Figure 4.

Activity deprivation triggered hyperexcitability in multi-spiking Fmr1 KO neurons. Activity deprivation led to exaggerated HIP in multi-spiking Fmr1 KO neurons, which resulted in a hyperexcitable phenotype compared with treated WT neurons. The excitability changes correlated with changes in the action potential waveform, which were changed to a greater extent in the Fmr1 KO. We hypothesize that increased phosphorylation of Nav channels contributes to exaggerated expression of HIP in Fmr1 KO neurons.