Fundamental Differences in Callosal Structure, Neurophysiologic Function, and Bimanual Control in Young and Older Adults
Fundamental Differences in Callosal Structure, Neurophysiologic Function, and Bimanual Control in Young and Older Adults
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DOI：
10.1093/cercor/bhr349
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发表时间：
2012-11-01
期刊：
影响因子：
3.7
通讯作者：
Seidler, R. D.
中科院分区：
文献类型：
--
作者：
Fling, B. W.;Seidler, R. D.
双手动作涉及协调的运动，但通常依赖于每只手执行的不同动作。老年人表现出差异更大的变化，双手的行动，其中每只手有一个独立的运动目标。这种行为依赖于通过胼胝体的半球间交流，包括促进和抑制的相互作用。在这里，我们调查是否年龄差异胼胝体结构和半球间的功能有助于这种选择性运动困难。参与者执行3个力产生任务：1）单手，2）双手同时，和3）双手独立。老年人有显着更大的大脑半球间的促进过程中自愿肌肉激活。我们还报告了一个根本的转变，随着年龄的胼胝体束微结构的完整性和半球间抑制（IHI）之间的关系。具体而言，老年人与胼胝体束微结构的完整性相对较大，有较少的IHI。此外，更大的IHI与较差的双手表现（评估占主导地位的手的力量变化）在老年人的所有任务，而这种关系只观察到在年轻人的双手独立的条件。这些研究结果表明，随着年龄的增长，大脑半球间的沟通，老年人可能会依赖于双边皮质合作在更大程度上比年轻人的手动操作的变化。
Bimanual actions involve coordinated motion but often rely on the movements performed with each hand to be different. Older adults exhibit differentially greater variability for bimanual actions in which each hand has an independent movement goal. Such actions rely on interhemispheric communication via the corpus callosum, including both facilitatory and inhibitory interactions. Here, we investigated whether age differences in callosal structure and interhemispheric function contribute to this selective movement difficulty. Participants performed 3 force production tasks: 1) unimanual, 2) bimanual simultaneous, and 3) bimanual independent. Older adults had significantly greater interhemispheric facilitation during voluntary muscle activation. We also report a fundamental shift with age in the relationship between callosal tract microstructural integrity and interhemispheric inhibition (IHI). Specifically, older adults with relatively greater callosal tract microstructural integrity have less IHI. Furthermore, greater IHI was related to poorer bimanual performance (assessed by dominant hand force variability) in older adults on all tasks, whereas this relationship was only observed in young adults for the bimanual independent condition. These findings indicate changes in interhemispheric communication with advancing age such that older adults may rely on bilateral cortical cooperation to a greater extent than young adults for manual actions.