The Actual Intrinsic Excitability of Granular Cells Determines the Ruling Neurovascular Coupling Mechanism in the Rat Dentate Gyrus
The Actual Intrinsic Excitability of Granular Cells Determines the Ruling Neurovascular Coupling Mechanism in the Rat Dentate Gyrus
复制标题
DOI：
10.1523/jneurosci.0472-14.2014
复制
发表时间：
2014-06-18
影响因子：
5.3
通讯作者：
Angenstein, Frank
中科院分区：
文献类型：
--
作者：
Angenstein, Frank
采用双脉冲刺激穿支通路的方法，研究大鼠齿状回颗粒细胞活动与由此产生的fMRI反应的关系。通过改变脉冲间隔(IPI)，双脉冲刺激在第二反应中引起：抑制(20ms IPI)、促进(100ms IPI)、抑制和促进的混合(30ms IPI)或无变化(500ms IPS)。在一个刺激序列中施加8个相同的脉冲对，同时测量诱发的场电位和产生的fMRI反应。连续刺激序列的应用导致电生理和功能磁共振反应随时间变化，这是每种刺激方案的特征。根据IPI的不同，fMRI反应的大小要么与颗粒细胞的尖峰或突触后活动密切相关，要么明显与其无关。只有当刺激方案导致记录的群体尖峰潜伏期增加时，才发现尖峰活动和由此产生的fMRI反应之间的强烈关系。如果潜伏期缩短，fMRI反应与所施加的输入活动更密切相关。穿透通路纤维单突触激活颗粒细胞，因此群体峰潜伏期的变化反映了它们内在兴奋性的变化。因此，在内在兴奋性增强时，颗粒细胞上游的信号级联决定了fMRI反应，而颗粒细胞活动相关机制控制着内在兴奋性降低时的fMRI反应。
Paired-pulse stimulation of the perforant pathway was used to study the relation between granular cell activity and the resultant fMRI response in the rat dentate gyrus. By varying the interpulse interval (IPI), paired-pulse stimulations caused: a depression (20 ms IPI), a facilitation (100 ms IPI), a mixture of depression and facilitation (30 ms IPI), or no change (500 ms IPS) in the second response. Eight identical paired pulses were applied during one stimulation train and the evoked field potentials and generated fMRI responses were measured simultaneously. Application of consecutive stimulation trains caused time-dependent variations in electrophysiological and fMRI responses, which were characteristic for each stimulus protocol. Depending on the IPI, the magnitude of the fMRI response either correlated strongly with or was apparently unrelated to the spiking or postsynaptic activity of the granular cells. A strong relation between spiking activity and resultant fMRI response was only found when the stimulation protocol caused an increase in the recorded population spike latency. If the latency was decreased, the fMRI response was more closely related to the applied input activity. Perforant pathway fibers monosynaptically activate granular cells, so variations in population spike latencies reflect changes in their intrinsic excitability. Therefore, during increased intrinsic excitability, signaling cascades upstream of the granular cells determine the fMRI response, whereas granular cell activity-related mechanisms control the fMRI response during decreased intrinsic excitability.