Neuroscience Training Program, University of Wisconsin-Madison, USA.
Behav Neurol. 2011;24(3):187-99. doi: 10.3233/BEN-2011-0331.
Functional imaging studies consistently find that older adults recruit bilateral brain regions in cognitive tasks that are strongly lateralized in younger adults, a characterization known as the Hemispheric Asymmetry Reduction in Older Adults model. While functional imaging displays what brain areas are active during tasks, it cannot demonstrate what brain regions are necessary for task performance. We used behavioral data from acute stroke patients to test the hypothesis that older adults need both hemispheres for a verbal working memory task that is predominantly left-lateralized in younger adults. Right-handed younger (age ⩽ 50, n = 7) and older adults (age > 50, n =21) with acute unilateral stroke, as well as younger (n =6) and older (n =13) transient ischemic attack (TIA) patients, performed a self-paced verbal item-recognition task. Older patients with stroke to either hemisphere had a higher frequency of deficits in the verbal working memory task compared to older TIA patients. Additionally, the deficits in older stroke patients were mainly in retrieval time while the deficits in younger stroke patients were mainly in accuracy. These data suggest that bihemispheric activity is necessary for older adults to successfully perform a verbal working memory task.
功能成像研究一致发现，老年人在认知任务中会募集双侧大脑区域，而这些区域在年轻人中是强烈偏侧化的，这种特征被称为老年人半球不对称性减少模型。虽然功能成像显示了在任务期间哪些大脑区域活跃，但它不能证明哪些大脑区域对任务表现是必要的。我们使用急性中风患者的行为数据来检验假设，即老年人需要两个半球来完成在年轻人中主要偏左侧的言语工作记忆任务。右侧利手的年轻（年龄 ⩽ 50，n = 7）和老年（年龄 > 50，n = 21）急性单侧中风患者，以及年轻（n = 6）和老年（n = 13）短暂性脑缺血发作（TIA）患者，执行了自我调节的言语项目识别任务。与老年 TIA 患者相比，中风至任何一侧半球的老年患者在言语工作记忆任务中出现缺陷的频率更高。此外，老年中风患者的缺陷主要在检索时间，而年轻中风患者的缺陷主要在准确性。这些数据表明，双半球活动对于老年人成功执行言语工作记忆任务是必要的。
