The Illusion of Memory

(Thought-Random)

Excerpts from a CBC news item on Health

A memory might seem like a permanent, precious essence carved deep into the circuits of the brain, but it is not. Instead, scientists are discovering that a memory changes every time you think about it.
"Every time you recall a memory, it becomes sensitive to disruption. Often that is used to incorporate new information into it." That's the blunt assessment from one of the world's leading experts on memory, Dr. Eric Kandel from Columbia University.

And that means our memories are not abstract snapshots stored forever in a bulging file in our mind, but rather, they're a collection of brain cells — neurons that undergo chemical changes every time they're engaged. So when we think about something from the past, the memory is called up like a computer file, reviewed and revised in subtle ways, and then sent back to the brain's archives, now modified slightly, updated, and changed.

"The memories can become unstored and have to be restored. And when they're being restored, it's an opportunity to either strengthen them, change their content to possible false memories, or weaken them," McGill University lab researcher Karim Nader said. "And if you weaken them, essentially it's the same as erasing memories."

"The old view of memory processing was that our memories got stored in the brain and once they're stored, you can't touch them," Nader said. But scientists now realize that memories are evolving all the time. "Every time someone recalls a memory, it's a chance to change it," Nader added.
That's because the memory has to be restored using a biochemical pathway that is very similar to the original storage. And there are ways to interfere with this memory "reconsolidation" using a drug. "You have to change the strength of the connection between neurons. It's almost like you've unwired the memory," Nader said.

For some, the idea that memories are unstable is an unsettling concept. But Eric Kandel says understanding the biology of memory doesn't dehumanize it.
"This does not take the magic out of it," Kandel said. "You know that your heart is a muscular pump that pushes blood around the circulation, but that doesn't mean you can't lose your heart to somebody. The metaphorical meaning is not in any way altered, but there is a biological underpinning to what the brain actually does."
"The modern view is that everything you and I do, from the most simple reflex act of hitting a racket in tennis to the most creative flights of ideas, comes from the brain," Kandel said. He won the Nobel Prize in 2000 for his research on the biological basis of memory. "You are who you are and I am who I am because of what we learn and what we remember and these are all biological processes," he said.

Understanding the neurochemical process of memory opens up possibilities for therapy in situations where memory is causing pain.
"People think that post-traumatic stress disorder might be susceptible to treatments of this kind. No one has shown this in a convincing way. But this is certainly an interesting avenue of investigation," Kandel said.
"There are many disorders of memory. Obviously, age-related memory loss, Alzheimer’s disease, schizophrenia, working memory loss, PTSD which is a hyperactivity of memory if you will," he explained.
Nader believes memory disruption could be helpful in a wide range of psychiatric disorders. He is collaborating with other researchers on drug addiction, and others are investigating the implications for obsessive compulsive disorder (OCD).

Other research has suggested that it might even be possible to block the memory reconsolidation without drugs, by asking a person to remember something and then, in those moments of remembering, replace the old memory with new information.  "Every time you remember something, it's an opportunity to change the content of it, that's just the way the brain is."
Karim Nader agrees that memory is much more transient than most people think.
"Yes, but that's not to say it's bad," he said. "The fact that memory turns out to be far from permanent is a positive thing for human survival. Evolution thinks it's the best way for it to work. Therefore, it's not a bad way. If it was a bad way, then we would have been extinct a while ago."


This is the conclusion of a four part series called Inside Your Brain on CBC's The National, World at Six and CBC.ca exploring how modern neuroscience is changing the way we think about the way we think.