(color online) Phase portraits on the different phase planes for fixed external forcing current , feedback gain coefficient k=0.5, autaptic conductance g=0.1, delay time τ =10.0 ms, and noise density D=0.04, where (a) V − m, (b) V − h, (c) V − n, and (d) . The solution orbit is calculated from t = 1000 ms to t = 3000 ms when autapse is activated at t = 120 ms and electromagnetic disturbance is triggered at t = 500 ms.