PROJECT SUMMARY/ABSTRACT Older adults, and particularly those with Parkinson disease (PD), may experience walking difficulties that negatively impact their daily function and quality of life. This project will examine the impact of music and singing on walking performance, with the goal of understanding what types of rhythmic cues are most helpful to people with Parkinson disease and older adults. Our pilot work suggests that imagined, mental singing while walking helps people walk faster with greater stability, whereas walking to music also helps people walk faster but with reduced stability. In Aim 1, we will compare walking while mentally singing to walking while listening to music, using personalized cues tailored to each person's walking performance. We will also test whether finger tapping, a rhythmic task similar to walking in many ways, responds similarly while mentally singing and listening to music. In Aim 2, we will investigate the brain mechanisms underlying the enhancements in movement performance seen with mental singing or music listening. We will use magnetic resonance imaging (MRI) to measure brain activity during finger tapping with and without various cues to understand which areas of the brain are more or less responsive to different types of cues. Using the information gained in the first two aims, we will then conduct an intervention study in Aim 3 to compare and contrast the effects of music-based vs. singing-based training for people with PD. We will determine which training method results in the greatest improvements in walking and tapping performance and measure changes in brain activity with training. We will also ask the participants how acceptable and usable the different training approaches are. This work is among the first to focus on singing as an intervention to improve walking in PD and is innovative in its use of this novel, untapped, highly accessible, adaptable, low-cost approach that has the potential to enhance walking, thereby improving everyday function and quality of life for people with PD.