By: Michael Rochelle
Why Post-Traumatic Amnesia?
I chose this topic because I want to understand how and why it occurs. I also want to understand why people still know how to talk, write, etc. while only their memories of events are lost. This could help me and others better understand the structure and organization of the brain and memory.
What is Post-Traumatic Amnesia?
PTA is a state of confusion or memory loss that comes after a traumatic brain injury. The person is disoriented and unable to events before (anterograde amnesia) and after the injury (retrograde amnesia), and may be able to state their name, where they are, what time it is, etc.
What Happens to the Brain?
PTA usually occurs when the frontal or anterior regions of the temporal lobe are damaged. The temporal lobe is involved in the retention of processing sensory input into visual memories, language comprehension, and encoding declarative long term memory, so it makes sense that when it gets damaged PTA occurs. There is also evidence that traumatic events, such as PTA, can lead to shrinking of the hippocampus, which is also highly involved in the making and processing of memories.
Why Do People Usually Retain Language and Other Skills?
There are two different types of memory, declarative and procedural. Procedural is linked to skills, conditioning, etc. Declarative has two subcategories, semantic and episodic. Semantic consists of facts that are independent of context, while episodic deals with information related to a certain context, like time or place. PTA usually only affects episodic memory, which explains why victims can recall how to speak and other skills, but not who they are and such.
Post-Traumatic Amnesia Experiments and Research
The first person to extensively document PTA was the British physician C.P. Symonds, who observed several amnesiac symptoms that followed cranial injury. It was also observed after WWI, when many soldiers who had seen extensive combat returned with PTA. It is commonly known as "shell shock".
A 32 year-old woman is the victim of serious PTA. After a hit-and-run accident that left her hospitalized, she could not remember the past 5 years of her life, and now wakes up every day believing she is her 5-16 year old self.