Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology.
Psychol Aging. 2013 Sep;28(3):729-43. doi: 10.1037/a0033236. Epub 2013 Aug 26.
Working memory declines with normal aging, but the nature of this impairment is debated. Studies based on detecting changes to arrays of visual objects have identified two possible components to age-related decline: a reduction in the number of items that can be stored, or a deficit in maintaining the associations (bindings) between individual object features. However, some investigations have reported intact binding with aging, and specific deficits arising only in Alzheimer's disease. Here, using a recently developed continuous measure of recall fidelity, we tested the precision with which adults of different ages could reproduce from memory the orientation and color of a probed array item. The results reveal a further component of cognitive decline: an age-related decrease in the resolution with which visual information can be maintained in working memory. This increase in recall variability with age was strongest under conditions of greater memory load. Moreover, analysis of the distribution of errors revealed that older participants were more likely to incorrectly report one of the unprobed items in memory, consistent with an age-related increase in misbinding. These results indicate a systematic decline with age in working memory resources that can be recruited to store visual information. The paradigm presented here provides a sensitive index of both memory resolution and feature binding, with the potential for assessing their modulation by interventions. The findings have implications for understanding the mechanisms underpinning working memory deficits in both health and disease.
工作记忆会随着正常衰老而下降，但这种衰退的性质仍存在争议。基于检测视觉对象数组变化的研究已经确定了与年龄相关的衰退的两个可能组成部分：可以存储的项目数量减少，或者在个体对象特征之间保持关联（绑定）的能力不足。然而，一些研究报告称，随着年龄的增长，绑定能力完好无损，只有在阿尔茨海默病中才会出现特定的缺陷。在这里，我们使用最近开发的连续回忆保真度测量方法，测试了不同年龄的成年人从记忆中再现探测数组项目的方向和颜色的精确程度。结果揭示了认知衰退的另一个组成部分：与年龄相关的视觉信息在工作记忆中保持的分辨率下降。这种随着年龄增长而增加的回忆可变性在更大的记忆负荷下最强。此外，对错误分布的分析表明，年龄较大的参与者更有可能在记忆中错误地报告一个未探测到的项目，这与年龄相关的错误绑定增加一致。这些结果表明，工作记忆资源随年龄系统下降，可以招募这些资源来存储视觉信息。这里提出的范式提供了记忆分辨率和特征绑定的敏感指标，具有评估干预措施对其调节的潜力。这些发现对于理解健康和疾病中工作记忆缺陷的机制具有重要意义。
