Video 12.3b Exogenous Rhythm. The electrode enters around cell 28. Resting potential is −50 to −60 mV, with 10 mV afterhyperpolarization. After an initial rapid volley of action potentials (common when a cell is penetrated), this neuron settles into a pattern of slow bursts with gentle oscillation of the resting potential. Many postsynaptic potentials of varying sizes occur. The bursting pattern is probably driven by synaptic input, and the burst frequency and duty cycle change over time.