Sampled time series of membrane potentials under the effects of electromagnetic disturbance and autapse for fixed external forcing current , feedback gain coefficient k=0.5, autaptic conductance g=0.1, delay time τ =10.0 ms, noise intensity (a) D=0.04 and (b) D=0.2. Autapse is activated at t = 120 ms and electromagnetic disturbance is triggered at t = 500 ms.