Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, Missouri, United States.
Department of Neurosurgery, Washington University in St. Louis School of Medicine, St. Louis, Missouri, United States.
J Neurophysiol. 2023 Sep 1;130(3):628-639. doi: 10.1152/jn.00172.2023. Epub 2023 Aug 16.
Electrical activity at high gamma frequencies (70-170 Hz) is thought to reflect the activity of small cortical ensembles. For example, high gamma activity (often quantified by spectral power) can increase in sensory-motor cortex in response to sensory stimuli or movement. On the other hand, synchrony of neural activity between cortical areas (often quantified by coherence) has been hypothesized as an important mechanism for inter-areal communication, thereby serving functional roles in cognition and behavior. Currently, high gamma activity has primarily been studied as a local amplitude phenomenon. We investigated the synchronization of high gamma activity within sensory-motor cortex and the extent to which underlying high gamma activity can explain coherence during motor tasks. We characterized high gamma coherence in sensory-motor networks and the relationship between coherence and power by analyzing electrocorticography (ECoG) data from human subjects as they performed a motor response to sensory cues. We found greatly increased high gamma coherence during the motor response compared with the sensory cue. High gamma power poorly predicted high gamma coherence, but the two shared a similar time course. However, high gamma coherence persisted longer than high gamma power. The results of this study suggest that high gamma coherence is a physiologically distinct phenomenon during a sensory-motor task, the emergence of which may require active task participation. Motor action after auditory stimulus elicits high gamma responses in sensory-motor and auditory cortex, respectively. We show that high gamma coherence reliably and greatly increased during motor response, but not after auditory stimulus. Underlying high gamma power could not explain high gamma coherence. Our results indicate that high gamma coherence is a physiologically distinct sensory-motor phenomenon that may serve as an indicator of increased synaptic communication on short timescales (∼1 s).
高伽马频率（70-170Hz）的电活动被认为反映了小皮质集合体的活动。例如，高伽马活动（通常通过光谱功率量化）可以在感觉运动皮层中响应感觉刺激或运动而增加。另一方面，皮质区域之间的神经活动同步（通常通过相干性量化）被假设为区域间通信的重要机制，从而在认知和行为中发挥功能作用。目前，高伽马活动主要作为局部幅度现象进行研究。我们研究了感觉运动皮层内的高伽马活动同步性，以及基础高伽马活动在运动任务期间解释相干性的程度。我们通过分析人类受试者在对感觉提示做出运动反应时的脑电图（ECoG）数据，对感觉运动网络中的高伽马相干性及其与功率的关系进行了表征。与感觉提示相比，我们发现运动反应期间高伽马相干性大大增加。高伽马功率不能很好地预测高伽马相干性，但两者具有相似的时间进程。然而，高伽马相干性持续的时间比高伽马功率长。这项研究的结果表明，高伽马相干性是感觉运动任务中一种生理上独特的现象，其出现可能需要主动参与任务。听觉刺激后的运动动作分别在感觉运动和听觉皮层中引起高伽马反应。我们表明，在运动反应期间，高伽马相干性可靠地大大增加，但在听觉刺激后不会增加。基础高伽马功率不能解释高伽马相干性。我们的结果表明，高伽马相干性是一种生理上独特的感觉运动现象，它可能作为短时间尺度（约 1s）上突触通讯增加的指标。
