Psychology Department, Faculty of Arts, Thompson Rivers University, Kamloops, British Columbia, Canada.
Biology Department, Faculty of Science, Thompson Rivers University, Kamloops, British Columbia, Canada.
PLoS One. 2024 Oct 14;19(10):e0312109. doi: 10.1371/journal.pone.0312109. eCollection 2024.
Researchers implementing non-invasive neuroimaging have reported distinct load-dependent brain activity patterns in older adults compared with younger adults. Although findings are mixed, these age-related patterns are often associated with compensatory mechanisms of cognitive decline even in the absence of direct comparisons between brain activity and cognitive performance. This study investigated the effects of cognitive load on brain-behavior relationships in younger and older adults using a data-driven, multivariate partial least squares (PLS) analysis of functional near-infrared spectroscopy (fNIRS) data. We measured bilateral prefrontal brain activity in 31 older and 27 younger adults while they performed single and dual 2-back tasks. Behavioral PLS analysis was used to determine relationships between performance metrics (reaction time and error rate) and brain oxygenation (HbO) and deoxygenation (HbR) patterns across groups and task loads. Results revealed significant age-group differences in brain-behavior relationships. In younger adults, increased brain activity (i.e., increased HbO and decreased HbR) was associated with faster reaction times and better accuracy in the single task, indicating sufficient neural capacity. Conversely, older adults showed a negative correlation between HbR and error rates in the single task; however, in the dual task, they demonstrated a positive relationship between HbO and performance, indicative of compensatory mechanisms under the higher cognitive load. Overall, older adults' showed relationships with either HbR or HbO, but not both, indicating that the robustness of the relationship between brain activity and behavior varies across task load conditions. Our PLS approach revealed distinct load-dependent brain activity between age groups, providing further insight into neurocognitive aging patterns, such as compensatory mechanisms, by emphasizing the variability and complexity of brain-behavior relationships. Our findings also highlight the importance of considering task complexity and cognitive demands in interpreting age-related brain activity patterns.
研究人员在实施非侵入性神经影像学时发现，与年轻成年人相比，老年人的大脑活动模式存在明显的与负荷相关的差异。尽管结果存在差异，但这些与年龄相关的模式通常与认知能力下降的代偿机制有关，即使在没有直接比较大脑活动与认知表现的情况下也是如此。本研究使用功能近红外光谱（fNIRS）数据的基于数据的多元偏最小二乘法（PLS）分析，研究了认知负荷对年轻和老年成年人的大脑-行为关系的影响。我们在 31 名老年和 27 名年轻成年人执行单任务和双任务 2 背任务时测量了他们双侧前额叶的大脑活动。行为 PLS 分析用于确定绩效指标（反应时间和错误率）与大脑氧合（HbO）和脱氧（HbR）模式之间的关系，以跨组和任务负荷。结果显示大脑-行为关系存在显著的年龄组差异。在年轻成年人中，大脑活动的增加（即 HbO 的增加和 HbR 的减少）与单任务中的反应时间更快和准确性更高相关，表明有足够的神经能力。相反，老年成年人在单任务中显示出 HbR 与错误率之间的负相关；然而，在双任务中，他们表现出 HbO 与表现之间的正相关，表明在更高的认知负荷下存在代偿机制。总的来说，老年成年人的大脑活动与 HbR 或 HbO 相关，但不是两者都相关，这表明大脑活动与行为之间的关系的稳健性因任务负荷条件而异。我们的 PLS 方法揭示了年龄组之间与负荷相关的大脑活动的差异，通过强调大脑-行为关系的可变性和复杂性，为神经认知老化模式（例如代偿机制）提供了进一步的见解。我们的研究结果还强调了在解释与年龄相关的大脑活动模式时，考虑任务复杂性和认知需求的重要性。
