Research press release


Nature Communications

Neuroscience: A new mechanism for forgetting


今回、Justin Hulbertたちは、381人の参加者による7つの実験で記憶想起の研究を行い、最近の出来事が忘れられてしまう機構を解明した。この実験で、参加者は、関連した一対の単語(例えば、「跳躍」と「バレエ」)を記憶する課題を行った。また、参加者に対しては、コンピューターの画面上に一方の単語が表示された後、それと対になる単語について考え、あるいは考えないように指示した。この実験では、ありそうにない出来事(駐車場にクジャクがいること)の画像が、時々コンピューター画面上に表示された。次に、特定の写真の背景部分を自動的に表示し、そこに写っていた物体を参加者に思い出させるという内容の記憶想起の検査が行われた。



Trying to suppress memories of past events leads people to forget unrelated experiences from periods surrounding the time of suppression, reports a study published online in Nature Communications. These findings could help explain memory lapses following traumatic events.

Justin Hulbert and colleagues elucidate the mechanism through which current events may be forgotten by studying memory retrieval in 381 participants across seven experiments. The participants were asked to memorize word-pair associations (such as ‘leap-ballet’). After the first word in the pair was displayed on a computer screen, they were instructed either to think of or suppress the thought of the second word. Occasionally, during the trials, pictures of improbable events were displayed (for instance, an image of a peacock in a parking lot). Subsequently, memory retrieval was tested by displaying the background of a given picture on its own and asking participants to recollect the object associated with it.

The authors found that the instruction to suppress the memory of words also made it harder to remember details about objects presented shortly before or after reminders of the to-be-suppressed words. They also used magnetic resonance imaging to scan brain activity of participants during suppression and showed that the impairment of memory formation was directly correlated with the degree of reduced activity in the hippocampus - a brain region known to be essential for the formation of new memories - as well as with the degree of activation in the lateral prefrontal cortex.

These results identify cognitively-triggered amnesia that begins with the voluntary suppression of an unwanted memory as a new mechanism for forgetting. This mechanism may help explain the memory deficits observed in patients suffering from post-traumatic stress disorder or other acute trauma.

doi: 10.1038/ncomms11003

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