Final answer:
The reticular formation is responsible for generating and monitoring arousal in the brain. Other brain structures like the amygdala and thalamus are involved in emotion and sensory information processing, respectively.
Step-by-step explanation:
The brain structure involved in generating and monitoring arousal is the reticular formation. This part of the brainstem plays a crucial role in controlling arousal and sleep-wake cycles. Meanwhile, when looking at other structures mentioned in various questions, the amygdala is involved in emotion regulation, especially fear and recognition of fearful faces, and is part of the limbic system. The thalamus acts as a sensory relay station for information except for the sense of smell. The hippocampus is central to memory formation. Structures such as the cerebellum are responsible for coordination during movement, and the superior colliculus helps coordinate head and eye movements when catching a ball.