Zammit Nowell, Muscat Richard
Centre for Molecular Medicine and Biobanking, University of Malta, Msida, Malta.
Department of Physiology and Biochemistry, University of Malta, Msida, Malta.
Front Neurosci. 2023 Sep 29;17:1267901. doi: 10.3389/fnins.2023.1267901. eCollection 2023.
There is much interest to understand how different neural rhythms function, interact and are regulated. Here, we focus on WM delay gamma to investigate its coupling with alpha/beta rhythms and its neuromodulation by methylphenidate. We address this through the use of human EEG conducted in healthy and ADHD subjects which revealed ADHD-specific electrophysiological deficits and MPH-induced normalization of gamma amplitude and its coupling with alpha/beta rhythms. Decreased alpha/beta-gamma coupling is known to facilitate memory representations via disinhibition of gamma ensembles coding the maintained stimuli. Here, we present EEG evidence which suggests that these dynamics are sensitive to catecholaminergic neuromodulation. MPH decreased alpha/beta-gamma coupling and this was related to the increase in delay-relevant gamma activity evoked by the same drug. These results add further to the neuromodulatory findings that reflect an electrophysiological dimension to the well-known link between WM delay and catecholaminergic transmission.
人们对了解不同神经节律如何发挥功能、相互作用以及受到调节有着浓厚的兴趣。在此，我们聚焦于工作记忆延迟期伽马节律，以研究其与阿尔法/贝塔节律的耦合以及哌甲酯对其的神经调节作用。我们通过对健康受试者和注意力缺陷多动障碍（ADHD）受试者进行人类脑电图（EEG）研究来解决这个问题，该研究揭示了ADHD特有的电生理缺陷以及哌甲酯诱导的伽马波幅正常化及其与阿尔法/贝塔节律的耦合。已知阿尔法/贝塔 - 伽马耦合的降低通过解除对编码持续刺激的伽马神经元群的抑制来促进记忆表征。在此，我们展示的脑电图证据表明，这些动态变化对儿茶酚胺能神经调节敏感。哌甲酯降低了阿尔法/贝塔 - 伽马耦合，这与同一药物诱发的与延迟相关的伽马活动增加有关。这些结果进一步补充了神经调节方面的研究结果，这些结果反映了工作记忆延迟与儿茶酚胺能传递之间著名联系的电生理维度。
