Although hearing often declines with age, prior research has shown that older adults may benefit from multisensory input to a greater extent when compared to younger adults, a concept known as inverse effectiveness. While there is behavioral evidence in support of this phenomenon, less is known about its neural basis. The present functional MRI (fMRI) study examined how older and younger adults processed multimodal auditory-visual (AV) phonemic stimuli which were either congruent or incongruent across modalities. Incongruent AV pairs were designed to elicit the McGurk effect. Behaviorally, reaction times were significantly faster during congruent trials compared to incongruent trials for both age-groups, and overall older adults responded more slowly. The interaction was not significant, suggesting that older adults processed the AV stimuli similarly to younger adults. Although there were minimal behavioral differences, age-related differences in functional activation were identified: Younger adults elicited greater activation than older adults in primary sensory regions including superior temporal gyrus, the calcarine fissure, and left postcentral gyrus. In contrast, older adults elicited greater activation than younger adults in dorsal frontal regions including middle and superior frontal gyri, as well as dorsal parietal regions. These data suggest that while there is age-related stability in behavioral sensitivity to multimodal stimuli, the neural bases for this effect differed between older and younger adults. Our results demonstrated that older adults underrecruited primary sensory cortices and had increased recruitment of regions involved in executive function, attention, and monitoring processes, which may reflect an attempt to compensate.

尽管听力通常会随着年龄的增长而下降，但先前的研究表明，与年轻人相比，老年人可能在更大程度上受益于多感官输入，这一概念被称为逆向效应。虽然有行为证据支持这种现象，但对其神经基础知之甚少。目前的功能性 MRI (fMRI) 研究检查了老年人和年轻人如何处理多模式听觉 - 视觉 (AV) 音素刺激，这些刺激在不同模式中是一致的或不一致的。不一致的 AV 对旨在引发 McGurk 效应。在行为上，与两个年龄组的不一致试验相比，一致试验期间的反应时间明显更快，总体上老年人的反应更慢。交互作用不显着，表明老年人处理 AV 刺激的方式与年轻人类似。尽管行为差异很小，但功能激活的年龄相关差异已被确定：在包括颞上回、距状裂和左中央后回在内的初级感觉区域，年轻人比老年人引起更大的激活。相比之下，老年人在背额叶区域（包括额中回和上回以及背顶叶区域）比年轻人引起更大的激活。这些数据表明，虽然对多模态刺激的行为敏感性存在与年龄相关的稳定性，但这种效应的神经基础在老年人和年轻人之间有所不同。