Previous work had established that emotion-associated enhancement of memory is caused, at least in part, by the action of stress hormones, in particular norepinephrine, on a part of the brain called the amygdala. He wondered if a similar mechanism was at work in the emotion-associated memory loss the team discovered.
The action of norepinephrine on the amygdala can be blocked by a drug called propranolol. When the researchers repeated their experiments on volunteers who had been dosed with this drug, they found, as expected, that those volunteers did not remember emotional words any better than neutral ones. In addition, however, they found that memory for neutral words which preceded emotional ones improved.
This comment, a small aside in an article on memory and emotion, woke me up. Beta blockers (propranolol, atenolol, etc) are very widely used medications. I'd never heard that they blocked norepinephrine action on the amygdala. I'd expect that to have an intriguing range of longterm neuropsychiatric actions. I'd love to see the full list.
On the other hand propranolol is an older beta blocker. The more common modern versions do not cross the blood-brain barrier as readily and might not have the same effects.
This is a good reminder, however, that the body uses the same substances and receptors to do very different things. The interpretations of the same substance/receptor combination depend on location (gut, brain, heart, etc). Actions on the brain may be the most subtle least appreciated of these. ACE inhibitors, for example, seem to have antidepressant or pro-euphoric activity, as well as inducing coughing in many people. I've long wondered what the longterm neurobehavioral effects of oral contraceptives have been...
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