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| Effects of aging on working memory performance and prefrontal cortex activity: A time-resolved spectroscopy study |
| Jie Shi1, Wenjing Zhou1, Tongchao Geng2, Huancong Zuo1, Masahiro Tanida3, Kaoru Sakatani4 |
1 Department of Neurosurgery, Tsinghua University Yuquan Hospital, Beijing 100040, China;
2 Department of Neurology, Tsinghua University Yuquan Hospital, Beijing 100040, China;
3 Shiseido Research Center, Shin-Yokohama 224-8558, Japan;
4 NEWCAT Research Institute, Nihon University College of Engineering, Fukushima 963-8642, Japan |
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Abstract Objective: This study aimed to employ time-resolved spectroscopy (TRS) to explore age-related differences in prefrontal cortex (PFC) activity while subjects performed a working memory task. Methods: We employed TRS to measure PFC activity in ten healthy younger and ten healthy older subjects while they performed a working memory (WM) task. All subjects performed the Sternberg test (ST) in which the memory-set size varied between one and six digits. Using TRS, we recorded changes in cerebral blood oxygenation as a measure of changes in PFC activity during the task. In order to identify left/right asymmetry of PFC activity during the working memory task, we calculated the laterality score, i.e., Δoxy-Hb (right Δoxy-Hb—left Δoxy-Hb); positive values indicate greater activity in the right PFC, while negative values indicate greater activity in the left PFC. Results: During the ST, statistical analyses showed no significant differences between the younger and older groups in accuracy for low memory-load and high memoryload. In high memory-load tasks, however, older subjects were slower than younger subjects (P < 0.05). We found that the younger group showed right lateral responses with a stronger right than left activation in the frontal pole, whereas the older group showed bilateral responses (P < 0.05). Conclusions: The present results are consistent with the hemispheric asymmetry reduction in older adults (HAROLD) model; working memory tasks cause asymmetrical PFC activation in younger adults, while older adults tend to show reduced hemispheric lateralization.
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Received: 06 January 2016
Published: 31 March 2016
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Corresponding Authors:
Kaoru Sakatani, E-mail: sakatani.kaoru@nihon-u.ac.jp
E-mail: sakatani.kaoru@nihon-u.ac.jp
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