Xu Mingdi, Hoshino Eiichi, Yatabe Kiyomi, Matsuda Soichiro, Sato Hiroki, Maki Atsushi, Yoshimura Mina, Minagawa Yasuyo
Department of Psychology, Faculty of Letters, Keio UniversityYokohama, Japan; Center for Life-Span Development of Communication Skills, Keio UniversityYokohama, Japan.
Department of Psychology, Faculty of Letters, Keio UniversityYokohama, Japan; Global Centre for Advanced Research on Logic and Sensibility, Keio UniversityTokyo, Japan.
Front Hum Neurosci. 2017 Jan 10;10:676. doi: 10.3389/fnhum.2016.00676. eCollection 2016.
The present study used functional near-infrared spectroscopy (fNIRS) to measure 5- to 6-month-old infants' hemodynamic response in the prefrontal cortex (PFC) to visual stimuli differing in saliency and social value. Nineteen Japanese 5- to 6-month-old infants watched video clips of Peek-a-Boo (social signal) performed by an anime character (AC) or a human, and hand movements without social signal performed by an AC. The PFC activity of infants was measured by 22-channel fNIRS, while behaviors including looking time were recorded simultaneously. NIRS data showed that infants' hemodynamic responses in the PFC generally decreased due to these stimuli, and the decrease was most prominent in the frontopolar (FP), covering medial PFC (MPFC), when infants were viewing Peek-a-Boo performed by an AC. Moreover, the decrease was more pronounced in the dorsolateral PFC (DLPFC) when infants were viewing Peek-a-Boo performed by an AC than by a human. Accordingly, behavioral data revealed significantly longer looking times when Peek-a-Boo was performed by an AC than by a human. No significant difference between Peek-a-Boo and non-Peek-a-Boo conditions was observed in either measure. These findings indicate that infants at this age may prefer stimuli with more salient features, which may be more effective in attracting their attentions. In conjunction with our previous findings on responses to self-name calling in infants of similar age, we hypothesize that the dynamic function of the MPFC and its vicinity (as part of default mode network (DMN): enhanced by self-focused stimuli, attenuated by externally focused stimuli), which is consistently observed in adults, may have already emerged in 5- to 6-month-old infants.
本研究使用功能近红外光谱技术（fNIRS）来测量5至6个月大婴儿前额叶皮质（PFC）对显著性和社会价值不同的视觉刺激的血流动力学反应。19名5至6个月大的日本婴儿观看了由动漫角色（AC）或人类表演的躲猫猫（社交信号）视频片段，以及由AC表演的无社交信号的手部动作。通过22通道fNIRS测量婴儿的PFC活动，同时记录包括注视时间在内的行为。近红外光谱数据显示，由于这些刺激，婴儿PFC的血流动力学反应总体上有所下降，当婴儿观看由AC表演的躲猫猫时，这种下降在额极（FP）最为明显，覆盖内侧前额叶皮质（MPFC）。此外，当婴儿观看由AC表演的躲猫猫时，背外侧前额叶皮质（DLPFC）的下降比观看由人类表演的躲猫猫时更为明显。因此，行为数据显示，由AC表演躲猫猫时的注视时间明显长于由人类表演时。在这两种测量中，躲猫猫和非躲猫猫条件之间均未观察到显著差异。这些发现表明，这个年龄段的婴儿可能更喜欢具有更显著特征的刺激，这可能在吸引他们的注意力方面更有效。结合我们之前关于同龄婴儿对叫自己名字的反应的研究结果，我们假设，在成年人中一直观察到的MPFC及其附近区域的动态功能（作为默认模式网络（DMN）的一部分：由自我关注刺激增强，由外部关注刺激减弱）可能在5至6个月大的婴儿中已经出现。
