Figure 11.

GABA current was potentiated by an epileptiform burst. A: Membrane potential of a hippocampal neuron in the presence of 4-aminopyridine (100 µM). Bursts of high frequency action potentials occur spontaneously. Data enclosed in the dashed box was used to create the stimulus waveform used in voltage-clamp experiments. B: Responses to GABA (1 or 10 µM) at a holding potential of −60 mV with and without epileptiform depolarization. Current amplitude was measured 0.2 and 2 s after the stimulus (see dashed lines in right panel) and compared to control currents at the same time points. C: Mean potentiation of GABA current by epileptiform depolarization at 0.2 s and 2 s after repolarization (n=4). D: Tonic current before and after epileptiform depolarization. Illustrated currents are the average of 3 trials from this cell recorded in presence of 0.3 µM exogenous GABA. E: Normalized tonic current amplitude from experiment in panel D. F: Mean potentiation of tonic current by epileptiform depolarization (n=7).