Patch-Clamp Slice Electrophysiology.

Electrophysiological recordings were performed in the whole-cell patch-clamp configuration (Reddy and Jian, 2010; Wu et al., 2013). Hippocampal slices (300 µm) were maintained in continuously oxygenated aCSF at 32°C in a holding chamber for 60 minutes, and then recordings were made at room temperature. Hippocampal DGGCs were visually identified with an Olympus BX51 microscope equipped with a ×40 water-immersion objective, infrared-differential interference contrast optics, and video camera. Physiologic bath solution for the slices comprised 124 mM NaCl, 3 mM KCl, 1.5 mM MgSO₄, 2.4 mM CaCl₂, 1.25 mM NaH₂PO₄, 26 mM NaHCO₃, and 10 mM glucose (pH adjusted to 7.4 with NaOH; osmolarity, 295–305 mOsm/kg). The recording pipette tip resistances were 4–6 MΩ for slice recordings and were filled with a cesium pipette solution containing 124 mM CsCl, 20 mM tetraethylammonium-chloride, 2 mM MgCl₂, 10 mM EGTA, 10 mM HEPES, 0.1 mM GTP, 4 mM ATP, and 5 mM lidocaine QX-314 [N-(2,6-dimethylphenylcarbamoylmethyl)triethylammonium bromide] (pH adjusted to 7.2 with CsOH; osmolarity, 295–305mOsm/kg). The current values were normalized to cell capacitance (pA/pF, as an index of current density).