Figure 6. Field and intracellular recordings in functionally disconnected slice.

Aa, simulatneous field (EC, CA3) and intracellular (subiculum, −60 mV) recordings during control (4AP) conditions reveals that this subicular cell is ‘silent’ at RMP. Note the presence of PSPs that are coincident with CA3 discharges (arrows) and the large isolated inhibitory postsynaptic potentials (IPSPs) (Control (4AP), asterisk). Superfusion of slices with picrotoxin discloses in these cells action potential discharges at RMP (Picrotoxin). Monitoring the evolution in the intracellular activity of these subicular neurones from the initial application of the GABA_A receptor antagonist (Picrotoxin (transition)) until the complete synchronization between hippocampal and parahippocampal structures (Picrotoxin (late)) reveals IPSP disappearance. Insets below traces demonstrate expansions of selected events. Note the presence of large IPSPs (asterisk) and smaller PSPs (arrows) within the subiculum prior to complete synchronization of limbic structures. Ab, firing properties of this cell reveal a non-bursting neurone.