Searching for lost memory: memory loss and recovery mechanisms observed in a patient with pure retrograde amnesia

We describe a patient who developed acute reversible amnesia characterized by impaired recollection of past events with preserved anterograde memory. This occurred after a mild head trauma and in the context of occupational stress. Isolated retrograde amnesia affected autobiographical memory (with lost of identity lasting a few days) and semantic knowledge. Isolated retrograde amnesia subsided for nine months. The patient was no longer able to access to his memories, which did not seem completely lost. Some answers to tests concerning historical events were better than those given at random; his answers to a TV quiz were automatic or he exhibited temporal transfer phenomena (ecmnesia). Gradual, progressive, irregular and spontaneous or "flash" recovery, which was also facilitated by dreams, associations or contextual clues. The persistent and vivid familiarity of the retrieved memories are reported here together with the organization of long-term memory and the clinical and neuropsychological traits of functional isolated retrograde amnesia.