During his initial postdoctoral fellowships in the laboratories of Dr. Barbara Beltz (Wellesley College, MA) and Dr. Pierre Meyrand (CNRS, France), Dr. Sullivan gained broad training in neuroanatomical and electrophysiological techniques. He then undertook a four-year postdoctoral fellowship at the Garvan Institute of Medical Research (Australia) in the laboratory of Dr. Sharon Oleskevich, to receive training in the study of stem cell and mouse models of human disease. His research in this laboratory focused on the development of adult stem cell-based therapies for the treatment of sensorineural hearing loss using multiple mouse models. He joined the laboratory of Dr. Charlotte Sumner at Johns Hopkins University School of Medicine in early 2011, where he has been developing and studying both cellular and animal models of TRPV4- and JAG1-mediated neurodegenerative disease. Through this work he has identified a novel mechanism of neuromuscular disease pathogenesis, in which neurodegeneration is driven solely by postnatal disruption of blood-neural barriers (BNBs). In September 2023, he was promoted to Assistant Professor at Johns Hopkins University School of Medicine. His current research is focused on determining how mutant TRPV4 disrupts BNBs, elucidating the molecular mechanisms via which TRPV4-mediated BNB impairments precipitate neurodegeneration, and developing therapeutic strategies for patients with TRPV4 mutations. In recent work, he has also partnered with Actio Biosciences to perform preclinical studies examining the capacity of a novel TRPV4 small molecule antagonist to abrogate disease phenotypes in mouse models of TRPV4-mediated disease.