Figure 1. MOB Photostimulation Drives Robust M/T Firing In Vivo.

(A) Extracellular recording of M/T action potential firing produced by uncaging (black), generated between resting activity coupled to respiration (gray; triangles show inspiration). Vertical line indicates uncaging pulse.

(B) Uncaging reliably produces high-frequency M/T firing (left, blue) comparable to robust odor responses (right, gray). Top, raw traces from a single trial (uncaging) or respiratory cycle (odors). Middle, rasters from successive trials or inhalations. Bottom, PSTH of mean spike count in 10 ms bins.

(C) Cumulative plot of latency to first photostimulated M/T spikes. Firing occurs with high efficacy and at short latency (>90% of M/Ts, horizontal dashed line; median latency ~5 ms).

(D) Comparison of peak M/T firing rates for uncaging (blue) and odorants (gray). Data show most effective uncaging sites or odorants for each neuron.

(E) Image of the OR map in the dorsal MOB from a mouse line with fluorescently labeling of axon terminals of sensory neurons. Arrowheads denote individual glomeruli. Scale bar, 200 μm.

(F) Map of spike output from a single M/T generated by in vivo scanning photostimulation of the dorsal MOB. Color indicates the mean spike count at each location; dots indicate ineffective sites (100 ms analysis window). Pipette shows recording location in the M/T layer. Scale bar, 200 μm. See also Figure S1.