Transformation in the Neural Code for Whisker Deflection Direction Along the Lemniscal Pathway
Transformation in the Neural Code for Whisker Deflection Direction Along the Lemniscal Pathway
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DOI：
10.1152/jn.00636.2009
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发表时间：
2009-11-01
影响因子：
2.5
通讯作者：
Petersen, Rasmus S.
中科院分区：
文献类型：
--
作者：
Bale, Michael R.;Petersen, Rasmus S.
Bale MR，Petersen RS.转换的神经代码的触须偏转方向沿着丘系通路。J Neurophysiol 102：2771-2780，2009.首次发表于2009年9月9日; doi：10.1152/jn.00636.2009。触须系统中神经元的一个突出特征是它们对触须偏转方向的选择性。本研究的目的是确定如何在丘系通路的连续水平上编码关于胡须方向的信息。我们在相同的条件下从三叉神经节，腹后内侧丘脑（VPM），和桶皮质的细胞外记录，而不同的方向的晶须偏转。我们发现一个显着增加的变化，单一单位的反应沿着的途径。为了研究这对信息处理的影响，我们使用互信息量化了反应。VPM单位传达了神经节单位传达的48%的互信息，皮层单位传达了12%。用于传递方向信息的神经元带宽分数从神经节的40%下降到VPM的24%和桶皮质的5%。为了测试在大脑皮层中，群体编码是否可以补偿这种信息丢失，我们进行了同步记录。我们发现，皮层神经元对传递的互信息是单个神经元传递的2.1倍。总的来说，这些发现表明了一个显着的转变，从皮质下的神经代码的基础上少量的可靠的神经元的皮质代码的基础上不可靠的神经元的群体。然而，神经节、丘脑和皮层的神经编码的基本形式是相似的，在每个阶段，第一个刺激后尖峰携带了大部分信息。
Bale MR, Petersen RS. Transformation in the neural code for whisker deflection direction along the lemniscal pathway. J Neurophysiol 102: 2771-2780, 2009. First published September 9, 2009; doi: 10.1152/jn.00636.2009. A prominent characteristic of neurons in the whisker system is their selectivity to the direction in which a whisker is deflected. The aim of this study was to determine how information about whisker direction is encoded at successive levels of the lemniscal pathway. We made extracellular recordings under identical conditions from the trigeminal ganglion, ventro-posterior medial thalamus (VPM), and barrel cortex while varying the direction of whisker deflection. We found a marked increase in the variability of single unit responses along the pathway. To study the consequences of this for information processing, we quantified the responses using mutual information. VPM units conveyed 48% of the mutual information conveyed by ganglion units, and cortical units conveyed 12%. The fraction of neuronal bandwidth used for transmitting direction information decreased from 40% in the ganglion to 24% in VPM and 5% in barrel cortex. To test whether, in cortex, population coding might compensate for this information loss, we made simultaneous recordings. We found that cortical neuron pairs conveyed 2.1 times the mutual information conveyed by single neurons. Overall, these findings indicate a marked transformation from a subcortical neural code based on small numbers of reliable neurons to a cortical code based on populations of unreliable neurons. However, the basic form of the neural code in ganglion, thalamus, and cortex was similar-at each stage, the first poststimulus spike carried the majority of the information.