Amanda Bynes -- On the Move ... To UCLA Medical Center

Amanda Bynes has been transferred to the UCLA Medical Center for further treatment of her mental illness ... TMZ has learned.

Amanda was shielded by a blanket as she was taken Thursday from the psychiatric facility in Ventura County to UCLA. We're told her mom -- who is now Amanda's temporary conservator -- wanted the actress admitted to UCLA because it has one of the best psych facilities in the nation.

Our sources say Amanda would have been transferred earlier but a bed wasn't available until Thursday.

As TMZ first reported ... we're told Amanda has shown clear signs of schizophrenia ... but doctors continue to perform tests to evaluate her condition.