Neural responses are typically characterized by computing the mean firing rate, but response variability can exist across trials. Many studies have examined the effect of a stimulus on the mean response, but few have examined the effect on response variability. We measured neural variability in 13 extracellularly recorded datasets and one intracellularly recorded dataset from seven areas spanning the four cortical lobes in monkeys and cats. In every case, stimulus onset caused a decline in neural variability. This occurred even when the stimulus produced little change in mean firing rate. The variability decline was observed in membrane potential recordings, in the spiking of individual neurons and in correlated spiking variability measured with implanted 96-electrode arrays. The variability decline was observed for all stimuli tested, regardless of whether the animal was awake, behaving or anaesthetized. This widespread variability decline suggests a rather general property of cortex, that its state is stabilized by an input.
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慣れない分野でタフな論文。理解が結構怪しいが。
●刺激後にneuronの活動（membrane potencial/firing rates）のvariabilityが低下することを、いくつかの指標を定義して証明。その指標を変化させるほかのfactorが影響しているわけではないことをなにやらごちゃごちゃと検討している・・・らしい・・・
●平均化することで失われてしまう情報に意味があるのではないかという問題提起
とすれば・・・
・個々のneuronのvariabilityがノイズであると考えれば、network全体として機能することでbufferingしている？
・むしろ個々のneuronのvariabilityはそれぞれの機能（処理している情報）の違いを反映している？
●Discussionより
"Mechanistically, the variance decline inplies that cortical curcuits become more stable when driven."
→こういうタイプのネットワークはいくつか考えられて、recurrent networkもその一つ。
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