A comatose person is not “brain dead.” The brain still performs the basic tasks that keep the body alive, such as breathing, circulating blood and sleeping. What is not present in a comatose brain is cognition. For this reason, a person in a coma does not respond to his or her surroundings in any meaningful way and does not exhibit higher levels of brain function. Put simply, a comatose brain does not “think,” but it is not in a state of complete shutdown either.