D a midrange exemplar as a (-)-Bicuculline methochloride Antagonist reference for the magnitude estimation test (Eadie and Doyle, 2002; Weismer and Laures, 2002). The outcome from the pilot experiment (see above) showed that the 7 stimulus was the midrange stimulus amongst all of the silicone stimuli. Participants touched the two references with their right index finger, one particular at a time beginning with the sham stimulus. They have been informed that the intensity values of stickiness have been 0 and 70 for the sham and 7 stimuli, respectively, where the intensity values were arbitrarily assigned for quantification in our experiment. Immediately after this initial calibration, participants performed the trials of magnitude estimation. In every single trial, participants 1st touched the two reference stimuli, followed by experiencing one of many eight stimuli (5 , 6 , 7 , 8 , 9 , ten , 15 and 30 ), and verbally reported the perceived intensity of stickiness on the provided stimulus. Participants had been instructed to report thefMRI ExperimentsAs this study aimed to discover brain regions underlying the tactile perception of stickiness, our investigation focused on the brain responses in the threshold of stickiness perception. Considering the fact that our pilot study indicated that tactile stickiness was perceived together with the stimuli with less than or equal to the catalyst ratio of 7 , we chosen the five and 6 stimuli, such as the 7 stimulus in the test set. Among the stimuli larger than 7 , we chose the 8 and 30 stimuli, which corresponded towards the minimum and maximum catalyst ratios, respectively. The 10 stimulus relating towards the typical catalyst ratio for PDMS was also added for the test stimulus set. Lastly, the acrylic sham stimulus was utilized for presenting a non-sticky stimulation. To sum up, the 5 , 6 , 7 , 8 , 10 and 30 silicone stimuli too because the acrylic sham stimulus had been used for fMRI experiments to investigate neural responses to the stimuli with various intensities of stickiness. Participants underwent two scanning sessions and T1 structure images were taken amongst the sessions. Through the functional image acquisition session, participants were comfortably laid inside a supine position though holding their ideal hand down on the MRI bed in a pronation position. They wore a MRI-compatible headphone to listen to the instructions for the duration of the experiment. The participants’ heads have been fixed to stop movement artifacts by inserting two foam cushions into the space between the head and the head coil. An event-related paradigm was adopted in our experiment. The process forFrontiers in Human Neuroscience | www.frontiersin.orgJanuary 2017 | Volume 11 | ArticleYeon et al.Neural Correlates of Tactile Stickinesseach trial is depicted in Figure 1. The stimulus presentation was carried out manually by an experimenter in the MRI room. Prior to a stimulus was offered, participants were relaxed using the “Resting” finger position. Then, when participants heard the verbal instruction with the “Ready (“Jun-bee” in Korean)”, they attached their suitable index finger to the offered stimulus and maintained the pose for three s until they heard a short beep sound indicating for them to stop. Immediately after participants detached their finger from the stimulus in the beep sound, they stayed in the “Resting” posture again for 15 s until the o-Methoxycinnamaldehyde supplier following trial. Each on the 7 stimuli was presented 10 occasions inside a random order, to ensure that a single scanning session consisted of 70 trials. In the beginning of every session, there was a 6-s interval and, hence, each and every session took approx.