When Associate Professor Donna Rose Addis gets study participants to imagine – for example, their dad in a laser tag park with an inflatable boat – she finds a surprising thing. The more variable their brain signal, the better the story the participants tell. The University of Auckland Associate Professor explains how a Marsden grant has helped her start to figure brain flexibility out.
How do you get people to imagine such crazy scenarios?
We first have participants recall 100 memories; in doing so, they generate information about people they know, places they have been and objects they have encountered. We then mix up these details, which sometimes results in weird combinations! Participants then imagine a future scenario involving these details – and depending on the nature of the combination, the resulting imagination could be really plausible or quite bizarre. In manipulating how incongruent the details are, we can tax the imagination system to different degrees.
That sounds fun. But why do you want people to imagine the future?
Imagination is adaptive as it allows us to plan and potentially enhance our future behaviour. Our first Marsden grant investigated the brain regions involved in imagining, which uses many of the same brain regions needed for remembering. Interestingly, the hippocampus – a canonical memory brain region – is actually more active when we imagine than when we remember.
Is imagining like remembering because we need our memories to make up stories?
One hypothesis is that the hippocampus forms memories of these mental simulations. This is important because mental troubleshooting can enhance our ability to deal with situations only if we can remember our plan when faced with the situation. We found that the hippocampus is more active when we simulate future events that we can later recall. However, the hippocampus is also very responsive to novelty, and we often imagine things that have not happened before. By manipulating how disparate the details comprising an imagination are, we can get a window into how the hippocampus responds to novelty.
You must hear some pretty hilarious scenarios…
You’d be surprised at how good people are at constructing stories even when the detail combinations are a little bizarre. Perhaps this is because humans are natural story tellers. Even so, there are certainly individual differences in imagination, and our current Marsden is investigating why some people can think in a much more flexible manner. Our hypothesis is that the ability to imagine is related to the variability in brain signal. This is a really novel idea, as most brain imaging studies examine the average signal (that is, how much activity a particular area brain shows). But brain variability focuses on how much activity in a brain region shifts around, moment-to-moment, the idea being that if you have high brain variability, then your brain is optimally placed to shift quickly in response to any change in the environment. Interestingly, brain variability peaks in your twenties, when cognitive function and reaction times are at their peak, and it then declines with advancing age. If your brain shows high variability, you should be able to switch quickly between cognitive states and explore multiple ideas, which in turn should enhance the ability to make links between disparate ideas – a process critical to imagination.
Can I help my brain become more flexible?
We don’t yet have results from our brain variability study, but we hope to establish whether task-switching abilities and/or divergent thinking are associated with brain variability. This may lead to the development of training tasks or interventions that could be used to improve your mental flexibility and brain variability – something to imagine for the future.
These interviews showcase researchers supported by the Marsden Fund which, since 1994, has been supporting fundamental, investigator-led research in New Zealand.