Figure 3.
Local increase of newborn cell survival after olfactory discrimination learning. A, B, Quantification of BrdU+ and Zif268+ cell distributions, through angular sectors of coronal sections, in the GL and GCL. A, A representative image showing the distinct layers and the medial position of the MOR23 glomerulus. GFP+ glomeruli were stained by immunohistochemistry with an anti-GFP antibody and VIP substrate as a chromogen (asterisk). B, The position of the MOR23 glomerulus was used to define the MOR23 axis (red dotted line) and all subsequent angular sectors. The defined sectors were grouped into four areas related to their location in the OB: lateral (sectors 12, 1, and 2), dorsal (sectors 3, 4, and 5), medial (sectors 6, 7, and 8), and ventral (sectors 9, 10, and 11). C, D, BrdU+ cell density in the GL (A) and GCL (B) after training. Values were normalized with respect to controls perfused 30 d after BrdU injections. Discrimination learning significantly increased the total density of BrdU+ cells when compared with unpaired and control animals in the GCL and with controls in the GL. *p < 0.05 and ##p < 0.01 with Fisher's PLSD test after ANOVA (n = 9–15). E, Distribution of normalized BrdU+ cell density throughout all angular sectors after discrimination training in GCL. *p < 0.05; ***p < 0.001 with Fisher's PLSD test after r-mANOVA. F, Distribution of normalized sensory inputs driven by odorant cues. Spatial distribution of normalized Zif268+ cells throughout the radial axis of coronal OB sections after lyral (pure) or acetophenone (10−3) exposure. *p < 0.05 between two odorants with Fisher's PLSD test after r-mANOVA. G, H, Survival of newborn neurons was highest where odor activation maps differed most. G, Color-coded representations showing learning-induced survival maps throughout MOR23-containing sections (supplemental methods and Fig. 4, available at www.jneurosci.org as supplemental material). H, A representation similar to that in G showing the acetophenone-specific activation map. EPL, External plexiform layer; L, lateral; D, dorsal; M, medial; V, ventral. Scale bar, 200 μm. Error bars indicate SE.