ABSTRACT
Any injury to the brain inevitably disturbs the normal functioning of brain systems. In trying to understand the effects of injury on the person it is appropriate therefore to ask, “What does the brain do?” The simplest and ultimately the most accurate answer is “Everything”. There is nothing that we sense, perceive, judge, do, think, recall, learn, feel, imagine, or create that is not done through the medium of brain mechanisms. Since most forms of injury have diffuse impacts, they are likely to interfere directly, to at least some extent, with a wide range of brain systems and therefore with a wide variety of brain functions. There are, of course, factors other than the brain injury that can cause disorders. These include the circumstances in which the injury occurred, its consequences for the individual’s personal, social, and economic independence, as well as the rebound effects of the impacts it has on family, friends, and society at large. All of these may lead to secondary or reactive disorders, although their appearances may well be atypical because of distortion of the mechanisms through which they are expressed or indeed perceived, as a result of direct damage from the trauma to the brain.
