Approximately 1.4 kg of grey and white matter and 86 billion nerve cells make up the most complex organ in the human body. Our brains are wired in the most fascinating way, shaping how we think, feel and perceive. Scientists have studied the brain for centuries unlocking its workings and exploring the riddle that is consciousness. Despite significant discoveries, questions still remain unanswered. View our selection showing the beauty and complexity of the brain. See the slideshow.