Fig. 6.

Blockade of GABA(A) receptors suppresses GDPs and induces an epileptiform activity. A, Spontaneous GDPs are transformed into interictal-like epileptiform events after addition of the GABA(A) receptor antagonist bicuculline. Whole-cell recordings of a stratum radiatum interneuron (E109) in voltage-clamp mode (holding potential, −50 mV). Single GDP (*) and interictal-like events (**) are shown on an expanded time scale below. In current-clamp mode, the interictal-like event generates burst of action potentials (***, resting potential −72 mV). B, Charge–voltage relationships of GDPs and bicuculline-induced interictal-like events. Note that the charge–voltage curve of the epileptiform events reverses near 0 mV and displays a negative slope at hyperpolarized potentials, suggesting a contribution of AMPA and NMDA receptors. C,Microphotograph of the recorded biocytin-labeled CA1 stratum radiatum interneuron.