Chris Nolan’s Memento (2000) does a great job of depicting the momentary struggle of living with anterograde amnesia, but it leaves us with a lot of unanswered questions (which also might be part of the portrayal…)
Each of us relies on a memory system known as working memory (also known as short-term memory) in which memories are encoded and prepared for long-term storage. New information comes to us through the senses, and that information is consolidated and made stable, and then stored as a memory. In a healthy human brain, the information is consciously available to us; for those with anterograde amnesia, the information is lost once something new catches their attention.
This form of amnesisa — opposed to its counterpart, retrograde, in which patients forget their identity or past events — occurs after a patient suffers damage to the hypothalamus and thalamus (or surrounding areas) or to the medial temporal lobes. This interrupts the consolidation process, which is a necessary element in the recollection of recent events or newly learned information.
In the movie, we learn that Leonard Shelby and his wife are the victims of a home invasion that leaves them both badly injured. It is unclear whether Leonard’s wife lives or dies, but Leonard suffers a blow to the head which results in anterograde amnesia. However, he retains the memory of the event that caused his amnesia, which is uncommon for most amnesiacs. I believe that this is the sole reason Leonard feels an insatiable drive to “find his wife’s killer”; his last and most-recent long-term memory was so emotionally traumatic that it was never properly consolidated — like in the case of those with PTSD — and it continues to haunt him.
Leonard compensates for his inability to form new, lasting memories by obsessively taking notes and tattooing “facts” on his body (almost as if he is trying to consolidate and stabilize the information into “facts” himself).
One such memory is of an experience Lenny had as an insurance salesman. He was selling to an amnesiac client named Sammy Jenkis, who ended up killing his wife because of his condition. The wife apparently didn’t trust that Jenkis was truly ill, and so she encouraged him to administer her diabetes medication multiple times, thinking that he would “snap out of it” in an effort to keep her from getting sick. Unfortunately, Sammy didn’t snap out of it. I interpret this memory to be a foggy, unconsolidated recollection of Leonard’s own experience with his wife after the accident.
After learning about the famous “H.M.” case of anterograde amnesia, I would say that the movie’s portrayal of amnesia is accurate, especially for such a complex condition. The movie puts us in Leonard’s shoes by showing the audience the final moment at the beginning, and playing each scene in reverse. The cinematography leaves us confused about each event presented to us — similar to the way Leonard’s character must be feeling.
Much like Leonard, I am left with many questions: Are Leonard and Sammy Jenkis one and the same? Did Leonard kill his wife? Do all amnesiacs remember that they have amnesia? The question asked by Leonard at the end of the film — “Would I lie to myself?” — is also very symbolic. As far as we can tell, Leonard is not as reasonable as he thinks.