Rypma Bart, Prabhakaran Vivek
School of Behavioral and Brain Sciences and Center for Brain Health, University of Texas at Dallas.
Intelligence. 2009 Mar 1;37(2):207-222. doi: 10.1016/j.intell.2008.12.004.
An enduring enterprise of experimental psychology has been to account for individual differences in human performance. Recent advances in neuroimaging have permitted testing of hypotheses regarding the neural bases of individual differences but this burgeoning literature has been characterized by inconsistent results. We argue that careful design and analysis of neuroimaging studies is required to separate individual differences in processing capacity from individual differences in processing speed to account for these differences in the literature. We utilized task designs which permitted separation of processing capacity influences on brain-behavior relationships from those related to processing speed. In one set of studies, participants performed verbal delayed-recognition tasks during blocked and event-related fMRI scanning. The results indicated that those participants with greater working memory (WM) capacity showed greater prefrontal cortical activity, strategically capitalized on the additional processing time available in the delay period, and evinced faster WM-retrieval rates than low-capacity participants. In another study, participants performed a digit-symbol substitution task (DSST) designed to minimize WM storage capacity requirements and maximize processing speed requirements during fMRI scanning. In some prefrontal cortical (PFC) brain regions, participants with faster processing speed showed less PFC activity than slower performers while in other PFC and parietal regions they showed greater activity. Regional-causality analysis indicated that PFC exerted more influence over other brain regions for slower than for faster individuals. These results support a model of neural efficiency in which individuals differ in the extent of direct processing links between neural nodes. One benefit of direct processing links may be a surplus of resources that maximize available capacity permitting fast and accurate performance.
实验心理学的一项长期事业一直是解释人类表现中的个体差异。神经成像技术的最新进展使得能够对有关个体差异神经基础的假设进行测试，但这一迅速发展的文献的特点是结果不一致。我们认为，需要对神经成像研究进行精心设计和分析，以将处理能力的个体差异与处理速度的个体差异区分开来，从而解释文献中的这些差异。我们采用了任务设计，这种设计能够将处理能力对脑-行为关系的影响与那些与处理速度相关的影响区分开来。在一组研究中，参与者在组块设计和事件相关功能磁共振成像扫描期间执行言语延迟识别任务。结果表明，那些工作记忆（WM）能力较强的参与者表现出更大的前额叶皮层活动，策略性地利用了延迟期内可用的额外处理时间，并且比低能力参与者表现出更快的WM检索率。在另一项研究中，参与者在功能磁共振成像扫描期间执行一项数字-符号替换任务（DSST），该任务旨在将WM存储容量要求降至最低，并将处理速度要求最大化。在一些前额叶皮层（PFC）脑区，处理速度较快的参与者比处理速度较慢的参与者表现出更少的PFC活动，而在其他PFC和顶叶区域，他们表现出更大的活动。区域因果分析表明，PFC对处理速度较慢的个体比对处理速度较快的个体对其他脑区施加了更大的影响。这些结果支持了一种神经效率模型，即个体在神经节点之间直接处理链接的程度上存在差异。直接处理链接的一个好处可能是资源过剩，从而最大限度地提高可用容量，实现快速准确的表现。
