Discharge regularity in the turtle posterior crista: comparisons between experiment and theory.
Discharge regularity in the turtle posterior crista: comparisons between experiment and theory.
复制标题
龟后嵴的放电规律：实验与理论的比较。
DOI：
10.1152/jn.00195.2013
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发表时间：
2013
影响因子：
2.5
通讯作者：
Holt,JosephC
中科院分区：
文献类型：
--
作者：
Goldberg,JayM;Holt,JosephC
轴突内记录是由乌龟后嵴末端附近的布顿纤维制成的。在静息活动期间，对定期和不定期放电单元的尖峰放电、微型兴奋性突触后电位（mEPSP）和后超极化（AHP）进行监测。通过散粒噪声理论估计量子大小（qsize）和量子速率（qrate）。理论上，突触噪声 (σV) 与阈值交叉附近的平均电压轨迹斜率 (dμV/dt) 之间的比率 σV/(dμV/dt) 应确定放电规律。层次分析法在常规单位中更深、更持久；因此，dμV/d越大，放电越规则。不规则单位中qsize较大，qrate较小；这些相反方向的趋势导致 σV 随放电规律变化很小。在这两个变量中，dμV/d 在确定规律性方面比几乎恒定的 σV 影响更大。 0.3 Hz 的正弦管管压痕导致尖峰放电和突触电压的调制。增益、两个调制的幅度之间的比率以及两个调制的相位超前重新压痕在不规则单位中更大。增益变化与突触后尖峰编码器的灵敏度平行，突触后尖峰编码器是一组将突触输入转换为尖峰放电的电导。相位变化反映了编码器的突触输入和突触后过程。使用随机积分和激发模型解释实验数据。不规则放电的优点包括增强的编码器增益和防止非线性锁相。规则和不规则单元分别在低频和高频头部旋转的编码中更有效。
Intra-axonal recordings were made from bouton fibers near their termination in the turtle posterior crista. Spike discharge, miniature excitatory postsynaptic potentials (mEPSPs), and afterhyperpolarizations (AHPs) were monitored during resting activity in both regularly and irregularly discharging units. Quantal size (qsize) and quantal rate (qrate) were estimated by shot-noise theory. Theoretically, the ratio, σV/(dμV/dt), between synaptic noise (σV) and the slope of the mean voltage trajectory (dμV/dt) near threshold crossing should determine discharge regularity. AHPs are deeper and more prolonged in regular units; as a result, dμV/dtis larger, the more regular the discharge. The qsize is larger and qrate smaller in irregular units; these oppositely directed trends lead to little variation in σVwith discharge regularity. Of the two variables, dμV/dtis much more influential than the nearly constant σVin determining regularity. Sinusoidal canal-duct indentations at 0.3 Hz led to modulations in spike discharge and synaptic voltage. Gain, the ratio between the amplitudes of the two modulations, and phase leads re indentation of both modulations are larger in irregular units. Gain variations parallel the sensitivity of the postsynaptic spike encoder, the set of conductances that converts synaptic input into spike discharge. Phase variations reflect both synaptic inputs to the encoder and postsynaptic processes. Experimental data were interpreted using a stochastic integrate-and-fire model. Advantages of an irregular discharge include an enhanced encoder gain and the prevention of nonlinear phase locking. Regular and irregular units are more efficient, respectively, in the encoding of low- and high-frequency head rotations, respectively.