武田 湖太郎

Functional near-infrared spectroscopy (fNIRS) is an optical neuroimaging method for recording cerebral hemodynamics. Tolerance of motion is considered an advantage of fNIRS when compared with other imaging techniques. However, fNIRS signals are often contaminated by scalp blood flow (SBF) signals due to motion of the subject. In the present study, we recorded changes in the concentrations of oxygenated and deoxygenated hemoglobin by multidistance source-detector probes during whole body tilting with the head and trunk fixed, and demonstrated that the change in body direction against gravity causes SBF signal contamination. Non-negligible parallel changes in oxygenated and deoxygenated hemoglobin during trunk tilt were observed in long-distance channels (conventional 30 mm), as well as those in short-distance channels (15 mm) reflecting SBF changes. Because the tilt angle-dependent changes in the long channels were correlated highly with those in the short channels, the fluctuation caused by the trunk tilt could be considered SBF signal contamination. The contamination was successfully removed by a multidistance method and by a hemodynamic modality separation method.

Purpose: The hand mental rotation task (HMRT), in which participants judge whether a picture of a hand is of the left or right hand, is thought to induce a participant’s motor imagery. This application of this task in rehabilitation has begun. However, the task performance strategy used on presentation with a picture of the back of the hand and the palm in elderly individuals has not been sufficiently elucidated. In this study, we examined the performance strategy of the HMRT in response to pictures of the back of the hand and the palm among elderly individuals. Participants and methods: A total of 75 right-handed individuals aged 65 years or older (38 men and 37 women, 74.9 ± 5.8 years old) were included in this study. From the position in which the middle finger was located at 0 degrees vertically, the pictures of the left/right hand and the back of the hand/the palm were turned in increments of 60 degrees in presentation, and the response time (RT) and correctness of responses were recorded. The RT to the left and right arrows was also measured, and the ΔRT was derived by subtracting the RT to the arrows from the RT to the hand pictures. A repeated measures ANOVA was conducted on the ΔRT with three factors: whether the hand was left or right, whether the back of the hand or the palm of the hand was pictured, and the presented angle. Conclusions: We suggest that the motor imagery strategy was combined with the visual imagery strategy when pictures of the back of the hand were presented and that the motor imagery strategy was used when pictures of the palm were presented. These results indicate that frequent use of pictures of the palm may be effective when the HMRT is used for rehabilitation of elderly individuals.