Rats ran an alley and pressed a lever for brain stimulation reward. At the end of the 10-min. intertrial interval, they received pretrial priming stimulation. Varying the amount (number of trains and number of pulses) of stimulation showed that both the lever-produced stimulation and the pretrial stimulation affected running speed. The 2 effects, however, had different parametric characteristics. An analysis of the transitional responses following changes in the amounts of stimulation further showed that one effect involved a memory for stimulation received on earlier trials, whereas the other effect did not. The experiment provided a paradigm for independently analyzing the 2 effects. A second experiment showed how this paradigm may be modified to permit automation of the entire procedure.

No abstract