Department of Neurological and Psychiatric Sciences, University of Florence, Italy.
Cortex. 2011 Jun;47(6):750-8. doi: 10.1016/j.cortex.2010.03.007. Epub 2010 Apr 11.
Previous neuropsychological, lesional and functional imaging studies deal with the lateralization of memory processes, suggesting that they could be determined by the stage of processing (encoding vs retrieval) or by content (verbal vs non-verbal stimuli). The aims of the present study were: 1) to investigate if tasks that can be carried out using different strategies depending on the verbalizability of the material induce a lateralization of the mean cerebral blood flow velocity (mCBFV) in the middle cerebral arteries (MCAs), as monitored by a functional transcranial Doppler (fTCD); 2) to evaluate if these patterns of cerebral activation differ in relation to age, gender and task performance.
Using TCD bilateral monitoring, we recorded mCBFV variations in 35 male and 35 female healthy, right-handed volunteers, classified as "young" (age range 21-40 years, n=35) or "old"(age range 41-60 years, n=35), performing four different cognitive tasks: encoding and recognition of Geometric Figures (GF), encoding and recall of Object Localization (OL) on a picture, encoding of a verbal Room Description (RD) and Arithmetic Skill (AS).
We found a significant right lateralization for the OL recall phase, and a significant left lateralization for RD and AS. When we took into consideration gender, age and performance, there was a strong effect of age on both OL encoding and recall phase, with significant right lateralization in young volunteers not seen in the older ones. No difference in gender was detected. We found a gender×performance interaction for RD, with poor performance females showing significant left lateralization.
According to our findings, hemispheric lateralization during memory encoding is material specific in both men and women, depending on the verbalizability of the material. mCBFV right lateralization during scene encoding and recall appears lost in older people, suggesting that healthy elderly could take advantage of mixed verbal and non-verbal strategies.
之前的神经心理学、病变和功能影像学研究都涉及记忆过程的偏侧化，表明其可能取决于加工阶段（编码与提取）或内容（言语与非言语刺激）。本研究的目的是：1）通过功能 transcranial Doppler（fTCD）监测，探讨是否可以通过不同的策略完成依赖于材料的可言语性的任务，从而导致大脑中动脉（MCA）的平均脑血流速度（mCBFV）的偏侧化；2）评估这些大脑激活模式是否因年龄、性别和任务表现而异。
我们使用 TCD 双侧监测，记录了 35 名男性和 35 名女性健康右利手志愿者的 mCBFV 变化，这些志愿者被分为“年轻”（年龄范围为 21-40 岁，n=35）或“年老”（年龄范围为 41-60 岁，n=35），执行四项不同的认知任务：几何图形的编码和识别（GF）、图片上物体定位的编码和识别（OL）、言语室描述（RD）和算术技能（AS）的编码。
我们发现 OL 回忆阶段存在明显的右侧偏侧化，RD 和 AS 编码和回忆阶段存在明显的左侧偏侧化。当我们考虑性别、年龄和表现时，OL 编码和回忆阶段的年龄有很大影响，年轻志愿者存在显著的右侧偏侧化，而年长志愿者则没有。性别差异不明显。我们发现 RD 存在性别×表现的交互作用，表现不佳的女性存在显著的左侧偏侧化。
根据我们的发现，在男性和女性中，记忆编码期间的半球偏侧化是依赖于材料的可言语性的。在老年人中，场景编码和回忆时的 mCBFV 右侧偏侧化似乎丢失，这表明健康的老年人可以利用混合的言语和非言语策略。
