Human Brain Activity Related to the Tactile Perception of Stickiness.
While the perception of stickiness serves as one of the fundamental dimensions for tactile sensation, little has been elucidated about the stickiness sensation and its neural correlates. The present study investigated how the human brain responds to perceived tactile sticky stimuli using functional magnetic resonance imaging (fMRI). To evoke tactile perception of stickiness with multiple intensities, we generated silicone stimuli with varying catalyst ratios. Also, an acrylic sham stimulus was prepared to present a condition with no sticky sensation. From the two psychophysics experiments-the methods of constant stimuli and the magnitude estimation-we could classify the silicone stimuli into two groups according to whether a sticky perception was evoked: theSupra-thresholdgroup that evoked sticky perception and theInfra-thresholdgroup that did not. In theSupra-thresholdvs.Shamcontrast analysis of the fMRI data using the general linear model (GLM), the contralateral primary somatosensory area (S1) and ipsilateral dorsolateral prefrontal cortex (DLPFC) showed significant activations in subjects, whereas no significant result was found in theInfra-thresholdvs.Shamcontrast. This result indicates that the perception of stickiness not only activates the somatosensory cortex, but also possibly induces higher cognitive processes. Also, theSupra- vs. Infra-thresholdcontrast analysis revealed significant activations in several subcortical regions, including the pallidum, putamen, caudate and thalamus, as well as in another region spanning the insula and temporal cortices. These brain regions, previously known to be related to tactile discrimination, may subserve the discrimination of different intensities of tactile stickiness. The present study unveils the human neural correlates of the tactile perception of stickiness and may contribute to broadening the understanding of neural mechanisms associated with tactile perception.
Brain-Computer Interface Lab, Department of Human Factors Engineering, Ulsan National Institute of Science and Technology Ulsan, South Korea.
Jiwon
J
Yeon
Brain-Computer Interface Lab, Department of Human Factors Engineering, Ulsan National Institute of Science and TechnologyUlsan, South Korea; Department of Brain and Cognitive Engineering, Korea UniversitySeoul, South Korea.
Junsuk
J
Kim
Center for Neuroscience Imaging Research, Institute for Basic ScienceSuwon, South Korea; Department of Biomedical Engineering, Magnetic Resonance Advanced Imaging Research Lab, Sungkyunkwan UniversitySuwon, South Korea.
Jaekyun
J
Ryu
Center for Neuroscience Imaging Research, Institute for Basic ScienceSuwon, South Korea; Department of Biomedical Engineering, Magnetic Resonance Advanced Imaging Research Lab, Sungkyunkwan UniversitySuwon, South Korea.
Jang-Yeon
JY
Park
School of Biomedical Engineering, Konkuk University Chungju, South Korea.
Soon-Cheol
SC
Chung
Brain-Computer Interface Lab, Department of Human Factors Engineering, Ulsan National Institute of Science and Technology Ulsan, South Korea.
Sung-Phil
SP
Kim
fMRI; human perception; neural correlates; stickiness; tactile