Department of Experimental Psychology, University of Cambridge, Cambridge, UK.
J Cogn Neurosci. 2010 Jul;22(7):1530-40. doi: 10.1162/jocn.2009.21321.
A common complaint of normal aging is the increase in word-finding failures such as tip-of-the-tongue states (TOTs). Behavioral research identifies TOTs as phonological retrieval failures, and recent findings [Shafto, M. A., Burke, D. M., Stamatakis, E. A., Tam, P., & Tyler, L. K. On the tip-of-the-tongue: Neural correlates of increased word-finding failures in normal aging. Journal of Cognitive Neuroscience, 19, 2060-2070, 2007] link age-related increases in TOTs to atrophy in left insula, a region implicated in phonological production. Here, younger and older adults performed a picture naming task in the fMRI scanner. During successful naming, left insula activity was not affected by age or gray matter integrity. Age differences only emerged during TOTs, with younger but not older adults generating a "boost" of activity during TOTs compared to successful naming. Older adults also had less activity than younger adults during TOTs compared to "don't know" responses, and across all participants, less TOT activity was affiliated with lower gray matter density. For older adults, lower levels of activity during TOTs accompanied higher TOT rates, supporting the role of an age-related neural mechanism impacting older more than younger adults. Results support a neural account of word retrieval in old age wherein, despite widespread age-related atrophy, word production processes are not universally impacted by age. However, atrophy undermines older adults' ability to modulate neural responses needed to overcome retrieval failures.
正常衰老的一个常见抱怨是单词查找失败的增加，例如舌尖状态（TOT）。行为研究将 TOT 识别为语音检索失败，最近的研究结果[Shafto，MA，Burke，DM，Stamatakis，EA，Tam，P.，和 Tyler，LK。在舌尖上：正常衰老中单词查找失败增加的神经相关性。认知神经科学杂志，19，2060-2070，2007]将与年龄相关的 TOT 增加与左脑岛的萎缩联系起来，左脑岛与语音产生有关。在这里，年轻和老年成年人在 fMRI 扫描仪中执行图片命名任务。在成功命名期间，左脑岛的活动不受年龄或灰质完整性的影响。只有在 TOT 期间才会出现年龄差异，与成功命名相比，年轻但不是老年成年人在 TOT 期间会产生“增强”的活动。与“不知道”的反应相比，老年成年人在 TOT 期间的活动也少于年轻成年人，并且在所有参与者中，较少的 TOT 活动与较低的灰质密度相关。对于老年成年人，TOT 期间的活动水平较低伴随着较高的 TOT 率，这支持了一种影响老年成年人而不是年轻成年人的与年龄相关的神经机制的作用。结果支持了一种在老年时期进行单词检索的神经解释，即尽管存在广泛的与年龄相关的萎缩，但单词产生过程并不普遍受到年龄的影响。然而，萎缩削弱了老年成年人调节神经反应以克服检索失败的能力。
