Figure 6.

p75−/− mice learn stronger CTAs than wild-type mice. (A) With the standard dose of LiCl (0.15 M, 2% of body weight), both wild-type (open ovals), and p75−/− mice (closed triangles) learn strong CTAs, reducing their consumption of saccharin in the first testing session to ~20% of training-session consumption (y-axis). Across further testing sessions (x-axis) both groups re-learned to consume saccharin (i.e., the CTA underwent extinction), but this occurred faster for wild-type mice (see text for statistics). (B) When the LiCl dose was reduced to 1% of body weight, the learning was accordingly milder. By lifting consumption away from the floor, it became possible to observe a difference in initial learning: p75 mice learned stronger CTAs (i.e., consumed less saccharin) than wild-type mice. This difference was maintained through several extinction trials. See text for statistical details.