Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Neuroimage. 2011 Jun 1;56(3):1608-21. doi: 10.1016/j.neuroimage.2011.03.017. Epub 2011 Mar 21.
Human performance exhibits strong multi-tasking limitations in simple response time tasks. In the psychological refractory period (PRP) paradigm, where two tasks have to be performed in brief succession, central processing of the second task is delayed when the two tasks are performed at short time intervals. Here, we aimed to probe the cortical network underlying this postponement of central processing by simultaneously recording electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) data while 12 subjects performed two simple number-comparison tasks. Behavioral data showed a significant slowing of response times to the second target stimulus at short stimulus-onset asynchronies, together with significant correlations between response times to the first and second target stimulus, i.e., the hallmarks of the PRP effect. The analysis of EEG data showed a significant delay of the post-perceptual P3 component evoked by the second target, which was of similar magnitude as the effect on response times. fMRI data revealed an involvement of parietal and prefrontal regions in dual-task processing. The combined analysis of fMRI and EEG data-based on the trial-by-trial variability of the P3-revealed that BOLD signals in two bilateral regions in the inferior parietal lobe and precentral gyrus significantly covaried with P3 related activity. Our results show that combining neuroimaging methods of high spatial and temporal resolutions can help to identify cortical regions underlying the central bottleneck of information processing, and strengthen the conclusion that fronto-parietal cortical regions participate in a distributed "global neuronal workspace" system that underlies the generation of the P3 component and may be one of the key cerebral underpinnings of the PRP bottleneck.
人类在简单反应时任务中表现出很强的多任务处理限制。在心理不应期（PRP）范式中，当两个任务必须在很短的时间间隔内连续执行时，第二个任务的中央处理会被延迟。在这里，我们旨在通过在 12 名受试者同时执行两个简单的数字比较任务时同时记录脑电图（EEG）和功能磁共振成像（fMRI）数据，来探测这种中央处理延迟的皮质网络。行为数据显示，在短的刺激起始间隔下，对第二个目标刺激的反应时间明显减慢，并且对第一个和第二个目标刺激的反应时间之间存在显著相关性，即 PRP 效应的标志。EEG 数据分析显示，第二个目标诱发的后知觉 P3 成分明显延迟，其与反应时间的影响相似。fMRI 数据显示，顶叶和前额叶区域参与了双重任务处理。基于 P3 的trial-by-trial 变异性对 fMRI 和 EEG 数据的联合分析表明，双侧下顶叶和中央前回的 BOLD 信号与 P3 相关活动显著相关。我们的研究结果表明，结合具有高时空分辨率的神经影像学方法可以帮助识别信息处理中央瓶颈的皮质区域，并加强以下结论：额顶皮质区域参与分布式“全局神经元工作空间”系统的生成，该系统是 P3 成分的关键脑基础之一，可能是 PRP 瓶颈的关键脑基础之一。
