In its moments of wandering, the brain activates its “default mode” network which anticipates the future event through two functions, one constructive and the other evaluative.
- The constructive function makes it possible to create and predict a future event.
- The evolutionary function judges whether this event is positive or negative.
- Two other sub-networks have been discovered and participate in the imaginative capacities of a future event.
When not called upon to solve a task, the brain likes to let go and wander, giving free rein to thoughts. In this case, he likes to look to future events and then activates what is called his “default mode” network. This region has been discovered recently, but its functioning is not well understood. In a study published on May 17 in the Journal of NeuroscienceAmerican researchers have provided more details and revealed two functions of this brain area: one constructive and the other evaluative.
Several parts of the brain involved
These two roles are complementary in the projection towards a future event. The first makes it possible to create and predict a future event, this is the constructive function, while the other assesses whether this event is positive or negative, the evaluative function. “It’s a clean divisionsays Joseph Kable, neuroscientist at the University of Pennsylvania in the United States and director of research. When psychologists explain why humans have the ability to imagine the future, it’s usually so that we can decide what to do, plan, make decisions. But a critical function is the evaluative function. It is not only about proposing a possibility, but also evaluating it as good or bad.”
This default mode network includes several parts of the brain such as the ventromedial prefrontal cortex, the posterior cingulate cortex, and the medial temporal and parietal lobe regions, such as the hippocampus. “When you put people in a brain scan and ask them to do nothing, just sit there, those are the regions of the brain that seem to be active.”, continues the neuroscientist.
Two subnets discovered
To find out, the researchers conducted a study involving 13 women and 11 men. Placed in a functional magnetic resonance imaging (fMRI) machine, they were each given several scenarios, such as “imagine you are sitting on a warm beach on a tropical island” Where “imagine you win the lottery next year”. They then had 7 seconds to read one of them, 12 seconds to think about it and, finally, 14 seconds to assess the liveliness and valence. “Vividness is the degree to which the image that comes to mind has a lot of detail and how much that detail appears subjectively instead of vaguesays Joseph Kable. Valence is an emotional evaluation. How positive or negative is the event? Is it something you want to see happen or not?“Participants performed this operation four times, and each time the researchers observed brain activity using fMRI.
These experiments enabled the researchers to highlight the existence of two sub-networks during the projection of a future event. “One network, which we will call the default mode backbone network, was influenced by the valencedescribed Joseph Kable. In other words, it was more active for positive events than for negative events, but it was not influenced at all by liveliness, which is involved in the evaluative function..” The other subnet, the belly network in default mode, is more active for fast events than for events without details. “But it was not influenced by the valenceadds the neuroscientist. It is also active for events, both positive and negative, showing that the network is really involved in building the imagination.”
Other research already launched
The researchers welcome these discoveries which open a first step towards understanding the basis of imaginative capacities. More complex assessments could offer further clues to this neural process, they point out. The latter have already indicated that they want to analyze the reasons why people do not give as much importance to future results as to immediate results. “One theory is that the future is not as vivid, not as tangible, detailed and concrete as something that lies right in front of us.says Joseph Kable. We started to use our identification of the subnet involved in the construct to ask the question: how active is this network when people are thinking about future outcomes versus the same outcome in the present?”
