Introduction | Definitions and Diagnostic Criteria | Epidemiology | Etiology | Assessment and Differential Diagnosis | Prevention | Treatment | Conclusion | References
The amnestic disorders are not frequently encountered clinically.1 When amnestic disorders do occur, however, they assume great clinical importance because of their effect on the individual. Persons with deficits in memory are typically disabled by their condition and may spend years of their life in a dependent role. One of the most famous patients with an amnestic disorder is "H.M.," who underwent bilateral medial temporal lobe resection for the treatment of severe epilepsy (Milner 1959; Milner et al. 1968). As a result of his operation, H.M. developed difficulty recalling some events of the past but an even more severe inability to make new memories. Because of his severe amnesia, he was said to have felt as if he were continuously waking from a dream. He would feel the events of the preceding moments slipping away from him even as he attempted to grasp them. The case of H.M. also highlights the relatedness of the concepts of memory and learning. Learning can be seen as the process of acquiring new information, whereas memory is the persistence of learning in such a way that it can be used at a later time. As Squire (1987) noted, "memory is the usual consequence of learning" (p. 3).