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. Author manuscript; available in PMC: 2016 Apr 1.
Published in final edited form as: J Comput Neurosci. 2014 Dec 20;38(2):263–283. doi: 10.1007/s10827-014-0541-5

Figure 1. Input resistance and AP firing rates are significantly greater in the aged neurons.

Figure 1

a) Top: voltage responses to 200 ms injected subthreshold current steps from representative young and old neurons. Scale bar: 10 mV and 40 ms. Bottom: voltage response vs. current step plots for the data shown above. Input resistance is calculated as the slope of the linear portion of the IV-relation, illustrated by the solid region of the best-fit lines shown. b) Trains of APs evoked by 2-s depolarizing current steps for representative young and aged neurons. Scale bar: 25 mV and 650 ms. Current steps were applied from a holding potential of −70 mV, shown as arrows in (a) and (b). c) Frequency-current plot demonstrating significantly increased mean frequency of AP firing evoked at each depolarizing current step for aged neurons (p < 0.05). d) AP firing rate in response to 2-s +230 pA current step versus input resistance of young and aged neurons. These responses were not assessed in one of the aged neurons, so only five aged neurons are shown in the graph.