You'd better tune into Oprah Winfrey's network OWN this Sunday if you want to hearLady Gaga -- because according to her, you won't see her sitting down with any other interviewer any time soon. Gaga and her mom, Cynthia Germanotta, are both profiled in this Sunday's episode ofOprah's Next Chapter, which features footage of the recent launch of Gaga and Mama Gaga's Born This Way Foundation at Harvard University.  It also includes Oprah's sit-down interview with Cynthia and Gaga in the Germanotta family apartment in New York City.  According to OWN, this is an "exclusive" look inside the apartment, where Gaga grew up and where she still lives when she's in town, and no other interviewer had previously been allowed inside. In a preview clip of the interview released by OWN, Gaga tells Oprah, "Other than this interview...I do not intend to speak to anyone for a very long time."  Considering that she has an upcoming tour to promote, that's hard to believe, but let's take Gaga at her word for now. Also in the preview, Cynthia reveals that she and Gaga's dad once believed that their daughter, well, wasn't quite all there, shall we say.  "Her father and I were like, 'I think she has a screw loose!'" says Cynthia, as Oprah cracks up. Watch the interview Sunday night, March 18 at 9 p.m. ET.