MAPT and frontotemporal dementia: Recently, another FTD-causing tau mutation (V337M) was reported to impair activity-dependent plasticity of the cytoskeleton in the axon initial segment (AIS), and extracellular recordings by multielectrode arrays (MEAs) revealed that the V337M tau mutation in human neurons led to an abnormal increase in neuronal activity in response to chronic depolarization (Sohn et al., 2019).