Pretty much everyone is interested in the big questions about the brain, and the biggest big question is: what is consciousness? Just as historically the vitalists could not imagine how life can be explained by just physics and chemistry — they believed that a non-physical 'life force' had to be involved — the dualists of today cannot believe our experience of the feeling of love or the redness of red could arise just through nerve impulses in a bunch of brain cells.
Francis Crick believed that, in biology, structure is the natural path to understanding function. In his later career, he applied this dictum to the study of consciousness.
The claustrum is a thin, irregular, sheet-like neuronal structure hidden beneath the inner surface of the neocortex in the general region of the insula. Its function is enigmatic. Its anatomy is quite remarkable in that it receives input from almost all regions of cortex and projects back to almost all regions of cortex. We here briefly summarize what is known about the claustrum, speculate on its possible relationship to the processes that give rise to integrated conscious percepts, propose mechanisms that enable information to travel widely within the claustrum and discuss experiments to address these questions.