Transient transfection was accomplished by using half of the manufacturer’s recommended amount of DNA (2 μg per 35 mm dish or 0.4 μg per 12 mm coverslip in 24-well dish) and Lipofectamine 2000 (5 μl per 35 mm

dish or 1 μl per 12 mm coverslip; Invitrogen, NY). Microelectrode recordings were performed in a perfused chamber with the bath temperature kept at 33°C–35°C by a temperature controller. The bath solution contained 150 mM NaCl, 4 mM KCl, 2 mM CaCl2, 1 mM MgCl2, 5 mM D-glucose, and 5 mM HEPES, pH 7.4. We used 3–5 MΩ glass patch pipettes (capillary tubing with 1.5/0.75 mm OD/ID-World Precision Instruments, FL) that were pulled on a P-97 Flaming/Brown type micropipette puller (Sutter Instrument Company, CA). The pipette solution contained 120 mM K-aspartate, 4 mM NaCl, 4 mM MgCl2, 1 mM check details CaCl2, 10 mM EGTA, 3 mM Na2ATP, and 5 mM HEPES, pH 7.2. Voltage-clamp recordings in the whole-cell IWR-1 in vitro configuration were performed using a Patch Clamp PC-505B amplifier (Warner Instruments, CT) with a holding potential of −70mV. Spontaneous activity of cultured hippocampal neurons

was recorded in current clamp mode without holding current injection. For stimulation experiments, action potentials were evoked by a 2 ms current injection. The pipette solution for neuron recordings contained 120 mM K-gluconate, 3 mM KCl, 7 mM NaCl, 4 mM Mg-ATP, 0.3 mM Na-GTP, 20 mM HEPES, and 14 mM Tris-phosphocreatin (pH adjusted with KOH to pH 7.3) (Popovic et al., 2011). Whole-cell patch-clamped cells were imaged either with a Nikon Eclipse E6000FN upright microscope with a water immersion objective, Nikon Rolziracetam Fluor 60×/1.00 N.A., or with a Nikon Eclipse TE300 inverted microscope with a 60×/1.40 N.A. oil immersion objective lens (Nikon, NY). For data collected with a 150 W Xenon arc lamp (Opti Quip, NY), we used two filter sets either an excitation filter HQ480/30X, a dichroic mirror 505DCXR and an emission filter HQ510LP (Chroma, Bellows Falls, VT) or GFP-3035B filter cube with an excitation filter 472/30 nm, dichroic mirror

495 nm, and emission filter 520/35 nm (Semrock, Rochester, NY). For data recorded with laser illumination, either a MLL-III-473 nm 50 mW or a MLL-FN-473 nm 50 mW (Changchun New Industries Optoelectronics Tech. Co., China) was used. The laser light was transmitted into the microscope by a multimode fiber coupler (Siskiyou, OR), a quartz light guide, and an Achromatic EPI-Fluorescence Condenser (Till Photonics, NY). For laser illumination, the excitation filter was removed from the filter cube. The fluorescence image was demagnified by an Optem zoom system, A45699 (Qioptiq LINOS Inc, NY), and projected onto the 80 × 80 pixel chip of a NeuroCCD-SM camera controlled by NeuroPlex software (RedShirtImaging, GA). The images were recorded at a frame rate of 1000 fps for HEK293 cells and at 2000 fps for neuron measurements. When we used laser excitation the recordings were from single trials.