Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India.
J Neurophysiol. 2012 Nov;108(9):2343-51. doi: 10.1152/jn.00530.2012. Epub 2012 Aug 29.
The presence and plasticity of dendritic ion channels are well established. However, the literature is divided on what specific roles these dendritic ion channels play in neuronal information processing, and there is no consensus on why neuronal dendrites should express diverse ion channels with different expression profiles. In this review, we present a case for viewing dendritic information processing through the lens of the sensory map literature, where functional gradients within neurons are considered as maps on the neuronal topograph. Under such a framework, drawing analogies from the sensory map literature, we postulate that the formation of intraneuronal functional maps is driven by the twin objectives of efficiently encoding inputs that impinge along different dendritic locations and of retaining homeostasis in the face of changes that are required in the coding process. In arriving at this postulate, we relate intraneuronal map physiology to the vast literature on sensory maps and argue that such a metaphorical association provides a fresh conceptual framework for analyzing and understanding single-neuron information encoding. We also describe instances where the metaphor presents specific directions for research on intraneuronal maps, derived from analogous pursuits in the sensory map literature. We suggest that this perspective offers a thesis for why neurons should express and alter ion channels in their dendrites and provides a framework under which active dendrites could be related to neural coding, learning theory, and homeostasis.
树突离子通道的存在和可塑性已得到充分证实。然而，文献对于这些树突离子通道在神经元信息处理中具体扮演什么角色存在分歧，也没有共识说明为什么神经元树突应该表达具有不同表达谱的不同离子通道。在这篇综述中，我们提出了一个观点，即通过感觉图谱文献的视角来看待树突信息处理，其中神经元内的功能梯度被视为神经元拓扑上的图谱。在这种框架下，我们从感觉图谱文献中进行类比，假设形成神经元内功能图谱的驱动力是两个目标，一是有效地编码沿不同树突位置传入的输入，二是在编码过程中需要改变时保持体内平衡。在得出这一假设的过程中，我们将神经元内图谱生理学与关于感觉图谱的大量文献联系起来，并认为这种隐喻关联为分析和理解单个神经元信息编码提供了一个新的概念框架。我们还描述了这种隐喻为神经元内图谱研究提供了具体研究方向的实例，这些方向源自感觉图谱文献中的类似研究。我们认为，这种观点提供了一个关于神经元为什么应该在树突中表达和改变离子通道的理论，并提供了一个框架，在此框架下，活跃的树突可以与神经编码、学习理论和体内平衡联系起来。
