Final answer:
Alarming stimuli drive the activity of sympathetic neurons, which are part of the autonomic nervous system and play a role in the 'fight or flight' response to threats.
Step-by-step explanation:
The activity of sympathetic neurons is driven by alarming stimuli. These neurons are part of the sympathetic division of the autonomic nervous system, which is activated during stressful 'fight or flight' situations.
When a threat is detected, the sympathetic system increases heart rate, breathing rate, and blood flow to skeletal muscles, and decreases blood flow to the digestive system. This response is important for survival in dangerous situations.