Foffani Guglielmo, Uzcategui Yoryani G, Gal Beatriz, Menendez de la Prida Liset
Fundación del Hospital Nacional de Parapléjicos para la Investigación y la Integración, SESCAM, Toledo 45071, Spain.
Neuron. 2007 Sep 20;55(6):930-41. doi: 10.1016/j.neuron.2007.07.040.
Ripples are sharp-wave-associated field oscillations (100-300 Hz) recorded in the hippocampus during behavioral immobility and slow-wave sleep. In epileptic rats and humans, a different and faster oscillation (200-600 Hz), termed fast ripples, has been described. However, the basic mechanisms are unknown. Here, we propose that fast ripples emerge from a disorganized ripple pattern caused by unreliable firing in the epileptic hippocampus. Enhanced synaptic activity is responsible for the irregular bursting of CA3 pyramidal cells due to large membrane potential fluctuations. Lower field interactions and a reduced spike-timing reliability concur with decreased spatial synchronization and the emergence of fast ripples. Reducing synaptically driven membrane potential fluctuations improves both spike-timing reliability and spatial synchronization and restores ripples in the epileptic hippocampus. Conversely, a lower spike-timing reliability, with reduced potassium currents, is associated with ripple shuffling in normal hippocampus. Therefore, fast ripples may reflect a pathological desynchronization of the normal ripple pattern.
涟漪是在行为静止和慢波睡眠期间于海马体中记录到的与尖波相关的场振荡（100 - 300赫兹）。在癫痫大鼠和人类中，已描述了一种不同且更快的振荡（200 - 600赫兹），称为快速涟漪。然而，其基本机制尚不清楚。在此，我们提出快速涟漪源自癫痫海马体中由不可靠放电引起的紊乱涟漪模式。增强的突触活动由于大的膜电位波动而导致CA3锥体细胞的不规则爆发。较低的场相互作用和降低的峰电位时间可靠性与空间同步性降低以及快速涟漪的出现同时发生。减少突触驱动的膜电位波动可提高峰电位时间可靠性和空间同步性，并恢复癫痫海马体中的涟漪。相反，在正常海马体中，峰电位时间可靠性较低且钾电流减少与涟漪紊乱有关。因此，快速涟漪可能反映了正常涟漪模式的病理性去同步化。
