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，即人们可以在网上记住的信息量，在认知中具有核心作用。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作为支撑 WM 能力的神经基础的关键作用。决定持续活动的最佳候选分子分别是大脑的主要兴奋性和抑制性神经递质、谷氨酸和γ-氨基丁酸 (GABA)。然而，我们对形成 WM 能力的这些神经生理学决定因素的了解仍然很少。使用磁共振波谱 (MRS)，我们检查了谷氨酸和 GABA 在左侧顶内沟 (IPS) 和左侧下/额中回 (FG) 在跟踪 WM 能力方面的贡献。在左侧 IPS 中的谷氨酸盐和 WM 容量之间发现了正相关。通过利用静息状态功能 MRI，我们发现顶扣带连接与 WM 容量之间存在负相关。IPS 中的谷氨酸能浓度解释了顶扣带连接的个体差异。此外，我们发现顶扣带连接介导顶间沟谷氨酸盐和 WM 容量之间的关系。这组研究结果揭示了一种新的机制洞察力，即 IPS 内的谷氨酸能浓度通过顶扣带连接性塑造 WM 容量。IPS 中的谷氨酸能浓度解释了顶扣带连接的个体差异。此外，我们发现顶扣带连接介导顶间沟谷氨酸盐和 WM 容量之间的关系。这组研究结果揭示了一种新的机制洞察力，即 IPS 内的谷氨酸能浓度通过顶扣带连接性塑造 WM 容量。IPS 中的谷氨酸能浓度解释了顶扣带连接的个体差异。此外，我们发现顶扣带连接介导顶间沟谷氨酸盐和 WM 容量之间的关系。这组研究结果揭示了一种新的机制洞察力，即 IPS 内的谷氨酸能浓度通过顶扣带连接性塑造 WM 容量。