Department of Neurology, Mayo Systems Electrophysiology Laboratory, Mayo Clinic, Rochester, Minnesota; and.
J Neurophysiol. 2013 Oct;110(8):1958-64. doi: 10.1152/jn.00341.2013. Epub 2013 Aug 7.
High-frequency oscillations (HFO; gamma: 40-100 Hz, ripples: 100-200 Hz, and fast ripples: 250-500 Hz) have been widely studied in health and disease. These phenomena may serve as biomarkers for epileptic brain; however, a means of differentiating between pathological and normal physiological HFO is essential. We categorized task-induced physiological HFO during periods of HFO induced by a visual or motor task by measuring frequency, duration, and spectral amplitude of each event in single trial time-frequency spectra and compared them to pathological HFO similarly measured. Pathological HFO had higher mean spectral amplitude, longer mean duration, and lower mean frequency than physiological-induced HFO. In individual patients, support vector machine analysis correctly classified pathological HFO with sensitivities ranging from 70-98% and specificities >90% in all but one patient. In this patient, infrequent high-amplitude HFO were observed in the motor cortex just before movement onset in the motor task. This finding raises the possibility that in epileptic brain physiological-induced gamma can assume higher spectral amplitudes similar to those seen in pathologic HFO. This method if automated and validated could provide a step towards differentiating physiological HFO from pathological HFO and improving localization of epileptogenic brain.
高频振荡（HFO；γ：40-100Hz，涟漪：100-200Hz，快涟漪：250-500Hz）在健康和疾病中得到了广泛的研究。这些现象可能作为癫痫大脑的生物标志物；然而，区分病理性和正常生理 HFO 的方法是必不可少的。我们通过测量每个事件在单次试验时频谱中的频率、持续时间和谱幅度，对视觉或运动任务引起的 HFO 期间诱导的任务诱导的生理 HFO 进行分类，并将其与同样测量的病理性 HFO 进行比较。病理性 HFO 的平均谱幅度较高，平均持续时间较长，平均频率较低。在个别患者中，支持向量机分析正确分类病理性 HFO 的灵敏度在 70-98%之间，特异性在所有患者中均>90%，除了一名患者。在这名患者中，在运动任务中运动开始前，运动皮层中观察到了罕见的高振幅 HFO。这一发现提出了这样一种可能性，即在癫痫大脑中，生理诱导的γ可以具有类似于病理性 HFO 中观察到的更高谱幅度。如果该方法实现自动化并得到验证，则可以为区分生理 HFO 和病理性 HFO 以及改善致痫性大脑的定位提供一个步骤。
