American Physiological Society Acta Medica Okayama 0022-3077 122 5 2019 Tactile angle discriminability improvement: roles of training time intervals and different types of training tasks 1918 1927 EN Wu Wang Graduate School of Natural Science and Technology, Okayama University Jiajia Yang Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama Qiong Wu Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University Jiabin Yu Graduate School of Natural Science and Technology, Okayama University Satoshi Takahashi Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University Yoshimichi Ejima Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University Jinglong Wu Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University Perceptual learning, which is not limited to sensory modalities such as vision and touch, emerges within a training session and between training sessions and is accompanied by the remodeling of neural connections in the cortex. However, limited knowledge exists regarding perceptual learning between training sessions. Although tactile studies have paid attention to between-session learning effects, there have been few studies asking fundamental questions regarding whether the time interval between training sessions affects tactile perceptual learning and generalization across tactile tasks. We investigated the effects of different training time intervals on the consecutive performance of a tactile angle discrimination (AD) task and a tactile orientation discrimination (OD) task training on tactile angle discriminability. The results indicated that in the short-interval training group, AD task performance significantly improved in the early stage of learning and nearly plateaued in the later stage, whereas in the long-interval training group, significant improvement was delayed and then also nearly plateaued in the later stage; additionally, improved OD task performance resulted in improved AD task performance. These findings suggest that training time interval affects the early stage of learning but not the later stage and that generalization occurs between different types of tactile tasks. No potential conflict of interest relevant to this article was reported.

Elsevier Acta Medica Okayama 24058440 5 8 2019 Stroking hardness changes the perception of affective touch pleasantness across different skin sites e02141 EN Jiabin Yu Cognitive Neuroscience Laboratory, Graduate School of Natural Science and Technology, Okayama University Jiajia Yang Cognitive Neuroscience Laboratory, Graduate School of Interdisciplinary, Science and Engineering in Health Systems, Okayama University Yinghua Yu Cognitive Neuroscience Laboratory, Graduate School of Interdisciplinary, Science and Engineering in Health Systems, Okayama University Qiong Wu Cognitive Neuroscience Laboratory, Graduate School of Interdisciplinary, Science and Engineering in Health Systems, Okayama University Satoshi Takahashi Cognitive Neuroscience Laboratory, Graduate School of Interdisciplinary, Science and Engineering in Health Systems, Okayama University Yoshimichi Ejima Cognitive Neuroscience Laboratory, Graduate School of Interdisciplinary, Science and Engineering in Health Systems, Okayama University Jinglong Wu Cognitive Neuroscience Laboratory, Graduate School of Interdisciplinary, Science and Engineering in Health Systems, Okayama University Human unmyelinated tactile afferents (CT afferents) in hairy skin are thought to be involved in the transmission of affective aspects of touch. How the perception of affective touch differs across human skin has made substantial progress; however, the majority of previous studies have mainly focused on the relationship between stroking velocities and pleasantness ratings. Here, we investigate how stroking hardness affects the perception of affective touch. Affective tactile stimulation was given with four different hardness of brushes at three different forces, which were presented to either palm or forearm. To quantify the physical factors of the stimuli (brush hardness), ten naïve, healthy participants assessed brush hardness using a seven-point scale. Based on these ten participants, five more participants were added to rate the hedonic value of brush stroking using a visual analogue scale (VAS). We found that pleasantness ratings over the skin resulted in a preference for light, soft stroking, which was rated as more pleasant when compared to heavy, hard stroking. Our results show that the hairy skin of the forearm is more susceptible to stroking hardness than the glabrous of the palm in terms of the perception of pleasantness. These findings of the current study extend the growing literature related to the effect of stroking characteristics on pleasantness ratings. No potential conflict of interest relevant to this article was reported.