For almost 150 years, reports have been accumulating about the manner in which the human brain works. Much of this evidence has been collected from reports of damaged brains rather than from those that are intact. The effects of brain damage following head injury or war traumas have contributed to the growing knowledge of brain functions, in addition to more recent accounts of surgery to remove brain tumours or to minimise the effects of severe epilepsy. In the case of tumours, damage to the brain is often diverse as they commonly affect larger areas of the brain tissue in contrast to confined injuries (called focallesions) caused by bullets or shrapnel which are more specific, and damage is usually confined to a small area.