Assessments
CORTEX, BRAIN
The assessments included a ball-rotation task, brain activity during the ball-rotation task, kinesthetic illusion, sense of body ownership, and sense of agency using a seven-point Likert scale.The ball-rotation task was performed with a 38-mm-diameter ball, and the participants were asked to perform it as quickly as possible with their left hand without letting the ball fall. The participants sat in a chair and performed the task on a table. A block design was used to simultaneously measure the brain activity in two sets: rest (5 s), task (20 s), rest (5 s) (Fig. Brain activity was measured using fNIRS (LABNIRS, Shimadzu Co., Ltd., Kyoto, Japan). This device produced a continuous wave with wavelengths of 780, 805, and 850 nm. fNIRS measures oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) based on the modified Beer–Lambert lawRegion of interest using the functional near-infrared spectroscopy. The probe position was set to 40 channels using 25 probes (13 sources and 12 detectors) of 5 × 5. The probe distance was set at 3 cm. The regions of interest were the dorsolateral prefrontal cortex (DLPFC, channels 1–4), frontal eye field (FEF, channels 5–9), premotor cortex (PMC, channels 10–22), primary motor area (M1, channels 23–27), somatosensory area (Sa, channels 28–31), and parietal area (Pa, channels 32–40).The seven-point Likert scale was used to assess the degree of kinesthetic illusion, sense of body ownership, and sense of agency