To assess if magnetic resonance spectroscopy (MRS)-measured Glutamate (Glu) and GABA reflect excitatory and inhibitory neural activities, respectively, we conducted MRS measurements along with two-photon mesoscopic imaging of calcium signals in excitatory and inhibitory neurons of living, unanesthetized mice. For monitoring stimulus-driven activations of a brain region, MRS signals and mesoscopic neural activities were measured during two consecutive sessions of 15-min prolonged sensory stimulations. In the first session, putative excitatory neuronal activities were increased, while inhibitory neuronal activities remained at the baseline level. In the second half, while excitatory neuronal activities remained elevated, inhibitory neuronal activities were significantly enhanced. We also assessed regional neurochemical and functional statuses related to spontaneous neural firing by measuring MRS signals and neuronal activities in a mouse model of Dravet syndrome under a resting condition. Mesoscopic assessments showed that activities of inhibitory neurons in the cortex were diminished relative to wild-type mice in contrast to spared activities of excitatory neurons. Consistent with these observations, the Dravet model exhibited lower concentrations of GABA than wild-type controls. Collectively, the current investigations demonstrate that the MRS-measured Glu and GABA can reflect spontaneous and stimulated activities of neurons producing and releasing these neurotransmitters in an awake condition.

中文翻译：

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MRS测量的谷氨酸对GABA反映了清醒小鼠的兴奋性神经活动与抑制性神经活动

为了评估磁共振波谱（MRS）测量的谷氨酸（Glu）和GABA是否分别反映了兴奋性和抑制性神经活动，我们进行了MRS测量以及活着的，未麻醉的小鼠的兴奋性和抑制性神经元中钙信号的双光子介观成像。 。为了监测刺激驱动的大脑区域的激活，在两个连续的15分钟延长的感觉刺激过程中，测量了MRS信号和介观神经活动。在第一阶段中，假定的兴奋性神经元活动增加，而抑制性神经元活动保持在基线水平。在下半年，虽然兴奋性神经元活性仍然升高，但抑制性神经元活性却显着增强。我们还通过在静止状态下测量Dravet综合征小鼠模型中的MRS信号和神经元活动来评估与自发神经放电相关的区域神经化学和功能状态。介观评估显示，与野生型小鼠相比，皮层中抑制性神经元的活性有所降低，而兴奋性神经元的剩余活性却与此相反。与这些观察结果一致，Dravet模型显示的GABA浓度低于野生型对照。总的来说，当前的研究表明，MRS测得的Glu和GABA可以反映在清醒状态下产生和释放这些神经递质的神经元的自发性和刺激性活动。