The locus coeruleus (LC), which produces catecholamines (norepinephrine and dopamine), is one of the earliest brain regions to accumulate abnormal tau protein in Alzheimer’s disease. Beyond its role in pathology, the LC is a key modulator of motivation, learning, and memory. However, how age-related changes in this neuromodulatory system affect these cognitive processes remains unclear. In this talk, I will introduce the anatomical and neurochemical functions of the LC and its relevance to cognitive aging. I will also present findings from my research, which uses a multimodal approach, including pupillometry, magnetic resonance imaging (MRI), and positron emission tomography (PET), to examine how age-related differences in LC function relate to motivation, information-seeking, and learning.