Characterization Of Neuropsychological Impairment In Sch

在过去的一年里，我们试图更全面地描述精神分裂症的认知障碍。特别是，我们已经开始研究精神分裂症患者记忆衰退的机制。患者的困难似乎不是由于对干扰、编码或所谓的错误记忆问题的易感性的定性异常。我们已经开始对精神分裂症的情景记忆障碍进行计算建模，以确定它们是由于普遍的噪音还是由于记忆处理的单一阶段。我们发现，对我们的结果的一个可能的解释涉及到上下文信息编码的缺陷（在我们的模型中，这是一种分配给海马旁回的功能）。我们使用不同的语义加工范式研究了精神分裂症的无组织言语。一般来说，患者的困难不在于词汇量的大小，而在于他们如何自动获取词汇，这在启动范式中得到了证明。因此，我们设计了一系列新颖的实验任务来评估精神分裂症患者是否表现出词汇完整性和语义异常之间的分离。本研究利用精神分裂症患者、阿尔茨海默病患者和儿童来发现言语词汇的大小与其组织之间的分离。如果是这样的话，那么它对正常的认知结构有重要的影响。我们还发现使用非语言变形任务和反应时间任务患者在理解实体是什么方面没有过度困难，他们理解事物之间关系的能力是不正常的。我们已经开始进行一项研究，将内部表征本身的完整性与使用各种类型的数字启动的表征之间激活的完整性进行比较。这种技术避免了判断单词相关性的问题。我们也开始采用一种计算丰富的技术，称为“潜在语义分析”，它使用可靠的计算机控制方法来判断精神分裂症话语的连贯性。我们初步发现，在不同的话语长度上，有奇怪的关联和连贯性的减弱。重要的是，该技术具有很高的可靠性；因为它与临床评分高度相关我们也认为它是有效的。最后，一项强调中间表型的精神分裂症遗传研究正在进行中。我们正在使用大量的神经认知测量来表征这种“中间”表型。我们的理论基础是，患者本身没有遗传精神分裂症，而是遗传了对认知障碍及其伴随的神经生理异常的各种易感性。我们已经发现，一些认知测量会产生较高的相对风险，而这些风险与诊断无关。这些任务包括工作记忆任务，包括威斯康星卡片排序和对时间编码和信息更新有高要求的N-Back工作记忆任务。此外，我们已经确定了一个基因（COMT）通过多巴胺信号对N - Back产生影响。我们还发现了一种基因（BDNF），它对人类海马功能有重大影响，包括情景记忆。

Over the past year we have attempted to characterize more completely the cognitive disturbances in schizophrenia. In particular we have begun work on the mechanisms accounting for failures in memory in schizophrenia. Patients' difficulties do not appear to be due to qualitative abnormalities in susceptibility to interference, encoding, or so called false memory problems. We have begun to comnputationally model the episodic memory impairments in schizophrenia in order to determine if they are due to general noise or a single stage in mnemonic processing. We found that one possibile explanation of our results involves defective encoding of context information (a function asigned to the parahippocampal gyrus in our model. We have examined disorganized speech in schizophrenia using various semantic processing paradigms. In general patients have difficulties not with the size of their lexicon but rather how they access it automatically, as evidenced in priming paradigms. Thus, we have devised a battery of novel experimental tasks to assess whether schizophrenic patients show a dissociation between lexical integrity and semantic abnormality. This study utilizes patients with schizophrenia, patients with Alzheimer's disease and children to find dissociations between the size of the verbal lexicon and its organization. If this is the case then it has important implications for normal cognitive architecture. We have also found using both a nonverbal morphing task and a reaction time task that patients do not have undue difficulty with understanding what an entitiy is, it is their ability to understand the relations between things that is abnormal. We have begun work on a study which compares the integrity of the internal representation itself to the integrity of activation among representations using various types of number priming. This technique circumvents problems in judging the relatedness of words. We have also begun to employ a computationally rich technique called "latent semantic analysis" which judges the coherence of schizophrenic discourse using reliable computer controlled methods. We have found preliminarily odd associations and diminished coherence over various discourse lenghts. Importantly the technique is highly reliable; because it was highly correlated with clinical ratings we also think that it is valid. Finally, a genetic study of schizophrenia with an emphasis on intermediate phenotypes is ongoing. We are using a large battery of neurocognitive measures to characterize this "intermediate" phenotype. We base this on the rationale that patients do not inherit schizophrenia per se but a variety of susceptibilities to cognitive impairments and their attendant neurophysiologic abnormalities. We have already found that some cognitive measures yield high relative risks that are not redundant with diagnosis. These include working memory tasks, including the Wisconsin Card SOrt and an N-Back working memory task with high demands for temporal encoding and information updating.Moreover, we have identified a gene (COMT) that has an impact on the N Back through dopamine signaling. We have alos identified a gene (BDNF) that has significant impact on human hippocampal function, including episodic memory.