Use of Vacuum Tube Amplification in Establishing Differential Motor Reactions

1. The electromyographic potentials arising from masticatory movements were picked up by electrodes chronically implanted in the brains of eight rats. The rats had been trained in a Skinner box to press a lever for food reinforcement on a 100 per cent schedule. Lever and food cup were separated by 180ddot] in a cylindrical metal box one foot in diameter.

2. The problem was to determine whether thoroughly trained animals would show AGRs as determined by the presence of electromyographic potentials when, in the course of pressing, food was suddenly withheld. Only two of the eight animals gave an AGR during the extinction process, and in one of these the phenomenon was minimal.

3. In the discussion it is pointed out that the absence of AGRs in the animals was possibly related to the short time interval intervening between depression of the lever and securing the food-pellet reward.