D a midrange exemplar as a 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 the silicone stimuli. Participants touched the two references with their appropriate index finger, 1 at a time beginning with all the sham stimulus. They have been informed that the intensity values of stickiness had been 0 and 70 for the sham and 7 stimuli, respectively, where the intensity values have been arbitrarily assigned for quantification in our experiment. Following this initial calibration, participants performed the trials of magnitude estimation. In every single trial, participants initially touched the two reference stimuli, followed by experiencing one of several eight stimuli (5 , six , 7 , eight , 9 , ten , 15 and 30 ), and verbally reported the perceived intensity of stickiness of the provided stimulus. Participants have 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. Because our pilot study indicated that tactile stickiness was perceived with all the stimuli with significantly less than or equal towards the Rubrofusarin Data Sheet catalyst ratio of 7 , we chosen the 5 and six stimuli, including the 7 stimulus inside the test set. Amongst the stimuli larger than 7 , we chose the 8 and 30 stimuli, which corresponded for the minimum and maximum catalyst ratios, respectively. The 10 stimulus relating for the regular catalyst ratio for PDMS was also added towards the test stimulus set. Lastly, the acrylic sham stimulus was utilized for presenting a non-sticky stimulation. To sum up, the 5 , six , 7 , eight , ten and 30 silicone stimuli also as the acrylic sham stimulus had been applied for fMRI experiments to investigate neural responses towards the stimuli with various intensities of stickiness. Participants underwent two scanning sessions and T1 structure pictures have been taken in between the sessions. For the duration of the functional image acquisition session, participants had been comfortably laid in a supine position though holding their right hand down on the MRI bed in a pronation position. They wore a MRI-compatible headphone to listen to the guidelines for the duration of the experiment. The participants’ heads have been fixed to prevent movement artifacts by inserting two foam cushions in to the space amongst the head plus the head coil. An event-related paradigm was adopted in our experiment. The procedure 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 Florfenicol amine supplier experimenter in the MRI area. Prior to a stimulus was provided, participants had been relaxed using the “Resting” finger position. Then, when participants heard the verbal instruction of your “Ready (“Jun-bee” in Korean)”, they attached their ideal index finger towards the provided stimulus and maintained the pose for 3 s until they heard a brief beep sound indicating for them to cease. After participants detached their finger in the stimulus in the beep sound, they stayed in the “Resting” posture once more for 15 s till the next trial. Each and every of the 7 stimuli was presented ten instances inside a random order, in order that a single scanning session consisted of 70 trials. At the starting of every session, there was a 6-s interval and, therefore, each and every session took approx.