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Localization of load sensitivity of working memory storage: Quantitatively and qualitatively discrepant results yielded by single-subject and group-averaged approaches to fMRI group analysis

机译：工作存储器存储的负载敏感度的本地化：fMRI组分析的单对象和组平均方法在数量和质量上存在差异

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摘要

The impetus for the present report is the evaluation of competing claims of two classes of working memory models: Memory systems models hold working memory to be supported by a network of prefrontal cortex (PFC)-based domain-specific buffers that act as workspaces for the storage and manipulation of information; emergent processes models, in contrast, hold that the contributions of PFC to working memory do not include the temporary storage of information. Empirically, each of these perspectives is supported by seemingly mutually incompatible results from functional magnetic resonance imaging (fMRI) studies that either do or do not find evidence for delay-period sensitivity to memory load, an index of storage, in PFC. We hypothesized that these empirical discrepancies may be due, at least in part, to methodological factors, because studies reporting delay-period load sensitivity in PFC typically employ spatially normalized group averaged analyses, whereas studies that don’t find PFC load sensitivity typically use a single-subject “case-study” approach. Experiment 1 performed these two approaches to analysis on the same data set, the results of which were consistent with this hypothesis. Experiment 2 evaluated one characteristic of the single-subject results from Experiment 1 – considerable topographical variability across subjects – by evaluating its test-retest reliability with a new group of subjects. Each subject was scanned twice, and the results indicated that, for each of several contrasts, test-retest reliability was significantly greater than chance. Together, these results raise the possibility that the brain bases of delay-period load sensitivity may be characterized by considerable intersubject topographical variability. Our results highlight how the selection of fMRI analysis methods can produce discrepant results, each of which is consistent with different, incompatible theoretical interpretations.
机译：本报告的推动力是评估两类工作内存模型的相互竞争的主张：内存系统模型保存工作内存，这些内存由基于前额叶皮层（PFC）的域特定缓冲区的网络支持，该缓冲区充当内存的工作区。信息的存储和操纵；相反，紧急过程模型认为PFC对工作内存的贡献不包括信息的临时存储。从经验上讲，功能磁共振成像（fMRI）研究似乎相互不兼容的结果支持了上述每个观点，这些研究结果发现或未发现证据表明PFC对存储负荷（存储的指标）具有延迟周期敏感性。我们假设这些经验差异可能至少部分是由于方法论因素造成的，因为报告PFC的延迟期负荷敏感性的研究通常使用空间归一化的组平均分析，而未发现PFC负荷敏感性的研究通常使用单主题“案例研究”方法。实验1对同一数据集执行了这两种分析方法，其结果与该假设一致。实验2通过评估一组新受试者的重测信度，评估了实验1的单项结果的一个特征-受试者之间的地形变化很大。每个受试者进行两次扫描，结果表明，对于几种对比中的每一种，重测信度都大大高于偶然性。总之，这些结果增加了以下可能性：延迟期负荷敏感性的脑基可能具有较大的受试者间形貌变异性。我们的结果强调了功能磁共振成像分析方法的选择如何产生差异的结果，每种结果都与不同的，不兼容的理论解释相一致。

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    Eva Feredoes; Bradley R. Postle;

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  • 年(卷),期 -1(35),2
  • 年度 -1
  • 页码 881–903
  • 总页数 38
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