Amnesias

Amnesia is the loss of memory. Several kinds of amnesia exist. Anterograde amnesia is when new memories cannot be stored. People with anterograde amnesia literally live in the present at all times. They have to be cared for because they could injure themselves or others. For example, they could decide to turn a burner on in the kitchen and not remember that it was on. People with anterograde amnesia can read the same newspaper every few minutes and not realize it. They do not remember reading it.

Oliver Sachs, the neurologist, describes the case of Jimmy, a 50 year-old-victim of anterograde amnesia. When Sachs first met Jimmy, he was greeted with a friendly, " Hi ya Doc." Half an hour later when they met again, Jimmy used the same greeting. Sachs asked whether they had ever met before. The answer was no. When Sachs asked how Jimmy knew that he was a doctor, Jimmy said it was because of the way Sachs was dressed. Jimmy was stuck in the year 1945, it turned out. He only remembered one or two events since that year. (One was the death of his brother, which says something about the relationship of emotions and encoding.) Sachs had the idea of showing Jimmy his face in the mirror. Sachs later said he was sorry for having done so, but, as you will see, in the long run it did not matter.

Sachs first asked Jimmy how old he was, and Jimmy said he was 18. Sachs then asked, "Does this look like the face of an 18-year-old?" Jimmy's face changed and he stalked off. An hour later he saw Sachs again and said, "Hi ya Doc." Jimmy was also very good at checkers, but could not play chess. Can you see why? Jimmy's condition was probably caused by alcohol- related damage to specific brain areas. Can you imagine what it would be like to have anterograde amnesia? Can you see how much of your life depends on long term memories? Manual Figure 8-1 shows a graphic representation of anterograde and retrograde amnesia.

In retrograde amnesia, subjects fail to recall items they have already encoded into long-term memory. Typically, the loss is linear and runs from the present to the past. (See Manual Figure 8-1.) One can judge the severity of retrograde amnesia by questioning subjects. For example, if they cannot remember their names, then you know that their amnesia extends far into their pasts.

The old Jan and Dean song, "Dead man's curve," is about retrograde amnesia. In that song, two drivers race to dead man's curve, and the narrator says:

" The last thing I remember Doc/ is that we started to swerve/ and then I knew everyone was right/Won't come back from Dead Man's curve."

The accident caused the narrator to forget everything from the time they started to swerve until he woke up. The loss of memory was caused by the accident, and is a case of organic amnesia.

Psychogenic amnesia is caused by psychological trauma like surviving a natural disaster, combat, or injury. For example, Sirhan Sirhan, the convicted assassin of Robert F. Kennedy, claimed he had no memory of being in the room or pulling the trigger, obviously many people disbelieve his testimony. You can think of psychogenic amnesia as a subconscious way of protecting yourself from memories of those traumatic events.

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