AMNESIA: Who are you anyway?

Biology 202
2000 First Web Report
On Serendip

AMNESIA: Who are you anyway?

Euree Choi

"Should the soul of a prince, carrying with it the consciousness of the prince's past life, enter and inform the body of a cobbler, as soon as deserted by his own soul, every one sees he would be the same person with the prince, accountable only for the prince's actions: but who would say it was the same man?" --"Of Identity and Diversity", John Locke

"Where am I? How did I get here?" "You were in a car accident last night. You're in the hospital, but you will be fine" "Accident? What accident? And who are you?" "Don't you know who I am? I'm your little sister."

Sound familiar? How about another scenario?

"Ladies and gentlemen of the jury, my client has been under the influence of some form of memory loss at the time of the murder. Studies and tests have proved that this is the case. Therefore, ladies and gentlemen, can we imprison a man for committing a crime for which he has no knowledge of recollecting?"

These two scenarios depict typical instances of patients with amnesia or at least claim to have amnesia. Amnesia means a loss of memory from a failure of some part of the memory system (1). It is defined as a special case of forgetting, since the loss of memory is greater than expected under ordinary circumstances (2). In severe cases of amnesia, memory loss can result from a two-sided or bilateral (both hemispheres) damage to parts of the brain vital for memory storage, processing, or recall. These parts involve the limbic system, which includes of the hippocampus in the medial temporal lobe of the brain) (1).

The hippocampus encodes memory for events and episodes. Memories, either short term or long term, are not stored in the hippocampus. But instead, information gets processed into memory in the hippocampus. Therefore, people suffering hippocampal damage might still have the storage capacity available for use, but memories cannot be processed for storage (3). Hippocampal injury disrupts the ability to convert short-term memories into long-term memories (4).

Some sources of brain alteration include aging, chronic emotional stress, car accidents, head injury, intense fear, physical traumas, drugs, rape, assault, sexual molestation during childhood, cold baths (5), surgery, stroke, hypoxia (lack of oxygen), closed head injury, electroconvulsive therapy (ECT)-usually temporary, Korsakoff's syndrome (alcoholism), or Alzheimer's disease. To illustrate, for example, immersion in cold water causes rapid depletion of serotonin and the release of opiates peptides which in turn negatively influence the hippocampus. Severe stress, emotional shock, as well as a blow to the head or a stroke can induce sudden and drastic alterations in neurotransmitter and arousal levels in the same respect (5).

Anterograde Amnesia affects the formation of new long-term memories, the intactness of the STM (working memory), influence of all modalities (visual, auditory, etc), the ability of skills to be learned. Retrograde amnesia involves the loss of memory for information occurring before damage (6). Many types of amnesias exist, but they generally fall into two major classes based on their cause-functional amnesia and organic amnesia.

Functional amnesia deals with disorders of memory that seem to result from psychological trauma, not an injury to the brain. Though traumatic events affect the brain in some way, people with functional amnesia appear to have nothing physically wrong with their brains (7). The second scenario presented at the beginning of this essay may be an example of functional amnesia. The client had supposedly murdered a person. He claims to have no recollection of the murder incident due to amnesia. Few well-documented cases exist in scientific literature for functional amnesias, although they appear as a recurrent theme of television shows and movies (7).

On the other hand, organic amnesia involves memory loss or traumatic forgetting caused by specific brain damage. Tumors, strokes, head trauma, or degenerative diseases (e.g. Alzheimer's disease) may involve organic amnesias. They may be temporary or permanent. The most well known amnesic patient is H.M. who had brain surgery in 1953 for epilepsy leaving him with dramatic anterograde amnesia (7). H.M. was unable to remember new information and events that occurred after his operation. His hippocampus was destroyed surgically in the course of operation to relieve the effects of epilepsy. The brain damage did not result in loss of learned motor skills, but the problem was with declarative memory (8). H.M. more specifically had organic amnesia with bilateral damage to his parahippocampal cortex, entorhinal cortex, and perirhinal cortex (9). The first scenario described above is an example of a patient who suffering memory loss from brain damage involving organic amnesia.

A study on three children revealed some new information concerning memory and learning. The three unrelated children suffered brain damage from oxygen deprivation. They achieved average grades in schools and learned to read, write, and spell as well as their classmates; yet they would get lost on the way to class, forget conversations they'd just had, forget TV programs they had just watched, and even forget what day it was. This study left researchers baffled (10) and raises questions such as what causes these strange selective memories?

The big question asks if a person's thinking is altered, is the person the same person or different persons? Is a person with amnesia, whose thinking is altered chemically, considered to be a different person? John Locke's view is quite intriguing. Locke believes that if a person does not experience two situations in the same consciousness or mind, he or she is not the same person. He used Socrates to illustrate his point; however, this is not true about Socrates in reality. "If the same Socrates waking and sleeping do not partake of the same consciousness, Socrates waking and sleeping is not the same person" (11). Therefore, two identities of Socrates exist according to this example. This idea is emphasized and questioned in the quote stated to initialize the essay as well. The "two" princes may have similar actions or behaviors, but does actions account for the same person?

Although, amnesia appears to have the ability to control our thoughts, I disagree with Locke concerning identity. How can the self or I-function be separated from the physical body? If we are only our minds, then when a person hits his or her head and suffers amnesia, can we judge those who are in question of imprisonment? The convict may have had amnesia, but the cause of the amnesia is another issue. What if excessive drug usage or physical trauma were the cause? Should the convict be imprisoned in these situations since the convict could have had expected something unnecessary to occur? Was the convict the same person during the murder? If the same tangible brain is used to think, are there different persons? The mystery remains unsolved.

WWW Sources

8)Amnesia 9)Briefing Notes: Amnesia 10)Children with amnesia cast new light on memory and learning 11)" Perry, John. Personal Identity. "John Locke: Of Identity and Diversity." University of California Press: Los Angeles, 1975. "

Comments made prior to 2007

Because little is known about the actual forming of memories in the human brain, this web page gave me some additional insight. You see, I had a severe TBI in February of 2004 from a paragliding accident, and your thoughts on this matter, ìforming of memories after a TBIî, are well known to me. As an additional insight, besides waking up wondering why one is ìin the hospitalî I have also become to realize from observing several individuals who have had TBIíS, oneís chronological age is "frozen" in time from the date one's "accident" occurred.

As additional notes from my observations, some individuals continue to believe that they will eventually fully recover. When I was in the hospital/rehab after my accident, I erroneously believed that it was just a matter of days and I would wake up one day and be normal. Some individual whose injuries were several years ago, still hold onto that idea. Initially after I came home 3 months after my accident, and read that 90% of one's recovery continues up to 2 years, I kept believing that when I reach that "mark" I would be a lot closer to who I was! As time continues to pass, I am realizing that this will not the case. I am still learning to accept the fact that, who I am today, is who I am, and that the old ìmeî is gone! ... Dan Keyser, 12 September 2007