Leptourgos Pantelis, Corlett Philip R
Department of Psychiatry, Connecticut Mental Health Center, Yale University, New Haven, CT, United States.
Front Big Data. 2020 Aug 14;3:27. doi: 10.3389/fdata.2020.00027. eCollection 2020.
Psychotic symptoms, i.e., hallucinations and delusions, involve gross departures from conscious apprehension of consensual reality; respectively, perceiving and believing things that, according to same culture peers, do not obtain. In schizophrenia, those experiences are often related to abnormal sense of control over one's own actions, often expressed as a distorted sense of agency (i.e., passivity symptoms). Cognitive and computational neuroscience have furnished an account of these experiences and beliefs in terms of the brain's generative model of the world, which underwrites inferences to the best explanation of current and future states, in order to behave adaptively. Inference then involves a reliability-based trade off of predictions and prediction errors, and psychotic symptoms may arise as departures from this inference process, either an over- or under-weighting of priors relative to prediction errors. Surprisingly, there is empirical evidence in favor of both positions. Relatedly, there is evidence for both an enhanced and a diminished sense of agency in schizophrenia. How can this be? We argue that there is more than one generative model in the brain, and that ego- and allo-centric models operate in tandem. In brief, ego-centric models implement corollary discharge signals that cancel out the effects of self-generated actions while allo-centric models compare several hypothesis regarding the causes of sensory inputs (including the self among the potential causes). The two parallel hierarchies give rise to different levels of agency, with ego-centric models subserving "feelings of agency" and allo-centric predictions giving rise to "judgements of agency." Those two components are weighted according to their reliability and combined, generating a higher-level "sense of agency." We suggest that in schizophrenia a failure of corollary discharges to suppress self-generated inputs results in the absence of a "feeling of agency" and in a compensatory enhancement of allo-centric priors, which might underlie hallucinations, delusions of control but also, under certain circumstances, the enhancement of "judgments of agency." We discuss the consequences of such a model, and potential courses of action that could lead to its falsification.
精神病性症状，即幻觉和妄想，涉及与对共识现实的有意识理解的严重背离；具体而言，是感知和相信一些在同一文化背景的同龄人看来并不存在的事物。在精神分裂症中，这些体验通常与对自身行为的异常控制感有关，常表现为一种扭曲的能动性感知（即被动性症状）。认知神经科学和计算神经科学已依据大脑对世界的生成模型，对这些体验和信念作出了解释，该模型支持对当前和未来状态的最佳解释进行推理，以便实现适应性行为。推理过程涉及基于可靠性的预测与预测误差的权衡，而精神病性症状可能因偏离这一推理过程而出现，即相对于预测误差，先验信息的权重过高或过低。令人惊讶的是，有实证证据支持这两种观点。相关地，也有证据表明精神分裂症患者的能动性感知既增强又减弱。这是怎么回事呢？我们认为大脑中存在不止一种生成模型，自我中心模型和他我中心模型协同运作。简而言之，自我中心模型实现伴随放电信号，以抵消自我产生的行为的影响，而他我中心模型则比较关于感觉输入原因的几种假设（包括潜在原因中的自我）。这两个并行的层级产生不同程度的能动性，自我中心模型支持“能动性感觉”，他我中心预测产生“能动性判断”。这两个成分根据其可靠性进行加权并合并，产生更高级别的“能动性感知”。我们认为，在精神分裂症中，伴随放电未能抑制自我产生的输入，导致“能动性感觉”缺失，并代偿性增强他我中心先验信息，这可能是幻觉、控制妄想的基础，在某些情况下，也可能是“能动性判断”增强的基础。我们讨论了这种模型的后果以及可能导致其被证伪的潜在行动方案。
