Neurons were infected with the Prox1∷eGFP lentiviral vector at 8 days differentiation. Neurons on glass coverslips were transferred to a recording chamber in a standard recording medium containing (in mM): 10 HEPES, 4 KCl, 2 CaCl2,1 MgCl2, 139 NaCl, 10 D-glucose (310 mOsm, pH 7.4). Whole-cell patch-clamp recordings were performed from Prox1∷eGFP highlighted DG-like neurons (the neurons patched were typically the larger cells, with the bright Prox1∷eGFP expression), usually after 20–30 days of differentiation and in a range of 10–45 days of differentiation. Patch electrodes were filled with internal solutions containing (in mM): 130 K-gluconate, 6 KCl, 4 NaCl, 10 Na-HEPES, 0.2 K-EGTA, 0.3 GTP, 2 Mg-ATP, 0.2 cAMP, 10 D-glucose, 0.15% biocytin and 0.06% rhodamine. The pH and osmolarity of the internal solution were brought close to physiological conditions (pH 7.3, 290–300 mOsm) (pipette tip resistance was typically 10–15 MΩ). Signals were amplified with a Multiclamp700B amplifier (Sunnyvale, CA, USA) and recorded with Clampex 10.2 software (Axon Instruments, Union City, CA, USA). Data were acquired at a sampling rate of 20 kHz and analyzed using Clampfit-10 and the software package MATLAB (release 2014b; The MathWorks, Natick, MA, USA). All measurements were conducted at room temperature.
