Figure 8. Pharmacological characterization of 4AP-induced activity in isolated subicular minislices.

Aa, simulatneous field (middle subiculum, distal subiculum) and intracellular (middle subiculum, −66 mV) recordings during control (4AP) conditions reveals that the slow interictal events correspond intracellularly to an early hyperpolarization followed by a sustained depolarization (left inset). In the presence of picrotoxin there is increased field activity in the isolated subiculum and robust network bursting can be recorded intracellularly (right inset). Ab, firing properties of this cell reveals that it was an intrinsically bursting neurone. Ac, intracellular traces of the 4AP-induced event at different membrane potentials reveals reversal of the hyperpolarizing component at negative membrane potentials (−73 mV and −76 mV). Note the truncated action potential riding on this reversed event at −76 mV. Ba, simulatneous field (middle subiculum, proximal subiculum) and intracellular (middle subiculum, −60 mV and −67 mV) recordings in control (4AP) and after 2 h of further CPP + CNQX application. Note that intracellular recordings were carried out from two different cells within the same slice and in the same subicular region. Insets demonstrate expansions of the slow synchronouns event during both conditions.