Anaesthetic numbs memory14th April 2008
A team of researchers in the United States has found that low doses of a commonly-used anaesthetic could prevent the formation of painful memories.
Sevorflurane gas stopped patients remembering images associated with difficult emotion by interfering with signals between two key areas of the brain.
The findings may be of use in helping to eradicate painful memories of surgery in the rare cases where patients remember what happened in spite of anaesthesia.
Writing in the journal Proceedings of the National Academy of Sciences, the researchers from the University of California said they had discovered an agent and method for blocking human emotional memory.
The team investigated the outcome of much lower doses of the gas than those used prior to surgery, treating volunteers either with the anaesthetic, or a placebo gas, and then showing them a series of photographs.
Some of the photographs were emotionally 'neutral', while others were far more powerful, eliciting an emotional response.
Volunteers were asked to recall as many of the images as they could a week later. The placebo group remembered approximately 29% of the powerful images, and 12% of the others.
Those who had received sevorflurane could remember just 5% of the "emotive" images and 10% of the others.
The gas appeared to interfere with impulses between the amygdala and hippocampus, areas of the brain known for their involvement in the processing of emotion and memory, according to brain scans of the sevoflurane group.
The researchers said their work might provide clues to "intraoperative awareness" - rare instances in which the memory-disrupting qualities of anaesthetic drugs fail and patients can recall the experience of undergoing surgery.
Anthony Absalom of Cambridge University, said approximately one in 5,000 patients reported remembering details of operations, something experts had struggled to understand.
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Title: Anaesthetic numbs memory
Author: Luisetta Mudie
Article Id: 6328
Date Added: 14th Apr 2008