Mixed and multiple aperiodic and ratio schedules of reinforcement were maintained by rats which had stainless steel electrodes surgically implanted in specific areas of their midbrains. The "reinforcing" stimulus used was a 100-cycle biphasic, square wave of a one-second duration. The voltage ranged from 1.0 to 2.0 volts and the current from .10 to .50 milliamperes. Four subjects (S's) were used in the study. Three of the S's received electrical brain stimulation (EBS) and the fourth received food pellets as reinforcement. Only the latter "food control" animal ,was run on a 36-hour food deprivation schedule. All other subjects were not food-deprived. Aperiodic (variable-interval) schedules of VI=15 to 60 seconds and ratio (fixed-ratio) schedules of FR= 5 to 20 were maintained consistently for one hour sessions every 24 hours with all four animals. At the time this paper was written, research was still in progress, therefore, final results were not then obtainable.
Flory '64, Randall K., "Schedules of Reinforcement With Intracranial Simulation" (1964). Honors Projects. Paper 134.