Fig. 7.

Pro-arousal slow-firing neurons fire together. A: example of cross-correlation between neuronal pairs. Panels show cross-correlation in each recording session as a whole (ALL) or cross-correlation broken down by states. Three types of neurons are shown: pro-arousal slow-firing (proA), other slow-firing (Other) and fast-firing (Fast) neurons. For every pair of panels, left panel shows cross-correlation of a pair of neurons from the same type and right panel shows cross-correlation of a pair of neurons from 2 different types. Cross-correlation between 2 pro-arousal slow-firing neurons is more prominent than that from other pairs in all behavioral states. B: proportion (average ± SE) of significant cross-correlation of all neuronal pairs at different time lags. Positive values depict original cross-correlations above the upper significant threshold (mean + 3SD); negative values depict those below the lower significant threshold (mean − 3SD). The proportion of positively significant cross-correlation is higher for pro-arousal slow-firing pairs than for other types of pairs. No pro-arousal slow-firing pairs showed negative cross-correlations. Color scheme is the same as in A. C: average cross-correlation values (average ± SE) of all neuronal pairs for different time windows. Cross-correlation between 2 pro-arousal slow-firing neurons is stronger than for other types of pairs. Color scheme is the same as in A. All comparisons tested were using 1-way ANOVA with Bonferroni-corrected multiple comparisons. Significance levels are labeled only when the value of the pair from 2 pro-arousal slow-firing neurons is significantly larger than that of any other types of pairs. ΔP < 0.05; +P < 0.01; #P < 0.001.