Clinical Neurological Sciences Department, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.
Campus Bio-Medico University of Rome, Rome, Italy; IRCCS San Camillo Hospital, Via Alberoni 80, 30126, Venice, Italy.
Neuroimage. 2024 Oct 15;300:120862. doi: 10.1016/j.neuroimage.2024.120862. Epub 2024 Sep 19.
Auditory-driven gamma synchrony (GS) is linked to the function of a specific cortical circuit based on a parvalbumin+ and pyramidal neuron loop. This circuit is impaired in neuropsychiatric conditions (i.e. schizophrenia, Alzheimer's disease, stroke etc.) and its relevance in clinical practice is increasingly being recognized. Auditory stimulation at a typical gamma frequency of 40 Hz can be applied as a 'stress test' of excitation/inhibition (E/I) of the entire cerebral cortex, to drive GS and record it with magnetoencephalography (MEG) or high-density electroencephalography (EEG). However, these two techniques are costly and not widely available. Therefore, we assessed whether a single EEG electrode is sufficient to provide an accurate estimate of the auditory-driven GS level of the entire cortical surface while expecting the highest correspondence in the auditory and somatosensory cortices.
We measured simultaneous EEG-MEG in 29 healthy subjects, utilizing 3 EEG electrodes (C4, F4, O2) and a full MEG setup. Recordings were performed during binaural exposure to auditory gamma stimulation and during silence. We compared GS measurement of each of the three EEG electrodes separately against full MEG mapping. Time-resolved phase locking value (PLVt) was computed between EEG signals and cortex reconstructed MEG signals.
During auditory stimulation, but not at rest, EEG captures a significant amount of GS, especially from both auditory cortices and motor-premotor regions. This was especially true for frontal (C4) and central electrodes (F4).
While hd-EEG and MEG are necessary for accurate spatial mapping of GS at rest and during auditory stimulation, a single EEG channel is sufficient to detect the global level of GS. These results have great translational potential for mapping GS in standard clinical settings.
听觉驱动的伽马同步（GS）与基于特定的包含中间神经元和锥体神经元的回路功能有关。该回路在神经精神疾病（如精神分裂症、阿尔茨海默病、中风等）中受到损害，其在临床实践中的相关性正日益得到认可。以典型的 40 Hz 伽马频率进行听觉刺激可以作为大脑皮层兴奋/抑制（E/I）的“应激测试”，驱动 GS 并通过脑磁图（MEG）或高密度脑电图（EEG）进行记录。然而，这两种技术都很昂贵，并且并不广泛可用。因此，我们评估了单个 EEG 电极是否足以提供整个皮质表面听觉驱动 GS 水平的准确估计，同时期望在听觉和体感皮质中具有最高的对应性。
我们在 29 名健康受试者中同时进行 EEG-MEG 测量，使用 3 个 EEG 电极（C4、F4、O2）和一个完整的 MEG 装置。在双耳暴露于听觉伽马刺激和安静状态下进行记录。我们将每个 EEG 电极的 GS 测量值分别与全 MEG 图谱进行比较。计算 EEG 信号和皮层重建 MEG 信号之间的时间分辨锁相值（PLVt）。
在听觉刺激期间，但在休息时，EEG 捕捉到大量的 GS，特别是来自听觉皮质和运动-运动前区。对于额（C4）和中央电极（F4）尤其如此。
虽然 hd-EEG 和 MEG 对于在休息和听觉刺激期间进行 GS 的精确空间映射是必要的，但单个 EEG 通道足以检测 GS 的整体水平。这些结果对于在标准临床环境中绘制 GS 具有很大的转化潜力。
