Key Inclusion Criteria:  Has a body mass index (BMI) between 18 and 30 kilogram per square meter (kg/m^2), inclusive and a total body weight >50 kilograms [110 pound (lb)].  Key Exclusion Criteria:  Participates in other studies involving treatment with an investigational drug within 30 days or 5 half-lives (whichever is longer) prior to randomization and/or during study participation. Previously participated in this study or previous studies with BIIB104.  NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.