Field excitatory postsynaptic potentials (fEPSPs)
recordings
Acute hippocampal slices were individually transferred into a submerged
recording chamber over the nylon mesh and continually superfused with
gassed aCSF solution at a constant flow (3 mL/min) and temperature (32
°C). Stimulation (rectangular 0.1 ms pulses, once every 15 seconds, S48
Square Pulse Stimulator, Grass Instruments) was delivered through a
concentric bipolar electrode placed on Schaffer collateral-commissural
fibbers, in the stratum radiatum near the CA3-CA1 border. The
stimulus intensity was set to elicit nearly 50% of the maximal response
and was maintained throughout the experiment. fEPSPs were recorded
through a microelectrode (2–6 MΩ resistance, filled with aCSF), placed
in CA1 stratum radiatum , coupled to an Axoclamp 2B amplifier
(Axon Instruments) and digitized BNC-2110 (National Instruments).
Individual responses were monitored, and averages of 8 consecutive
responses were continuously stored on a personal computer with the
WinLTP software (Anderson and Collingridge, 2007). Test drugs were added
to the superfusing aCSF after obtaining a stable baseline of recordings
for at least 15 minutes.