Mice primary hippocampal neuronal cultures were prepared as previously described by others 57 (link). Except when otherwise indicated, all reagents were from Gibco. Briefly, hippocampi were dissected from P2 mouse pups in cold Hanks’ balanced salt solution (HBSS) supplemented with 0.08% D-glucose (Sigma-Aldrich), 0.17% Hepes, and 1% penicillin-streptomycin (Pen-Strep); filter-sterilized; and adjusted to pH 7.3. After dissection, the hippocampi were washed twice with cold HBSS and individually incubated at 37°C for 20 min in papain dissociation solution (45 U of papain (Worthington), 0.01% deoxyribonuclease (DNase), 1 mg of DL-cysteine, 1 mg of bovine serum albumin (BSA) and 25 mg of D-glucose (all from Sigma-Aldrich) in phosphate-buffered saline (PBS). After digestion, the hippocampi were washed twice with DMEM preheated to 37°C and supplemented with 10% FBS and dissociated by 10 cycles of aspiration through a micropipette tip. Dissociated neurons were then resuspended in warm DMEM supplemented with 10% FBS and plated in 6-well plates containing 25-mm sonicated glass coverslips pretreated with 50 μg/ml poly-L-lysine (PLL, Sigma-Aldrich). After 1 hour, the medium was replaced with Neurobasal-A medium, which was supplemented with 2% B-27 and 0.25% GlutaMAX (neuronal medium). Primary neurons were maintained in a standard tissue culture incubator at 37°C with 5.5% CO2.