller was writing at a time when, according to the prevailing interpretation, the sensory nerves were considered to be merely passive conductors, transmitting centrally the physical qualities of whatever external stimulus might be applied to them. He took exception to this view. He called attention to the fact that mechanical or electrical stimulation of the nerves of each special sense organ called forth sensations appropriate to that organ, and no other. He said:⁸⁹ “Mechanical irritation excites in one nerve a luminous spectrum; in another, a humming sound; in a third, pain. An increase of the stimulus of the blood causes in one organ spontaneous sensations of light; in another, sound; in a third, itching, pain, etc.—We do not feel the knife which gives us pain, but the painful state of our nerves.—Sensation, therefore, consists in the communication to the sensorium, not of the quality or state of the external body, but the condition of the nerves themselves, excited by the external cause.”