ABSTRACT
The somatosensory function of humans spans over several modalities, including the ability to perceive mechanical, thermal, and chemical stimuli. Impairment of this function can be a major feature of neurological diseases. Objective measurement of the nature and degree of sensory disturbances is needed to understand and characterize disorders and to evaluate the treatments for these disorders. The superficial layers of the skin are essential for the induction of the sensations of pain, temperature, and touch sensation. The skin is richly provided with sensory nerve fibers. These fibers are connected with various specialized receptor structures such as corpuscles and hair follicles or end up as free, naked nerve endings. A general definition of a threshold as being the intensity of a stimulus that produces a response 50% of the times it is applied. The psychophysical threshold or “sensory” threshold in clinical parlance is the minimal energy required to reach perception.
