Hyperthymesia

My name is Srikar Bhimmanapalli. This project is for Understanding the Brain: The Neurobiology of Everyday Life.

1. Hyperthymesia or Highly Superior Autobiographical Memory (HSAM) By: Srikar Bhimmanapalli Understanding the Brain: The Neurobiology of Everyday Life

2. What is Hyperthymesia? Hyperthymesia (otherwise mentioned as Highly Superior Autobiographical Memory, or HSAM) is an extremely rare condition that gives an individual the abnormal ability to recall any specific event from their own past with extreme detail, given a date. There are currently around 20 people in the world with confirmed hyperthymesia. For example, when given any date from their life following adolescence (say, July 7, 1984) a hyperthymestic can remember, with vivid detail, what happened to them or what they were doing that day, whether it was watching a T.V. show, or visiting San Francisco for the first time. They can also recall what they were wearing, what they were eating, facial expressions, emotions, and other episodic details from that day.

3. 3 Distinct Characteristics There are 3 things that define HSAM: They tend to spend a greater amount of time recalling personal history compared to most people. They have an abnormal ability to remember specific events from their own past more clearly than most people. Hyperthymestics can remember over 200 events in the span of a given year, while most people generally remember around 8 to 11.

4. Important Facts Hyperthymesia is much different from photographic memory. Hyperthymesia is considered having an extremely detailed autobiographical memory, while photographic memory is remembering facts and figures as well as autobiographical events. Even though their ability can be helpful, hyperthymestics can indirectly apply their condition to better themselves at schoolwork, but not in the same way photographic memory theoretically can. It is important to note that individuals with HSAM do not purposefully try to remember personal events. They do not use mnemonics or other memory devices to remember things. They are described as involuntary episodes that come automatically.

5. How it feels like to have HSAM Every person with HSAM interprets their condition in a different way. Some are able to organize these memories so they are not reminded of them every moment, but some still feel it as as a constant burden. For example, Jill Price describes it as being “haunted by the neverending stream of memory”. Nonetheless, most hyperthymestics are glad of their gift.

6. Parts of the Nervous System that are Active in HSAM Hippocampus and the Temporal Lobe The hippocampus plays a great role in converting working memory to declarative memory. Semantic memories are stored within the neocortex, and episodic memories are stored in the neocortex as well. However, in order to recall episodic memories, they would need to come back to the hippocampus. This “episodic loop” renders episodic memories even more labile and easier to forget each time it goes through the loop. Hyperthymestics seem to lack this forgetfulness trait for autobiographical memory. In fact, researchers found a significantly enlarged temporal lobe, containing the hippocampus, when doing an MRI on one patient.

7. Apparent Functions of HSAM The memory formation circuitry is an apparent function of HSAM. Even though it is unclear exactly how hyperthymestics are able to retain such a large and detailed autobiography, it has been proposed that information retrieved by hyperthymestics is semantic, but is interpreted as episodic. However this memory automatically reminds the individual of another memory, and another memory, and so on, called spreading activation. This is why so many people with hyperthymesia remark how one memory triggers another, and so on, and how they are powerless to stop it. Another theory to explain hyperthymesia is that it is caused by individuals reviewing memories to an obsessive-compulsive degree. This is less satisfying than other theories, however it explains why the caudate nucleus as well as the temporal lobe is significantly enlarged. The caudate nucleus is theorized to be involved in obsessive-compulsive disorder, among other things (executive function, memory, slow wave sleep). It is located in the basal ganglia.

8. How this Course has Helped Me While learning this course, I was able to give connections of everyday activities to functions of the brain. Everything I did finally had a neurological reason behind it. Also it was good to be able to basically learn more about the world we live in, and terminate any suspicions I had. This course also sparked a new interest in me, which I will follow to learn more. Using the knowledge from this course, I can better myself at ordinary tasks, as well as new ones. But most importantly, this course has given me the basics of neurobiology, as well as the opportunity to learn more about a much more complex and intriguing subject of science.

9. References http://www.webpronews.com/marilu-henners-amazing-memory-inspired-new-book-2012-04 http://www.ncbi.nlm.nih.gov/pubmed/22519463 http://en.wikipedia.org/wiki/Hyperthymesia http://www.ncbi.nlm.nih.gov/pubmed/24248358 http://www.mylifememory.info/ Henner, Marilu. Total Memory Makeover. Gallery Books, 2013 http://en.wikipedia.org/wiki/Caudate_nucleus#Cognitive_Functions