The Frontal Lobes

Abstract Although this is a time of unprecedented progress in cognitive neuroscience, clinicians who evaluate and treat frontal lobe dysfunction still face many of the frustrations encountered by prior generations. Damage to the frontal lobes can disrupt in various ways a set of very complex neuroanatomical and functional systems, which for the most part remain incompletely understood. The frontal lobes make up over one-third of the human cerebral cortex and have diverse anatomical units, each with distinct connections to other cortical and subcortical regions and to each other. Although progress has been made in elucidating the connectional pattern and physiology of some of its subregions in nonhuman primates (see below), the means have not existed to map equivalent complexity in the human brain. Paralleling the challenges presented by the anatomical complexity of the frontal lobes are those that stem from the nature of the signs and symptoms of frontal damage, and most saliently, the fact that such signs and symptoms do not lend themselves easily to quantitative analysis in a laboratory setting. Nonetheless, new findings on frontal lobe dysfunction are appearing regularly and have provided support for some longheld suppositions, as well as new ideas regarding the operations of the frontal lobes. For example, the central role of the frontal lobes in higher cognitive activities is not in question, and there is also growing evidence that frontal dysfunction may contribute to certain psychiatric disorders.