Approximate, not Perfect Synchrony Maximizes the Downstream Effectiveness of Excitatory Neuronal Ensembles.
Approximate, not Perfect Synchrony Maximizes the Downstream Effectiveness of Excitatory Neuronal Ensembles.
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DOI：
10.1186/2190-8567-4-10
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发表时间：
2014-12
影响因子：
2.3
通讯作者：
Kopell N
中科院分区：
文献类型：
--
作者：
Börgers C;Li J;Kopell N
通常归因于大脑同步性的最基本功能作用是放大兴奋性神经元信号。推理很简单：当正电荷在正持续时间的时间窗口内注入泄漏目标神经元时，在目标中触发动作电位之前，其中一些电荷将有时间泄漏回来，从这个意义上说，它会被浪费。如果目标是使用尽可能少的电荷在目标中引发发射响应，那么似乎最好一次性提供所有电荷，即完美同步。在本文中，我们证明，仅当假设输入在目标跨过射击阈值时但在实际射击之前停止时，这种推理才是正确的。如果输入稍后停止——例如，响应由目标发射触发的反馈信号——传递输入的“最经济”方式（需要最少输入总量的方式）不再是精确同步，而只是近似同步。如果目标是异构网络，就像它总是在大脑中一样，那么“当目标超过发射阈值时”停止输入就不是一个选择，因为不存在超过发射阈值的单一时刻。从这个意义上说，精确的同步在大脑中从来都不是最佳的。本文的在线版本 (doi:10.1186/2190-8567-4-10) 包含补充材料，可供授权用户使用。
The most basic functional role commonly ascribed to synchrony in the brain is that of amplifying excitatory neuronal signals. The reasoning is straightforward: When positive charge is injected into a leaky target neuron over a time window of positive duration, some of it will have time to leak back out before an action potential is triggered in the target, and it will in that sense be wasted. If the goal is to elicit a firing response in the target using as little charge as possible, it seems best to deliver the charge all at once, i.e., in perfect synchrony. In this article, we show that this reasoning is correct only if one assumes that the input ceases when the target crosses the firing threshold, but before it actually fires. If the input ceases later—for instance, in response to a feedback signal triggered by the firing of the target—the “most economical” way of delivering input (the way that requires the least total amount of input) is no longer precisely synchronous, but merely approximately so. If the target is a heterogeneous network, as it always is in the brain, then ceasing the input “when the target crosses the firing threshold” is not an option, because there is no single moment when the firing threshold is crossed. In this sense, precise synchrony is never optimal in the brain. The online version of this article (doi:10.1186/2190-8567-4-10) contains supplementary material, which is available to authorized users.