Evoked activity in WT and KO OSNs. (A and B) Representative responses to 100 µM IBMX stimulation (50 ms) for two different OSNs from WT (A) and KO mice (B). Data represent loose-patch recordings from dendritic knobs of OSNs located in the septum. The bottom panels show the regions enclosed by the dashed boxes on an expanded time scale. Broken red lines represent the onset of IBMX stimulation, and the red bars in the bottom panels its duration. (C and D) Raster plots on an enlarged time scale for the same cells shown in A and B. (E) Averaged responses to IBMX as in A and B, normalized to the number of neurons (n = 9 from 7 WT mice, n = 15 from 8 KO mice; bin 300 ms). The broken red line represents the onset of stimulation, and data belong to WT and KO PSTH distributions. *, 0.01 < P < 0.05; and **, P < 0.01. (F–H) Scatter and boxplots of ISI of the first four spikes (F; 47 ± 21 ms in WT, 47 ± 21 ms in KO), of the total number of spikes (G; 14 ± 13 spike/response in WT, 21 ± 18 spike/response in KO), and of the response duration (H; 1.1 ± 1.8 s in WT, 1.5 ± 1.4 s in KO; mean ± SD). In the box plots the squares represent the mean, lines represent the median, upper and lower box boundaries represent the 25th and 75th percentile, and upper and lower whiskers represent the 5th and 95th percentiles. Data were not statistically different (one-tail t test for data in F; Mann-Whitney U test, one tail, P > 0.05 for data in G and H). The number of experiments is indicated in parentheses.