BACKGROUND Brain activity is constrained by and evolves over a network of structural and functional connections. Corticocortical evoked potentials (CCEPs) have been used to measure this connectivity and to discern brain areas involved in both brain function and disease. However, how varying stimulation parameters influences the measured CCEP across brain areas has not been well characterized. OBJECTIVE To better understand the factors that influence the amplitude of the CCEPs as well as evoked gamma-band power (70-150 Hz) resulting from single-pulse stimulation via cortical surface and depth electrodes. METHODS CCEPs from 4370 stimulation-response channel pairs were recorded across a range of stimulation parameters and brain regions in 11 patients undergoing long-term monitoring for epilepsy. A generalized mixed-effects model was used to model cortical response amplitudes from 5 to 100 ms post-stimulation. RESULTS Stimulation levels <5.5 mA generated variable CCEPs with low amplitude and reduced spatial spread. Stimulation at ≥5.5 mA yielded a reliable and maximal CCEP across stimulation-response pairs over all regions. These findings were similar when examining the evoked gamma-band power. The amplitude of both measures was inversely correlated with distance. CCEPs and evoked gamma power were largest when measured in the hippocampus compared with other areas. Larger CCEP size and evoked gamma power were measured within the seizure onset zone compared with outside this zone. CONCLUSION These results will help guide future stimulation protocols directed at quantifying network connectivity across cognitive and disease states.

中文翻译：

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影响癫痫患者颅内诱发电位参数的系统探索


背景技术大脑活动受到结构和功能连接网络的约束并在其上演化。皮质诱发电位 (CCEP) 已被用来测量这种连接性并识别涉及大脑功能和疾病的大脑区域。然而，不同的刺激参数如何影响整个大脑区域测量的 CCEP 尚未得到很好的表征。目的 更好地了解影响 CCEP 幅度的因素以及通过皮层表面和深度电极进行单脉冲刺激产生的诱发伽马带功率 (70-150 Hz)。方法 记录 11 名接受长期癫痫监测的患者的一系列刺激参数和大脑区域的 4370 个刺激-反应通道对的 CCEP。使用广义混合效应模型对刺激后 5 至 100 毫秒的皮质反应幅度进行建模。结果<5.5 mA 的刺激水平产生低振幅且空间扩散减小的可变 CCEP。 ≥5.5 mA 的刺激在所有区域的刺激-反应对上产生了可靠且最大的 CCEP。当检查诱发的伽马带功率时，这些发现是相似的。两种测量的幅度均与距离成反比。与其他区域相比，在海马体中测量的 CCEP 和诱发伽马功率最大。与该区域外相比，在癫痫发作区域内测量到更大的 CCEP 尺寸和诱发伽马功率。结论这些结果将有助于指导未来的刺激方案，旨在量化跨认知和疾病状态的网络连接。