Perceptual Mechanisms of Visual Hallucinations and Illusions in Psychosis

项目摘要 在严重的精神病理学中，大脑的功能是如何引起精神病体验的，目前尚不清楚。 因此，现有的治疗精神病的方法通常效果不大。视觉异常 感知在精神病(如幻觉)中很明显，并在具有精神病遗传易感性的人中被注意到 精神病理学(例如，高度幻觉)。目前的证据表明精神病患者存在早期视觉异常 这可能会引发一连串错误的神经活动，造成视觉体验的扭曲；然而，它是 不清楚大脑的基本视觉和复杂的引导功能是如何分别对视觉做出贡献的 精神病精神病病理学中的误解。拟议工作的总体目标是使用 复杂的心理物理任务和神经成像，以a)精确地表征行为和神经 精神障碍患者在视觉感知过程中的异常，b)详细说明 通过开发和测试计算模型产生的视觉幻觉和扭曲c) 确定机械性异常是否也标志着精神病的遗传易感性。 这一目标将通过研究患有精神障碍(IPDS)的人来实现，一个一级学位 每个IPD的亲生兄弟姐妹(SibIPDS)和人口统计上与其他两个相似的健康对照(HCS) 组。我们假设易产生视觉幻觉的个体表现出稳定的神经异常 早期视皮层(V1、V2)导致视觉元素加工错误，并产生视觉幻觉 当更多的前部区域(LOC/梭形、前额叶皮质)对视觉产生背景影响时，IPDS就会发生 感知变得不正常。容易出现异常视错觉但没有精神障碍的个体包括 假设在反映在异常中的对视觉感觉的高水平影响中表现出稳定的减少 区域间神经同步化。我们将采用对比度歧视，环绕抑制， 注意调节和模糊物体任务，以评估早期视觉知觉过程，有无 在IPD患者、其未受影响的亲生兄弟姐妹(SibIPD)和健康对照(HC)中，上下文调制为 确定任务绩效何时预测自我报告的视觉错觉。我们将计算大脑皮层 通过7特斯拉(T)功能磁共振成像功能本地化的248通道脑磁图数据的源信号，以详细说明 视觉知觉任务中神经反应的位置、定时和同步 IPD、SibIPD和HC中的远程过程，以及确定任务如何引发神经反应 预测自我报告的视觉错觉的变化。我们还将描述所有任务中的视觉反应 使用最初由Schwartz等人(2009)发表并最近在 我们的工作是对多个场景分割线索进行泛化(邱，2013)。我们将使用这个模型来测试 是否在所有IPD中选择性地减少了反映局部抑制的术语，以及该术语的强度 代表远距离调制与视觉幻觉的频率相关。

Project Summary It is unknown how functions of the brain give rise to psychotic experiences in severe psychopathology. Consequently, available treatments for psychotic disorders are often marginally effective. Abnormal visual perception is evident in psychosis (e.g., hallucinations) and noted in people with genetic liability for psychotic psychopathology (e.g., heightened illusions). Current evidence points to early visual abnormalities in psychosis that may trigger a cascade of errant neural activity creating distortions in one's visual experience; however, it is unclear how basic visual and complex guidance functions of the brain separately contribute to visual misperception in psychotic psychopathology. The overarching goal of the proposed work is to use sophisticated psychophysical tasks and neuroimaging to a) precisely characterize behavioral and neural abnormalities in individuals with psychotic disorders during visual perception, b) detail the mechanisms of visual hallucinations and distortions through the development and testing of a computational model c) determine if the mechanistic anomalies also mark genetic liability for psychosis. The goal will be accomplished by studying individuals with psychotic disorders (IPDs), one first-degree biological sibling of each IPD (SibIPDs), and healthy controls (HCs) demographically similar to the other two groups. We hypothesize that individuals prone to visual hallucinations exhibit stable neural abnormalities in early visual cortex (V1, V2) causing errors in the processing of visual elements, and that visual hallucinations occur in IPDs when contextual influences of more anterior regions (LOC/fusiform, prefrontal cortex) on visual perception become deviant. Individuals prone to anomalous visual illusions but without a psychotic disorder are hypothesized to exhibit a stable decrement in high-level influences on visual perception reflected in anomalies of inter-regional neural synchronization. We will employ contrast discrimination, surround suppression, attention regulation, and ambiguous object tasks to assess early visual perceptual processes, with and without contextual modulation, in IPDs, their unaffected biological siblings (SibIPDs), and healthy controls (HCs), to determine when task performance predicts self-reported visual misperceptions. We will compute cortical source signals from 248-channel MEG data functionally localized through 7 Tesla (T) fMRI to detail the location, timing, and synchronization of neural responses during visual perceptual tasks assessing local and long-range processes in IPDs, SibIPDs, and HCs, as well as determine how neural responses elicited by tasks predict variation in self-reported visual misperception. We will also characterize visual responses in all tasks using the Gaussian Scale Mixture model originally published by Schwartz et al (2009) and recently extended in our work to generalize across multiple scene segmentation cues (Qiu, 2013). We will use this model to test whether terms reflecting local inhibition are selectively reduced in all IPDs and whether the strength of the term representing long-range modulation correlates with frequency of visual hallucinations.