ON TEMPORAL CODES AND THE SPATIOTEMPORAL RESPONSE OF NEURONS IN THE LATERAL GENICULATE-NUCLEUS
ON TEMPORAL CODES AND THE SPATIOTEMPORAL RESPONSE OF NEURONS IN THE LATERAL GENICULATE-NUCLEUS
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DOI：
10.1152/jn.1994.72.6.2990
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发表时间：
1994-12-01
影响因子：
2.5
通讯作者：
SHRAIMAN, BI
中科院分区：
文献类型：
--
作者：
GOLOMB, D;KLEINFELD, D;SHRAIMAN, BI
1. 目前的工作将最近视觉刺激时间编码的实验研究（McClurkin, Optican, Richmond, and Gawne, Science 253: 675, 1991）与灵长类动物外侧膝状体内神经元时空感受野的测量联系起来。2.我们分析了新的和先前描述的大细胞和小细胞单个单位。该单元的时空脉冲响应函数定义为响应在给定位置和时间闪烁的微弱刺激的时间分辨平均放电率，其特征在于奇异值分解。这种分析允许用少量（两到三个）空间和时间模式来表示脉冲响应。大细胞和细细胞单位都是弱不可分离的，主要模式和次要模式分别占响应的 78% 和 22%。两种类型的主要时间模式在前 100 毫秒内基本相同。随后，大细胞单位的响应改变符号并缓慢衰减，而小细胞单位的响应衰减相对较快。3．当线性响应理论有效时，时空脉冲响应函数完全决定了单元对任意刺激的响应。使用测量的脉冲响应，结合校正神经元输入输出关系，我们计算对由“沃尔什”函数构造的完整空间亮度模式集的响应。我们预测的时间反应与细小细胞单位的报告定性一致（McClurkin, Optican, Richmond, and Gawne, J. Neurophysiol. 66: 794, 1991）。在泊松统计对尖峰概率和合理的背景发射率的附加假设下，我们预测了沃尔什模式辨别任务中单元的性能，并通过互信息进行量化。我们的预测再次与报告的结果一致。4．最后，我们考虑线性响应内的时间编码问题。对于固定时间间隔呈现的刺激，奇异值分解提供了神经元响应的时间模式与刺激的空间模式之间的自然关系。尽管很容易将每个时间模式解释为对刺激的正交特征进行编码的独立通道，但连续的高阶模式越来越不可靠，并且不会显着增加单元的辨别能力。
1. The present work relates recent experimental studies of the temporal coding of visual stimuli (McClurkin, Optican, Richmond, and Gawne, Science 253: 675, 1991) to the measurements of the spatiotemporal receptive fields of neurons within the lateral geniculate of primate.2. We analyze both new and previously described magnocellular and parvocellular single units. The spatiotemporal impulse response function of the unit, defined as the time-resolved average firing rate in response to a weak stimulus flashed at a given location and time, is characterized by the singular value decomposition. This analysis allows one to represent the impulse response by a small number, two to three, of spatial and temporal modes. Both magnocellular and parvocellular units are weakly nonseparable, with major and minor modes that account, respectively, for similar to 78 and 22% of the response. The major temporal mode for both types is essentially identical for the first 100 ms. At later times the response of magnocellular units changes sign and decays slowly, whereas the response of parvocellular units decays relatively rapidly.3. The spatiotemporal impulse response function completely determines the response of a unit to an arbitrary stimulus when linear response theory is valid. Using the measured impulse response, combined with a rectifying neuronal input-output relation, we calculate the responses to a complete set of spatial luminance patterns constructed of ''Walsh'' functions. Our predicted temporal responses are in qualitative agreement with those reported for parvocellular units (McClurkin, Optican, Richmond, and Gawne, J. Neurophysiol. 66: 794, 1991). Under the additional assumptions of Poisson statistics for the probability of spiking and a plausible background firing rate, we predict the performance of a unit in the Walsh pattern discrimination task as quantified by mutual information. Our prediction is again consistent with the reported results.4. Last, we consider the issue of temporal coding within linear response. For stimuli presented for fixed time intervals, the singular value decomposition provides a natural relation between the temporal modes of the neuronal response and the spatial pattern of the stimulus. Although it is tempting to interpret each temporal mode as an independent channel that encodes orthogonal features of the stimulus, successively higher order modes are increasingly unreliable and do not significantly increase the discrimination capabilities of the unit.