Lea-Carnall Caroline A, Williams Stephen R, Sanaei-Nezhad Faezeh, Trujillo-Barreto Nelson J, Montemurro Marcelo A, El-Deredy Wael, Parkes Laura M
Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK.
Division of Informatics, Imaging and Data Science, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK.
iScience. 2020 Oct 8;23(11):101657. doi: 10.1016/j.isci.2020.101657. eCollection 2020 Nov 20.
Frequency-dependent reorganization of the primary somatosensory cortex, together with perceptual changes, arises following repetitive sensory stimulation. Here, we investigate the role of GABA in this process. We co-stimulated two finger tips and measured GABA and Glx using magnetic resonance (MR) spectroscopy at the beginning and end of the stimulation. Participants performed a perceptual learning task before and after stimulation. There were 2 sessions with stimulation frequency either at or above the resonance frequency of the primary somatosensory cortex (23 and 39 Hz, respectively). Perceptual learning occurred following above resonance stimulation only, while GABA reduced during this condition. Lower levels of early GABA were associated with greater perceptual learning. One possible mechanism underlying this finding is that cortical disinhibition "unmasks" lateral connections within the cortex to permit adaptation to the sensory environment. These results provide evidence in humans for a frequency-dependent inhibitory mechanism underlying learning and suggest a mechanism-based approach for optimizing neurostimulation frequency.
重复感觉刺激后，初级体感皮层会出现频率依赖性重组以及知觉变化。在此，我们研究γ-氨基丁酸（GABA）在此过程中的作用。我们对两个指尖进行联合刺激，并在刺激开始和结束时使用磁共振波谱测量GABA和谷氨酰胺-谷氨酸复合物（Glx）。参与者在刺激前后执行一项知觉学习任务。有两个阶段，刺激频率分别处于或高于初级体感皮层的共振频率（分别为23赫兹和39赫兹）。仅在高于共振频率的刺激后出现了知觉学习，而在此条件下GABA减少。早期较低水平的GABA与更大程度的知觉学习相关。这一发现背后的一种可能机制是，皮层去抑制“揭开”了皮层内的侧向连接，以允许对感觉环境进行适应。这些结果为人类学习背后存在频率依赖性抑制机制提供了证据，并提出了一种基于机制的方法来优化神经刺激频率。
