FIG. 6.

Intrinsic membrane excitability of excitatory neurons is increased in Fmr1 KO mice. A: traces from excitatory neurons obtained from 4-wk-old animals showing that for a 50-pA current step, Fmr1 KO cells fire more action potentials. Scale bars: 20 mV, 200 ms. B: average data from 2- and 4-wk data groups showing that more APs occurred for each current step examined. C: in 4 wk cells, the minimum current required to evoke an action potential (threshold current) was decreased in Fmr1 KO mice. D: the increase in membrane excitability may partly be due to an increase in input resistance in Fmr1 KO cells. *P < 0.04. **P < 0.004.