Department of Psychology, Neuroimaging Center, Department of Psychology and Institute of General Psychology, Biopsychology, and Methods of Psychology, Technische Universität Dresden, Germany.
Hum Brain Mapp. 2013 Jan;34(1):12-35. doi: 10.1002/hbm.21420. Epub 2011 Oct 14.
A large body of behavioural research has used the cued task-switching paradigm to characterize the nature of trial-by-trial preparatory adjustments that enable fluent task implementation when demands on cognitive flexibility are high. This work reviews the growing number of fMRI studies on the same topic, mostly focusing on the central hypothesis that preparatory adjustments should be indicated by enhanced prefrontal and parietal BOLD activation in task switch when compared with task repeat trials under conditions that enable advance task preparation. The evaluation of this straight-forward hypothesis reveals surprisingly heterogeneous results regarding both the precise localization and the very existence of switch-related preparatory activation. Explanations for these inconsistencies are considered on two levels. First, we discuss methodological issues regarding (i) the possible impact of different fMRI-specific experimental design modifications and (ii) statistical uncertainty in the context of massively multivariate imaging data. Second, we discuss explanations related to the multidimensional nature of task preparation itself. Specifically, the precise localization and the size of switch-related preparatory activation might depend on the differential interplay of hierarchical control via abstract task goals and attentional versus action-directed preparatory processes. We argue that different preparatory modes can be adopted relying either on advance goal activation alone or on the advance resolution of competition within action sets or attentional sets. Importantly, while either mode can result in a reduction of behavioral switch cost, only the latter two are supposed to be associated with enhanced switch versus repeat BOLD activation in prepared trial conditions.
大量的行为研究使用提示任务转换范式来描述在认知灵活性要求较高时，能够流畅地执行任务的试次间预备调整的性质。这项工作综述了越来越多的关于同一主题的 fMRI 研究，主要集中在中心假设上，即与任务重复试验相比，在能够进行提前任务准备的条件下，预备调整应该表现为前额叶和顶叶 BOLD 激活增强。评估这个直接的假设揭示了关于与转换相关的预备激活的精确定位和存在的惊人的异构结果。关于这些不一致性的解释在两个层面上进行了讨论。首先，我们讨论了与（i）不同的 fMRI 特定实验设计修改的可能影响和（ii）在大规模多元成像数据背景下的统计不确定性相关的方法学问题。其次，我们讨论了与任务准备本身的多维性质相关的解释。具体来说，与转换相关的预备激活的精确定位和大小可能取决于通过抽象任务目标和注意与行动导向的预备过程的分层控制的差异相互作用。我们认为，可以采用不同的预备模式，这些模式要么依赖于仅提前激活目标，要么依赖于在行动集或注意集内提前解决竞争。重要的是，虽然任何一种模式都可以减少行为转换成本，但只有后两种模式才应该与在预备试验条件下增强的转换与重复 BOLD 激活相关。
