Like other senses, tactile perception is subject to adaptation effects in which systematic changes in the pattern of sensory input lead to predictable changes in perception. In this thesis, aftereffects of adaptation to tactile motion are used to reveal the processes that give rise to tactile motion perception from the relevant sensory inputs. The first aftereffect is the tactile speed aftereffect (tSAE), in which the speed of motion appears slower following exposure to a moving surface. Perceived speed of a test surface was reduced by about 30% regardless of the direction of the adapting stimulus, indicating that the tSAE is not direction sensitive. Additionally, higher adapting speeds produced a stronger tSAE, and this dependence on adapting speed could not be attributed to differences in temporal frequency or spatial period that accompanied the different adapting speeds. The second motion aftereffect that was investigated is the dynamic tactile motion aftereffect (tMAE), in which a direction-neutral test stimulus appears to move in the opposite direction to previously felt adapting motion. The strength of the tMAE depended on the speed of the adapting motion, with higher speeds producing a stronger aftereffect. Both the tSAE and the tMAE showed evidence of an intensive speed code in their underlying neural populations, with faster adapting speeds resulting in stronger aftereffects. In neither case was any evidence of speed tuning found, that is, neither aftereffect was strongest with a match between the speeds of the adapting and test stimuli. This is compatible with the response properties of motion sensitive neurons in the primary somatosensory cortex. Despite these shared features, speed and direction are unlikely to be jointly coded in the same neurons because the lack of direction sensitivity of the tSAE requires neural adaptation effects to be uniform across neurons preferring all directions, whereas the tMAE requires direction selective adaptation.
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