The basal forebrain has received considerable attention in recent years. This emphasis resulted from observations that the cortically projecting cholinergic neurons found in this region are critical for normal information processing. However, to achieve a complete understanding of such a complex function as "information processing" it is necessary to consider the basal forebrain not as an autonomous structure with a solitary task, but one that plays an integrative role; a structure that is connected intimately with many brain regions. This view evolved from the realization that the basal...