Brain Organization during Passive Touch and Tactile Discrimination and the Influence of Learning -a Functional MRI Study-

Abstract

[Purpose] We evaluated brain organization during passive touch and tactile discrimination using functional magnetic resonance imaging and examined the influence of learning. [Methods] The subjects were 7 persons who were experienced Mahjong player and were able to distinguish a Mahjong tile pattern by thumb touch without visual clues and 10 persons who were novices with no Mahjong experience. During magnetic resonance imaging, all subjects lay resting in the supine position, with their eyes closed. They were given touch and tactile discrimination tasks using the dominant thumb. [Results] In both groups, contralateral (thumb) sensorimotor cortex activation occurred during touch and bilateral sensorimotor cortex activation occurred during tactile discrimination. In both groups, there was a significant difference between the touch and tactile discrimination tasks. Compared to touch, the activation area was significantly increased during tactile discrimination. No significant between group difference was observed in either the touch or tactile discrimination task, but during tactile discrimination, the activation area tended to be larger in the experienced group. [Conclusion] Brain organization clearly differed between passive touch and passive tactile discrimination. Our findings suggest that with passive tactile discrimination, brain area activation may increase with learning.