Differences in afterdischarge threshold determination methods: implications for experimental designs.

Hippocampal afterdischarge (AD) thresholds were determined twice using different threshold determination methods. Fourty-five days later thresholds were redetermined using each of the methods. Method A [3] produced higher AD thresholds which were less stable over time than were those produced using method B [4]. In addition, threshold level ADs produced using method A were of longer duration in the second phase of the experiment than in the first. No such changes were seen over time in the durations of method B ADs.