Spampanato Jay, Mody Istvan
Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095-7335, USA.
J Neurophysiol. 2007 Jul;98(1):96-104. doi: 10.1152/jn.00188.2007. Epub 2007 May 2.
Network activity in the 200- to 600-Hz range termed high-frequency oscillations (HFOs) has been detected in epileptic tissue from both humans and rodents and may underlie the mechanism of epileptogenesis in experimental rodent models. Slower network oscillations including theta and gamma oscillations as well as ripples are generated by the complex spike timing and interactions between interneurons and pyramidal cells of the hippocampus. We determined the activity of CA3 pyramidal cells, stratum oriens lacunosum-moleculare (O-LM) and s. radiatum lacunosum-moleculare (R-LM) interneurons during HFO in the in vitro low-Mg(2+) model of epileptiform activity in GIN mice. In these animals, interneurons can be identified prior to cell-attached recordings by the expression of green-fluorescent protein (GFP). Simultaneous local field potential recordings from s. pyramidale and on-cell recordings of individual interneurons and principal cells revealed three primary firing behaviors of the active cells: 36% of O-LM interneurons and 60% of pyramidal cells fired action potentials at high frequencies during the HFO. R-LM interneurons were biphasic in that they fired at high frequency at the beginning of the HFO but stopped firing before its end. When considering only the highest frequency component of the oscillations most pyramidal cells fired on the rising phase of the oscillation. These data provide evidence for functional distinction during HFOs within otherwise homogeneous groups of O-LM interneurons and pyramidal cells.
在人类和啮齿动物的癫痫组织中均检测到了频率范围在200至600赫兹的网络活动，即高频振荡（HFOs），其可能是实验性啮齿动物模型中癫痫发生机制的基础。包括theta和gamma振荡以及涟漪在内的较慢网络振荡是由海马体中间神经元和锥体细胞之间复杂的尖峰时间和相互作用产生的。我们在GIN小鼠癫痫样活动的体外低镁（2+）模型中，测定了HFO期间CA3锥体细胞、腔隙-分子层的原层（O-LM）和辐射层的腔隙-分子层（R-LM）中间神经元的活动。在这些动物中，在进行细胞贴附记录之前，可以通过绿色荧光蛋白（GFP）的表达来识别中间神经元。从锥体层同时进行局部场电位记录以及对单个中间神经元和主细胞进行细胞上记录，揭示了活动细胞的三种主要放电行为：36%的O-LM中间神经元和60%的锥体细胞在HFO期间高频发放动作电位。R-LM中间神经元具有双相性，即在HFO开始时高频发放，但在HFO结束前停止发放。当仅考虑振荡的最高频率成分时，大多数锥体细胞在振荡的上升阶段发放。这些数据为在原本同质的O-LM中间神经元和锥体细胞群体的HFO期间的功能差异提供了证据。
