Please answer a question about the following article about Madonna (entertainer):

Madonna gave another provocative performance later that year at the 2003 MTV Video Music Awards, while singing "Hollywood" with Britney Spears, Christina Aguilera, and Missy Elliott. Madonna sparked controversy for kissing Spears and Aguilera suggestively during the performance. In October 2003, Madonna provided guest vocals on Spears' single "Me Against the Music". It was followed with the release of Remixed & Revisited. The EP contained remixed versions of songs from American Life and included "Your Honesty", a previously unreleased track from the Bedtime Stories recording sessions. Madonna also signed a contract with Callaway Arts & Entertainment to be the author of five children's books. The first of these books, titled The English Roses, was published in September 2003. The story was about four English schoolgirls and their envy and jealousy of each other. Kate Kellway from The Guardian commented, "[Madonna] is an actress playing at what she can never be—a JK Rowling, an English rose." The book debuted at the top of The New York Times Best Seller list and became the fastest-selling children's picture book of all time.

When did Madonna collaborated as guest vocals for Spears single?
October 2003