For direct contact cultures, 18 mm Menzel glass coverslips were fitted into 12 wells after alcohol sterilization and then coated by spraying with PDL-collagen-acetic acid-mix (1:1:3); PDL (0.5 mg/ ml; Sigma), collagen (3.66 mg/ ml; Corning), acetic acid (17 mM; VWR) then air dried and UV sterilized for 20 minutes. For indirect contact cultures, 12 well plates were picked with a hot needle to make little bumps in four corners of each well, and then sterilized in UV light for 20 minutes. Primary astrocytes cultured from P0 pups of pregnant female Wistar rats (From Harlan) were passaged once and frozen. When required for co-cultures, the frozen astrocytes were plated on the coated coverslips or in indirect contact wells at a density of 25k cells per 3.8 cm2. Astrocytes were let to grow confluent in astrocytes medium (DMEM with Glutamax (Gibco, 31966–021), 10% FCS, NEAA (100x, Sigma, M7145), Pen/strep (100x)) for about 5–6 days. At this point (day 7 of the astrocytes), neurons were plated directly on astrocyte coverslips for direct contact mode. For indirect contact mode, neurons were plated on
