Memory and Forgetting

Listened to Memory and Forgetting, a Podcast in Radio lab. How memories are formed, stored and retrieved in our brain. The easy way to think about memory is by comparing it with computer hardware. The memory stored as binary digits or yes and no (1 and 0). The file cabinets with various memories. But the reality is much complex than that. Studies in LeDoux lab shows memories (in Rats can selectively erased). They make use of Pavlovian reflex in rats. First animals will be exposed to a sound followed by an electric shock. After a while when the animals hear the sound they freeze out of fear (with the expectation of the shock that follows). Injection of anisomycin (protein synthesis inhibitor) to lateral amygdala after training inhibited fear towards the sound. More interestingely another group of animals were conditioned with two different sounds followed with electric shock. After training to one of the sound(retrieval of memory a while after training) the injection was given and animal forgot the fear feeling associated with that sound whereas the fear associated with other sound was intact. It shows the memory to different reflexes, although formed simultaneously, are stored seperately in same part of brain.

They also discuss several interesting aspect of memory. For example one can implant false memory into once brain. Dr. Elizabeth Loftus explains that with proper set of questions and recreation of a particular experience you can meke one believe that a particular incident have happened in ones life. It challenges the validity of eye witness.

Another part of the show describe the story of Clive Wearing, a British musician afflicted with anterograde and retrograde amnesia. He was contracted with Herpes simplex encepalitis virus, which resulted in loss of memory. He is unable to remember any thing more than 7-15 min and have no recollection of any thing that happened in the past. But there are certain aspect of memory that is intact. For example he can still play Piano although he does not remember learing it. It shows the procedural memory (Implicit memory: aquired skills and tasks peroformed with out being too conscious about it, for example riding a bycycle) is intact. He loves and recognize his wife althoug he does not remember her name.

So, different types of memories are stored at different parts of the brain. Another patient of amnesia visit doctor every week. The doctor has to explain everything time who he was and why she is there etc. One day the doctor hid a pin in his hand and while shaking the hand gave a prick on the palm. Next time she visited him he greeted her and explained as usual but when he reached out his hand she froze. It was surprising because she can not remember anything about the Doctor who he was and why was she meeting him, but she could recognize a threat, suggesting the survival instinct is stored some other part of brain.

Brain, the final frontier of science. The basic biology research may not be sufficient to uncover the secrets of brain. Its too complex for that. Who knows how it works and how it reached todays form and how is it going to be like tomorrow?