Garrity Abigail G, Pearlson Godfrey D, McKiernan Kristen, Lloyd Dan, Kiehl Kent A, Calhoun Vince D
Trinity College, Hartford, CT, USA.
Am J Psychiatry. 2007 Mar;164(3):450-7. doi: 10.1176/ajp.2007.164.3.450.
The "default mode" has been defined as a baseline condition of brain function and is of interest because its component brain regions are believed to be abnormal in schizophrenia. It was hypothesized that the default mode network would show abnormal activation and connectivity in patients with schizophrenia.
Patients with schizophrenia (N=21) and healthy comparison subjects (N=22) performed an auditory oddball task during functional magnetic resonance imaging (fMRI). Independent component analysis was used to identify the default mode component. Differences in the spatial and temporal aspects of the default mode network were examined in patients versus comparison subjects.
Healthy comparison subjects and patients had significant spatial differences in the default mode network, most notably in the frontal, anterior cingulate, and parahippocampal gyri. In addition, activity in patients in the medial frontal, temporal, and cingulate gyri correlated with severity of positive symptoms. The patients also showed significantly higher frequency fluctuations in the temporal evolution of the default mode.
Schizophrenia is associated with altered temporal frequency and spatial location of the default mode network. The authors hypothesized that this network may be under- or overmodulated by key regions, including the anterior and posterior cingulate cortex. In addition, the altered temporal fluctuations in patients may result from a change in the connectivity of these regions with other brain networks.
“默认模式”已被定义为脑功能的一种基线状态，因其组成脑区在精神分裂症中被认为存在异常而备受关注。研究假设精神分裂症患者的默认模式网络会出现异常激活和连接。
精神分裂症患者（N = 21）和健康对照受试者（N = 22）在功能磁共振成像（fMRI）期间执行听觉oddball任务。使用独立成分分析来识别默认模式成分。比较患者与对照受试者在默认模式网络的空间和时间方面的差异。
健康对照受试者和患者在默认模式网络中存在显著的空间差异，最明显的是在额叶、前扣带回和海马旁回。此外，患者内侧额叶、颞叶和扣带回的活动与阳性症状的严重程度相关。患者在默认模式的时间演变中还表现出明显更高的频率波动。
精神分裂症与默认模式网络的时间频率和空间位置改变有关。作者假设该网络可能受到包括前扣带回和后扣带回皮质在内的关键区域的调制不足或过度调制。此外，患者时间波动的改变可能是由于这些区域与其他脑网络连接性的变化所致。
