Brain scan images courtesy of Dr. Vadim Axelrod .
(photo credit: Courtesy)
Researchers at Bar-Ilan University are bringing us closer to understanding memory: how we can vividly recall an episode from childhood; remember what we did just five minutes ago; imagine and plan in detail our next vacation; and be moved to tears by the story of an absolute stranger or even a fictitious character.
Our versatile brain makes possible an enormous number of diverse internal experiences, but until now scientists have not had much of a clue about how it accomplishes this. The study, published in the British journal Nature Human Behaviour, was carried out by Dr. Vadim Axelrod and Prof. Moshe Bar, from Bar-Ilan’s Gonda (Goldschmied) Multidisciplinary Brain Research Center, along with Prof. Geraint Rees from the Institute of Cognitive Neuroscience at University College London.
“We have a subjective impression that each of our internal experiences is a unitary, indivisible entity. Yet the brain, according to prevalent view in the scientific community, realizes each of our experiences through a combination of different components,” said Axelrod, the principal investigator at the research center and lead author of the paper. “When we recall a recent birthday party, for example, the brain likely activates a number of different systems such as a system responsible for retrieving memory of events, a system responsible for building a vivid scene in our mind, and one responsible for moving back in time. In our study we aimed to test this hypothesis.”
The researchers scanned 41 healthy volunteers using functional MRI. The participants took part in four different experiments. Three of the experiments were used to identify three brain systems. The main result showed that these three systems were simultaneously active during the fourth experiment. The researchers thus showed that internal experiences, such as recalling personal memories, are associated with the simultaneous activity of different cognitive systems.
They found it possible to see separate components of internal thoughts – by seeing increased blood flow to activated areas of the brain – while participants as they were lying in the MRI with their eyes closed, recalling their personal lives. “Obviously, our internal experience is mediated by much more than three cognitive systems. We hope that the approach we used will help in the future to identify additional systems,” the scientists wrote.
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