Models of healthy brain function and psychiatric conditions assume that excitatory and inhibitory activity are balanced in the human brain at multiple spatial and temporal scales. In human neuroimaging, concentrations of the major excitatory (glutamate) and inhibitory (γ-aminobutyric acid, GABA) neurotransmitters are measured in vivo using magnetic resonance spectroscopy (MRS). However, despite the central importance of E/I balance to theories of brain function, a relationship between regional glutamate and GABA levels in the human brain has not been shown. We addressed this question in a large corpus of edited MRS data collected at 19 different sites (n=220). Consistent with the notion of E/I balance, we found that levels of glutamate+glutamine (Glx) and GABA+ were highly correlated (R = 0.52, p = 2.86 x 10-14). This relationship held when controlling for site, scanner vendor, and demographics. Controlling for neurochemicals associated with neuronal density and metabolism (i.e. N-acetylaspartate and creatine) significantly reduced the correlation between GABA+ and Glx, suggesting that the levels of GABA+ and Glx may be critically linked to regional metabolism. These results are consistent with the notion that excitation and inhibition are balanced in the human brain.

中文翻译：

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静息人脑中谷氨酸+谷氨酰胺和GABA+之间的区域平衡

健康大脑功能和精神疾病模型假设人脑中的兴奋性和抑制性活动在多个空间和时间尺度上是平衡的。在人类神经影像学中，使用磁共振波谱 (MRS) 在体内测量主要兴奋性（谷氨酸）和抑制性（γ-氨基丁酸，GABA）神经递质的浓度。然而，尽管 E/I 平衡对大脑功能理论至关重要，但尚未显示人脑中区域谷氨酸和 GABA 水平之间的关系。我们在 19 个不同站点 (n=220) 收集的大量经过编辑的 MRS 数据中解决了这个问题。与 E/I 平衡的概念一致，我们发现谷氨酸+谷氨酰胺 (Glx) 和 GABA+ 的水平高度相关（R = 0.52，p = 2.86 x 10-14）。在控制站点、扫描仪供应商和人口统计时，这种关系成立。控制与神经元密度和代谢相关的神经化学物质（即 N-乙酰天冬氨酸和肌酸）显着降低了 GABA+ 和 Glx 之间的相关性，表明 GABA+ 和 Glx 的水平可能与局部代谢密切相关。这些结果与人脑中兴奋和抑制平衡的观点一致。