Somatosensory Cortex: Neural Coding of Motion
The tactile perception of motion involves the perception of movement of an object across the skin. Neural processing in the somatosensory cortex transforms the information originating from populations of afferents into a percept of the direction and speed of the tactile motion.
Two Sources of Tactile Motion Information
The perception of tactile motion is thought to rely on two types of signals at the somatosensory periphery: the sequential activation of slowly adapting type 1 (SA1) (Johansson and Vallbo 1979) and rapidly adapting (RA) afferents (Kirman 1974; Sherrick and Rogers 1966) as an object moves across the skin and the activation of slowly adapting type 2 (SA2) afferents (Olausson et al. 2000) caused by friction-induced skin stretch resulting from motion (Olausson and Norrsell 1993).
Direction Tuning Emerged in the Primary Somatosensory Cortex
SA1 and RA afferents encode...