Brain researchers at Bar-Ilan University have brought us closer to understanding the phenomenon of how humans vividly recall an episode from childhood, what we did just five minutes ago, how we imagine and plan in detail our next vacation and how we are moved to tears by the story of an absolute stranger or even of a fictitious character.Our versatile brains make possible an enormous number of diverse internal experiences, but until now, scientists have not had much of a clue about how they accomplish this.The new study, published in the journal Nature Human Behaviour, was carried out by Dr. Vadim Axelrod and Prof. Moshe Bar from Bar-Ilan’s Gonda 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 the 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 the memory of events, a system responsible for building a vivid scene in our mind, and the one responsible for moving back in time. In our study, we aimed to test this hypothesis.”The Ramat Gan researchers scanned 41 healthy volunteers using a functional MRI. The participants took part in four different experiments. The authors used three of the experiments to identify three brain systems.The main result was that these three systems were active at the same time 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 of the participants as they were lying in the MRI with their eyes closed and 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 summarized.