A major neurotransmitter that controls alertness and arousal; undersupply can depress mood.

A major neurotransmitter that controls alertness and arousal; undersupply can depress mood.

• A. Dopamine
• B. Serotonin
• C. Norepinephrine
• D. GABA

Answer: (C)

Norepinephrine drives arousal and alertness, acting through brainstem systems like the locus coeruleus to keep you awake and attentive. When its signaling is reduced, energy and mood tend to dip, which fits the idea that an undersupply can depress mood. This neurotransmitter also participates in the body’s stress response, linking waking state with emotional tone. Medications that boost norepinephrine transmission can alleviate certain depressive symptoms, underscoring its role in both wakefulness and mood regulation. Dopamine centers on reward, motivation, and movement; serotonin influences mood more broadly but not specifically as the primary driver of alertness; GABA is inhibitory and reduces neural activity, not directly tied to sustaining alertness.

Norepinephrine drives arousal and alertness, acting through brainstem systems like the locus coeruleus to keep you awake and attentive. When its signaling is reduced, energy and mood tend to dip, which fits the idea that an undersupply can depress mood. This neurotransmitter also participates in the body’s stress response, linking waking state with emotional tone. Medications that boost norepinephrine transmission can alleviate certain depressive symptoms, underscoring its role in both wakefulness and mood regulation.

Dopamine centers on reward, motivation, and movement; serotonin influences mood more broadly but not specifically as the primary driver of alertness; GABA is inhibitory and reduces neural activity, not directly tied to sustaining alertness.