Step-through passive-avoidance task

The step-through passive-avoidance test, referring to natural aversion of rodents to lighted places, was used as a measure of long-term memory. The task was previously outlined in detail by Borowicz et al. [14]. In the present study, however, a manual, but fully automated apparatus was used with specific hardware and software features [Multi Conditioning System (MCS), TSE Systems GmbH, Bad-Homburg, Germany]. The MCS software features are compliant with the Good Laboratory Practice. The apparatus allows entire isolation of animals from external stimuli that may interfere with their behavior. Therefore, the test results are more reliable when compared to the manual method. Thanks to a camera placed inside the chamber, MCS enables continuous observation of the animal's behavior on the monitor. A punishing electrical stimulus (0.3 mA for 2 s) was triggered in the dark compartment by rods in a greed floor.

Like in the chimney test, the antiepileptic drugs were applied alone at their ED₅₀s or in combinations with sotalol (100 mg/kg). The results were presented as medians (with 25 and 75 percentiles) of time needed by animals to enter the dark box. Control animals (remembering an aversive electrical stimulus) did not enter the dark compartment within 180 s.