Figure 2.

S6K knockout mice have deficits in taste learning. (A) The ratio of water/0.5% saccharin consumed during novel taste training was comparable between the S6K1 knockout (KO) and wild type (WT) (S6K1 KO: 1.158 ± 0.197, n = 5; WT: 0.972 ± 0.107, n = 7; t-test; P = 0.529). (B) Similarly, this ratio was not different between S6K2 KO and wild type (S6K2 KO: 0.859 ± 0.092, n = 7; WT: 0.848 ± 0.087, n = 7; t-test; P = 0.096). (C) S6K1 knockout mice show less aversion than wild-type mice to a novel taste (0.5% saccharin) that was paired with LiCl (WT = 0.78 ± 0.04, n = 5; S6K1 KO = 0.62 ± 0.05, n = 7). (D) Extinction training over four days reveals that S6K1 KO mice do not maintain taste aversion to the same degree as WT mice (coefficient of extinction: WT = -0.07 ± 0.03; S6K1 KO = -0.18 ± 0.02). However, S6K1 KO mice were able to express natural aversion to 0.04% quinine, demonstrating that gustatory responses are intact (data not shown). (E) S6K2 KO mice exhibit normal taste aversion (CTA test: WT = 0.86 ± 0.05, n = 5; S6K2 KO = 0.77 ± 0.11, n = 5). However, two pre-exposures to the novel taste prior to the CTA training session revealed that S6K2 KO mice maintain a high aversion index (latent-inhibition, LI-right) whereas WT mice do not (LI test: WT = 0.42 ± 0.10, n = 7; S6K2 KO = 0.71 ± 0.04, n = 7). (*, P < 0.05 compared with WT littermates with a Student’s t-test).