Facilitation of an operant task in the rat following injection of whole brain extract.

It has been shown that the administration of trained donor brain extract to naive rats results in facilitation of performance on the same task. In the present study a group of food deprived rats was trained to press a lever for food on a continuous schedule of reinforcement until they reached criterion. The animals were then sacrificed, their brains excised, homogenized and the small proteins (m.w. less than 3500) extracted. A group of untrained rats was also sacrificed and their brains extracted. Three groups of rats were used as recipients, receiving either trained donor or untrained donor brain extract or saline. The animals were tested individually for one-hour sessions at 18, 42 and 66 hours after the injection. The number of bar presses made by each rat was noted and the group mean plus or minus the standard deviation were calculated for each session. The results of a one-way analysis of variance showed that the group which received trained donor brain extract performed at a higher rate than either control group. These data suggest that some factor, (specific or non-specific), associated with the task has been transferred.