Peter Jessica, Kaiser Jannis, Landerer Verena, Köstering Lena, Kaller Christoph P, Heimbach Bernhard, Hüll Michael, Bormann Tobias, Klöppel Stefan
Freiburg Brain Imaging, Faculty of Medicine, University of Freiburg, Germany; Department of Neurology, Faculty of Medicine, University of Freiburg, Germany; Department of Psychiatry and Psychotherapy, Section of Gerontopsychiatry and Neuropsychology, Faculty of Medicine, University of Freiburg, Germany.
Freiburg Brain Imaging, Faculty of Medicine, University of Freiburg, Germany; Department of Psychiatry and Psychotherapy, Section of Gerontopsychiatry and Neuropsychology, Faculty of Medicine, University of Freiburg, Germany.
Neuropsychologia. 2016 Dec;93(Pt A):21-29. doi: 10.1016/j.neuropsychologia.2016.09.024. Epub 2016 Sep 30.
The exploration and retrieval of words during category fluency involves different strategies to improve or maintain performance. Deficits in that task, which are common in patients with amnestic mild cognitive impairment (aMCI), mirror either impaired semantic memory or dysfunctional executive control mechanisms. Relating category fluency to tasks that place greater demands on either semantic knowledge or executive functions might help to determine the underlying cognitive process. The aims of this study were to compare performance and strategy use of 20 patients with aMCI to 30 healthy elderly controls (HC) and to identify the dominant component (either executive or semantic) for better task performance in category fluency. Thus, the relationship between category fluency, design fluency and naming was examined. As fluency tasks have been associated with the superior frontal gyrus (SFG), the inferior frontal gyrus (IFG), and the temporal pole, we further explored the relationship between gray matter volume in these areas and both performance and strategy use. Patients with aMCI showed significantly lower performance and significantly less strategy use during fluency tasks compared to HC. However, both groups equally improved their performance when repeatedly confronted with the same task. In aMCI, performance during category fluency was significantly predicted by design fluency performance, while in HC, it was significantly predicted by naming performance. In HC, volume of the SFG significantly predicted both category and design fluency performance, and strategy use during design fluency. In aMCI, the SFG and the IFG predicted performance during both category and design fluency. The IFG significantly predicted strategy use during category fluency in both groups. The reduced category fluency performance in aMCI seems to be primarily due to dysfunctional executive control mechanisms rather than impaired semantic knowledge. This finding is directly relevant to patients in the different stages of Alzheimer's disease as it links the known semantic fluency deficit in this population to executive functions. Although patients with aMCI are impaired in both performance and strategy use compared to HC, they are able to increase performance over time. However, only HC were able to significantly improve the utilization of fluency strategies in both category and design fluency over time. HC seem to rely more heavily on the SFG during fluency tasks, while in patients with aMCI additional frontal brain areas are involved, possibly reflecting compensational processes.
在类别流畅性任务中对单词的探索和检索涉及不同的策略来提高或维持表现。该任务中的缺陷在遗忘型轻度认知障碍（aMCI）患者中很常见，反映了语义记忆受损或执行控制机制功能失调。将类别流畅性与对语义知识或执行功能要求更高的任务联系起来，可能有助于确定潜在的认知过程。本研究的目的是比较20例aMCI患者与30例健康老年对照（HC）的表现和策略使用情况，并确定在类别流畅性中实现更好任务表现的主导成分（执行或语义）。因此，研究了类别流畅性、设计流畅性和命名之间的关系。由于流畅性任务与额上回（SFG）、额下回（IFG）和颞极有关，我们进一步探讨了这些区域的灰质体积与表现和策略使用之间的关系。与HC相比，aMCI患者在流畅性任务中的表现显著更低，策略使用也显著更少。然而，当两组反复面对相同任务时，他们的表现均有同等程度的提高。在aMCI中，设计流畅性表现显著预测了类别流畅性任务中的表现，而在HC中，命名表现显著预测了类别流畅性任务中的表现。在HC中，SFG的体积显著预测了类别和设计流畅性表现以及设计流畅性任务中的策略使用。在aMCI中，SFG和IFG预测了类别和设计流畅性任务中的表现。IFG显著预测了两组在类别流畅性任务中的策略使用。aMCI中类别流畅性表现降低似乎主要是由于执行控制机制功能失调，而非语义知识受损。这一发现与阿尔茨海默病不同阶段的患者直接相关，因为它将该人群中已知的语义流畅性缺陷与执行功能联系起来。尽管与HC相比，aMCI患者在表现和策略使用方面均受损，但他们能够随着时间推移提高表现。然而，只有HC能够随着时间显著改善在类别和设计流畅性中对流畅性策略的运用。HC在流畅性任务中似乎更依赖SFG，而aMCI患者涉及额外的额叶脑区，这可能反映了代偿过程。
