脑神经活动还存在年龄差异吗?

2008-06-20 20:02:56 来源: 中科院心理所
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情节记忆提取是对老化过程最敏感的认知活动之一。功能性神经成像研究已发现在情节提取过程中存在广泛的年龄差异。但目前存在的一个问题是:已发现的这些年龄差异是否仅仅反映了老年组和青年组在行为操作成绩上的差异?

为了回答这个问题,老年心理研究中心李娟研究员和合作者A.M. Morcom以及M.D. Rugg利用事件相关的功能性磁共振成像(event-related fMRI)技术开展了情节提取年老化研究。该研究通过操纵图片刺激的呈现次数,匹配了两年龄组来源记忆成绩。比较对来源做出正确判断的旧项目与正确识别的新项目,发现两年龄组激活大量相同皮层区域。但同时也观察到一些令人吃惊的结果:在老年组中,与提取相关的脑激活增强较青年组更为广泛,幅度也更大。此外,仅仅在青年组中观察到了与提取相关的脑激活减弱。这些结果提示:在认知成绩不存在年龄差异时,老年人的加工效率可能已经下降。该研究结果发表于Cerebral Cortex杂志上。Morcom AM, Li J, Rugg MD. Age effects on the neural correlates of episodic retrieval: increased cortical recruitment with matched performance. Cereb Cortex. 2007;17(11):2491-506.(SCI IF = 6.37)

Differential activity within and across age groups for easy condition source hits versus CRs, rendered onto the MNI reference brain. Representative effects are also displayed on transverse sections of the same reference brain. Positive old/new effects are shown in red and negative old/new effects in green, with the exception of the interaction map. Here, red indicates regions in which activity for source hits minus CRs is greater in the older group. (A) Old/new effects in the young group alone. (B) Old/new effects in the older group alone. (C) Age-related differences in old/new effects. (D) Age-invariant old/new effects. The maps in (A) were inclusively masked with those in (B), with the interactions illustrated in (C) removed by exclusive masking (see Materials and Methods for details).

乾坤 本文来源:中科院心理所 责任编辑:王晓易_NE0011
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