Fig. 1

a Scheme of micrograting (GR) substrates: the pattern has 1-μm ridge (R) and 1-μm groove (G) lines (lateral period = 2 μm; T2) and GR depth (d) = 500 nm. b Scanning electron microscopy image of thermoplastic GRs (scale bar = 1 μm). c Scheme of axon/dendrite tracings for 2 neurons: axon = white continuous line, starting from cell soma; dendrites = dotted red lines; the alignment of each neurite was calculated as the alignment angle α between each neuritic trace (here outlined only for axons such as example) and the underlying GR direction (showed as inset, side 50 μm). d–g Representative confocal images of WT (d), AS (e), WT+UBE3A (f), and AS+UBE3A (g) HNs. WT and AS neurons were cultured on GRs, transfected (at early DIV2) with empty-Tomato vector (d–e) or with UBE3A 2/3-Tomato vector (f–g) (WT+UBE3A, model of UBE3A overexpression) and immunostained for axonal marker (SMI312, green) and dendrite marker (MAP2, red) (at DIV4); the asterisk indicates axons; the underlying GR pattern is reported as inset (scale bars = 50 μm)