Electrophysiological recordings were performed to test functionality and maturity of hiPSC-derived cortical neurons in co-cultures treated with DAPT. Whole-cell patch clamp recordings showed a gradual maturation of single cells within the network over time (Fig. 2d), as evident by a more negative resting membrane potential (p = 0.0113). In support of the progressive maturation, an increase in rheobase was observed37 (i.e. the minimal current sufficient to induce an action potential) at the second and third week after final plating (p = 0.0112). The number of neurons firing action potentials (wk1: 52%, wk2: 55%, wk3: 64%, wk4–5: 100% of all neurons recorded) and the respective firing frequency also increased over time (p = 0.0187) confirming maturation of cortical neurons37.
