The Brain had only one single, "Kick the Donkey"/"Nightmares in Red," issued on Parlophone in mid-1967. The flip side was an absolutely loony bit of psychedelic tomfoolery, with strained humor and wordless shrieks and gurgles suggesting a patient in the aftermath of electroshock treatment. It has been written that the group included, or was perhaps solely composed of, Peter Giles, his brother Michael Giles, and Robert Fripp, prior to the album they made under the name Giles, Giles & Fripp, and of course two years prior to the release of the debut album of King Crimson, which featured Fripp and Michael Giles. However, according to Sid Smith's biography In the Court of King Crimson, only the Giles brothers appear on "Nightmare in Red," as they had yet to even meet Fripp. According to the liner notes of the psychedelic rarities compilation Syde Tryps Seven (which has some unreleased Brain tracks), the Brain's lineup was actually Michael Giles on drums and vocals, Peter Giles on bass and vocals, Allan Azern on piano and vocals, and Michael Blakesley on trombone and vocals.
Peter Giles was the author of "Nightmares in Red," which was reissued on Nightmares in Wonderland, a compilation LP of British psychedelic rarities. Much more of the Brain's musical history was revealed on the aforementioned Syde Tryps Seven, with five unreleased tracks the band recorded for EMI between March 14 and June 1 in 1967. These had a subdued wittiness that was both far poppier and far more whimsical than what Michael Giles would perform in the early King Crimson, though they were undeniably far less musically innovative and interesting. They were far closer to the dainty, eccentric, slightly psychedelic pop the Giles brothers played with Robert Fripp on the sole Giles, Giles & Fripp album in 1968. Among them were an earlier version of a song ("One in a Million") that would be re-recorded for Giles, Giles & Fripp's 1968 album, as well as another ("Murder") that also showed up, again in re-recorded form, on the Giles, Giles & Fripp demo collection The Brondesbury Tapes (1968). The remaining three Brain tracks on Syde Tryps weren't quite as memorable, including a couple Michael Giles originals and an unlikely (though straightforward) cover of Bob Dylan's "Most Likely You Go Your Way (And I'll Go Mine)."