FMR1 and fragile X syndrome: While numerous ex vivo studies have found evidence for hyperexcitability in the somatosensory cortex of FMR1 KO animals (see Section “Hyperexcitable Neurons and Networks in Fragile X Syndrome”), no differences in overall whisker-evoked activity were seen in FMR1 KO mice in this study, as assessed by two-photon Ca2+ imaging of layer 2/3 neurons (He et al., 2017).