Rodríguez-Aranda Claudia, Castro-Chavira Susana A, Espenes Ragna, Barrios Fernando A, Waterloo Knut, Vangberg Torgil R
Department of Psychology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway.
Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, Mexico.
Front Hum Neurosci. 2020 Jun 5;14:203. doi: 10.3389/fnhum.2020.00203. eCollection 2020.
Semantic verbal fluency is among the most employed tasks in cognitive aging research and substantial work is devoted to understanding the underlying mechanisms behind age-related differences at the neural and behavioral levels. The present investigation aimed to evaluate the role of moderating variables, such as age, sex, MMSE, and proxies of cognitive reserve (CR) on the hemodynamic response evoked by semantic verbal fluency in healthy young and healthy older adults. So far, no study has been conducted to this end. To elucidate the exclusive effect of the mentioned variables on brain activation during semantic fluency, finger tapping was included as a control task. Results showed that disregarding adjustments for age, older adults displayed important parietal activations during semantic fluency as well as during finger-tapping. Specifically, the anterior intra-parietal sulcus (IPS) and left inferior parietal lobule (IPL) were areas activated in both tasks in the older group. Younger adults, only displayed parietal activations related to age and sex when these demographics were employed as predictors. Concerning proxies of CR in semantic fluency, the only vocabulary was an important moderator in both age groups. Higher vocabulary scores were associated with lesser activation in occipital areas. Education did not show significant correlations with brain activity during semantic fluency in any of the groups. However, both CR proxies were significantly correlated to brain activations of older adults during finger tapping. Specifically, vocabulary was associated with frontal regions, while education correlated with parietal lobe and cingulate gyrus. Finally, the effects of MMSE were mostly observed on brain activation of older adults in both tasks. These findings demonstrate that the effects of moderating variables on shaping brain activation are intricate and not exclusive of complex verbal tasks. Thus, before adjusting for "nuisance variables," their importance needs to be established. This is especially true for samples including older adults for whom a motor task may be a demanding operation due to normal age-related processes of dedifferentiation.
语义言语流畅性是认知衰老研究中使用最广泛的任务之一，大量工作致力于从神经和行为层面理解与年龄相关差异背后的潜在机制。本研究旨在评估年龄、性别、简易精神状态检查表（MMSE）以及认知储备（CR）指标等调节变量对健康年轻人和健康老年人语义言语流畅性诱发的血流动力学反应的作用。到目前为止，尚未有研究为此目的而开展。为了阐明上述变量在语义流畅性期间对大脑激活的独特影响，将手指敲击作为对照任务纳入研究。结果显示，在不考虑年龄调整的情况下，老年人在语义流畅性任务以及手指敲击任务期间均表现出重要的顶叶激活。具体而言，老年组在这两项任务中激活的区域均为顶内沟前部（IPS）和左侧顶下小叶（IPL）。年轻成年人仅在将这些人口统计学特征作为预测因素时，才表现出与年龄和性别相关的顶叶激活。关于语义流畅性中CR的指标，唯一的词汇量在两个年龄组中都是一个重要的调节因素。较高词汇量得分与枕叶区域较小的激活相关。在任何一组中，教育程度与语义流畅性任务期间的大脑活动均未显示出显著相关性。然而，在手指敲击任务期间，这两个CR指标均与老年人的大脑激活显著相关。具体而言，词汇量与额叶区域相关，而教育程度与顶叶和扣带回相关。最后，MMSE的影响主要体现在两项任务中老年人的大脑激活上。这些发现表明，调节变量对塑造大脑激活的影响错综复杂，并非复杂言语任务所独有。因此，在对“干扰变量”进行调整之前，需要确定它们的重要性。对于包括老年人的样本而言尤其如此，因为由于正常的与年龄相关的去分化过程，运动任务可能是一项具有挑战性的操作。
