Slices used for whole-cell recordings were prepared as previously described23,56. Briefly, slices were placed in a submerged recording chamber and continuously perfused at 2–3 ml/min with oxygenated (95% O2/5% CO2) ACSF at 32°C. Whole-cell recordings were made with 3–5 MΩ recording pipettes filled with solution of the following composition (in mM): 130 K-gluconate, 0.1 EGTA, 0.5 MgCl2, 10 HEPES, 2 ATP (pH 7.25, 285 mosM) using an Axopatch 200A amplifier (Molecular Devices). Miniature excitatory postsynaptic currents (mEPSCs) were recorded at a holding potential of −70 mV in the presence of tetrodotoxin (1 μM) and bicuculline (50 μM). Data were filtered at 2 kHz, digitized at 1–5 kHz, stored on a computer, and analyzed off-line using Mini Analysis Program (Synaptosoft), Origin (OriginLab), and pCLAMP 7 (Molecular Devices) software.
