The frontal lobes, it is often said, are the regions of the brain which have undergone the greatest expansion in evolution, represent the highest centers of human intelligence, and are the sites of the most complex and highly evolved mental functions. In human and animal studies, the frontal lobes have been associated with self-consciousness, moral behavior and foresight, the awareness of social norms, habituation, drive, abstract thinking and judgment. Frontal lobe mechanisms which have been proposed to underlie these capacities include synthetic or integrative functions, motivation, recent memory, selective attention, and planning.
In view of these claims, therefore, it is surprising that experimental and clinical studies have not yet succeeded in defining a set of symptoms or deficits clearly associated with damage to the frontal lobes, nor in isolating those aspects of behavior, apart from movement and speech, which depend on frontal lobe mechanisms. There are several reasons why this is so. Symptoms of frontal lobe damage are often subtle and appear only on careful testing. Neuropsychological studies tend to compare performance on a few tests in disparate populations, while case reports with anatomical correlation are often incomplete from the linguistic and psychological standpoint. The literature on prefrontal lobotomy has led to more confusion than insight, while problems in left frontal cases are often confounded by the presence of aphasia.
In spite of these difficulties, there is still much to be said regarding the functions of the frontal lobes. This article will review behavioral effects of frontal lobe damage in several different populations: cases of frontal lobotomy or lobectomy; mixed pathological groups; and single case studies. The frontal syndrome in monkey will also be discussed. The article will not deal with motor, oculomotor or autonomic____________________