Measuring neural activity during communication is essential for understanding social brain processes and contributes to improving the diagnosis and treatment of communication disorders. Hyperscanning (simultaneous recording of brain activity from multiple individuals) is a highly effective method for this purpose. Magnetoencephalography (MEG) hyperscanning is particularly suitable owing to its high spatiotemporal resolution. However, conventional MEG with superconducting quantum interference devices (SQUIDs) is cumbersome and requires liquid helium to maintain superconductivity. Moreover, the rising cost of liquid helium is currently a major obstacle in SQUID-based MEG operation. In contrast, novel optically pumped magnetometer (OPM)-MEG is gaining attention because it is compact, portable, and does not require liquid helium for operation. However, OPM-MEG remains costly, and its widespread adoption is expected to take time. Therefore, until OPM-MEG becomes more widely available, a hybrid hyperscanning approach combining OPM-MEG and SQUID-MEG may be a more practical solution. In the present study, we constructed a hyperscanning system using a 48-channel OPM-MEG (HEDscan, FieldLine) and a 306-channel SQUID-MEG (Vectorview, Elekta Neuromag). Twelve pairs of adults (14 women and 10 men), aged 21.5 ± 2.7 years, participated in a turn-taking verbal communication task with meaningful words and meaningless syllables. We calculated normalized amplitudes of alpha band activity during the 2-s pre-speech interval and performed a two-way mixed-design analysis of variance (ANOVA) with MEG type (OPM and SQUID) as the between-subjects factor and condition (meaningful and meaningless) as the within-subjects factor. ANOVA revealed no significant interaction and no main effect related to MEG type F(1, 22) = 0.171, p = 0.684; F(1, 22) = 0.061, p = 0.807, respectively. In contrast, there was a significant main effect of condition F(1, 22) = 11.489, p = 0.003, which indicated that the normalized amplitude of alpha band activity during the meaningless condition was larger than that of the meaningful condition. This finding is consistent with previous research using a SQUID-MEG hyperscanning system, indicating successful measurement of differing brain activities across conditions regardless of MEG sensors. This study demonstrates the feasibility of hyperscanning using OPM-MEG and SQUID-MEG.
USHIJIMA et al. (Thu,) studied this question.