婴儿社会和情绪脑机制的早期发展

能够快速扫描并锁定周围环境中可能存在的危险刺激并给予优先反应对人类生存至关重要.大脑中可能存在功能特异性的神经网络模块加工此类刺激.行为研究表明,该神经网络可能早在1岁前就开始形成和发展.近年随着认知神经科学研究技术的成熟,研究者利用EEG,fNIRS和fMRI等方法,直接研究社会和情绪脑机制的早期发展(0~1岁).本文从面孔表情、情绪性语音和早期社会交往3个方面系统总结了婴儿社会性和情绪发展的研究,并描述了相应社会-情绪神经网络的发展进程.在此基础上,采用经验-期待性机制和经验-依赖性机制讨论了早期社会经验对社会与情绪脑机制的影响,认为社会-情绪的神经网络不是先天形成、独立于社会经验的加工模块.虽然在个体发展的早期阶段(0~3个月),社会和情绪脑的核心结构已经形成,但出生后5~7个月,经验-期待性机制将会重塑社会和情绪脑,通过知觉窄化过程,该神经网络开始功能特异化,而只对特定的社会刺激敏感.在此期间的社会剥夺则会对社会-情绪神经网络的发展产生不可逆的影响.出生7个月以后,该神经网络通过经验-依赖性机制的调节逐渐趋于完善,并形成较稳定的个体差异.

Early development of the social and emotional brain in infancy

An important function of the brain is to scan one’s surroundings for the presence of biologically relevant features and grant them priority for attention and action. The significance of this function for an individual’s well-being and survival has given rise to the argument that specialized neural mechanisms for processing biologically salient stimuli may exist and that these mechanisms may require little, if any, experience for normal development. As evidenced by behavioral studies, the ontogeny of this network and associated cognitive capacities may emerge before the age of one year. With technological advances in recent years, researchers have been able to utilize electroencephalography, functional near-infrared spectroscopy, and functional magnetic resonance imaging to directly explore the early development of social-emotional brain mechanisms. In this paper, we systematically review three major aspects of early social and emotional development in infancy—facial expression, emotional voice, and early socialization. Based on empirical evidence, we describe the developmental process of the corresponding social and emotional neural network. We then discuss the impact of early social experience on the development of the social and emotional brain in terms of experience-expectant and experience-dependent mechanisms. We argue that the social-emotional neural network is not a congenital processing module that is independent of social experience. The core structure of the human social and emotional brain seems to reach anatomical maturity relatively early in development (zero to three months); however, the basic organization of the social-emotional network may be specified by an experience-expectant neural circuitry that emerges at five to seven months of age and is rapidly refined by exposure to universal features of social experience during a sensitive period of development. The network retains some plasticity throughout a person’s lifetime and can be fine-tuned by individual-specific experiences, i.e., experience-dependent development. Functional connectivity between emotion-processing networks and other prefrontal regulatory systems continues to develop into adolescence. Finally, based on the present study of the early development of the social and emotional brain, we indicate three promising directions for future research.