Which neurotransmitter is synthesized in the locus coeruleus, projects broadly to the brain and spinal cord, and degenerates in Parkinson's disease, contributing to orthostatic hypotension, sleep disturbances, and depressive symptoms?

Prepare for the American Board of Professional Psychology (ABPP) Exam with flashcards and multiple-choice questions. Each question includes insights and explanations to help you excel. Get ready for your certification journey!

The key idea is that the locus coeruleus is the brain’s main source of norepinephrine, with widespread projections to the cortex, spinal cord, and limbic and brainstem structures. This noradrenergic system helps regulate arousal, attention, autonomic function, and mood. In Parkinson’s disease, degeneration of neurons in the locus coeruleus reduces norepinephrine signaling, contributing non-motor symptoms such as orthostatic hypotension (autonomic dysfunction), sleep disturbances, and depressive symptoms. Therefore, the neurotransmitter synthesized in the locus coeruleus and linked to these broad brain and spinal projections, and to PD non-motor symptoms, is norepinephrine. Serotonin comes from the raphe nuclei, acetylcholine from basal forebrain and brainstem cholinergic groups, and GABA is a widespread inhibitory transmitter, none of which specifically capture the locus coeruleus–noradrenergic role described here.