Lise Meitner Research Group Cognition and Plasticity, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstrasse 1a, 04103, Leipzig, Germany; Language & Aphasia Laboratory, Department of Neurology, University of Leipzig Medical Center, Liebigstrasse 20, 04103, Leipzig, Germany.
Lise Meitner Research Group Cognition and Plasticity, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstrasse 1a, 04103, Leipzig, Germany.
Brain Stimul. 2023 Sep-Oct;16(5):1346-1357. doi: 10.1016/j.brs.2023.09.009. Epub 2023 Sep 11.
The continuous decline of executive abilities with age is mirrored by increased neural activity of domain-general networks during task processing. So far, it remains unclear how much domain-general networks contribute to domain-specific processes such as language when cognitive demands increase. The current neuroimaging study explored the potential of intermittent theta-burst stimulation (iTBS) over a domain-general hub to enhance executive and semantic processing in healthy middle-aged to older adults.
We implemented a cross-over within-subject study design with three task-based neuroimaging sessions per participant. Using an individualized stimulation approach, each participant received once effective and once sham iTBS over the pre-supplementary motor area (pre-SMA), a region of domain-general control. Subsequently, task-specific stimulation effects were assessed in functional MRI using a semantic and a non-verbal executive task with varying cognitive demand.
Effective stimulation increased activity only during semantic processing in visual and dorsal attention networks. Further, iTBS induced increased seed-based connectivity in task-specific networks for semantic and executive conditions with high cognitive load but overall reduced whole-brain coupling between domain-general networks. Notably, stimulation-induced changes in activity and connectivity related differently to behavior: While stronger activity of the parietal dorsal attention network was linked to poorer semantic performance, its enhanced coupling with the pre-SMA was associated with more efficient semantic processing.
iTBS modulates networks in a task-dependent manner and generates effects at regions remote to the stimulation site. These neural changes are linked to more efficient semantic processing, which underlines the general potential of network stimulation approaches in cognitive aging.
随着年龄的增长，执行能力持续下降，而在任务处理过程中，域普遍网络的神经活动增加。到目前为止，当认知需求增加时，域普遍网络对语言等特定领域的过程有多大贡献还不清楚。目前的神经影像学研究探讨了间歇性 theta 爆发刺激（iTBS）对域普遍中枢的潜在作用，以增强健康中年至老年人的执行和语义处理能力。
我们采用了一种交叉式的个体参与者设计，每个参与者在三个基于任务的神经影像学会议中接受一次有效和一次假 iTBS。使用个性化的刺激方法，每位参与者接受一次有效的和一次假 iTBS 刺激，刺激位置为预备运动区（pre-SMA），这是一个域普遍控制的区域。随后，使用语义和非言语执行任务，通过功能磁共振成像评估特定任务的刺激效果，这些任务具有不同的认知需求。
有效刺激仅在语义处理期间增加了视觉和背侧注意网络的活动。此外，iTBS 诱导了语义和执行条件下高认知负荷下任务特异性网络的种子连接增加，但总体上降低了域普遍网络之间的全脑耦合。值得注意的是，刺激诱导的活动和连接变化与行为有不同的相关性：虽然顶叶背侧注意网络的更强活动与较差的语义表现相关，但它与 pre-SMA 的增强耦合与更有效的语义处理相关。
iTBS 以任务依赖的方式调节网络，并在刺激部位以外的区域产生效应。这些神经变化与更有效的语义处理有关，这强调了网络刺激方法在认知老化中的普遍潜力。
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