Abstract
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: the Supra-threshold group that evoked sticky perception and the Infra-threshold group that did not. In the Supra-threshold vs. Sham contrast 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 the Infra-threshold vs. Sham contrast. This result indicates that the perception of stickiness not only activates the somatosensory cortex, but also possibly induces higher cognitive processes. Also, the Supra- vs. Infra-threshold contrast 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.
Highlights
People commonly place less importance on tactile than visual or auditory senses (Goldstein, 2013), the sense of touch is crucial for humans in interacting with the environment
We examined the BOLD effect of the stickiness perception by the Supra-threshold vs. Sham contrast and found that the contralateral postcentral gyrus (BA 1–3, S1) and ipsilateral middle frontal gyrus (BA 9, dorsolateral prefrontal cortex (DLPFC)) were significantly activated when participants felt stickiness in their index finger (Figure 4A, Table 1)
We presented participants with siliconebased sticky stimuli to induce tactile feelings of stickiness with different intensities
Summary
People commonly place less importance on tactile than visual or auditory senses (Goldstein, 2013), the sense of touch is crucial for humans in interacting with the environment. Previous works on the perceptual dimensions of tactile textures suggest 2–5 distinctive dimensions (Hollins et al, 2000; Ballesteros et al, 2005; Yoshioka et al, 2007; Tiest, 2010; Okamoto et al, 2013; Bensmaia, 2015). Hollins et al (2000) investigated the tactile texture perception of 17 different materials using the multidimensional scaling (MDS) method and constructed three fundamental dimensions representing ‘‘Rough/Smooth’’, ‘‘Soft/Hard’’ and ‘‘Sticky/Slippery’’. In addition to those three dimensions, other psychophysical studies have suggested ‘‘warm/cold’’ as another fundamental perceptual dimension (Tiest, 2010; Bensmaia, 2015). Taking a consensus of those previous findings, tactile sensation can generally be classified in four fundamental dimensions: roughness, hardness, stickiness and warmness
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
