Retention memory was not altered either 24 hours or one week after training in transgenic mice, both genotypes showing increased retention latencies.
Number of pokes (errors) in each hole and latency to reach the virtual target hole were measured on day 1, 2, 3 and 4. Number of pokes in the target hole (targets) and latency to reach the virtual target hole were measured on day 5 and 12 in order to assess both short- and mid-term retention memory.
At day 5 and day 12, the latency to reach the target hole was significantly increased in the R6/2 mice while the number of targets was significantly lower (Figure 2), indicating altered short- and mid-term retention memory in HD mice.
The effect sizes for acquisition and retention memory were also examined relative to study quality score.
To further explore heterogeneity among studies, metaregression was conducted for acquisition and retention memory.
Ginsenoside Rg1 exhibited the highest protective effect on both acquisition and retention memory.
For both acquisition and retention memory, significant beneficial effects were noted for all doses of ginsenosides.
The stratified analysis revealed that ginsenoside Rg1 had the greatest effect on acquisition and retention memory in AD models.
To further explore the heterogeneity among studies, meta-regression was conducted for the acquisition and retention memory results.
The effect sizes for acquisition and retention memory also were examined relative to the study quality score.
For retention memory, animal species, quality score, and type of anesthetic agent were significant sources of heterogeneity (P < 0.05).
