Musical training can improve fine motor skills, cognitive abilities and induce macrostructural brain changes. However, it is not clear whether the changes in motor skills occur simultaneously with changes in cognitive and neurophysiological parameters. In this study, 156 healthy, musically naïve, and right-handed older adults were recruited and randomly assigned to a piano training or a music listening group. Before, after six and twelve months participants were scanned using MRI and assessed for fine motor skills, auditory working memory and processing speed. A Bayesian multilevel modeling approach was used to examine behavioral and neurophysiological group differences. The relationships between motor and cognitive and between motor and neurophysiological parameters were determined using latent change score models. Compared to music listening, practicing piano resulted in greater improvement in fine motor skills and probably working memory. Only in the piano group, unimanual fine motor skills and gray matter volume of the contralateral M1 changed together during the 6–12-month period. Additionally, M1 co-developed with ipsilateral putamen and thalamus. Playing piano induced more prevalent coupling between the motor and cognitive domain. However, there is little evidence that fine motor control develops concurrently with cognitive functions. Playing an instrument promotes motor, cognitive and neural development into older age. During the learning process, the consolidation of piano skills appears to take place in sensorimotor networks, enabling musicians to perform untrained motor tasks with higher acuity. Relationships between the development of motor acuity and cognition were bidirectional and can be explained by a common cause as well as by shared resources with compensatory mechanisms.