Insulin intranasal delivery (IND) changes basal firing behavior and leads to a reduced spike frequency following acute insulin stimulation.

<p>Representative basal action potential activity and the associated raster plot generated in response to an 8 day insulin IND (Control) and following subsequent, acute insulin stimulation over time (Insulin 20, Insulin 40). Two different patterns of basal action potential firing behavior were observed following insulin IND, (A) Type I and (B) Type II, as reported in the text. Time notations and raster plot generation as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0024921#pone-0024921-g003" target="_blank">Figure 3</a>. Evoked activity was elicited using a 5 s long perithreshold current injection of 50 pA while recording near the natural resting potential of-63 mV. See also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0024921#pone-0024921-t003" target="_blank">Table 3</a>.