Chemotopic, combinatorial, and noncombinatorial odorant representations in the olfactory bulb revealed using a voltage-sensitive axon tracer - PubMed (original) (raw)

Top. Specific responses of glomeruli to pheromones and Sap. A, Voltage signals induced by two putative zebrafish pheromones, PGF and_17,20P-S_ (each at 1 μ

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), in a view of the whole OB. Each putative pheromone induced a single focus of activity (arrowheads). Scale bar, 200 μm. B, Fluorescence image of the ventral group of glomeruli labeled by Di8-ANEPPQ and activity induced by PGF (1 μ

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) and Sap (40 mg/l) in the same view.PGF and Sap each activated a single glomerulus (vmG and vtG2, respectively) within the ventral group. Note that activity is also visible in the innervating axon fascicles. In the lateral OB, part of which is visible at the_bottom_ of the images, activity was elicited by_Sap_ (see also Fig. 3) but not by PGF.C, D, Responses of ventral glomeruli to_PGF_ and Sap in different animals. The correlation between the anatomy of glomeruli and the distribution of signal is indicated by the false color images that are overlaid onto the fluorescence images of labeled glomeruli.False color images were thresholded at 0.0175% (resulting in the scale on the far right), made partially transparent, and merged with the anatomical images. The_top_ images are overlays of the images shown in B. The outlines of vmG and vtG2 are indicated by_red_ and blue dots, respectively.Large dots depict the outline of the glomeruli themselves; small dots depict the afferent axon fascicles. Downward arrowheads depict subcompartments of vmG (in the top image in C, only the anterior subcompartment was in focus). Color scales, −0.035% to 0.14%; the black lines indicate Δ_F_/F = 0. Scale bars:A–D, 50 μm. E, Time courses of fluorescence signals induced by PGF and_17,20P-S_ in A. Frame rate, 40 Hz.Region 1 covers the focal response to_PGF_, region 2 is the response to_17,20P-S_, and region 3 is a control region in which no signal was detected. The locations of these regions are shown as boxes in the insets.F, Time course of the response to PGF in_B_. Frame rate, 33 Hz. Region 1 covers vmG, which responds to PGF; regions 2–4_cover other glomeruli of the ventral group, which did not respond to_PGF. Stimulus onset was between 0.5 and 1 sec. See Table1 for abbreviations used.