Progress on Memory Erasure Mechanisms?
Scientists at the Centre National de la Recherche Scientifique have published a paper in Nature Neuroscience describing their success in erasing the memories of traumatic incidents in rats without damaging other associated memories. The research is intended to help develop therapeutic regimes for Post Traumatic Stress Disorders. Cordis reports that,
…researchers trained rats to be frightened of two distinct sounds by playing the sounds and then sending an electric shock to their paws. The next day, half the rats received a drug which is known to cause amnesia for events recalled from memory, and the researchers played one of the sounds again.
On the following day, the researchers again played both sounds to all the rats. They found that the animals who had not received the drug were still frightened by both sounds. However, the rats which had received the drug were no longer disturbed by the sound they had heard while drugged. By playing one note and prompting the recall of the electric shock memory while under the influence of the drug, the traumatic memory was erased. However, the memory of the shock associated with the other note remained intact. [Cordis]
The mechanism and interpretation are summarised in the paper as the following sequence:
… when reconsolidation is disrupted, a reduction of potentiation at thalamo-amygdala synapses is observed, but only to the tone presented during reactivation. This in turn suggests ‘de-consolidation’ of the fear memory trace in the lateral amygdala; that is, possibly an erasure of initial encoded plasticity. These findings provide the neurophysiological basis for content-limited modifications during the updating of fear memories. They also lend some validity for therapeutic use of agents that disrupt reconsolidation to reduce the fear-arousing aspects of emotional memory in post-traumatic stress disorder, as such treatments may have highly specific and potentially permanent effects. (D
biec,
- Doyère, V., Dbiec, J., Monfils, M-H., Schafe, G.E., LeDoux, J.E. (2007) “Synapse-specific reconsolidation of distinct fear memories in the lateral amygdala“. Nature Neuroscience 10, pp414 - 416 Published online: 11 March 2007; doi:10.1038/nn1871
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