Emergence of theory of mind in young children, explored with functional MRI and Virtual Reality (VR)

将心理状态和知识归因于他人(即他们的信仰、意图和感觉)并因此理解和预测他们的行为的能力(称为“心理理论”)是人类心理的一个基本特征，它出现在18个月到5岁之间的幼儿时期(Frith等人)。2005)。它对日常社会交往和社区参与是必不可少的，在许多精神健康障碍中发现了改变的心理理论，也被认为是包括自闭症在内的神经发育疾病的基础(Senju 2012)。然而，至关重要的是，人们对这一关键人类技能背后的大脑处理知之甚少，部分原因是设计合适的实验固有的挑战，这些实验可以在典型的僵化的神经成像研究设计中探索这种复杂的结构，这些设计也难以代表真实世界的社交互动。这对功能磁共振成像(FMRI)等方法尤其有问题。功能磁共振成像(FMRI)可以提供关于神经活动的详细全脑信息，但必须在受限和非自然的MRI扫描仪环境中涉及行为刺激和图像获取。尽管如此，最近的研究强调了功能磁共振成像利用视频刺激提供洞察力的潜力，创造性的分析方法表明，青少年和成人大脑中的相关活动发生在一个分布的区域网络中，包括内侧前额叶皮质、颞顶交界处(TPJ)、颞后上沟(PSTS)、后扣带回皮质(PCC)和楔前叶(Gao等人)。2019年)。然而，由于幼儿经常难以遵循详细的说明和/或难以容忍在像核磁共振扫描仪这样的陌生环境中获取数据(因此必须在睡觉时进行研究)，因此对大脑及其活动如何变化以使心理理论首次出现知之甚少(Yates等人)。2021年)。考虑到这些因素，监督团队最近开发了一种新颖的MR兼容虚拟现实(VR)系统，它为用户提供了一个躺在核磁共振扫描仪内的交互式模拟环境(钱等人。2021年)。当使用该系统时，受试者通过放置在扫描仪孔内的MR兼容投影仪完全沉浸在视觉环境中，该投影仪直接投射到VR耳机上，并通过主动降噪耳机接受听觉刺激。该系统的另一个关键功能是在耳机内安装一对集成的MRI兼容摄像机，提供有关用户视觉行为的额外实时信息。使用稳健的凝视估计算法，这不仅可以精确测量视觉注意力，还允许受试者将凝视作为一种直观和自然的交流手段，就像他们在日常生活中所做的那样(钱等人)。2021年)。通过同时获取fMRI数据，同时受试者自然探索并与VR环境交互，这将成为一个基于fMRI的大脑活动询问的变革性新平台，其核心是克服传统僵化研究设计固有的上述限制，并首次能够详细描述幼儿心理理论背后的大脑处理过程。

The capacity to ascribe mental states and knowledge to other people (ie, their beliefs, intentions and feelings) and thus understand and predict their behaviour (known as "theory of mind") is an essential feature of the human psyche, which emerges in early childhood between 18 months of 5 years of age (Frith et al. 2005). It is essential for everyday social interaction and community participation, with altered theory of mind found in numerous mental health disorders and is also thought to underlie neurodevelopmental conditions including autism (Senju 2012). Crucially however, the brain processing that underlies this key human skill is poorly understood partly due to the challenges inherent to designing suitable experiments that can explore this complex construct within typically rigid neuroimaging study designs which also struggle to represent real-world social interact.This is particularly problematic for methods such as functional MRI (fMRI) which can provide detailed whole-brain information about neural activity but must involve behavioural stimulation and image acquisition inside the restricted and unnatural MRI scanner environment. Despite this, recent studies have highlighted the potential of fMRI to provide insight using video stimuli and creative analysis methods showing that the related activity in the adolescent and adult brain occurs a distributed network of areas that include the medial prefrontal cortex, temporal-parietal junction (TPJ), posterior superior temporal sulcus (pSTS), posterior cingulate cortex (PCC) and precuneus (Gao et al. 2019). However, as young children often struggle to follow detailed instructions and/or find it difficult to tolerate data acquisition inside an alien environment like a MRI scanner (and so must be studied when sleeping), very little is known about how the brain and its activity changes to enable theory of mind to first emerge(Yates et al. 2021). With these factors in mind, the supervisory team has recently developed a novel MR compatible virtual reality (VR) system which provides users with an interactive simulated environment whilst lying inside the MRI scanner (Qian et al. 2021). When using the system, subjects are fully immersed in a visual environment via an MR compatible projector placed inside the scanner bore which projects directly into a VR headset and also receive auditory stimulation via active noise-cancelling headphones. A further key feature of the system is a pair of integrated MRI compatible video cameras inside the headset that provide additional real-time information about the user's visual behaviour. Using a robust gaze estimation algorithm, this not only allows precise measurementof visual attention but also allows subjects to use their gaze as an intuitive and natural means of communication as they would in their daily lives (Qian et al. 2021). By simultaneously acquiring fMRI data whilst the subject naturally explores and interacts with the VR environment, there is huge potential for this to be a transformative new platform for fMRI-based interrogation of brainactivity which at its core, overcomes the aforementioned limitations inherent to traditional rigid study designs and can enable for the first time, detailed characterisation of the brain processing underlying theory of mind in young children.