Neural correlates of tactile hardness intensity perception during active grasping

Ji-Hyun Kim; Junsuk Kim; Jiwon Yeon; Jang-Yeon Park; Dongil Chung; Sung-Phil Kim

doi:10.7717/peerj.11760

Neural correlates of tactile hardness intensity perception during active grasping

PeerJ. 2021 Aug 2:9:e11760. doi: 10.7717/peerj.11760. eCollection 2021.

Authors

Ji-Hyun Kim¹, Junsuk Kim², Jiwon Yeon³, Jang-Yeon Park^{4

5}, Dongil Chung¹, Sung-Phil Kim¹

Affiliations

¹ Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea.
² Department of Industrial ICT Engineering, Dong Eui University, Busan, Republic of Korea.
³ Department of Psychology, Georgia Institute of Technology, Atlanta, Georgia, United States.
⁴ Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea.
⁵ Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, Republic of Korea.

Abstract

While tactile sensation plays an essential role in interactions with the surroundings, relatively little is known about the neural processes involved in the perception of tactile information. In particular, it remains unclear how different intensities of tactile hardness are represented in the human brain during object manipulation. This study aims to investigate neural responses to various levels of tactile hardness using functional magnetic resonance imaging while people grasp objects to perceive hardness intensity. We used four items with different hardness levels but otherwise identical in shape and texture. A total of Twenty-five healthy volunteers participated in this study. Before scanning, participants performed a behavioral task in which they received a pair of stimuli and they were to report the perceived difference of hardness between them. During scanning, without any visual information, they were randomly given one of the four objects and asked to grasp it. We found significant blood oxygen-level-dependent (BOLD) responses in the posterior insula in the right hemisphere (rpIns) and the right posterior lobe of the cerebellum (rpCerebellum), which parametrically tracked hardness intensity. These responses were supported by BOLD signal changes in the rpCerebellum and rpIns correlating with tactile hardness intensity. Multidimensional scaling analysis showed similar representations of hardness intensity among physical, perceptual, and neural information. Our findings demonstrate the engagement of the rpCerebellum and rpIns in perceiving tactile hardness intensity during active object manipulation.

Keywords: Active grasping; Brain; GLM; Hardness; Tactile; fMRI.

Grants and funding

This work was supported by an NRF Grant funded by the Korean Government (NRF-2018-Global Ph.D. Fellowship Program), the U-K (UNIST-Ulsan, South Korea) research brand program (1.210046.01) funded by UNIST (Ulsan National Institute of Science & Technology, Ulsan, South Korea) and the Brain Convergence Research Program of the National Research Foundation (NRF) funded by the Korean government (MSIT) (NRF-2019M3E5D2A01058328). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.