Calcium dependent hyperexcitability in human stem cell derived Rett syndrome neuronal networks

•Reverberating super-bursts (RSBs) follow a stereotypic form of a large initial network burst followed by several smaller amplitude high-frequency mini-bursts.•RSBs occur more often in MECP2 null excitatory networks.•MECP2 null excitatory networks with increased RSBs show a hyperexcitable network burst phenotype relative to isogenic controls.•The calcium chelator, EGTA-AM, decreases RSBs and rescues the dynamics of MECP2 null hyperexcitable networks.