Information theoretic analysis of dynamical encoding by four identified primary sensory interneurons in the cricket cercal system.
Information theoretic analysis of dynamical encoding by four identified primary sensory interneurons in the cricket cercal system.
复制标题
板球尾部系统中四个已识别的初级感觉中间神经元动态编码的信息论分析。
DOI：
10.1152/jn.1996.75.4.1345
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Miller,JP
中科院分区：
文献类型：
--
作者：
Theunissen,F;Roddey,JC;Stufflebeam,S;Clague,H;Miller,JP
1.利用电生理技术研究了蟋蟀颈感觉系统中4个初级感觉中间神经元的刺激/反应特性。这四个细胞被认为代表了cercal系统的功能离散亚基：它们是编码关于低强度刺激向更高中心的刺激方向的信息的唯一细胞。先前的研究描述了这些细胞编码的关于水平面气流方向的信息量。在这里报道的实验中，我们表征了编码在细胞引发的反应中的信息的数量和质量，这些反应是关于在其最佳刺激方向上呈现的气流波形的动态的。总样品组包括22个细胞。2.这种表征是通过使用随机系统分析和信息论的方法确定细胞的频率灵敏度和编码精度来实现的。用于分析的具体方法是“刺激重建”技术，其中导出函数扩展以将观察到的尖峰串响应转换为最佳估计（即，“重建”）的实际刺激。一个新的推导的关键方程。反向的方法相比，更传统的正向分析，其中的扩展是来自的刺激，转换为预测的尖峰列车响应。考虑这些分析方法的应用的重要方面。3.发现所有四个中间神经元具有相同的频率调谐，如通过刺激波形的不同频率分量可以用线性扩展重建的准确度所评估的。中间神经元编码有关5至80 Hz之间的刺激频率的重要信息，其峰值灵敏度约为15 Hz。4.发现所有四个中间神经元具有相同的刺激/反应延迟。刺激成分和相应的引发尖峰之间的平均潜伏期为17毫秒。所有四个interneurons也有相同的整合时间。通过刺激持续时间测量的整合时间（可能影响尖峰电位的概率）约为50 ms。编码的准确性可以表示为信噪比，其中噪声是原始信号与信号的最佳估计之间的缩放差。仅使用线性扩展项，在所有刺激功率水平上获得细胞的峰值信噪比约为1。数据分析表明，考虑二阶非线性变换的刺激不会增加计算的编码精度。6.编码精度也可以以比特/秒的信息理论单位表示，其表征小区的信息传输速率。对于我们实验组中的22个不同单元，位/秒值在10和80之间变化。信息率值与中间神经元的平均发放率高度相关，但与刺激功率水平无关。然而，在每种情况下，通过平均尖峰速率对绝对信息速率进行归一化，产生了在所有实验中显著不变的比特/尖峰的测量。对于所有实验，测得的比特/尖峰速率约为1。这一结果的背景下，最近的理论研究最佳编码进行了讨论。7.虽然四个中间神经元的动态灵敏度是相同的，但它们的方向灵敏度是正交的。因此，细胞是互补的，从一个功能...
1. The stimulus/response properties of four identified primary sensory interneurons in the cricket cercal sensory system were studied using electrophysiological techniques. These four cells are thought to represent a functionally discrete subunit of the cercal system: they are the only cells that encode information about stimulus direction to higher centers for low intensity stimuli. Previous studies characterized the quantity of information encoded by these cells about the direction of air currents in the horizontal plane. In the experiments reported here, we characterized the quantity and quality of information encoded in the cells' elicited responses about the dynamics of air current waveforms presented at their optimal stimulus directions. The total sample set included 22 cells. 2. This characterization was achieved by determining the cells' frequency sensitivities and encoding accuracy using the methods of stochastic systems analysis and information theory. The specific approach used for the analysis was the "stimulus reconstruction" technique in which a functional expansion was derived to transform the observed spike train responses into the optimal estimate (i.e., "reconstruction") of the actual stimulus. A novel derivation of the crucial equations is presented. The reverse approach is compared with the more traditional forward analysis, in which an expansion is derived that transforms the stimulus to a prediction of the spike train response. Important aspects of the application of these analytical approaches are considered. 3. All four interneurons were found to have identical frequency tuning, as assessed by the accuracy with which different frequency components of stimulus waveforms could be reconstructed with a linear expansion. The interneurons encoded significant information about stimulus frequencies between 5 and 80 Hz, which peak sensitivities at approximately 15 Hz. 4. All four interneurons were found to have identical stimulus/response latencies. The mean latency between a stimulus component and the corresponding elicited spike was 17 ms. All four interneurons also had identical integration times. The integration time, measured by the duration of stimulus, which could affect the probability of spiking, was approximately 50 ms. 5. The accuracy of the encoding can be expressed as a signal-to-noise ratio, where the noise is a scaled difference between the original signal and the best estimate of the signal. Peak signal-to-noise ratios of approximately 1 were obtained for the cells across all stimulus power levels, using only the linear expansion term. Analysis of the data indicated that the consideration of second-order nonlinear transformations of the stimulus would not have increased the calculated encoding accuracy. 6. The encoding accuracy also can be expressed in the information theoretic units of bits/second, which characterizes the information transmission rate of the cell. Bits/second values varied between 10 and 80 for the 22 different cells in our experimental set. The information rate values were highly correlated with the mean spike rates of the interneurons, but were not correlated with the stimulus power levels. However, normalizing the absolute information rates by the mean spike rate in each case yielded a measure of bits/spike that was remarkably invariant across all experiments. The measured bits/spike rate was approximately 1 for all experiments. This result is discussed in the context of recent theoretical studies on optimal encoding. 7. Although the dynamic sensitivities of the four interneurons were identical, their directional sensitivities are known to be orthogonal. Thus the cells are complementary to one another from a functional …