Being unfamiliar with Starfleet protocols, she had a hard time adjusting to life on Voyager.
She and three other former Maquis, Kenneth Dalby, Chell and Gerron, were selected by Commander Chakotay to participate in Lieutenant Tuvok's Starfleet Academy-style crash-course aimed at bringing former Maquis members unfamiliar with Starfleet up to date. (VOY: "Learning Curve")
Background information Edit
Mariah Henley was played by Catherine MacNeal.
Henley's first name was not mentioned in the episode itself, but was in the script.