In an opening gig for Television July 30, 1976, Talking Heads performed the instrumental song as a three-piece band, Rolling Stone reported.
The song was posted online for the first time at talking-heads.net.
The recording begins with frontman David Byrne telling the audience, "This is an instrumental."
When a fan from the audience asks, "No title?" he responds, "We call it 'Theme,' but then we just keep it to ourselves."
The report did not say how the long-lost recording was found.