<p>(A), recording of resting membrane potential, showing spontaneous action potential firing at 18.1 Hz. Right panel: a single action potential on an expanded time scale, with dashed cursor lines indicating method of measuring amplitude (between top and bottom horizontal cursors: 65.3 mV) and duration at ½ maximal amplitude (between vertical cursors: 1.10 ms). (B), superimposed records of membrane potential showing response to successive 200 ms hyperpolarizing pulses of current (not shown) injected in multiples of 0.2 nA from baseline of zero (ie. resting potential). (C), voltage-current plot derived from a series of current pulses injected in multiples of 0.1 nA into the same cell [including those in (B)] in which steady-state voltage attained near end of current pulse [dashed vertical line in (B)] is plotted. Slope of line (best fit in range −55 to −75 mV) yields input resistance value of 45 MΩ. All records from the same cell.</p
