title: Interpersonal frontopolar neural synchronization in group communication: An exploration toward fNIRS hyperscanning of natural interactions.
abstract: Research of interpersonal neural synchronization (INS) using functional near-infrared spectroscopy (fNIRS) hyperscanning is an expanding nascent field. This field still requires the accumulation of findings and establishment of analytic standards. In this study, we therefore intend to extend fNIRS-based INS research in three directions: (1) verifying the enhancement of frontopolar INS by natural and unstructured verbal communication involving more than two individuals; (2) examining timescale dependence of the INS modulation; and (3) evaluating the effects of artifact reduction methods in capturing INS. We conducted an fNIRS hyperscanning study while 12 groups of four subjects were engaged in cooperative verbal communication. Corresponding to the three objectives, our analyses of the data (1) confirmed communication-enhanced frontopolar INS, as expected from the region's roles in social communication; (2) revealed the timescale dependency in the INS modulation, suggesting the merit of evaluating INS in fine timescale bins; and (3) determined that removal of the skin blood flow component engenders substantial improvement in sensitivity to communication-enhanced INS and segregation from artifactual synchronization, and that caution for artifact reduction preprocessing is needed to avoid excessive removal of the neural fluctuation component. Accordingly, this study provides a prospective technical basis for future hyperscanning studies during daily communicative activities.
authors.affiliation: Department of Ubiquitous Sensing, Institute of Development, Aging and Cancer, Tohoku University, Sendai 980-8575, Japan. Electronic address: takayuki.nozawa.b5@tohoku.ac.jp.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nozawa
authors.affiliation: Department of Functional Brain Imaging, Institute of Development, Aging and Cancer, Tohoku University, Sendai 980-8575, Japan.
authors.forename: Yukako
authors.initials: Y
authors.lastname: Sasaki
authors.affiliation: Department of Functional Brain Imaging, Institute of Development, Aging and Cancer, Tohoku University, Sendai 980-8575, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Sakaki
authors.affiliation: Department of Functional Brain Imaging, Institute of Development, Aging and Cancer, Tohoku University, Sendai 980-8575, Japan; School of Medicine, Kobe University, Kobe 650-0017, Japan.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Yokoyama
authors.affiliation: Department of Ubiquitous Sensing, Institute of Development, Aging and Cancer, Tohoku University, Sendai 980-8575, Japan; Department of Functional Brain Imaging, Institute of Development, Aging and Cancer, Tohoku University, Sendai 980-8575, Japan.
authors.forename: Ryuta
authors.initials: R
authors.lastname: Kawashima
mesh_terms: D001931:Brain Mapping / Q000379:methods*; D003142:Communication; D003344:Cortical Synchronization / Q000502:physiology*; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods*; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D017397:Prefrontal Cortex / Q000502:physiology*; D012680:Sensitivity and Specificity; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D055815:Young Adult
keywords: Artifact reduction; Hyperscanning; Interpersonal neural synchronization; Skin blood flow; Social cognition; fNIRS