PROJECT SUMMARY/ABSTRACT Adult mammalian brains have a remarkable plasticity, but its study in humans is challenging to conduct because real-world needs and experiences are frequently unexpected or unpredictable. This proposal focuses on the basic science of neuroplasticity in adult brains by studying early cochlear implant use in humans and rodents. Cochlear implants are auditory neuroprostheses that restore hearing and speech perception to humans with severe or profound hearing loss. Attaining adequate speech perception, however, does not happen instantaneously and can take weeks or months, and in some rare cases years. This proposal aims to investigate how the brain coordinates early adaptations to cochlear implants, resulting in something that is initially unintelligible (i.e., initial cochlear implant use) becoming behaviorally meaningful. Understanding these neuroplastic processes promises to guide strategies for neurorehabilitation including setting expectations for outcomes, counseling on how holistic real-world experiences factor into outcomes, and developing therapeutic targets for improving outcomes. My long-term career goal is to establish an independent research program that investigates the fundamental mechanisms and impactful outcomes of neuroplasticity within the auditory system in relation to cochlear implant function. I propose to expand my skillset with additional training in longitudinal studies of human cochlear implant users and to perform complimentary studies in rodent models of cochlear implant use. During the K99 phase of the award, I will continue working toward independence by acquiring the remaining and essential tools and skills to establish and run a lab. This includes attending workshops on putting together a successful job application and chalk talk, learning effective strategies for the job interview, and developing lab management tools. By the end of the R00 phase, I will have a strong publication record and preliminary data needed for a successful R01 application. The K99 phase of the award will take place at the New York University Langone Medical Center, spanning the Neuroscience Institute, Department of Otolaryngology, Cochlear Implant Center (CIC), Clinical and Translational Science Institute (CTSI), and Rusk Rehabilitation. My primary mentors Dr. Robert C. Froemke and Mario A. Svirsky have a combined 60+ years of experience in neuroscience, neuroplasticity, and neuroprosthetics, I will benefit from their expertise and mentorship in rodent and human studies of cochlear implant use. Additionally, with the support from Dr. Karen Adloph, Dr. John-Ross Rizzo, and Cochlear Ltd. I will begin to study how early cochlear implant use in the real-world engages neuroplasticity within central auditory pathways to improve speech perception.