Beta Peak Frequencies at Rest Correlate with Endogenous GABA+/Cr Concentrations in Sensorimotor Cortex Areas

Neuronal oscillatory activity in the beta band (15–30 Hz) is a prominent signal within the human sensorimotor cortex. Computational modeling and pharmacological modulation studies suggest an influence of GABAergic interneurons on the generation of beta band oscillations. Accordingly, studies in humans have demonstrated a correlation between GABA concentrations and power of beta band oscillations. It remains unclear, however, if GABA concentrations also influence beta peak frequencies and whether this influence is present in the sensorimotor cortex at rest and without pharmacological modulation. In the present study, we investigated the relation between endogenous GABA concentration (measured by magnetic resonance spectroscopy) and beta oscillations (measured by magnetoencephalography) at rest in humans. GABA concentrations and beta band oscillations were measured for left and right sensorimotor and occipital cortex areas. A significant positive linear correlation between GABA concentration and beta peak frequency was found for the left sensorimotor cortex, whereas no significant correlations were found for the right sensorimotor and the occipital cortex. The results show a novel connection between endogenous GABA concentration and beta peak frequency at rest. This finding supports previous results that demonstrated a connection between oscillatory beta activity and pharmacologically modulated GABA concentration in the sensorimotor cortex. Furthermore, the results demonstrate that for a predominantly right-handed sample, the correlation between beta band oscillations and endogenous GABA concentrations is evident only in the left sensorimotor cortex.

β频段（15–30 Hz）的神经元振荡活动是人类感觉运动皮层内的显著信号。计算建模与药理学调控研究表明，γ-氨基丁酸能（GABAergic）中间神经元对β频段振荡的产生具有调控作用。相应地，已有人类研究证实γ-氨基丁酸浓度与β频段振荡功率之间存在相关性。然而，目前仍不清楚γ-氨基丁酸浓度是否同样会影响β峰频率，且这种影响是否存在于静息状态下、未经过药理学调控的感觉运动皮层中。
本研究针对人类静息状态下的内源性γ-氨基丁酸浓度（通过磁共振波谱（Magnetic Resonance Spectroscopy）检测）与β振荡（通过脑磁图（Magnetoencephalography）检测）之间的关联展开了探究。我们对左右侧感觉运动皮层与枕叶皮层区域的γ-氨基丁酸浓度及β频段振荡进行了测量。结果发现，左侧感觉运动皮层的γ-氨基丁酸浓度与β峰频率之间存在显著的正线性相关，而右侧感觉运动皮层与枕叶皮层则未发现显著相关性。
本研究结果揭示了静息状态下内源性γ-氨基丁酸浓度与β峰频率之间的全新关联。这一发现佐证了此前的研究结果——后者曾证实感觉运动皮层内的β振荡活动与经药理学调控的γ-氨基丁酸浓度之间存在关联。此外，本研究结果还表明，在以右利手为主的受试样本中，β频段振荡与内源性γ-氨基丁酸浓度之间的相关性仅存在于左侧感觉运动皮层。