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| Neurons in cortical networks continuously show spontaneous firing even in the absence of sensory stimuli. The spontaneous firing is highly irregular and the firing rate is small. While it seems just background noise of cortical activity, recent experiments reported that spontaneous activity bidirectionally interacts with stimulus-evoked activity and actually affects animals perception. There has been much recent interest in the spontaneous irregular activity. However, the origin and functional roles of the activity remain almost completely unknown. In this study, by focusing on the recent experimental finding that amplitudes of postsynaptic potentials (PSP) between cortical neurons distribute with a highly skewed long-tailed distribution, we reveal that cortical networks can robustly generate the spontaneous irregular activity with neither internal noise source nor external input. We also find that spike information is transmitted in the cortical network most reliably by the help of t
he spontaneous activity. Our results identify a simple mechanism for internal noise generation supporting both stability and optimal spike-based communication between cortical neurons. |
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