Even most fearful memories get erased over time: study

June 22nd, 2009 - 11:38 am ICT by IANS  

Toronto, June 22 (IANS) Debunking the traditional view that memories are difficult to erase, a new study shows that even our most fearful memories get erased over time.
Researchers at Montreal-based McGill University have discovered molecular mechanisms that regulate how a human brain recalls, restores and even changes old memories.

This process, called memory re-consolidation, provides clues into how memory works, said a university statement Sunday.

The researchers also identified brain mechanisms that determine whether a memory will or will not undergo re-consolidation.

Led by Professor Karim Nader, the researchers found that even our most fearful memories, which initially don’t undergo re-consolidation, get unwired over time.

“The old theory is that once a memory is wired in your brain, it stays that way. But our discovery shows that once you remember something, it doesn’t stay wired in your brain, it becomes unwired and needs to be restored again - re-consolidation,” said Nader who has previously proved that fearful memories (in experiments on rats) can be chemically erased.

The latest research sheds light on the molecular basis by which the brain controls which memories do and do not undergo re-consolidation.

Nader said: “These findings are very exciting because we have always known that not every memory undergoes re-consolidation. But there was nothing known about the mechanisms that determine when a memory does or does not undergo re-consolidation.

“These findings suggest a neurobiological principle that controls this process. Understanding these mechanisms is crucial because they tell us what has to happen on a neurobiological level in order to turn re-consolidation on and off.

“This is clinically important because in the clinic we want to be able to turn re-consolidation on and off if possible.”

The re-consolidation therapy involves administering a common blood pressure drug, Propranolol, as a traumatic event is recounted. Propranolol partially blocks the re-consolidation of the fear associated with the memory.

The study was published Sunday in the journal Nature Neuroscience.

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