Rawdon Caroline, Murphy Jennifer, Blanchard Mathieu M, Kelleher Ian, Clarke Mary C, Kavanagh Fergal, Cannon Mary, Roche Richard A P
BMC Psychiatry. 2013 May 1;13:125. doi: 10.1186/1471-244X-13-125.
Deficits in working memory are widely reported in schizophrenia and are considered a trait marker for the disorder. Event-related potentials (ERPs) and imaging data suggest that these differences in working memory performance may be due to aberrant functioning in the prefrontal and parietal cortices. Research suggests that many of the same risk factors for schizophrenia are shared with individuals from the general population who report psychotic symptoms.
Forty-two participants (age range 11-13 years) were divided into those who reported psychotic symptoms (N = 17) and those who reported no psychotic symptoms, i.e. the control group (N = 25). Behavioural differences in accuracy and reaction time were explored between the groups as well as electrophysiological correlates of working memory using a Spatial Working Memory Task, which was a variant of the Sternberg paradigm. Specifically, differences in the P300 component were explored across load level (low load and high load), location (positive probe i.e. in the same location as shown in the study stimulus and negative probe i.e. in a different location to the study stimulus) and between groups for the overall P300 timeframe. The effect of load was also explored at early and late timeframes of the P300 component (250-430 ms and 430-750 ms respectively).
No between-group differences in the behavioural data were observed. Reduced amplitude of the P300 component was observed in the psychotic symptoms group relative to the control group at posterior electrode sites. Amplitude of the P300 component was reduced at high load for the late P300 timeframe at electrode sites Pz and POz.
These results identify neural correlates of neurocognitive dysfunction associated with population level psychotic symptoms and provide insights into ERP abnormalities associated with the extended psychosis phenotype.
工作记忆缺陷在精神分裂症中被广泛报道，并被认为是该疾病的一个特质标记。事件相关电位（ERP）和影像学数据表明，工作记忆表现的这些差异可能归因于前额叶和顶叶皮质的功能异常。研究表明，精神分裂症的许多相同风险因素也存在于报告有精神病症状的普通人群个体中。
42名参与者（年龄范围11 - 13岁）被分为报告有精神病症状的组（N = 17）和报告无精神病症状的组，即对照组（N = 25）。使用空间工作记忆任务（Sternberg范式的一个变体），探讨了两组之间在准确性和反应时间方面的行为差异以及工作记忆的电生理相关性。具体而言，在负荷水平（低负荷和高负荷）、位置（正性探针，即与研究刺激中所示位置相同，以及负性探针，即与研究刺激位置不同）以及整个P300时间范围内的组间差异方面，对P300成分进行了探索。还在P300成分的早期和晚期时间范围（分别为250 - 430毫秒和430 - 750毫秒）探讨了负荷的影响。
在行为数据中未观察到组间差异。在后部电极部位，有精神病症状组相对于对照组观察到P300成分的波幅降低。在电极部位Pz和POz，晚期P300时间范围的高负荷条件下，P300成分的波幅降低。
这些结果确定了与人群水平精神病症状相关的神经认知功能障碍的神经相关性，并为与扩展精神病表型相关的ERP异常提供了见解。
