Operant conditioning of large magnitude, 12-hour duration,heart rate elevations in the baboon

Two baboons were prepared with arterial and venous catheters and their heart rate and blood pressure were monitored continuously thereafter. Following a 2 to 3 week interval during which baseline cardiovascular levels were determined, the animals were exposed to daily 12 hr conditioning sessions (alternating with 12-hr “rest” or “Conditioning Off’ sessions) during which food reward and shockavoidance were programmed as contingent consequences of pre-specified increases in heart rate. Initially, the criterion heart rate was set at 10–15 bpm above the animal’s pre-experimental resting baseline level, with progressive increases programmed to occur at a rate approximating 7 bpm per week over a period of 8–10 weeks. Within this 2–3 month interval, heart rate doubled, reaching levels maintained above 160 bpm for more than 95 per cent of each daily 12-hour “Conditioning On” period. Propranolol selectively eliminated the conditioned heart rate increase but not the blood pressure elevation, indicating the contribution of sympathetic nervous activity to these operantly conditioned cardiovascular changes.