Research Paper Volume 15, Issue 13 pp 5990—6010

Figure 3. Intermediate-term retention of everyday spatial memory in aging. (A) Rats received a strong encoding trial (3 rewards, filled circle). Six hours later, they were tested in a probe trial with 5 non-rewarded sandwells (open circles). (B) The percentage of correct digging was not significantly above chance (dashed line) in older rats without prior training (one-sample t-test, t₁₂ = 1.88, p = 0.085) but significantly above chance in older rats with prior training (one-sample t-test, t₁₂ = 4.45, p < 0.001). The group difference was significant (unpaired t-test, t₂₄ = 2.2, p = 0.04). (C) Similar to procedures in A except that exploration in a novel box (green box) was introduced or omitted at 30 min after a weak encoding trial (1 reward). (D) An example of a novel box. (E) In rats with no prior training, the percentage of correct digging was not significantly above chance (dashed line; one-sample t-test, t₁₂ = 1.74, p = 0.11) after weak encoding and was significantly above chance after weak encoding with novelty (one-sample t-test, t₁₁ = 2.89, p = 0.015). No difference was observed between the absence or presence of novelty (paired t-test, t₁₁ = 0.87, p = 0.4). (F) In rats with prior training, the percentage of correct digging was significantly above chance (dashed line) in both conditions (absence of novelty: one-sample t-test, t₁₂ = 2.8, p = 0.02; presence of novelty: one-sample t-test, t₁₂ = 4.34, p = 0.00). No difference was observed between the absence or presence of novelty (paired t-test, t₁₂ = 0.99, p = 0.34). Data are presented as mean ± SD. ^*p < 0.05, ^***p < 0.005.