Broggini Ana Clara Silveira, Esteves Ingrid Miranda, Romcy-Pereira Rodrigo Neves, Leite João Pereira, Leão Richardson Naves
Department of Neurosciences and Behavior, Ribeirao Preto Medical School, University of Sao Paulo (USP), Av Bandeirantes 3900, CEP 14049-900 Ribeirao Preto, SP, Brazil.
Department of Neurosciences and Behavior, Ribeirao Preto Medical School, University of Sao Paulo (USP), Av Bandeirantes 3900, CEP 14049-900 Ribeirao Preto, SP, Brazil.
Exp Neurol. 2016 May;279:232-242. doi: 10.1016/j.expneurol.2016.03.007. Epub 2016 Mar 4.
The pathologically synchronized neuronal activity in temporal lobe epilepsy (TLE) can be triggered by network events that were once normal. Under normal conditions, hippocampus and medial prefrontal cortex (mPFC) work in synchrony during a variety of cognitive states. Abnormal changes in this circuit may aid to seizure onset and also help to explain the high association of TLE with mood disorders. We used a TLE rat model generated by perforant path (PP) stimulation to understand whether synchrony between dorsal hippocampal and mPFC networks is altered shortly before a seizure episode. We recorded hippocampal and mPFC local field potentials (LFPs) of animals with spontaneous recurrent seizures (SRSs) to verify the connectivity between these regions. We showed that SRSs decrease hippocampal theta oscillations whereas coherence in theta increases over time prior to seizure onset. This increase in synchrony is accompanied by a stronger coupling between hippocampal theta and mPFC gamma oscillation. Finally, using Granger causality we showed that hippocampus/mPFC synchrony increases in the pre-ictal phase and this increase is likely to be caused by hippocampal networks. The dorsal hippocampus is not directly connected to the mPFC; however, the functional coupling in theta between these two structures rises pre-ictally. Our data indicates that the increase in synchrony between dorsal hippocampus and mPFC may be predictive of seizures and may help to elucidate the network mechanisms that lead to seizure generation.
颞叶癫痫（TLE）中病理同步的神经元活动可由曾经正常的网络事件触发。在正常情况下，海马体和内侧前额叶皮质（mPFC）在各种认知状态下协同工作。该回路的异常变化可能有助于癫痫发作的开始，也有助于解释TLE与情绪障碍的高度相关性。我们使用通过穿通通路（PP）刺激产生的TLE大鼠模型，以了解癫痫发作前短时间内背侧海马体和mPFC网络之间的同步性是否发生改变。我们记录了患有自发性复发性癫痫（SRS）的动物的海马体和mPFC局部场电位（LFP），以验证这些区域之间的连通性。我们发现，SRS会降低海马体的theta振荡，而在癫痫发作前，theta振荡的相干性会随着时间的推移而增加。这种同步性的增加伴随着海马体theta振荡与mPFCγ振荡之间更强的耦合。最后，使用格兰杰因果关系分析，我们表明在发作前期海马体/mPFC同步性增加，这种增加可能是由海马体网络引起的。背侧海马体与mPFC没有直接连接；然而，这两个结构之间的theta功能耦合在发作前上升。我们的数据表明，背侧海马体和mPFC之间同步性的增加可能预示着癫痫发作，并可能有助于阐明导致癫痫发作的网络机制。
