Historically, it was believed that emotional stress, particularly during aversive conditioning, disrupts cardiovascular regulation in animals. However, a study published in **1988** challenged that notion by showing that the **baroreflex**, a key mechanism in blood pressure control, remains operational in dogs even under stress-inducing training paradigms.
Researchers used a specialized technique to **isolate the carotid sinus region** of dogs and examined how arterial pressure and heart rate responded to varying levels of sinus pressure. They compared responses during **operant shock-avoidance** and **classical aversive conditioning** to those in a neutral environment.
The findings were revealing:
- Both heart rate and blood pressure were elevated during conditioning, suggesting an **upward resetting** of the baroreflex.
- Despite this reset, the **range of baroreflex control** over cardiovascular parameters actually increased during stress.
- **Baroreceptor sensitivity** (gain) remained unchanged in operant conditioning but **increased in classical conditioning**, enhancing response precision.
These results indicate that although the **set point of regulation changes** under emotional stress, the underlying baroreflex mechanism is **not impaired**. Instead, it adapts to maintain functional control at a new, elevated level—a crucial insight into how animals physiologically navigate high-stress environments.
This study contributes to a more nuanced understanding of how **emotional states impact autonomic regulation** and supports more humane and effective strategies for **training and behavioral conditioning** in dogs.
Source: R. Shammas, A. L. Denison, T. Pfennig, D. P. Hemker, R. B. Stephenson. Published in American Journal of Physiology, Volume 254, Part 2, June 1, 1988, Pages R1025–R1034.
