Insulin decreases the interspike interval (ISI) and cluster pause duration of mitral cell action potential activity.

<p>(A) (left) Line plot of the mean ISI in response to various somatic current injections as indicated, applied for a 1000 ms duration. Same notation, sample size, and statistical design as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0024921#pone-0024921-g001" target="_blank">Figure 1</a> except time point used for calculations was 15 minutes of insulin stimulation. (right) Histogram distributions of the interspike interval (ISI) for a representative neuron prior (Control) and following insulin stimulation taken at both the 15 and 90 minute time points (Insulin,15 min; Insulin, 90 min). Shown are three different current steps (100–300 pA). Plots were fit by Gaussian functions (solid red lines) to determine mean ISI as reported in panel A. * = Significantly different by blocked factorial ANOVA with Student Newman Kuels (<i>snk</i>) followup test, α ≤0.05. (B) (left) Frequency distribution plot of the pause duration between spike clusters for a neuron prior (Control, black bars) and following insulin stimulation (Insulin, red bars) taken at the 15 minute time point. (right) The neuron was stimulated using a 10 pA perithreshold current injection of 5000 ms duration, while recording near the natural resting potential of -64 mV. A pause was defined as a lack of spike activity for greater than 100 ms, while a cluster was defined as a minimum of 3 or more action potentials, but more typically 10 to 30.