ABSTRACT
Organic amnesia is a syndrome with four major features. First, patients show anterograde amnesia in which there is impaired recall and recognition of postmorbidly experienced facts and personal episodes. Second, they show retrograde amnesia in which there is impaired recall and recognition for premorbidly experienced facts and personal episodes. Third, they may show preservation of intelligence. Fourth, they may show preservation of short-term or immediate memory as assessed by the digit span or Corsi blocks tests. These ·'(eatures can be found following lesions to anyone of several interconnected brain regions including the medial temporal lobes, the midline diencephalon, and the basal forebrain. It remains unresolved whether the deficits characteristic of amnesia are dissociable and, therefore, whether one or more kind of functional deficit underlies the syndrome. The characteristics of this or these functional deficits also remain unresolved. Relevant to the resolution of these issues is the neuroanatomy of amnesia, because the precise location of the lesions within the medial temporal lobes, midline diencephalon, and basal forebrain will help determine whether one or more deficits underlie amnesia, and perhaps even what their characteristics are likely to be.
