Sample recordings from 7-week-old hESC-derived Cerebral Organoids (COs). Mean spectral power of week 7 WT and KO COs in baseline conditions. The line marks 0.25-1 Hz frequency range. Statistical significance was determined using two-tailed unpaired Welch's t-test (WT: n=14 slices, 5 organoids, 3 batches. KO: n=14 slices, 8 organoids, 3 batches).   Normalized area under the curve of the mean spectral power in (B) for the 0.25-1 Hz frequency range. Data represented by mean ± SEM. Statistical significance was determined using two-tailed unpaired Welch's t-test. The numerals in all bars indicate the number of analyzed slices and organoids (i.e. slices (organoids)).   