Hippocampal neurogenesis<span> is impacted by environmental factors such as age, excercise, stress and anti-depressant use.</span>
Air will move from hot area to colder area as the temperature at both lands should be equal.
The situation is an example of negative reinforcement.
In the condition of negative reinforcement, a stimulus especially an unpleasant stimulus is removed due to a particular behavior of the person. In this case, the unpleasant behavior is the headache, and taking aspirin is a behavior of Nancy, which cut of the stimuli, that is pain relieving. In negative reinforcement a particular behavior is increased, in order to remove the unpleasant stimulus.
I think the answer is your <span>cerebellum</span>
