EFFECTS OF TRANSIENT DEPOLARIZING POTENTIALS ON THE FIRING RATE OF CAT NEOCORTICAL NEURONS
EFFECTS OF TRANSIENT DEPOLARIZING POTENTIALS ON THE FIRING RATE OF CAT NEOCORTICAL NEURONS
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DOI：
10.1152/jn.1993.69.5.1673
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发表时间：
1993-05-01
影响因子：
2.5
通讯作者：
FETZ, EE
中科院分区：
文献类型：
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作者：
REYES, AD;FETZ, EE
1.兴奋性突触后电位（EPSP）对新皮层神经元锋电位间期（ISI）的影响可以用电流注入产生的脉冲电位（PP）来模拟。本报告记录了ISI缩短对PPs和EPSP振幅以及受影响神经元放电频率的依赖性。在节律性放电的新皮层神经元中，由在ISI中特定时间到达的PP引起的ISI缩短可以用缩短延迟（S-D）曲线来描述。S-D曲线产生PP缩短ISI的能力的三个量度：1）平均ISI缩短，S; 2）最大缩短，S（max）;和3）有效间隔，定义为其中PP一致地缩短ISI的ISI部分。在80 μ V~3.6 mV范围内（细胞放电速度为25 imp/s），平均缩短随振幅h的增加而增加，S（ms）= 1.2 * h（mV）1.24（r = 0.94; P <0.01）。S（max）在4.9ms/mV时与振幅呈线性关系（r = 0.86，P <0.01）。有效间期（作为ISI的百分比）随着PP振幅的增加而略有增加，平均值为65 +/-21%（平均值+/-SD）。刺激诱发的EPSP的S-D曲线随EPSP振幅的变化与PP的变化相似。刺激诱发的EPSP与同一细胞的PP之间的关系无统计学差异.为了确定放电率的影响，当神经元以8至71 imp/s的频率放电时应用PP。S和S。近似与基线燃烧速率（f（o））成反比，并且可以描述为：S或S（max）= kf（o）-m。指数m（+/-SD）的平均值为0.96 +/-0.25（S）和1.2 +/-0.4（S（max））。这些值与值1无统计学差异（1组，双尾t检验）。有效间隔不随放电频率的变化而变化.将S对PP振幅和基线放电频率的依赖性纳入由以频率f（s）发生的PP产生的放电频率的平均变化（Δ f）的表达式中：Δ f = 0.03 h 1.24 f（s）。DELTAf随PP振幅增加而增加，但与基线放电率无显著差异。从S-D曲线计算的DELTAf值与直接从尖峰序列计算的值相匹配。将由短电流脉冲产生的Δ f与由稳定施加的电流的相同净增量产生的Δ f进行比较，揭示出脉冲产生了显著更大的点火速率的增加。因此，以瞬时脉冲形式同步到达的突触输入对皮层神经元的放电率的影响比异步到达的相同输入更大。
1. The effects of excitatory postsynaptic potentials (EPSPs) on interspike intervals (ISIs) of neocortical neurons can be mimicked by pulse potentials (PPs) produced by current injection. The present report documents the dependence of the ISI shortening on the amplitudes of PPs and EPSPs and on the firing rate of the affected neuron.2. In rhythmically firing neocortical neurons, the ISI shortenings caused by PPs arriving at specific times in the ISI can be described by a shortening-delay (S-D) curve. The S-D curve yields three measures of the PPs' ability to shorten the ISI: l) the mean ISI shortening, S; 2) the maximum shortening, S(max); and 3) the effective interval, defined as the portion of the ISI in which the PP consistently shortens the ISI. For PPs ranging between 80 muV and 3.6 mV (and cells firing at 25 imp/s), the mean shortening increased with amplitude h as S (ms) = 1.2 * h (mV)1.24 (r = 0.94; P < 0.01). S(max) increased linearly with amplitude as 4.9 ms/ mV (r = 0.86, P < 0.01). The effective interval (as a percentage of the ISI) increased slightly with PP amplitude and had a mean value of 65 +/- 21% (mean +/- SD).3. S-D curves obtained with stimulus-evoked EPSPs varied with EPSP amplitude in a manner similar to those of PPs. The relations obtained for stimulus-evoked EPSPs were not statistically different from those obtained for PPs in the same cells.4. To determine the effect of firing rate, PPs were applied while neurons fired at frequencies ranging from 8 to 71 imp/s. Both S and S. were approximately inversely proportional to the baseline firing rate (f(o)) and could be described as: S or S(max) = kf(o)-m. The mean value of the exponent m (+/-SD) was 0.96 +/- 0.25 for S and 1.2 +/- 0.4 for S(max) These values were not statistically different from a value of 1 (1 group, 2-tailed t test). The effective interval did not vary significantly with firing rate.5. The dependence of S on PP amplitude and baseline firing rate was incorporated into an expression for the average change in firing rate (DELTAf) produced by PPs occurring at rate f(s): DELTAf = 0.03 h1.24 f(s). The DELTAf increased with PP amplitude but did not vary significantly with the baseline firing rate. The values of DELTAf calculated from the S-D curves matched the values that were computed directly from the spike trains.6. Comparison of DELTAf produced by brief pulses of current with DELTAf produced by the same net increment in current applied steadily revealed that the pulses produced significantly larger increases in the firing rate. Thus synaptic inputs arriving synchronously as transient pulses have a greater effect on the firing rate of cortical neurons than the same inputs arriving asynchronously.