Figure 3

Enriched environment (EE) housing corrects cognitive deficits in Tg4-42^het mice and Tg4-42^hom mice. Tg4-42^het mice (12 months) and Tg4-42^hom mice (6 months) housed under SH or EE conditions were tested in the Morris water maze task (a–f). (a, d) All tested mice showed decreased average (Avg) escape latencies over 3 days of training, whereas no differences could be assessed between SH and EE mice. (b, e) During the acquisition training mice showed progressively reduced escape latencies over 5 days of training. Tg4-42^het SH mice showed an impaired spatial learning as seen by higher escape latencies over the whole training period. No differences in escape latencies could be assessed between Tg4-42^hom SH and EE mice (c, f) While Tg4-42^het SH and Tg4-42^hom SH mice had no preference for any of the quadrants in the probe trial, EE mice showed an intact spatial reference memory as they spent significantly more time in the target quadrant (T) compared with all the other quadrants (L, left; R, right; O, opposite) in both heterozygous and homozygous Tg4-42 mice. Recognition memory was tested using the novel object recognition task (NOR) (g–i). (g) Schematic representation of the NOR task. (h) In the exploration phase, SH and EE mice spent ~50% of the time with the novel (N) and familiar (F) object. (i) During the test trial, EE mice showed a clear preference for the novel object, whereas SH mice showed no preference for any of the objects. All data were given as means±s.e.m. ***P<0.001; *P<0.05.