Wellcome Centre for Integrative Neuroimaging, Department of Experimental Psychology, University of Oxford, UK.
Wellcome Centre for Integrative Neuroimaging, Department of Experimental Psychology, University of Oxford, UK.
Neuroscience. 2021 Mar 1;457:12-19. doi: 10.1016/j.neuroscience.2020.10.037. Epub 2020 Nov 17.
Working memory (WM) capacity, the amount of information one can hold online in mind, has a central role in cognition. Previous electrophysiological and imaging studies revealed the pivotal role of persistent activity within parietal and frontal regions as the neural foundations underpinning WM capacity. The best candidate molecules determining persistent activity are the brain's major excitatory and inhibitory neurotransmitters, glutamate and gamma-aminobutyric acid (GABA), respectively. However, our knowledge of these neurophysiological determinants in forming WM capacity is still poor. Using magnetic resonance spectroscopy (MRS), we examined the contribution of glutamate and GABA within the left intraparietal sulcus (IPS) and the left inferior/middle frontal gyrus (FG) in tracking WM capacity. A positive association was found between glutamate within the left IPS and WM capacity. By utilising resting-state functional MRI, we identified a negative association between parieto-cingulate connectivity and WM capacity. Individual variation in parieto-cingulate connectivity was explained by glutamatergic concentration in the IPS. Moreover, we found that parieto-cingulate connectivity mediated the relationship between interparietal sulcus glutamate and WM capacity. This set of findings reveals a novel mechanistic insight by which glutamatergic concentration within the IPS shapes WM capacity via parieto-cingulate connectivity.
工作记忆（WM）容量是指一个人在大脑中在线保留信息的数量，它在认知中起着核心作用。先前的电生理学和成像研究揭示了顶叶和额叶区域内持续活动的关键作用，是支持 WM 容量的神经基础。决定持续活动的最佳候选分子是大脑的主要兴奋性和抑制性神经递质，分别是谷氨酸和γ-氨基丁酸（GABA）。然而，我们对这些神经生理决定因素在形成 WM 容量中的作用的了解仍然很差。使用磁共振波谱（MRS），我们检查了左顶内沟（IPS）和左额下回/中回（FG）内的谷氨酸和 GABA 对 WM 容量的贡献。发现左 IPS 内的谷氨酸与 WM 容量之间存在正相关。通过利用静息态功能磁共振成像（rs-fMRI），我们发现顶-扣带连接与 WM 容量之间存在负相关。顶-扣带连接的个体差异可以用 IPS 中的谷氨酸浓度来解释。此外，我们发现顶-扣带连接介导了 IPS 内谷氨酸与 WM 容量之间的关系。这一系列发现揭示了一种新的机制见解，即 IPS 内的谷氨酸浓度通过顶-扣带连接来塑造 WM 容量。
