Experimental Neurology   2016 年 280 卷

2016.06.01

Neuroadaptations and alterations in neuronal excitability are critical in brain maturation and many neurological diseases. Fragile X syndrome (FXS) is a pervasive neurodevelopmental disorder characterized by extensive synaptic and circuit dysfunction. It is still unclear about the alterations in intrinsic excitability of individual neurons and their link to hyperexcitable circuitry. In this study, whole cell patch-clamp recordings were employed to characterize the membrane and firing properties of layer IV cells in slices of the somatosensory cortex of Fmr-1 knockout (KO) mice. These cells generally exhibited a regular spiking (RS) pattern, while there were significant increases in the number of cells that adopted intrinsic bursting (IB) compared with age-matched wild type (WT) cells. The cells subgrouped according to their firing patterns and maturation differed significantly in membrane and discharge properties between KO and WT. The changes in the intrinsic properties were consistent with highly facilitated discharges in KO cells induced by current injection. Spontaneous activities of RS neurons driven by local network were also increased in the KO cells, especially in neonate groups. Under an epileptiform condition mimicked by omission of Mg