RAWM Test

Ten days before surgery, the rats will be trained twice a day in the RAWM. The retention of this task will be assessed one week after surgery, following the same protocol used during the daily acquisition training.

The RAWM consists of an eight-arm radial maze enclosed with a 140cm steel water tank. The water depth will be held constant at 55 cm deep, and the temperature of the water will be held constant at 20 °C. A 75-Watt lamp will be placed above the center of the maze. The extramaze cues will be placed around the maze and be kept in the same location throughout the whole experiment. The rodents will be placed on the center platform held 2 mm below the surface of the water and be surrounded by a transparent piece of Plexiglas to keep them in place for ten seconds. Then the rats will be lowered into the water and have the option to swim into any of the eight arms of the maze. Throughout the experiment the same four arms contain escape platforms, which allow the rats to lift themselves out of the water on the platform. After a ten-second interval, the platforms will be released and the rats will be lowered back into the water to swim until they find another platform. The platforms that have been visited by the rats will remain submerged in the water. After the rats have visited all four platforms in three minutes, they will be towel-dried and placed back in their cages. Data taken from the RAWM testing will include reference memory errors and the number of working memory errors. Reference memory errors (RME) are defined in this experiment as number of times the rat swims into an arm that never contains a platform. Working memory errors (WME) refer to the number of times the rat swims into the arm that has already been visited. The average RME and WME of the daily acquisition tests will be calculated and the savings percentage will be evaluated according to the following formula: % savings = (average training errors – retention errors)/average training errors ´ 100.