Phase II: Spatial Training
Following pretraining, rats are given 8 trials a day for 10 days. On each trial, water is placed in a single well. For each rat, the water is always located in the same position relative to the testing room and distal spatial cues. Four different target well locations are used; 1 in the center of each quadrant, to control for any position biases the rats might have. The target well location to which each rat is assigned is counterbalanced within each experimental group. Local cues are made irrelevant (including odor trails) by rotating the entire apparatus a predetermined distance and direction after each trial. However, the water is always placed in the same location relative to the testing room and distal spatial cues.
In addition to the groups trained to find water by using spatial cues, another group (RANDOM) is given an equivalent amount of training, except that the location of the water varies randomly from trial to trial and could appear in any of the 426 wells. Thus, this group could develop optimal strategies for finding the water efficiently, but memory of specific locations is irrelevant. The RANDOM group provides a measure of where rats with no spatial memory of a trained location will spend their search time during probe trials. The probe trials for this group are administered 14 days after the end of training.
At the beginning of each acquisition trial, the rats are placed at 1 of 4 start points (North, South, East, and West) around the edge of the board. Across the 8 trials of each day (intertrial interval was approximately 15 min), 2 trials are given from each of the 4 start points, and the sequence is counterbalanced within each group. A trial is terminated when the rat locates the water or after 5 min, whichever comes first. If the rat fails to find the water within 5 min, it is guided to the correct well and allowed to drink. Once the water is located, the rat is allowed to drink the water before being returned to his home cage. Following each training session, the rats are allowed to drink freely for 1 h.
Read more about this topic: Oasis Maze
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