Chacron Maurice J
Department of Zoology, University of Oklahoma, 730 Van Vleet Oval, Norman, OK 73019, USA.
J Neurophysiol. 2006 May;95(5):2933-46. doi: 10.1152/jn.01296.2005. Epub 2006 Feb 22.
Understanding the mechanisms by which sensory neurons encode and decode information remains an important goal in neuroscience. We quantified the performance of optimal linear and nonlinear encoding models in a well-characterized sensory system: the electric sense of weakly electric fish. We show that linear encoding models generally perform better under spatially localized stimulation than under spatially diffuse stimulation. Through pharmacological blockade of feedback input and spatial saturation of the receptive field center, we show that there is significantly less synaptic noise under spatially diffuse stimuli as compared with spatially localized stimuli. Modeling results suggest that pyramidal cells nonlinearly encode sensory information through shunting in their dendrites and clarify the influence of synaptic noise on the performance of linear encoding models. Finally, we used information theory to quantify the performance of linear decoders. While the optimal linear decoder for spatially localized stimuli could capture 60% of the information in pyramidal cell spike trains, the optimal linear decoder for spatially diffuse stimuli could only capture 40% of the information. These results show that nonlinear decoders are necessary to fully access information in pyramidal cell spike trains, and we discuss potential mechanisms by which higher-order neurons could decode this information.
理解感觉神经元编码和解码信息的机制仍然是神经科学的一个重要目标。我们在一个特征明确的感觉系统——弱电鱼的电觉中，对最优线性和非线性编码模型的性能进行了量化。我们发现，线性编码模型在空间局部刺激下的表现通常优于空间扩散刺激下的表现。通过反馈输入的药理学阻断和感受野中心的空间饱和，我们发现与空间局部刺激相比，空间扩散刺激下的突触噪声明显更少。建模结果表明，锥体细胞通过其树突中的分流对感觉信息进行非线性编码，并阐明了突触噪声对线性编码模型性能的影响。最后，我们用信息论来量化线性解码器的性能。虽然用于空间局部刺激的最优线性解码器可以捕捉锥体细胞尖峰序列中60%的信息，但用于空间扩散刺激的最优线性解码器只能捕捉40%的信息。这些结果表明，非线性解码器对于完全获取锥体细胞尖峰序列中的信息是必要的，并且我们讨论了高阶神经元解码此信息的潜在机制。
