Ruling out and ruling in neural codes
Ruling out and ruling in neural codes
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DOI：
10.1073/pnas.0900573106
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发表时间：
2009-04-07
影响因子：
11.1
通讯作者：
Nirenberg, Sheila
中科院分区：
文献类型：
--
作者：
Jacobs, Adam L.;Fridman, Gene;Nirenberg, Sheila
神经编码的主题已经引起了很多争论。关键问题是神经系统是使用粗编码还是精细编码。每一种都有不同的优点和缺点，因此对大脑的计算方式有不同的含义。例如，粗编码的强度在于它对峰值到达时间的波动具有鲁棒性；下游神经元不需要跟踪脉冲序列的细节。然而，缺点是单个细胞不能携带太多的信息，因此下游神经元必须在细胞和/或时间之间汇集信号，以获得足够的信息来代表感官世界并指导行为。相比之下，通过精细编码，单个细胞可以携带更多的信息，但下游神经元必须解析尖峰序列结构才能获得信息。在这里，我们建立了一个策略来确定哪些代码是可行的，我们把它应用到视网膜上作为一个模型系统。我们记录了动物用于解决任务的所有视网膜输出细胞，在动物评估它们的时间内评估细胞的脉冲序列，并使用最优，即贝叶斯解码。这种方法可以获得代码性能的上限，从而消除那些不充分的代码，即那些不能解释行为性能的代码。结果表明，标准粗编码（尖峰计数编码）是不够的；更精细、信息更丰富的代码是必要的。
The subject of neural coding has generated much debate. A key issue is whether the nervous system uses coarse or fine coding. Each has different strengths and weaknesses and, therefore, different implications for how the brain computes. For example, the strength of coarse coding is that it is robust to fluctuations in spike arrival times; downstream neurons do not have to keep track of the details of the spike train. The weakness, though, is that individual cells cannot carry much information, so downstream neurons have to pool signals across cells and/or time to obtain enough information to represent the sensory world and guide behavior. In contrast, with fine coding, individual cells can carry much more information, but downstream neurons have to resolve spike train structure to obtain it. Here, we set up a strategy to determine which codes are viable, and we apply it to the retina as a model system. We recorded from all the retinal output cells an animal uses to solve a task, evaluated the cells' spike trains for as long as the animal evaluates them, and used optimal, i.e., Bayesian, decoding. This approach makes it possible to obtain an upper bound on the performance of codes and thus eliminate those that are insufficient, that is, those that cannot account for behavioral performance. Our results show that standard coarse coding (spike count coding) is insufficient; finer, more information-rich codes are necessary.