Fig. 2
Dopamine D1/D5 receptor-dependent novelty-induced enhancement of persistence of object location memory in rats. Graphs display the percentage of time spend exploring the object in the novel location, relative to the total object exploration time, during the first 2 min of both the encoding and the test trials. The dashed line represents the chance level. (A) A schematic of experimental design, along with the results from a 20-min encoding protocol, showing 1-h memory but not 24-h memory in behavioral batch 2. Welch’s t-test revealed a significant difference between 1-h (n = 18) and 24-h memory (n = 6) (68.10 ± 2.60% vs. 52.95 ± 6.73%; t(22) = 2.576, p = 0.017). Effect size calculations demonstrated an extremely high Hedges’ g-value (g = − 1.172; lower 95% confidence interval (CI) = − 2.117, upper CI = − 0.205). Preference during encoding was unaffected by the experimental setup (52.16 ± 1.78% vs. 46.99 ± 3.71%; t(22) = 1.160, p = 0.201). (B) A schematic of experimental design, along with the results showing the effects of contextual novelty exploration on 24-h memory in behavioral batch 3. Welch’s t-test indicated a significant increase in 24-h memory after contextual novelty exploration (n = 10) compared with controls (n = 10) (46.95 ± 3.71% vs. 64.73 ± 4.54%; t(18) = 3.035, p = 0.007). Effect size calculations revealed an extremely high Hedges’ g-value (g = 1.300; lower CI = 0.346, upper CI = 2.225). Experimental conditions had no effects on encoding preference (49.08 ± 2.15% vs. 47.69 ± 2.62%; t(18) = 0.389, p = 0.702). (C) A schematic of experimental design, together with the results showing the effects of dopamine D1/D5 receptor antagonist on contextual novelty-induced enhancement of memory retention in behavioral batch 4 is shown. Welch’s t-test revealed a significant decrease in 24-h memory for the SCH 23390-treated group (SCH, n = 16) compared with the vehicle-treated group (Veh, n = 17) (61.79 ± 2.95% vs. 53.67 ± 2.64%; t(31) = 2.046, p = 0.049). Effect size calculations revealed a moderately high Hedges’ g-value (g = − 0.695; lower CI = − 1.378, upper CI = − 0.002). Experimental conditions did not affect preference during encoding (50.50 ± 1.90% vs. 48.70 ± 2.14%; t(31) = 0.613, p = 0.546). All data are presented as mean ± SEM. *p < 0.05, **p < 0.01