Selves require bodies as well as brains, material environments as well as bodies, and societies as well as material environments.
However, this presumes a conventional, organic kind of Self, one shaped by a human body and by a human-centric material environment and society. As a thought experiment, say we hook up a living human brain to a sophisticated piece of machinery, effectively creating a cyborg. One could argue that the cyborg would thus be conscious and so have a Self, but a Self that would be very different to the Self that Tallis argued depended on non-brain factors. The brain remains the prime ingredient, without which we wouldn’t be able to even speak of Selves.