Revealing tonic inhibitory currents in lamina II neurons of adult mice. A). Traces on the left side show sIPSCs recorded in normal bath solution (control), following the applications of either 2 μM strychnine (Stry) or 20 μM bicuculline (Bic). Traces on the right side are the average of 100 sIPSCs. τ is time constant for averaged trace. B). Sample trace (top panel) shows the shift of baseline holding current following the application of 20 μM bicuculline. The lower traces show at an expanded scale the baselines before and during bicuculline application as well after wash off bicuculline. C). Sample trace shows that application of strychnine (2 μM) inhibited some sISPCs but did not affect baseline holding current. D). Bar graph shows pooled results of baseline shift following the application of either 20 μM bicuculline (n = 30) or 2 μM strychnine (n = 6). Bicuculline or strychnine was applied for 3 min in each experiment.