Figure 1  Odor Learning and Discrimination Is Enhanced in GluR-BΔECS:FB Mice
(A) Schematic diagram depicting Cre-mediated activation of GluR-B(Q) by removing the loxP-flanked TK-neo (TK-neo pA, GluR-Bneo) element in intron 11, which is acting as a suppressor in expression from the Q/R site editing deficient GluR-Bneo allele. Exon 10 and 11 encode membrane-spanning segments 1, 2, and 3 (M1, 2, 3) of the GluR-B subunit. The intronic element necessary for editing the Q/R site is shown for the wild-type allele (+).
(B) Scheme of an individual trial. Breaking a light barrier, the mouse initiates a trial. An odor is presented, and (depending on the odor denotation and the mouse's response) the mouse is rewarded or retracts its head. A small (2- to 4-μl) water reward is given at the end of an S+ odor if the mouse continuously licks at the delivery tube during the 2-s trial. A trial is counted as correct if the mouse licks continuously upon presentation of a rewarded (S+) odor or does not lick continuously with a nonrewarded (S−) odor [3].
(C) Twelve experimentally naïve animals (six GluR-BΔECS:FB [orange] and six GluR-B+/+ littermate controls [black]) were trained on 1% AA versus 1% EB for two tasks of 200 trials each. Both groups acquired the task (> 70% correct); however, the GluR-BΔECS:FB were both quicker, and performed better overall, than the littermate controls (group effect: F(1,10 ) = 10.2; p < 0.01). AA, amylacetate; EB, ethylbutyrate.
(D) Average head position for one mouse and 50 presentations of the S+ (green) and 50 presentations of the S− (red) odor. “1” indicates the breaking of the light beam (head in the sampling port [3]). Note the rapid head retraction for the S− odor.
(E) Difference of the average head positions from (D) for S+ and S− odors. Blue line indicates sigmoidal fit. “Discrimination index” refers to the maximum of the fitted sigmoid.
(F) As (C) but depicting the discrimination index as a function of trial number (group effect: F(1,10) = 1.7; p < 0.01).