Electric shock delivery system for rhesus monkeys: its effect on escape responding

The present experiment evaluated a simple chronic electric shock delivery system for rhesus monkeys restrained by a harness and arm arrangement used in experiments involving intravenous drug delivery. Electric shock was delivered via two small electrodes surgically implanted in the lumbar muscle. During experimental sessions, responding on a fixed-ratio 10 schedule terminated the delivery of a train of 100 electric shock pulses and produced a 3 min timeout. A maximum of 19 trials were possible during each daily session. Overall rate of responding increased as electric shock intensity was increased from 0 to 4 mA and the characteristics of responding were similar to previous studies using other systems and species. The results demonstrate that electric shock delivered by the present system is a negative reinforcer. In addition, the system is easy to implant, causes little tissue damage, relatively long-lasting and can be used in experimental situations which involve responding maintained by intravenous drug delivery in rhesus monkeys.