Dendritic design implements algorithm for synaptic extraction of sensory information
Dendritic design implements algorithm for synaptic extraction of sensory information
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DOI：
10.1523/jneurosci.5354-07.2008
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发表时间：
2008-04-30
影响因子：
5.3
通讯作者：
Oka, Kotaro
中科院分区：
文献类型：
--
作者：
Ogawa, Hiroto;Cummins, Graham I.;Oka, Kotaro
虽然感觉信息是由单个感觉神经元的放电模式编码的，但它也由神经元群体活动的时空模式来表示。突触后中间神经元解码群体反应并提取特定的感觉信息。突触前活动所代表的信息提取是定义突触后神经元输入-输出功能的关键过程。为了理解提取的“算法”，我们检查了蟋蟀颈感觉系统中两种具有不同树突几何形状的风敏感中间神经元（INs）树突中突触前和突触后Ca2+反应的方向敏感性。在In 10-3中，树突分布在与峰值起始区（SIZ）的不同电紧张距离上，树突Ca2+反应的方向敏感性与突触前传入事件中Ca2+信号在该树突上的指示相对应。单个枝晶的定向调谐特性各不相同，离SIZ最近的枝晶的定向灵敏度主导着尖峰响应的调谐特性。在树突与SIZ等距的In - 10-2中，不同树突的定向调谐特性彼此相似，每种响应特性都可以用树突与Ca2+升高的突触前末端空间重叠的方向分布来解释。对于in10 -2，不同树突分支提取的方向灵敏度对整体调谐的贡献相同。树突几何结构导致的突触权重分布差异可能与突触后中间神经元的感觉信息提取算法有关。
While sensory information is encoded by firing patterns of individual sensory neurons, it is also represented by spatiotemporal patterns of activity in populations of the neurons. Postsynaptic interneurons decode the population response and extract specific sensory information. This extraction of information represented by presynaptic activities is a process critical to defining the input - output function of postsynaptic neuron. To understand the "algorithm" for the extraction, we examined directional sensitivities of presynaptic and postsynaptic Ca2+ responses in dendrites of two types of wind-sensitive interneurons (INs) with different dendritic geometries in the cricket cercal sensory system. In IN 10-3, whose dendrites arborize with various electrotonic distances to the spike-initiating zone (SIZ), the directional sensitivity of dendritic Ca2+ responses corresponded to those indicated by Ca2+ signals in presynaptic afferents arborizing on that dendrite. The directional tuning properties of individual dendrites varied from each other, and the directional sensitivity of the nearest dendrite to the SIZ dominates the tuning properties of the spiking response. In IN 10-2 with dendrites isometric to the SIZ, directional tuning properties of different dendrites were similar to each other, and each response property could be explained by the directional profile of the spatial overlap between that dendrite and Ca2+-elevated presynaptic terminals. For IN 10-2, the directional sensitivities extracted by the different dendritic-branches would contribute equally to the overall tuning. It is possible that the differences in the distribution of synaptic weights because of the dendritic geometry are related to the algorithm for extraction of sensory information in the postsynaptic interneurons.