Trautner P, Rosburg T, Dietl T, Fell J, Korzyukov O A, Kurthen M, Schaller C, Elger C E, Boutros N N
Department of Epileptology, University of Bonn, Sigmund-Freud-Str. 25, D-53115 Bonn, Germany.
Neuroimage. 2006 Aug 15;32(2):790-8. doi: 10.1016/j.neuroimage.2006.04.203. Epub 2006 Jun 30.
Oscillatory activity in the gamma band range (30-50 Hz) and its functional relation to auditory evoked potentials (AEPs) is yet poorly understood. In the current study, we capitalized on the advantage of intracranial recordings and studied gamma band activity (GBA) in an auditory sensory gating experiment. Recordings were obtained from the lateral surface of the temporal lobe in 34 epileptic patients undergoing presurgical evaluation. Two kinds of activity were differentiated: evoked (phase locked) and induced (not phase locked) GBA. In 18 patients, an intracranial P50 was observed. At electrodes with maximal P50, evoked GBA occurred with a similar peak latency as the P50. However, the intensities of P50 and evoked GBA were only modestly correlated, suggesting that the intracranial P50 does not represent a subset of evoked GBA. The peak frequency of the intracranial evoked GBA was on average relatively low (approximately 25 Hz) and is, therefore, probably not equivalent to extracranially recorded GBA which has normally a peak frequency of approximately 40 Hz. Induced GBA was detected in 10 subjects, nearly exclusively in the region of the superior temporal lobe. The induced GBA was increased after stimulation for several hundred milliseconds and encompassed frequencies up to 200 Hz. Single-trial analysis revealed that induced GBA occurred in relatively short bursts (mostly <<100 ms), indicating that the duration of the induced GBA in the averages originates from summation effects. Both types of gamma band activity showed a clear attenuation with stimulus repetition.
γ频段范围（30 - 50赫兹）内的振荡活动及其与听觉诱发电位（AEP）的功能关系目前仍知之甚少。在本研究中，我们利用颅内记录的优势，在听觉感觉门控实验中研究了γ频段活动（GBA）。记录取自34例接受术前评估的癫痫患者颞叶外侧表面。区分了两种活动：诱发（锁相）和诱导（非锁相）GBA。在18例患者中观察到了颅内P50。在P50最大的电极处，诱发GBA的出现潜伏期与P50相似。然而，P50和诱发GBA的强度仅呈中等程度相关，这表明颅内P50并不代表诱发GBA的一个子集。颅内诱发GBA的峰值频率平均相对较低（约25赫兹），因此可能与颅外记录的GBA不等同，颅外记录的GBA通常峰值频率约为40赫兹。在10名受试者中检测到了诱导GBA，几乎都在上颞叶区域。刺激后几百毫秒内诱导GBA增加，频率高达200赫兹。单试验分析显示，诱导GBA以相对较短的爆发形式出现（大多<<100毫秒），这表明平均诱导GBA的持续时间源于叠加效应。两种类型的γ频段活动在刺激重复时均表现出明显衰减。
