Détári L, Semba K, Rasmusson D D
Department of Comparative Physiology, Eötvos Loránd University, Budapest, Hungary.
Eur J Neurosci. 1997 Jun;9(6):1153-61. doi: 10.1111/j.1460-9568.1997.tb01469.x.
The basal forebrain can be considered to be a rostral extension of the ascending reticular activating system. A large number of neurons in the basal forebrain have been shown to display higher firing rates when low-voltage fast activity is present in the cortical EEG as opposed to states characterized by large slow waves in both unanaesthetized and anaesthetized animals. However, a smaller number of cells with increased discharge rate during slow waves was also observed in most of these studies. While it is likely that these two types of neurons have opposite roles in the regulation of cortical activation, it is not known how they respond to inputs from the brainstem or the periphery. In the present study, extracellular recordings were made in the basal forebrain of urethane-anaesthetized rats. A total of 52 neurons were studied in which the firing rate was significantly higher during fast cortical EEG waves (F-cells), and 14 neurons in which activity was significantly greater during slow waves (S-cells). The two cell types responded differently to stimulation of the pedunculopontine tegmental nucleus (PPT) and dorsal raphe nucleus (DRN) with short (0.5-1 s) trains of pulses and to noxious sensory stimuli (tail pinch). These stimulations excited most F-cells (80-96%) and inhibited the majority of S-cells (55-67%). In the few F-cells that were inhibited by stimulation, the response varied with the background firing rate of the cell: the higher the firing rate at the time of stimulation, the higher the probability of observing an inhibitory response. In contrast, single electrical pulses delivered to the PPT and DRN excited the majority (72%) of both F- and S-cells. Previous in vitro studies have shown that the application of acetylcholine or serotonin has predominantly inhibitory effects on basal forebrain cholinergic neurons. The predominantly excitatory effect of noxious, PPT and DRN stimulation on F-cells therefore suggests that glutamatergic or other excitatory afferents play a more dominant role in regulating basal forebrain neurons. We have previously shown that F-cells are more prevalent than S-cells. In combination, these findings suggest that basal forebrain neurons, and F-cells in particular, are important in mediating the ascending excitatory drive from the brainstem to the cerebral cortex.
基底前脑可被视为上行网状激活系统的嘴侧延伸。已表明，在未麻醉和麻醉动物中，当皮层脑电图出现低电压快活动而非以大慢波为特征的状态时，基底前脑的大量神经元会表现出更高的放电频率。然而，在大多数这些研究中，也观察到少数在慢波期间放电率增加的细胞。虽然这两类神经元可能在皮层激活的调节中具有相反的作用，但尚不清楚它们如何对来自脑干或外周的输入做出反应。在本研究中，对氨基甲酸乙酯麻醉的大鼠的基底前脑进行了细胞外记录。共研究了52个神经元，其在快速皮层脑电图波期间放电率显著更高（F细胞），以及14个在慢波期间活动显著更强的神经元（S细胞）。这两种细胞类型对脚桥被盖核（PPT）和中缝背核（DRN）的短（0.5 - 1秒）脉冲串刺激以及有害感觉刺激（夹尾）的反应不同。这些刺激兴奋了大多数F细胞（80 - 96%）并抑制了大多数S细胞（55 - 67%）。在少数被刺激抑制的F细胞中，反应随细胞的背景放电率而变化：刺激时的放电率越高，观察到抑制反应的概率越高。相反，向PPT和DRN施加单个电脉冲兴奋了大多数F细胞和S细胞（72%）。先前的体外研究表明，应用乙酰胆碱或5-羟色胺对基底前脑胆碱能神经元主要具有抑制作用。因此，有害、PPT和DRN刺激对F细胞的主要兴奋作用表明，谷氨酸能或其他兴奋性传入在调节基底前脑神经元中起更主导的作用。我们先前已表明F细胞比S细胞更普遍。综合这些发现表明，基底前脑神经元，尤其是F细胞，在介导从脑干到大脑皮层的上行兴奋性驱动中很重要。
