Karnup S V
Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino.
Neuroscience. 1992 Jun;48(4):915-24. doi: 10.1016/0306-4522(92)90279-b.
The background firing activity was recorded extracellularly in experiments on guinea-pig neocortical slices maintained in vitro. The following types of background firing activity were revealed: (i) high regular single spikes (48%), (ii) irregular single spikes (15%), (iii) bursts (7%), (iv) groups (7%), (v) mixed activity where single spikes alternated with bursts or groups (28%). The specific interspike interval distribution and the specific shape of autocorrelogram corresponded to each of these background firing activity types. Furie analysis of autocorrelograms showed periodic components in spike sequences with the maxima at 3, 12, and 28 Hz. When blocking synaptic transmission with 100 mM adenosine, about 70% of the background active cells "fell silent" and the remaining 30% of neurons continued to generate action potentials. The latter seem to be actual spontaneously active neurons, i.e. they were capable of autonomous spike generation. We failed to find any correlation between the type of neuronal firing and the ability of neurons to be spontaneously active. The selective blockade of inhibitory synapses with 100 mM picrotoxine did not practically change the character of background firing activity though the responses to stimulation became epileptic. An important conclusion to emerge from this study is that the background firing activity in cortical slices can include the actual spontaneous discharges related to intrinsic cell properties as well as those concerned with synaptic actions. Furthermore, a small number of spontaneously active neurons seem to be able to synaptically activate twice the number of cells. The inhibitory interneurons did not significantly influence the propagation of excitation with the absence of stimulation.
在体外维持的豚鼠新皮质切片实验中，细胞外记录了背景放电活动。发现了以下几种背景放电活动类型：（i）高频规则单峰放电（48%），（ii）不规则单峰放电（15%），（iii）爆发式放电（7%），（iv）簇状放电（7%），（v）单峰放电与爆发式放电或簇状放电交替出现的混合活动（28%）。每种背景放电活动类型都对应着特定的峰间间隔分布和自相关图形状。自相关图的傅里叶分析显示，放电序列中存在周期性成分，其最大值出现在3Hz、12Hz和28Hz。用100mM腺苷阻断突触传递时，约70%的背景活动细胞“沉默”，其余30%的神经元继续产生动作电位。后者似乎是真正的自发活动神经元，即它们能够自主产生动作电位。我们未能发现神经元放电类型与神经元自发活动能力之间存在任何相关性。用100mM印防己毒素选择性阻断抑制性突触，实际上并没有改变背景放电活动的特征，尽管对刺激的反应变得具有癫痫样特征。这项研究得出的一个重要结论是，皮质切片中的背景放电活动可能包括与细胞内在特性相关的实际自发放电以及与突触作用有关的放电。此外，少数自发活动神经元似乎能够通过突触激活两倍数量的细胞。在没有刺激的情况下，抑制性中间神经元对兴奋的传播没有显著影响。
