Role of Ca channels and transmitters in cortical oscillatory activity

神经元的振荡和/或同步活动被认为在维持意识和执行高级中枢神经系统功能方面发挥着重要作用。为了阐明通过IO通道和局部网络控制振荡活动的机制，在保留丘脑-皮质神经联系的脑片上记录了自发或刺激诱发的振荡兴奋。使用电压敏感染料对膜电位的光学记录显示，丘脑和初级体感区域(桶状皮质)在切片平面内相连。用全细胞膜片钳方法，观察到1-2个S的膜电压/电流在刺激向大脑皮质供应信息的内囊时出现10-40 Hz的波动。然而，这种振荡活动不受镍(T型和R型电压依赖性钙通道阻断剂：VDCC)或荷包牡丹碱(GABAA受体拮抗剂)的影响，这表明该活动既不是来自网络相互作用，也不是强烈依赖于上述VDCC。因此，策略略有修改，以追求海马CA3区的网络振荡。增加神经元兴奋性的药物，如卡巴胆碱，引起10赫兹的神经元活动增加，而低频的神经元活动减少。这一作用依赖于灌流液的温度和获得制剂的动物的年龄。异丙酚是一种静脉麻醉剂，它减少了卡巴胆碱诱发振荡的作用。

The oscillatory and/or synchronous neuronal activities are considered to play important roles in maintenance of the consciousness and in performance of higher CNS functions. In order to elucidate the mechanisms controlling the oscillatory activity in terms of io* channels and local network, spontaneous or stimulus-evoked oscillatory excitation wa* recorded electrophysiologically from the slice preparation which reserved thalamo-cortica* neural connections. Optical recordings of the membrane potential using a voltage-sensitive dye revealed that the thalamus and the primary somatosensory area (the barrel cortex) are connected within the slice plane. Using whole-cell patch-clamp methods, 10-40 Hz fluctuation of the membrane voltage/current for 1-2 s was observed in response to tetani* stimulation of the internal capsule which supplies inputs to the cortex. However, this oscillatory activity was not affected by application of Ni (a blocker of the T-type and R-type voltage-dependent calcium channels: VDCC) or bicuculline (a GABAA receptor antagonist), suggesting that the activity is neither derived from the network interactions an* nor strongly dependent on the above-mentioned VDCCs. Therefore, strategy was slightl* modified to pursue the network oscillations in the hippocampal CA3 region. The agent which increase neuronal excitability such as carbachol induced an increase in the neuronal activities of >10 Hz and a decrease in those of lower frequency. This action was dependent on the temperature of the perfusate and on the age of the animals from which the preparations were obtained. Propofol, an intravenous anesthetic, reduced the action c* carbachol to induce oscillation.