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Spike-timing patterns are crucial for synaptic plasticity and neural computation, yet their statistical patterns in various brain regions which cross different mammalian species have not been examined in a systematic manner. Neurons in vivo discharge spikes with enormous variability. This irregularity often models as a Poisson-like random process. Here, we systematically examine statistical behaviors of spike-time irregularity in 13 different cortical and subcortical regions from mouse, hamster, cat and monkey brains. We show that spike-timing patterns of interneurons and various projection neurons - including cortical excitatory principal cells, hippocampal pyramidal cells, inhibitory striatal medium spiny neurons, as well as dopaminergic neurons - all conform to the gamma distribution model. Moreover, gamma shapes of spike-timing patterns remain robust over different states - such as sleep and awake periods and under fearful events. Interestingly, there are significant regional variations of the spike-timing’s regularities - that is, DA neurons, the somatosensory cortex and motor cortices showing increased regularity, whereas the V1 cortex, retrosplenial cortex, anterior cingulate cortex, striatum, amygdala, and hippocampus tend to exhibit greater irregularity. Furthermore, we observe that ketamine-induced anesthesia largely deranges the gamma-like spike-timing patterns. Such a conserved gamma distribution pattern, coupled with characteristic regional variations, may influence how spike-timing patterns exert dynamic actions on neural coding and network-level plasticity.

Spike-timing patterns are crucial for synaptic plasticity and …