Sherrington considers the brain

Charles Sherrington, The brain and its mechanism (Cambridge University Press, 1933), pp. 21-22.

We have seen the brain as an input-output signalling system. The signals entering it are not mental, nor are the executant signals which issue. But signalling which travels certain ways in the brain for instance through the great new nerve-net seems to get, so to say, mental existence, though losing it again before even the penultimate exit-path. No microscopical, no physical or chemical means detect there anything radically other than in nerve-nets elsewhere. All is as elsewhere, except greater complexity.... The spectacle drowns any naive notion that the activity of a single cell by itself can ever amount to a mental experience. For that, we have to seek rather some attribute of the organization itself.