In "Unimatrix Zero (component 1)", it was so the Doctor could observe her REM rest and try out to relieve her nightmares about Unimatrix Zero. In "Imperfection", it was to keep track of the performance of her malfunctioning cortical node. Given that Voyager was stranded in the Delta Quadrant as a end result of Janeway's steps, whatever the causes powering them, this could be a scenario of her having "kicked upstairs." It can be observed both way.