Neural and behavioral alterations of a real-time interpersonal distance (IPD) development process in differing social status interactions

概要

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学
（

位 論 文 要 約
A b s t r a c t ）

博士論文題目 Title of dissertation
Neural and behavioral alterations of a real-time interpersonal distance (IPD) development process
in differing social status interactions (対人距離形成過程におけるリアルタイムの神経・行動的変化：
異なる社会的地位の人同士と類似の社会的地位の人同士での比較)

東北大学大学院医学系研究科
機能医科学 講座
氏名 Name

障害科学 専攻

肢体不自由学

分野

黄 欣欣

Background: Interpersonal distance (IPD) is a physical distance between individuals, and we deal the IPD by
interacting with different people in our daily life under various situations. It is vital to make a systematical and
deepened comprehension of the IPD interactions as it contains rich non-verbal information in human social
interactions. IPD interactions provide a vivid and reliable reference for social relationship changes. Evidence showed
neural changes in IPD interaction, and neural activities are affected by relationships (such as friends or strangers).
Behavior studies also proved that social status strongly affects IPD between two persons. However, how the differing
social status impacts neural alterations in the IPD interactions remains unknown.
Objectives: The teacher-student relationship is a typical representation of the difference in social status. The present
study aims to investigate the IPD performance and brain processes underlying differing social status during the
development process from real-time teacher-student interactions. The present study tried to uncover the neural
changes in a series of IPD tasks under a real-time IPD developmental process. I also investigated the neural
differences in differing social status.
Methods: I designed three within-subject experiments corresponding to the inclusion, control, and affection stages of
IPD according to the Fundamental Interpersonal Relations Orientation (FIRO) theory. Altogether, 38 valid healthy
student participantsfrom Tohoku University participated in three experiments with a teacher (differing social status
condition, DS condition) and a peer student (peer social status condition, PS condition) separately. The present study
employed functional near-infrared

spectroscopy (fNIRS) which contains 16-channels cover the PFC area, and

modified real-time stop-distance paradigms to record IPD performance and neural processes. The IPD-Inclusion stage
contained the evaluation and action periods on active IPD and passive IPD tasks. IPD-Control stage included the
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deprivation and controllable processes in social IPD (1.2 m), personal IPD (0.6 m), and intimate IPD (0.3 m). IPD
Affection stage tested the IPD effects (positive or negative) on IPD performance and neural changes. The IPD
performance in the IPD-Inclusion and IPD-Affection stage were tested by repeated measure ANOVAs. The IPD
preferences in the IPD-Control stage was test by chi-square test. I calculated the activation channels by t-tests after
NIRS data processing by the NIRS-SPM software across three IPD stages. Moreover, three-way repeated measure
ANOVA was adopted to test the differences between the DS and PS conditions across three IPD stages. Besides,
correlations were performed by the Pearson correlations in the IPD-Inclusion and IPD-Affection stage.
Results: For IPD performance, significantly larger IPD gaps were shown in the DS condition than in the PS condition,
and IPD feedback affected IPD performance. For channel activations under IPD tasks, activated frontopolar area [FPA,
Brodmann area (BA) 10], dorsolateral prefrontal cortex (DLPFC, BA9/BA46), and Broca’s area (BA45) were
observed across the IPD stages. Specifically, in the IPD-Inclusion stage, activation channels located in the FPA (BA10)
in evaluating the passive IPD were both found in the DS and PS conditions; and channels in FPA (BA10), DLPFC
(BA9/BA45), and Broca’s area (BA45) were activated to the IPD actions. I also found enhanced channels in the FPA
(BA10) and DLPFC (BA9/BA46) in the intimated IPD (0.3 m) of the IPD-Control stage. In the IPD-Affection stage,
channels activated in the FPA (BA10), DLPFC (BA9/BA46), and Broca’s area (BA45) during the evaluation period
after IPD feedback both in the DS and PS conditions. In addition, results showed that differences in Oxy-Hb changes
were located in the FPA(BA10), DLPFC (BA9/BA46), and Broca’s area (BA45) between the DS and PS conditions
across IPD stages based on the IPD tasks. Additionally, negative correlations were found between Oxy-Hb changes
and IPD performance.
Conclusions: We propose prefrontal cortex (PFC) and Broca’s area involvement in IPD interactions, initially focusing
on evaluation and action periods, and later on IPD evaluation processes after feedback. In addition, a difference in
Oxy-Hb activities implies the complexity of relationships and social status in IPD interactions. Therefore, I proposed
that the IPD performance be impacted by social status and that FPA (BA10), DLPFC(BA9/BA46), and Broca’s area
(BA45) play critical roles in real-time differing social status IPD interactions. The present study demonstrated the
nature of behavior and neural changes in differing social status IPD interactions under real-time IPD development. ...