Distinct Instantaneous Firing Rate (IFR) distributions in PNs and ENs.

<p>(<b>A</b>) Examples of three typical PN-units (columns). Each column includes the dot displays for the different odors consisting of 10 repetitions (trials) were each dot corresponds to one action potential. At the very bottom of each column the mean IFR is shown (grey = 1-hexanol, green = 2-octanone, black = mixture). Odor stimulation is marked in grey. (<b>B</b>) Same as in (A), but for three typical EN-units. Both, PN- and EN-units show on and off responses, which were relatively sharp in the EN-units. In addition a tonic component appears to be very prominent in the PN-unit responses (A). (<b>C</b>) IFR distribution functions (IFRs) of all PN-unit's (N = 111) and all EN-units (N = 75) broken down by odor (color code same as in A). In both, PN-units and EN-units IFRs were significantly different (Wilcoxon rank sum test: p<0.001) for all odors. (<b>D</b>) Averaged across odors the mean IFRs clearly separate the recorded PN-ensemble from the recorded EN-ensemble (Wilcoxon rank sum test: p<0.001). Note, the IFRs of the PNs were dominated by the stimulus outlasting tonic response component, whereas EN IFRs reflecting the phasic activity around stimulus on- and off- set.