Extended Data Fig. 1: Backbone units occupy the tail of skewed firing rate distributions.
From: Preconfigured neuronal firing sequences in human brain organoids
a, A histogram of the distribution of average firing rates for all units in organoid 1. The majority of units have low average firing rates, while a long tail in the distribution contains a small subset of units with high average firing rates. A lognormal distribution is fitted to the histogram. The inset shows the histogram for the logarithm of the average firing rates of the same organoid. A normal distribution is fitted to the histogram. b, Normal distributions fit to the logarithm of the average firing rate per unit for the 8 different organoids. c, The R2 values for the fitted normal distributions shown in b. R2 = 0.97 ± 0.04 (mean ± s.d.) across the 8 human brain organoids. Backbone neurons alone are not well described by a lognormal distribution. R2 values are 0.45 ± 0.30 across the 8 human brain organoids. d, The distribution of average firing rates per organoid for backbone and non-rigid units separated. Red bars mark the distribution medians. The backbone units populate the tail of the skewed average firing rate distributions in all organoids. See Fig. 7a for statistical comparisons.
