Novel object recognition This task of recognition selleckbio memory utilizes the fact that animals will spend more time exploring a novel object compared with an object that they are familiar with in order to satisfy their innate curiosity/exploratory instinct. The test apparatus consisted of an open field box measuring 39.4 cm ?? 78.8 cm change confirmed. in diameter, and all sessions were video-recorded. On day 1 the animal was allowed to explore the open field box for a 15-minute time period. The following day the animals were each exposed to a 10-minute information session (that is, the A/A session with identical objects present). This information session was followed by a 1-hour delay during which the animals were returned to their home cages. After the delay the animals performed a 10-minute dissimilar stimuli session (A/B).

The objects were made of hard plastic and had previously been counterbalanced to control for any object preference bias. The total amount of time spent with each object was recorded and scored using fully automated EthoVision XT 8.0 video tracking software (Noldus Information Technology). The time spent was operationally defined as occurring when an animal directed its nose to the object at a distance <2.0 cm and/or by the animal touching the object with its nose or mouth. Data are presented as the D2 discrimination index. The D2 index is a common measure of discrimination between novel and familiar objects, and is considered one of the most reliable measures of discrimination because it corrects for total exploratory activity of each animal [29].

The D2 index is calculated for an A/B session by examining the difference in time spent exploring Drug_discovery the novel and familiar objects divided by the total exploration time for both objects: D2=(novel???familiar)/(novel?+?familiar) The D2 index thus corrects for total exploratory behavior of each mouse. Statistical analysis All statistical analyses were performed using GraphPad Prism Version 5.00 (GraphPad Software, San Diego, CA?USA). In the cross-sectional study design, experimental groups consisted of two genotypes at four different ages: 7 months, 11 months, 15 months, and 24 months. Each group used a ~50:50 ratio of males to females. The number of mice used per group was 5 to 12 mice per group.

Unless otherwise indicated, for WT mice there were 10 aged 7 months, nine aged 11 months, five aged 15 months, and 10 aged 24 months; and for KI mice, there were nine aged 7 months, five aged 11 months, 10 aged 15 months, and five aged 24 months. Comparison between individual experimental groups was performed by unpaired t test where appropriate. Regression analysis compound libraries for RAWM and novel object recognition (NOR) cognitive data was modeled via linear regression in GraphPad with genotype, age, and errors/D2 index as independent variables and using a 95% confidence interval. Data are expressed as the mean ?? the standard error of the mean.