FMR1 and fragile X syndrome: On the other hand, analyzing calcium traces extracted from the SLOW population, likely ascribable to glial cells and differentiating neuronal cells, we found that FMRP-KO cells displayed spontaneous calcium events characterized by higher amplitude (Fig. 5F left) but similar frequency (Fig. 5F middle and right) and synchronization with respect to FMRP-WT cells, suggesting that also the astrocytic network is more active in FXS cortical cultures.