2017年第44卷第9期目录
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封面故事:深部脑刺激采用脉冲频率接近或者大于100 Hz的高频电刺激(HFS),在临床上已用于治疗多种脑神经系统疾病.但是,时长不同的高频刺激对于脑神经系统具有不同的作用.数秒时长的短促刺激可通过“点燃”效应制作动物癫痫模型,也可以产生突触可塑性变化;而延长刺激至数分钟以上却可以安全地用于临床.周文杰等在大鼠海马CA1区的输入轴突纤维Schaffer侧支上分别施加5 s和2 min两种时长的100 Hz刺激,并监测刺激结束后下游神经元群体对于单脉冲测试的响应电位(群峰电位,PS).结果表明,长时刺激可以改变前期短促刺激对于下游神经网络的作用,即消除短刺激可能产生的长时程兴奋效应.此发现对于深入了解高频刺激的作用机制、促进深部脑刺激的临床应用具有重要意义.
(周文杰,封洲燕,邱 晨,马维健.持续高频刺激改变短刺激产生的神经网络效应,本期第769~775页)
Cover Story:High frequency stimulations (HFS) of electrical pulses with different durations have different effects on the nervous system in brain. A short HFS train with a duration of several seconds can be used to establish epilepsy models in animals via a kindling effect. It can also produce changes of synaptic plasticity that may persist. However, a long HFS train with a duration several minutes or longer can be safely applied in deep brain stimulation to treat various brain diseases in clinic. Therefore, we speculate that a sustained HFS could change the neuronal responses induced by a short HFS. To verify this hypothesis, 100 Hz HFS with durations of 5 s and 2 min were applied to the Schaffer collateral of afferent fibers in the hippocampus CA1 region of rats. The response potentials of downstream populations of neurons, i.e., population spikes (PS), evoked by a single test pulse were monitored after the termination of HFS trains. The evoked-PS potentials following the two types of stimulation were compared. The results showed that after-discharge events with epileptiform activity appeared immediately following 5 s short HFS trains. In addition, the changes of amplitude and latency of the evoked-PS suggest an increase of excitability persisting for tens of minutes after the termination of 5 s short HFS. In contrast, silent periods of a few tens of seconds without any neuronal firing appeared immediately following 2 min long HFS trains. Furthermore, the amplitude of evoked-PS by test pulses recovered to the baseline level in a few minutes after the termination of long HFS. Because long HFS trains include short HFS trains, these results indicate that the late stimulation of long trains can change the effects on the downstream neural networks produced by their early phases and eliminate the long-term excitatory effects induced by short trains.
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