Eight arm radial maze

The cognitive bias task was implemented using an eight arm radial maze (Med-Associates Inc.; Fig 3). Each arm was 46 cm long and 9 cm wide and the central arena was 28 cm in diameter. The bottom of the maze was backlit with infrared light which eliminated tracking errors associated with automated tracking [55 (link)]. A computer with Ethovision XT software (Noldus, Version 9) recorded the animal’s movement in the maze via a video camera equipped with an infrared pass filter, and automatically activated contingencies when the animal entered an arm or the end of an arm. The detection settings for Ethovision XT were selected so that both the percentage of samples in which the subject was not found and the percentage of samples skipped were less than 1% per trial. For both training and testing, the time spent in each arm and the number of arm entries was automatically recorded.

Mice were trained and tested on an eight arm radial maze (Med-Associates Inc.; Fig 2). Each arm was 46 cm long and 9 cm wide and the diameter of the central arena was 28 cm. The bottom of the maze was backlit with infrared light which eliminated tracking errors associated with automated tracking [54 (link)]. A computer with Ethovision XT software (Noldus, Version 9) recorded the animal’s movement in the maze via a video camera equipped with an infrared pass filter and automatically activated contingencies when the animal entered an arm or the end of an arm. The detection settings for EthoVision XT were selected so that both the percentage of samples in which the subject was not found and the percentage of samples skipped were less than 1% per trial.