Testing a Bayesian model of auditory verbal hallucinations in the adolescent brain

听性言语幻觉(AVH)是精神分裂症等精神状态的特征症状。青少年特别容易患上AVH和精神分裂症(Dalsgaard等人，2020年)。必须对精神病的发展机制进行描述和建模，并开发有效的方法进行早期发现和诊断，以优化干预措施。关于大脑是如何产生动静脉搏的，目前尚无定论。一些理论认为，AVH是由于未能监控自己的内部言语、言语思维或记忆，从而被认为是外来的或外部的(Frith，2014)。其他人声称AVH是大脑无法抑制的侵入性记忆(通常来自童年创伤事件)(Waters等人，2006年)。由于这些模型中的每一个都将AVH的病理局限于一个症状维度或认知机制，因此没有一个模型能够单独解释AVH的全部复杂性。“贝叶斯推理”已经变得越来越有影响力，因为它有可能在一个普遍的理论框架下统一AVH的多种机制。大脑可能会使用不同的机制来计算给定先前经验和当前感觉的知觉概率。因此，语言是否被听到最终取决于大脑对先前经验(先验)和当前听到的内容的重视程度。当大脑具有非常强烈和不变的先前预期时，在没有刺激的情况下可能发生AVH(Corlett等人，2019年)。目前的项目旨在测试AVH的贝叶斯模型，以表征和模拟青少年AVH的发展机制。我们将招募15-25岁的人，并：(1)通过在一系列信号检测任务中对实验操纵的先前信念(听到言语)和感觉证据(是否存在言语)进行建模，证明建模方法的概念(Brookwell等人，2013年)；(2)测试贝叶斯建模是否可以比测量必然放电、来源监控或记忆抑制的任务更可靠地区分健康、高危和临床群体；(3)使用脑电将先前信念的变化定位到大脑中的电生理信号(姚等人，2021年)，以确定非侵入性脑刺激治疗的潜在生物标志物。博士将受益于认知神经科学和临床心理学的跨学科专业知识，并在贝叶斯建模、统计分析和脑电数据处理以及精神病症状的临床评估和研究管理方面接受全面的量化技能培训。

Auditory verbal hallucinations (AVH) are a characteristic symptom of psychotic states such as schizophrenia. Adolescents are particular vulnerable to developing AVH and schizophrenia (Dalsgaard et al., 2020). It is imperative to characterise and model the developmental mechanisms of psychosis and to develop effective methods for early detection and diagnosis to optimize interventions. Little is certain about how the brain produces AVH. Some theories propose that AVH result from a failure to monitor one's own inner speech, verbal thoughts or memories so that they are perceived to be foreign or external (Frith, 2014). Others claim that AVH are intrusive memories (often from childhood traumatic events) that the brain fails to suppress (Waters et al., 2006). Because each of these models localises the pathology of AVH to one symptom dimension or cognitive mechanism, none can explain the full complexity of AVH alone. 'Bayesian inferencing' has become increasingly influential as it has the potential to unify multiple mechanisms of AVH under a generalised theoretical framework. The brain may use different mechanisms to compute the probability of a perception given prior experience and the current sensations. So whether speech is heard ultimately depends on the weight the brain attaches to previous experience (the priors) and to what is currently being heard. AVH may occur in the absence of a stimulus when the brain has a very strong and unchanging prior expectation (Corlett et al., 2019). The current project aims to test the Bayesian model of AVH to characterise and model the developmental mechanisms of AVH in adolescents. We will recruit people aged 15-25yo and: (1) prove the concept of a modelling approach by modelling experimentally manipulated prior beliefs (of hearing a speech) and sensory evidence (of whether the speech is present) in a series of signal detection tasks (Brookwell et al., 2013); (2) test if Bayesian modelling can separate healthy vs. at-risk and clinical groups more reliably than tasks measuring corollary discharge, source monitoring or memory inhibition; (3) localise the changes of prior beliefs to electrophysiological signatures in the brain using EEG (Yao et al., 2021), to identify potential biomarkers for non-invasive brain stimulation treatments. The PhD will benefit from interdisciplinary expertise in cognitive neuroscience and clinical psychology and receive comprehensive training in quantitative skills in Bayesian modelling, statistical analysis and EEG data processing, as well as in clinical assessment of psychotic symptoms and research governance