" Global amnesia refers to a dense and circumscribed deficit in memory in the context of otherwise preserved intelligence. It encompasses the acquisition of events and facts encountered postmorbidly (anterograde amnesia), as well as the retreival of information acquired premorbidly (retrograde amnesia). Patients with amnesia are capable of holding a limited amount of information in mind for a very brief period of time, but with increased retention interval or increased interference, their recall and recognition of the information inevitably fails. Anterograde amnesia is usually global, in that memory for all new information is affected - regardless of the nature of the information (i.e. verbal or nonverbal) or the modality in which it is presented (i.e. auditory or visual). In most patients, anrerograde amnesia is associated with some degree of retrograde loss, although its extent is more variable. The reverse, however, is not necessarily the case, as some patients have been described who demonstrate relatively focal retrograde amnesia in the absence of anterograde memory loss (Kapur, 1993; Kopelman, 2000)."
I've had several cases recently in which some degree of memory impairment has been reported. As a result, I've contined to focus on various aspects of memory impairment, which explains the recent posts on memory-related topics. I thought this paragraph effectively described the issues associated with the two general types of amnesia: 1) Anterograde - from the point of onset, a person cannot form new memories, and; 2) Reterograde - a person cannot recall memories from a particular time period in the past, but is able to form new memories.
With respect to anterograde amnesia, two movies that have portrayed this issue are: 1) 50 First Dates, in a lighthearted, comedic manner, and; 2) Memento, in a darker, film noir manner. In each case, a head injury impairs the individual to the point where they can no longer form long-term memories; once time passes, or new information is presented (interference), the preceeeding stimuli is lost. Memento is particularly effective in demonstrating the impact this sort of problem can have, utilizing a clever time-sequencing device to impart the memory problem onto the audience. If one is interested in reading a fascinating portrayal of this type of problem, I highly recommend the chapter "The Last Hippie" from Oliver Sacks' An Anthropologist on Mars .
Retrograde amnesia has been shown in film as well. In the case of a brain injury, Overboard with Goldie Hawn presents a woman who loses memory of her past after a fall and subsequent hit on the head. More common in the movies (liely due to theatrical potential) is psychogenic retrograde amnesia (amnesia for past events for psychological, not medical, reasons). In The prince of Tides, Nick Nolte works through a childhood trauma for which he cannot recall the event; many movies will portray memory loss of this type as a result of a traumatic event (including the comission of a crime), often using this set up as a plot device.
As time and interest permits, I'll keep posting stuff I think might be interesting!