One of my wife’s favorite movies is The English Patient, primarily because she loves Ralph Fiennes, the male lead. I like it because the depiction of amnesia is very realistic. The word comes from Greek and refers to a memory disturbance, and the experience is more global than a person being able to recall who he or she is.
Memory is a complex process that includes recognizing an event, person, or object and then storing it in the brain. But memories are of no value unless they can also be retrieved. Typically, amnesia results from disrupting either the laying down or the retrieval of memory. The causes have traditionally been divided into “organic” or “functional.” Organic causes include damage to the brain through physical injury (like the plane crash in The English Patient), neurological disease such as Alzheimer’s disease, or the use of certain (generally sedative) drugs (my favorite is alcohol). Functional causes are psychological factors such as mental disorder, post-traumatic stress or, in psychoanalytic terms, defense mechanisms.
As we experience things the circuits in our brain are activated and monitored by the process we call consciousness. This is purely an electrical phenomenon served by multiple networks of neurons. The moment our attention turns to something else, so does the firing of the involved neurons. But for several seconds a trace of activity remains, just like the spot that lingers after staring into a bright light and closing your eyes. This is the first hint of memory, because the trace is now of something in the past. If this is not worth saving the signal is overtaken by other experiences. If, however, it’s something we want to remember a chemical reaction begins that takes several hours. Scientists are not exactly sure how memories are stored chemically, but hints suggest it involves a protein. Sleep, particularly slow-wave sleep, probably has a significant role in consolidating memories.
Also poorly understood is how memories are retrieved and brought back to consciousness. Specific brain areas, such as the temporal lobe, are rich in memories, but removal of a temporal lobe does not necessarily result in significant memory loss. However, the destruction of both hippocampi results in the inability to lay down or retrieve memory.
So what does this have to do with Doug’s forensic theme? Well, for one thing, it points out how fragile the entire memory process is, how easily it may be influenced, and that one of the first things a good defense lawyer will attack is a witness’s memory.
Dr. Allen Wyler, a native of Seattle, WA, is the author of the medical thrillers DEAD HEAD and DEADLY ERRORS. He practiced neurosurgery for many years before retiring to become Medical Director for Northstar Neuroscience, a start-up medical technology company. In 2007 he left that position to write full time.