Interaction of baseline synaptic noise and Ia EPSPs: evidence for appreciable negative correlation under physiological conditions.
Interaction of baseline synaptic noise and Ia EPSPs: evidence for appreciable negative correlation under physiological conditions.
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基线突触噪声和 Ia EPSP 的相互作用：生理条件下明显负相关的证据。
DOI：
10.1152/jn.1991.65.4.927
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发表时间：
1991
影响因子：
2.5
通讯作者：
Rudomin,P
中科院分区：
文献类型：
--
作者：
Solodkin,M;Jimenez,I;Collins3rd,WF;Mendell,LM;Rudomin,P
1.在麻醉猫，同时从脊髓运动神经元对细胞内记录，看看是否在两个细胞的单纤维兴奋性突触后电位（EPSP）的幅度波动在一个协调的方式，这将表明相关的机制，无论是在前或突触后水平。尽管这些记录显示基线中的相关波动，但使用尖峰触发平均技术记录的单纤维Ia/EPSP没有显示相关波动，并且出乎意料地，与EPSP相关的基线方差几乎没有增加。然而，这些实验是在高基线突触噪声的条件下进行的事实（即，由于EPSP和突触噪声之间的相互作用，肌肉拉伸）可能影响结果，并明确评估了这种可能性。2.在低噪声下，通过在没有肌肉拉伸的情况下电刺激单个Ia纤维来研究给定的连接。在高噪声条件下，通过肌肉拉伸激活纤维和所有其他拉伸感受器传入，并通过使用尖峰触发平均提取EPSP来分析相同的连接。在低噪声和高噪声条件下，在给定连接处的平均EPSP振幅差异极小。3.然后确定EPSP振幅的波动，以确定这些是否受到基线突触噪声的影响，以及相互作用是否是非线性的。使用两种方法来测量EPSP波动：测量与EPSP相关的方差，以及使用反卷积方法确定与EPSP相关的离散振幅分量。4.在低噪声条件下诱发的EPSP过程中，观察到基线方差的增加，在所有六个连接以这种方式研究。当在高噪声下检查时，这种增加在其中两个连接处消失。这可能有助于解释在成对运动神经元中获得的结果。5.反卷积结果用于计算无噪声EPSP的方差。发现这不同于直接从与EPSP相关的基线方差变化测量的EPSP振幅分布的方差。分析技术表明，在大多数情况下，这种差异可以解释为EPSP和基线突触噪声之间的负相关。这些考虑导致了一种分析方法来评估反褶积结果的可靠性。6.仿真研究表明，与EPSP相关的基线方差增加也高度依赖于信号和噪声之间的相关性。（400字处删节）
1. In the anesthetized cat, simultaneous intracellular recordings from pairs of spinal motoneurons were undertaken to see whether the amplitude of single-fiber excitatory postsynaptic potentials (EPSPs) in both cells fluctuated in a coordinated manner that would indicate correlative mechanisms at either pre- or post-synaptic level. Although these recordings revealed correlated fluctuations in the baseline, the single-fiber Ia/EPSPs recorded with the spike-triggered averaging technique exhibited no correlated fluctuations and, unexpectedly, virtually no increase in baseline variance associated with the EPSP. However, the fact that these experiments were carried out under conditions of high baseline synaptic noise (i.e., with muscle stretch) may have influenced the outcome because of interaction between EPSP and synaptic noise, and this possibility was evaluated explicitly. 2. A given connection was studied under low noise by electrically stimulating a single Ia fiber in the absence of muscle stretch. The same connection was analyzed under conditions of high noise by activating the fiber and all other stretch receptor afferents with muscle stretch and by using spike-triggered averaging to extract the EPSP. The differences in mean EPSP amplitude at a given connection under conditions of low noise and high noise were minimal. 3. Fluctuations in EPSP amplitude were then determined to see whether these were influenced by presence of baseline synaptic noise and whether the interaction was nonlinear. Two methods were used to measure EPSP fluctuations: measurement of the variance associated with the EPSP, and determination by the use of deconvolution methods of the discrete amplitude components associated with the EPSP. 4. An increase in baseline variance was observed during the EPSP evoked under low noise conditions at all six connections studied in this way. This increase disappeared at two of these connections when examined under high noise. This may help to explain the results obtained in pairs of motoneurons. 5. The deconvolution results were used to calculate the variance of the noise-free EPSP. This was found to differ from the variance of the EPSP amplitude distribution measured directly from the change in baseline variance associated with the EPSP. Analytic techniques suggested that this difference could be explained in most cases by negative correlation between the EPSP and baseline synaptic noise. These considerations led to an analytic method to assess the reliability of the deconvolution result. 6. Simulation studies revealed that the baseline variance increase associated with the EPSP is also highly dependent on the correlation between signal and noise.(ABSTRACT TRUNCATED AT 400 WORDS)