Scientists block fear response in human volunteers

March 12th, 2009 - 1:01 pm ICT by ANI  

London, March 12 (ANI): Dutch researchers have successfully reduced the fear response in human volunteers by administering them the beta-blocker propranolol.
The study carried out by Merel Kindt, Marieke Soeter and Bram Vervliet at the Universiteit van Amsterdam showed that the weakened fear memories did not return over the course of time.
While it has been thought to date that it was impossible to deleted the fear memory, Klindt’’s work has shown that changes can indeed be effected in the emotional memory of human beings.
The researchers point out that there is a temporary labile phase before fear memories are stored in the long-term memory, during which protein synthesis takes place that records the memories.
They say that the traditional idea was that the memory is established after this phase and can no longer be altered, reports Nature magazine.
They, however, add that a labile phase once again occurs when memories are retrieved from the memory, and that they managed to successfully intervene in that phase.
During the study, the researchers showed images of two different spiders to the human volunteers: one of the spider images was accompanied by a pain stimulus, while the other was not.
The team said that the volunteers showd a fear response upon seeing the first spider without the pain stimulus being administered, and the anxiety for that spider had therefore been acquired.
The fear memory was reactivated a day later, due to which the protein synthesis occurred again.
The researchers revealed that the volunteers were administered the beta-blocker propranolol just before the reactivation.
According to them, the volunteers who had been administered propranolol no longer exhibited a fear response on seeing the spider even on the third day, unlike the control group who had been administered a placebo.
The group that had received propranolol, but whose memory was not reactivated, still showed a strong fear response.
After the treatment with propranolol and memory reactivation, fear memories could no longer be recalled by means of a much-used method in which the individual pain stimuli are re-administered.
Kindt has revealed that her team would next investigate the long-term effects of administering propranolol, as they believe that their findings may contribute to a new procedure for the treatment of patients with anxiety disorders.
The study has been published in the journal Nature Neuroscience. (ANI)

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