Center for Neural Engineering, Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA, USA.
Eur J Neurosci. 2012 Jul;36(2):2201-12. doi: 10.1111/j.1460-9568.2012.08132.x.
Cortical oscillations arise during behavioral and mental tasks, and all temporal oscillations have particular spatial patterns. Studying the mechanisms that generate and modulate the spatiotemporal characteristics of oscillations is important for understanding neural information processing and the signs and symptoms of dynamical diseases of the brain. Nevertheless, it remains unclear how GABAergic inhibition modulates these oscillation dynamics. Using voltage-sensitive dye imaging, pharmacological methods, and tangentially cut occipital neocortical brain slices (including layers 3-5) of Sprague-Dawley rat, we found that GABAa disinhibition with bicuculline can progressively simplify oscillation dynamics in the presence of carbachol in a concentration-dependent manner. Additionally, GABAb disinhibition can further simplify oscillation dynamics after GABAa receptors are blocked. Both GABAa and GABAb disinhibition increase the synchronization of the neural network. Theta frequency (5-15-Hz) oscillations are reliably generated by using a combination of GABAa and GABAb antagonists alone. These theta oscillations have basic spatiotemporal patterns similar to those generated by carbachol/bicuculline. These results are illustrative of how GABAergic inhibition increases the complexity of patterns of activity and contributes to the regulation of the cortex.
皮层振荡出现在行为和心理任务中，所有的时间振荡都有特定的空间模式。研究产生和调节振荡时空特征的机制对于理解神经信息处理以及大脑动力学疾病的迹象和症状很重要。然而，GABA 能抑制如何调节这些振荡动力学仍然不清楚。我们使用电压敏感染料成像、药理学方法和从 Sprague-Dawley 大鼠的枕叶新皮层脑片（包括第 3-5 层）进行的横切实验发现，GABAA 受体拮抗剂荷包牡丹碱（bicuculline）在乙酰胆碱（carbachol）存在下以浓度依赖性方式逐渐简化振荡动力学，GABAB 受体拮抗剂巴氯芬（baclofen）也可以进一步简化振荡动力学。GABAA 和 GABAB 受体的抑制均可增加神经网络的同步性。单独使用 GABAa 和 GABAb 拮抗剂组合可可靠地产生θ频率（5-15-Hz）振荡。这些θ振荡具有与乙酰胆碱/荷包牡丹碱产生的基本时空模式相似的基本时空模式。这些结果说明了 GABA 能抑制如何增加活动模式的复杂性，并有助于皮层的调节。
