Figure 1.

In vivo intracellular recording reveals odor-evoked subthreshold and suprathreshold activity of AON neurons. A, Membrane potential response of a typical AON neuron to injected current pulses. The resting membrane potential of this AON neuron was −75 mV without current injection. The injected current pulses were +0.25 and −0.30 nA, respectively. Calibration: 20 mV, 100 ms. B, Verification of the recording site in C. Left, A schematic diagram of a coronal section of a mouse brain. D, Dorsal; V, ventral; AOD, dorsal AON; AOL, lateral AON; AOM, medial AON; AOV, ventral AON. Right, The morphology of the AON neuron recorded in C, as revealed by intracellular neurobiotin staining (cell body location depicted by inverted triangle in the left panel). Scale bars: left, 500 μm; right, 100 μm. C, Odor-evoked responses in a typical AON neuron. The top panel shows the intracellular recording trace and respiration activity trace. Calibration: 20 mV, 1 s. The raster plots and poststimulus time histogram in the middle panel show consistent suprathreshold responses. The bottom panel shows the averaged net membrane potential change. During odor presentation (2 s; indicated by the black bar), the cell is strongly excited, as revealed by both an increase in the firing rate and a depolarization of membrane potential, both of which are in phase with the respiratory rhythm (n = 6).