Fig. 1. The activity of α⁵-containing γ-aminobutyric acid subtype A receptors does not modify long-term potentiation (LTP) evoked by high frequency stimulation but mediates etomidate-induced LTP impairment. (  A ) L-655,708 does not potentiate LTP above control levels. This suggests minimal involvement for α⁵-containing γ-aminobutyric acid subtype A receptors in theta burst stimulation (TBS) LTP. (  B ) Input–output curves before and after TBS in the presence and absence of L-655,708. There were no differences between vehicle-treated and L-655,708-treated slices, although excitability increased after TBS in both groups. (  C ) Etomidate blocked LTP, and this effect was reversed by applying both L-655,708 and etomidate. (  D ) Input–output curves before and after TBS with etomidate application in the presence and absence of L-655,708. There were no differences between vehicle-treated and L-655,708-treated slices. Raw traces presented above the LTP plots represent the no-drug baseline field excitatory postsynaptic potential (fEPSP) and drug baseline fEPSP (1 and 2) and the drug post-TBS fEPSP.  3 Calibration bars : 0.5 mV, 10 ms .