Effects of large excitatory and inhibitory inputs on motoneuron discharge rate and probability.
Effects of large excitatory and inhibitory inputs on motoneuron discharge rate and probability.
复制标题
大的兴奋性和抑制性输入对运动神经元放电速率和概率的影响。
DOI：
10.1152/jn.1999.82.2.829
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Powers,RK
中科院分区：
文献类型：
--
作者：
Turker,KS;Powers,RK
我们使用阈上注入电流步骤与叠加噪声的组合来模拟生理激活过程中可能发生的突触驱动，从而在大鼠脑干切片中记录的舌下运动神经元中引发重复放电。通过进一步添加不同形状和大小的注入电流瞬变序列来模拟传入神经的重复整体刺激的效果。通过计算周刺激时间直方图（PSTH）和周刺激频率图（PSF）来测量给定电流瞬变对运动神经元放电时间和放电速率的影响。通过将电流瞬变与运动神经元的被动脉冲响应的估计进行卷积来计算电流瞬变产生的模拟突触后电位（PSP）的幅度和时间过程。然后，我们将注入电流瞬变和模拟 PSP 的形状与 PSTH 和 PSF 记录的轮廓进行比较。兴奋性 PSP (EPSP) 产生的 PSTH 的特点是放电概率大幅短延迟增加，持续时间略长于 EPSP 的上升阶段，随后在 EPSP 的下降阶段放电概率降低。相比之下，PSF 分析显示，尽管在下降阶段出现的峰值相对较少，但 EPSP 整个剖面上的放电率成比例增加。与抑制性 PSP (IPSP) 相关的 PSTH 表明在 IPSP 的初始超极化阶段放电概率降低，随后在其随后的复极化阶段放电概率增加。使用 PSF 分析，IPSP 的初始阶段在记录中表现为一个大洞，其中发生了非常少量的放电或没有发生放电。 IPSP 的后续阶段与低于背景值的频率值相关。 PSTH 和 PSF 的主要特征可用于估计基础 EPSP 和 IPSP 的相对幅度。然而，PSTH 包含次要波峰和波谷，这些波峰和波谷与基础 PSP 没有直接关系，而是反映了受 PSP 影响的波峰的定期重复出现。 PSF 分析对于指示总持续时间和基础 PSP 的概况更有用。底层 PSP 的形状可以直接从 PSF 记录中获得，因为尖峰的放电频率非常接近 PSP，特别是对于 EPSP。
We elicited repetitive discharge in hypoglossal motoneurons recorded in slices of rat brain stem using a combination of a suprathreshold injected current step with superimposed noise to mimic the synaptic drive likely to occur during physiological activation. The effects of repetitive en mass stimulation of afferent nerves were simulated by the further addition of trains of injected current transients of varying shapes and sizes. The effects of a given current transient on motoneuron discharge timing and discharge rate were measured by calculating a peristimulus time histogram (PSTH) and a peristimulus frequencygram (PSF). The amplitude and time course of the simulated postsynaptic potentials (PSPs) produced by the current transients were calculated by convolving the current transient with an estimate of the passive impulse response of the motoneuron. We then compared the shape of the injected current transient and the simulated PSP to the profiles of the PSTH and the PSF records. The PSTHs produced by excitatory PSPs (EPSPs) were characterized by a large, short-latency increase in firing probability that lasted slightly longer than the rising phase of the EPSP, followed by a reduced discharge probability during the falling phase of the EPSP. In contrast, the PSF analysis revealed a proportionate increase in discharge rate over the entire profile of the EPSP, even though relatively few spikes occurred during the falling phase. The PSTHs associated with inhibitory PSPs (IPSPs) indicated a reduction in discharge probability during the initial, hyperpolarizing phase of the IPSP, followed by an increase in the discharge probability during its subsequent repolarizing phase. Using the PSF analysis, the initial phase of the IPSP appeared as a large hole in the record where a very small number or no discharges occurred. The subsequent phase of the IPSP was associated with frequency values that were lower than the background values. The primary features of both PSTHs and PSFs can be used to estimate the relative amplitudes of the underlying EPSPs and IPSPs. However, PSTHs contain secondary peaks and troughs that are not directly related to the underlying PSP but instead reflect the regular recurrence of spikes following those affected by the PSP. The PSF analysis is more useful for indicating the total duration and the profile of the underlying PSP. The shape of the underlying PSP can be obtained directly from the PSF records because the discharge frequency of the spikes follow the PSPs very closely, especially for EPSPs.