Alvarado-Rojas Catalina, Huberfeld Gilles, Baulac Michel, Clemenceau Stéphane, Charpier Stéphane, Miles Richard, de la Prida Liset Menendez, Le Van Quyen Michel
Brain and Spine Institute, Pitié-Salpêtrière Hospital, Paris, France; Pierre and Marie Curie University, Paris.
Ann Neurol. 2015 Feb;77(2):281-90. doi: 10.1002/ana.24324. Epub 2014 Dec 19.
Transient high-frequency oscillations (HFOs; 150-600Hz) in local field potentials generated by human hippocampal and parahippocampal areas have been related to both physiological and pathological processes. The cellular basis and effects of normal and abnormal forms of HFOs have been controversial. This lack of agreement is clinically significant, because HFOs may be good markers of epileptogenic areas. Better defining the neuronal correlate of specific HFO frequency bands could improve electroencephalographic analyses made before epilepsy surgery.
Here, we recorded HFOs in slices of the subiculum prepared from human hippocampal tissue resected for treatment of pharmacoresistant epilepsy. With combined intra- or juxtacellular and extracellular recordings, we examined the cellular correlates of interictal and ictal HFO events.
HFOs occurred spontaneously in extracellular field potentials during interictal discharges (IIDs) and also during pharmacologically induced preictal discharges (PIDs) preceding ictal-like events. Many of these events included frequencies >250Hz and so might be considered pathological, but a significant proportion were spectrally similar to physiological ripples (150-250Hz). We found that IID ripples were associated with rhythmic γ-aminobutyric acidergic and glutamatergic synaptic potentials with moderate neuronal firing. In contrast, PID ripples were associated with depolarizing synaptic inputs frequently reaching the threshold for bursting in most pyramidal cells.
Our data suggest that IID and PID ripple-like oscillations (150-250Hz) in human epileptic hippocampus are associated with 2 distinct population activities that rely on different cellular and synaptic mechanisms. Thus, the ripple band could not help to disambiguate the underlying cellular processes.
人类海马体和海马旁回区域产生的局部场电位中的瞬态高频振荡（HFOs；150 - 600Hz）与生理和病理过程均有关联。HFOs正常和异常形式的细胞基础及影响一直存在争议。这种不一致在临床上具有重要意义，因为HFOs可能是致痫区域的良好标志物。更好地定义特定HFO频段的神经元相关性可改善癫痫手术前的脑电图分析。
在此，我们记录了从因药物难治性癫痫而切除的人类海马组织制备的下托切片中的HFOs。通过细胞内或细胞旁与细胞外记录相结合的方式，我们研究了发作间期和发作期HFO事件的细胞相关性。
HFOs在发作间期放电（IIDs）期间以及在类似发作事件之前的药物诱导发作前期放电（PIDs）期间自发地出现在细胞外场电位中。这些事件中的许多频率>250Hz，因此可能被认为是病理性的，但很大一部分在频谱上与生理涟漪（150 - 250Hz）相似。我们发现发作间期涟漪与有适度神经元放电的节律性γ-氨基丁酸能和谷氨酸能突触电位相关。相比之下，发作前期涟漪与在大多数锥体细胞中频繁达到爆发阈值的去极化突触输入相关。
我们的数据表明，人类癫痫海马体中的发作间期和发作前期涟漪样振荡（150 - 250Hz）与依赖不同细胞和突触机制的两种不同群体活动相关。因此，涟漪频段无助于区分潜在的细胞过程。
