Back to the Future: The Mental Time Machine

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Science Translational Medicine  31 Oct 2012:
Vol. 4, Issue 158, pp. 158ec195
DOI: 10.1126/scitranslmed.3005203

The distinction between the past, present and future is only a stubbornly persistent illusion. Albert Einstein

Not all time travel requires a DeLorean. Mental time travel, the capacity to remember the past and imagine the future, develops in children as early as 3 to 5 years of age. Yet, we know relatively little about how the brain performs these functions in children and adolescents. Now, Ostby et al. have evaluated the neural basis of memory formation and imagination in a group of 103 typically developing children and adolescents between the ages of 9 and 21 years.

To test for individual differences in the subjective quality of memories, the authors began by testing their subjects with a recall–imagination cue-word task, where the children were asked to either remember past events or image future events related to a particular cue-word. Neuroimaging was then performed on a separate day—to ensure a resting state separate from the recall-imagination task. Interestingly, the functional connectivity of this so-called default-mode network (resting state connectivity) correlated with the quality of past remembering as well as marginally to future imagination in children and adolescents. These results support previous studies that suggest there is a common neuronal substrate for memory and imagination, and provide evidence that when children travel mentally in time, they use task-independent areas of the brain. An advanced analysis of brain structural area showed that the way in which the brain is structurally organized also contributed to recall of the past and imagination of the future. These findings underscore the benefits of studying both functional and structural properties to understand the brain basis for complex human cognition.

These results demonstrate brain characteristics that govern complex cognitive processes in healthy developing children. A prospective evaluation would enhance understanding of how memory functions develop over time and would provide additional information about the interactions between brain structure and function related to memory and imagination. Nevertheless, these authors demonstrate the benefits of a multimodal neuroimaging approach for understanding the neural basis for individual differences in complex human cognitive processes—and they didn’t even have to accelerate to 88 miles per hour.

Y. Ostby et al. Mental time travel and default-mode network functional connectivity in the developing brain. Proc. Natl. Acad. Sci. U.S.A. 109, 16800–16804 (2012). [Online Journal]

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