Figure 1

Experimental design. (A) To transfect cortical neurons, EUE was performed: a DNA solution (green) was injected into the ventricular system of an embryonic day 14.5 mouse brain (left), current was applied across the head (middle), and cells of the ventricular zone (VZ) transfected (right). The dorsal telencephalon was then dissected and cortical cells were dissociated and plated under conditions that promote neuronal differentiation, either into MEA chambers to monitor neural activity (top) or onto coverslips for morphological analyses (bottom). (B) MEA chambers contain an 8 × 8 grid of electrodes. (C) Transfected neurons plated into MEA chambers were visible within 24 hours of EUE. (D) Spontaneous activity arising from the developing cortical network was recorded from each electrode. (E) In culture, cortical cells differentiate and forge elaborate connections. (F-H) Dendritic spines from the second dendritic branch (F) of transfected neurons were imaged (G) and their shape was characterized according to the scheme shown (H), modified from Irwin et al. [55].