Sigman Mariano, Dehaene Stanislas
Physics Department, Integrative Neuroscience Laboratory, University of Buenos Aires, 1428 Buenos Aires, Argentina.
J Neurosci. 2008 Jul 23;28(30):7585-98. doi: 10.1523/JNEUROSCI.0948-08.2008.
The psychological refractory period (PRP) refers to the fact that humans typically cannot perform two tasks at once. Behavioral experiments have led to the proposal that, in fact, peripheral perceptual and motor stages continue to operate in parallel, and that only a central decision stage imposes a serial bottleneck. We tested this model using neuroimaging methods combined with innovative time-sensitive analysis tools. Subjects performed a dual-task visual-auditory paradigm in which a delay of 300 ms was injected into the auditory task either within or outside of the dual-task interference period. Event-related potentials indicated that the first approximately 250 ms of processing were insensitive to dual-task interference, and that the PRP was mainly reflected in a delayed global component. By a clustering analysis based on time-resolved functional magnetic resonance imaging, we identified networks with qualitatively different timing properties: sensory areas tracked the objective time of stimulus presentation, a bilateral parietoprefrontal network correlated with the PRP delay, and an extended bilateral network that included bilateral posterior parietal cortex, premotor cortex, supplementary motor area, anterior part of the insula, and cerebellum was shared by both tasks during the extent of dual-task performance. The results provide physiological evidence for the coexistence of serial and parallel processes within a cognitive task.
心理不应期（PRP）指的是人类通常无法同时执行两项任务这一事实。行为实验提出，实际上，外周感知和运动阶段继续并行运作，只有一个中央决策阶段形成了一个串行瓶颈。我们使用神经成像方法结合创新的时间敏感分析工具对该模型进行了测试。受试者执行了一种双任务视觉 - 听觉范式，其中在双任务干扰期内或之外，在听觉任务中注入了300毫秒的延迟。事件相关电位表明，最初大约250毫秒的处理对双任务干扰不敏感，并且PRP主要反映在一个延迟的全局成分中。通过基于时间分辨功能磁共振成像的聚类分析，我们识别出具有定性不同时间特性的网络：感觉区域跟踪刺激呈现的客观时间，一个双侧顶叶前额叶网络与PRP延迟相关，并且在双任务执行期间，一个扩展的双侧网络（包括双侧后顶叶皮层、运动前区皮层、辅助运动区、岛叶前部和小脑）在两项任务中都有共享。这些结果为认知任务中串行和并行过程的共存提供了生理学证据。
