Remember that one time when.....

How much of our personality, our soul, is composed of our memories?  I think who we are stems from what we've done and how we've learned from those actions.  But imagine an existence where you could no longer form memories.  This is the situation faced by neurological patient H.M.- now know as Henry Molaison.

Henry Molaison passed away in 2008.

Henry suffered from debilitating seizures caused by tissue in his temporal lobes.  Historically, patients before him had undergone surgery to remove the epicenter in the brain that caused the seizures and this usually solved the problem.  But for Henry, the seizures were caused by 2 epicenters- one on each temporal lobe.  So when surgeon Scoville removed the defective tissue in 27 year old Henry Molaison, he had to take large portions from both sides.

But a strange thing happened when Henry recovered from his surgery.  He was no longer able to form new memories.  Semantic information (facts and dates) from before his surgery was untouched but when it came to recalling simple episodic information (like what he had eaten for breakfast), he couldn't recall a thing.

Neuroscientists Brenda Milner and Suzanne Corkin took on the case of H.M. in the hopes of learning more about memory and its storage in the human brain.  They found that the hippocampus, which was almost completely removed, is vital for processing memories.  You could view it as a sort of clearing house where short term memory gets transferred into long term storage.  But without this structure, Henry could no longer process his memories.  In other words, he was forever stuck in the mindset of his 27 year old self.

Hi-lighted in yellow is the portion that H.M. lost.

A similar deficit was found in a Korsakoff's syndrome patient mentioned by Oliver Sacks in his book The Man Who Mistook His Wife for a Hat.  This man was also unable to form new memories, leaving him trapped in a time that has already passed.

Now while there are some technical differences on the types of memories and amount of retrieval between these patients, they both hold an amount of melancholy in my mind.  To be deprived of the ever changing world.  To be able to grow and expand.  These two men lost so much.

I am a firm believer that our genetics set the blue print but our experiences are really what make us unique. And our capacity to change is what makes us so fantastic.  My heart goes out to these two men and all who suffer from anterograde amnesia.  It's a hard world to imagine.

But what about you?  Would you rather suffer anterograde amnesia (where you can't form new memories) or retrograde amnesia (where you can't remember your past from a certain point back)?  It's no easy choice.