Navarro V, Le Van Quyen M, Martinerie J, Rudrauf D, Baulac M, Menini C
CNRS UPR 640, Cognitive Neurosciences and Brain Imaging, LENA, Hôpital de la Pitié-Salpêtrière, Paris, 75651, France.
Neuroscience. 2007 Aug 10;148(1):304-13. doi: 10.1016/j.neuroscience.2007.05.031. Epub 2007 Jul 12.
Interrupting a focal, chronic infusion of GABA to the rat motor cortex initiates the progressive emergence of a sustained spiking electroencephalographic (EEG) activity, associated with myoclonic jerks of the corresponding body territory. This activity is maintained over several hours, has an average frequency of 1.5 Hz, is localized to the infusion site and never generalizes. The GABA withdrawal syndrome (GWS) has therefore features of partial status epilepticus. Changes in EEG signals associated with the GWS were studied in freely moving rats by measuring the phase synchrony between bilateral epidural records from the neocortex. Our results showed (i) epileptic activity was associated with a striking decrease in phase synchrony between all pairs of electrodes including the focus, predominantly in the 1-6 Hz frequency range. There was a mean decrease of 75.34+/-5.26% in phase synchrony levels between the period before GABA interruption and the period after epileptic activity appeared. (ii) This reduction in synchrony contrasted with an increase of power spectral density in the corresponding EEG channels over the same 1-6 Hz frequency range, (iii) neither changes in synchrony nor in nonlinear dynamics were detected before the first EEG spikes, (iv) systemic injection of ketamine, an antagonist of N-methyl-d-aspartic acid (NMDA) receptors, modified transiently both epileptic activity and the synchrony profile. (v) Spiking activity and synchrony changes were suppressed by reperfusion of GABA. Our data suggest that, during a partial status epilepticus, interactions between the epileptic focus and connected neocortical neuronal populations are dramatically decreased in low frequencies.
中断向大鼠运动皮层进行的局灶性慢性γ-氨基丁酸（GABA）输注，会引发持续的尖峰脑电图（EEG）活动逐渐出现，该活动与相应身体部位的肌阵挛性抽搐相关。这种活动会持续数小时，平均频率为1.5赫兹，局限于输注部位，且从不扩散。因此，GABA戒断综合征（GWS）具有部分癫痫持续状态的特征。通过测量新皮层双侧硬膜外记录之间的相位同步性，研究了自由活动大鼠中与GWS相关的EEG信号变化。我们的结果显示：（i）癫痫活动与包括病灶在内的所有电极对之间的相位同步性显著降低有关，主要在1-6赫兹频率范围内。在GABA中断前的时期与癫痫活动出现后的时期之间，相位同步性水平平均下降了75.34±5.26%。（ii）这种同步性的降低与同一1-6赫兹频率范围内相应EEG通道中功率谱密度的增加形成对比，（iii）在首次EEG尖峰出现之前，未检测到同步性或非线性动力学的变化，（iv）全身性注射N-甲基-D-天冬氨酸（NMDA）受体拮抗剂氯胺酮，会短暂改变癫痫活动和同步性特征。（v）GABA再灌注可抑制尖峰活动和同步性变化。我们的数据表明，在部分癫痫持续状态期间，癫痫病灶与相连的新皮层神经元群体之间在低频下的相互作用显著减少。
