Basar-Eroglu Canan, Brand Andreas, Hildebrandt Helmut, Karolina Kedzior Karina, Mathes Birgit, Schmiedt Christina
Institute of Psychology and Cognition Research and Center for Cognitive Sciences, University of Bremen, Grazer Str. 4, 28359 Bremen, Germany.
Int J Psychophysiol. 2007 Apr;64(1):39-45. doi: 10.1016/j.ijpsycho.2006.07.007. Epub 2006 Sep 7.
Recent reports show that the capability of neural networks supporting high-frequency synchronization is reduced in the brain of schizophrenia patients. Specifically, deficits in gamma activity have been shown in schizophrenia patients during perception and simple cognitive tasks. However little is known about alterations in gamma responses during complex and higher cognitive processing. The main objective of this study was to investigate modulation of event-related gamma responses in tasks varying working memory (WM) load in schizophrenia patients (N=10) and healthy controls (N=10). Gamma amplitude values were obtained for a simple choice reaction task, a low WM demand task, and a high WM demand task. During all three tasks schizophrenia patients showed significantly slower reaction times and higher error rates than controls. A gradual increase of gamma amplitudes after stimulus onset was associated with increase of WM load in controls. In contrast, high amplitude gamma oscillations remained constant regardless of task difficulty in patients. These results suggest that healthy subjects used various cognitive strategies depending on task difficulty, while schizophrenia patients needed to initiate complex cognitive processes similar to those used during processing of novel contexts or stimuli even for the simple choice reaction task with low cognitive demand.
最近的报告显示，精神分裂症患者大脑中支持高频同步的神经网络能力有所下降。具体而言，在感知和简单认知任务期间，精神分裂症患者已出现γ活动缺陷。然而，对于复杂和高级认知处理过程中γ反应的变化知之甚少。本研究的主要目的是调查精神分裂症患者（N = 10）和健康对照者（N = 10）在不同工作记忆（WM）负荷任务中事件相关γ反应的调节情况。针对简单选择反应任务、低WM需求任务和高WM需求任务获取了γ振幅值。在所有这三项任务中，精神分裂症患者的反应时间明显比对照组慢，错误率也更高。刺激开始后γ振幅的逐渐增加与对照组WM负荷的增加相关。相比之下，患者的高振幅γ振荡无论任务难度如何都保持不变。这些结果表明，健康受试者会根据任务难度使用各种认知策略，而精神分裂症患者即使在认知需求较低的简单选择反应任务中，也需要启动类似于处理新情境或刺激时所使用的复杂认知过程。
