Figure 3.

Pyramidal cells still receive functional inhibition during paroxysmal discharges in TLE. (A) A pyramidal neuron (KA model) was recorded in the whole cell configuration and voltage clamped (Cs-gluconate). Stimulation of stratum radiatum evoked a large glutamatergic current at the reversal potential of GABA_A receptor-mediated currents (−60 mV) and a large GABAergic one at the reversal potential of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/N-methyl-d-aspartate receptor-mediated currents (0 mV). Biphasic currents were measured between these potentials. Application of CNQX (10 μM) and D-APV (50 μM) disclosed isolated IPSCs that reversed at −60 mV. Note the presence of spontaneous IPSCs. (B) Spontaneous paroxysmal discharges recorded (same protocol as in A) in a pyramidal cell of a pilocarpine rat. Note the large GABAergic current at +20 mV and the biphasic pattern at −40 mV. (C) Bicuculline treatment increased the duration of evoked epileptiform discharges in a KA pyramidal cell recorded in the cell attached configuration.