精神分裂症空间工作记忆任务的fMRI研究

Functional MRI study of spatial working memory task on patients with schizophrenia

目的采用fMRI技术探讨精神分裂症患者空间工作记忆损害的神经机制。方法收集18例精神分裂症患者和18名正常受试者进行空间n-back任务的fMRI扫描。采用SPM 8进行数据预处理和统计分析,单样本t-检验用于分析两组各自脑激活结果,双样本t-检验用于工作记忆相关脑激活的组间比较。采用FDR方法进行多重比较校正。利用SPSS 17.0软件对工作记忆任务中的行为学结果 (正确率和反应时间)进行组间比较。结果与对照组相比,精神分裂症患者空间工作记忆任务反应时间延长(882.00±50.31)ms,正确率下降(83.60±2.90)%(P<0.05)。精神分裂症患者在n-back空间工作记忆任务时所激活的脑区分布与对照组基本一致,主要包括双侧前额皮层、颞顶叶皮层及部分基底核团。但组间比较显示精神分裂症患者多个脑区激活强度及范围明显增加,包括双侧前额皮层背外侧、双侧后顶叶皮层、右侧中央前回、左侧颞中回、右扣带回和双侧小脑(FDR校正,P<0.05)。结论执行空间工作记忆任务时精神分裂症患者脑区激活增加,但行为学表现下降,提示患者脑区活动效率低下,可能是工作记忆能力损害的神经基础。

Objective To investigate the neural mechanism of spatial working memory impairment in patients with schizophrenia.Methods Functional MRI （fMRI） with n-back spatial working memory task was performed on 18 patients with schizophrenia and 18 healthy subjects.The fMRI data were preprocessed with statistical parameter mapping （SPM 8） software.Intragroup brain activation was detected using simple sample t-test;intergroup differences in brain activation were compared using two-sample ttest.FDR method was used to correct the multiple comparisons.SPSS 17.0 software package was used to perform intergroup comparison of reaction time and accuracy performing the task.Results Compared to the healthy subjects,the patients with schizophrenia exhibited significantly longer reaction time （882.00±50.31）ms and lower accuracy （83.60±2.90）% performing the n-back spatial working memory task （P〈0.05）.The distributions of activated brain areas related to spatial working memory task were similar between the two groups,which involved the bilateral prefrontal cortex,temporal and parietal cortex,and basal ganglions.Intergroup comparison showed significantly increased extent and intensity of activation in the bilateral dorsal lateral prefrontal cortex,bilateral posterior parietal cortex,right precentral gyrus,left middle temporal gyrus,right cingulate gyrus and bilateral cerebellum of patients with schizophrenia （P〈0.05,FDR correction）.Conclusion Decreased behavioral performance and increased brain activation in patients with schizophrenia performing spatial working memory task suggest inefficient brain activity,which may be one of the neural bases of spatial working memory impairment.