Seidenbecher T, Staak R, Pape H C
Institut für Physiologie, Otto-von-Guericke-Universität, Magdeburg, Germany.
Eur J Neurosci. 1998 Mar;10(3):1103-12. doi: 10.1046/j.1460-9568.1998.00123.x.
In a rat model of generalized absence epilepsies (Genetic Absence Epilepsy Rats from Strasbourg, GAERS), multiunit activity was recorded simultaneously at different sites of the thalamocortical system under neurolept anaesthesia (fentanyl-droperidol). Under these conditions, bilaterally synchronized spike-and-wave-discharges (SWDs) occurred spontaneously on the electroencephalogram (EEG) that were in principle identical to those reported earlier from unanaesthetized preparations. The generation of SWDs on the EEG was associated with spike-concurrent, rhythmic burst-like activity in (mono-)synaptically connected regions of specific (somatosensory) thalamic regions and layers IVN of the somatosensory cortex, and the reticular thalamic nucleus. Precursor activity was typically recorded in cortical units, concomitant with 'embryonic' SW seizures on the EEG, before the paroxysm was evident on the gross EEG and in the thalamus. On average, SWD-correlated activity in layers IVN of the somatosensory cortex started significantly earlier than correlated burst-like firing in reticular and in ventrobasal thalamic neurons. Cellular peak firing in thalamus and cortex during bilaterally synchronized SWDs was related to the spike component on the gross EEG with the temporal rank order ventroposteromedial > ventrolateral > or = ventroposterolateral thalamic > > rostral reticular thalamic nuclei > or = cortex (layers IVN) = caudal reticular thalamic nucleus. A spike-related depression and wave-related increase in firing was recorded in anteroventral ventrolateral thalamic areas, presumably reflecting their peculiar anatomical arrangement within the thalamus. These results from an in vivo preparation with intact synaptic connections that spontaneously produces SWDs indicate that SWDs spread within the thalamocortical network, involving short and long delays. The order of concurrent rhythmic firing observed in thalamocortical circuits during SW seizures are supportive of the hypothesis that the processes of rhythmogenesis recruit local thalamic networks, while cortical mechanisms appear to synchronize rhythmic activities on a larger spatiotemporal scale, thereby providing an important contribution to the generalization of epileptiform activity and expression of SWDs on the EEG.
在全身性失神癫痫大鼠模型（来自斯特拉斯堡的遗传性失神癫痫大鼠，GAERS）中，在神经安定麻醉（芬太尼-氟哌利多）下，同时记录丘脑皮质系统不同部位的多单位活动。在这些条件下，脑电图（EEG）上自发出现双侧同步的棘波-慢波放电（SWDs），这些放电原则上与先前未麻醉标本中报告的放电相同。EEG上SWDs的产生与特定（体感）丘脑区域和体感皮层IVN层以及丘脑网状核的（单）突触连接区域中与棘波同时出现的节律性爆发样活动有关。在EEG上出现明显的发作和丘脑中发作明显之前，通常在皮层单位记录到前驱活动，同时伴有EEG上的“胚胎性”SW发作。平均而言，体感皮层IVN层中与SWD相关的活动比网状核和腹侧基底丘脑神经元中相关的爆发样放电开始得明显更早。双侧同步SWDs期间丘脑和皮层中的细胞放电峰值与EEG上的棘波成分相关，时间顺序为腹后内侧>腹外侧>或=腹后外侧丘脑>>丘脑网状核头端>或=皮层（IVN层）=丘脑网状核尾端。在前腹侧腹外侧丘脑区域记录到与棘波相关的放电抑制和与慢波相关的放电增加，这可能反映了它们在丘脑中特殊的解剖排列。这些来自具有完整突触连接且自发产生SWDs的体内标本的结果表明，SWDs在丘脑皮质网络内传播，涉及短延迟和长延迟。在SW发作期间丘脑皮质回路中观察到的同步节律性放电顺序支持这样的假设，即节律发生过程招募局部丘脑网络，而皮层机制似乎在更大的时空尺度上同步节律性活动，从而为癫痫样活动的泛化和EEG上SWDs的表达做出重要贡献。
