By the medulla in rats, scientists were able to cause a cessation in breathing. fb by the amygdala in rats, scientists were able to trigger aggressive behavior.

By lesioning the medulla in rats, scientists were able to cause a cessation in breathing. By electrically stimulating the amygdala in rats, scientists were able to trigger aggressive behaviour.
The medulla or medulla oblongata is found in the brainstem and is the structure that regulates autonomic functions of breathing, heart rate and blood pressure. Lesioning is a surgical term which describes the process of injuring a specific part of the brain. Therefore, when the medulla is lesioned, it can no longer function properly and the autonomic process of breathing is interrupted. 
The amygdala is comprised of two nuclei within the temporal lobes of the brain and is considered part of the limbic system. Its functions include the processing of memory, decision-making and emotional responses. It has been shown that by electrically stimulating the amygdala in animals, their aggressive behaviour is increased.