ABSTRACT
The neural pathway that is connected to a single class of sensory receptor and which, when stimulated, gives rise to a readily identifiable type of sensation is called a labeled line. The correspondence between receptor class and the nature of the sensation occurs because a sensory receptor responds only to a specific type of stimulus. Individual receptors may vary in the strength of the stimulus that will make their afferent fire on 50% of the occasions it is delivered, the threshold stimulus. Individual warm thermoreceptors respond over different ranges of temperature, that is, they differ in the dynamic range over which they operate. Many perceived sensations do not correspond to what can be produced by activating a single labeled line. These compound sensations arise from the activation of several receptor types by a single stimulus.
