HCN channels are open persistently.

<p>(<b>A</b>) An example of the effect of HCN channels blocker ZD7288 (20 µM) on neuronal excitability (left) and post-burst AHP (right). The protocols for excitability test and post-burst AHP recording were run alternately every 30 seconds. (<b>B</b>) Excitability before and during 15-min application of ZD7288 (left). Group histograms showing that ZD7288 enhances the neuronal excitability of mPFC neurons (right) (*p<0.05 for ZD7288 vs. baseline, paired <i>t-</i>test). (<b>C</b>) Input resistance before and during 15-min application of ZD7288 (left). In set, the representative voltage responses upon hyperpolarizing current injection (30 pA) in baseline and ZD7288 application. Group histograms showing that ZD7288 enlarges the input resistance significantly (*p<0.05 for ZD7288 vs. baseline, paired <i>t-</i>test), DA or SKF 81297 application respectively does not change the input resistance anymore in the presence of ZD7288 (right) (p>0.05 for DA+ZD7288 vs. ZD7288; p>0.05 for SKF 81297+ZD7288 vs. ZD7288, one way ANOVA). (<b>D</b>) Amplitude of post-burst AHP before and during 15-min application of ZD7288 (left). Group histograms showing that ZD7288 does not change the amplitude of post-burst AHP (right) (p>0.05 for ZD7288 vs. baseline, paired <i>t-</i>test). (<b>E</b>) Decay time of post-burst AHP before and during 15-min application of ZD7288 (left). Group histograms showing that ZD7288 prolongs the decay time of post-burst AHP (right) (*p<0.05 for ZD7288 vs. baseline, paired <i>t-</i>test).