Hendrikse Joshua, Thompson Sarah, Suo Chao, Yücel Murat, Rogasch Nigel C, Coxon James P
Turner Institute for Brain and Mental Health and School of Psychological Sciences, Monash University, Melbourne, Victoria, Australia.
Hopwood Centre for Neurobiology, Lifelong Health Theme, South Australian Health and Medical Research Institute (SAHMRI), Australia.
Neuroimage Rep. 2021 Sep 9;1(4):100049. doi: 10.1016/j.ynirp.2021.100049. eCollection 2021 Dec.
Working memory (WM) refers to the capacity to temporarily retain and manipulate finite amounts of information; a critical process in complex behaviours such as reasoning, comprehension, and learning. This cognitive function is supported by a parietal-prefrontal network and linked to the activity of key neurotransmitters, such as gamma-aminobutyric acid (GABA). Impairments in WM are seen in a range of psychiatric and neurological disorders, and there are currently no effective treatments. In this study, we analysed secondary outcome measures from a trial investigating the effects of multi-day rTMS on cognition. Participants received four days of 20 Hz rTMS to an individualised region of left parietal cortex in one week, and an individualised region of pre-supplementary motor area (pre-SMA) in a separate week. We assessed changes to WM function before and after each week of stimulation (N = 39), and changes to GABA concentration before and after stimulation in week one using MR spectroscopy (N = 18 per stimulation condition). We hypothesised that parietal rTMS would enhance WM and alter GABA concentration at the site of stimulation, but this was not observed. Instead, we report some evidence of improved WM function following the first week of pre-SMA rTMS stimulation, and a generalised increase in GABA concentration across both parietal and pre-SMA voxels following pre-SMA rTMS. Additionally, we found that higher cardiorespiratory fitness was associated with greater WM improvement following pre-SMA stimulation. This study does not support the use of parietal multi-day rTMS for the enhancement of working memory. In contrast, the results suggest that increasing cardiorespiratory fitness may provide a novel approach to enhance the effects of pre-SMA rTMS on cognition.
工作记忆（WM）是指暂时保留和处理有限信息量的能力；这是诸如推理、理解和学习等复杂行为中的关键过程。这种认知功能由顶叶-前额叶网络支持，并与关键神经递质（如γ-氨基丁酸（GABA））的活性相关。在一系列精神和神经疾病中都可见到工作记忆受损，目前尚无有效的治疗方法。在本研究中，我们分析了一项试验的次要结果指标，该试验调查了多日重复经颅磁刺激（rTMS）对认知的影响。参与者在一周内接受四天20赫兹的rTMS刺激，刺激部位为左侧顶叶皮质的个体化区域，在另一周接受四天的rTMS刺激，刺激部位为补充运动前区（pre-SMA）的个体化区域。我们评估了每次刺激周前后工作记忆功能的变化（N = 39），并在第一周使用磁共振波谱评估了刺激前后GABA浓度的变化（每种刺激条件下N = 18）。我们假设顶叶rTMS会增强工作记忆并改变刺激部位的GABA浓度，但未观察到这种情况。相反，我们报告了一些证据，表明在补充运动前区rTMS刺激的第一周后工作记忆功能有所改善，并且在补充运动前区rTMS后，顶叶和补充运动前区体素中的GABA浓度普遍增加。此外，我们发现较高的心肺适能与补充运动前区刺激后更大的工作记忆改善相关。本研究不支持使用多日顶叶rTMS来增强工作记忆。相比之下，结果表明提高心肺适能可能为增强补充运动前区rTMS对认知的影响提供一种新方法。
