Different parts of the brain get activated when we perform different tasks. But what happens inside the brain when we are not doing anything?
Previous studies have shown that when the brain is at rest a network called the “default mode network” (DMN) gets activated. This network is associated with daydreaming, thinking about the past, planning for the future and creativity. The precise function of this network has been unclear, although abnormal activity in this region is linked to various disorders such as Alzheimer’s disease, schizophrenia, attention-deficit/hyperactivity disorder (ADHD) and disorders of consciousness.
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Scientists have not been able to decipher the role that DMN plays in human cognition – until now.
Researchers from the University of Cambridge conducted a study which involved 28 volunteers. They took part in a task while lying inside a magnetic resonance imaging (MRI) scanner.
In the task participants were shown four cards and were asked to match a target card such as two red diamonds. They could match by colour, by number or by shape. However the volunteers were not told of these rules and had to work it out by trial and error.
Interesting differences were noted between two stages – acquisition (where the participants were learning the rules by trial and error) and application (where the participants had learned the rule and were now applying it).
During the acquisition stage, the researchers noticed that the dorsal attention network – associated with the processing of attention- demanding information – was more active. However during the application stage, the DMN was more active.
During this stage, the researchers noted that the stronger the relationship between activity in the DMN and in regions of the brain associated with memory, such as the hippocampus, the faster and more accurately the volunteer was able to perform the task.
This suggests that volunteers could perform a task more efficiently by utilising rules from memory.
The scientists suggest that rather than waiting passively for things to happen, the brain is constantly trying to predict the environment around us and this is possible due to the DMN which acts as an autopilot and enables us to make fast decisions when we know the rules of the environment we are in.
For example when we are driving on a familiar route in the mornings, the DMN kicks in and enable us to perform the task without much effort in making every decision.
It seems that the “daydreaming” network plays an important role in enabling us to perform task on autopilot.
This research has important implications in the understanding of healthy brain processing and its relevance in brain injuries especially those where problems with memory and impulsivity can compromise social reintegration. The finding may also help those with mental disorders such as addiction, depression and obsessive compulsive disorder, where particular thought patterns generate repeated behaviours.
The human brain never ceases to amaze us in how it functions and new discoveries like this help us understand how the healthy brain adapts and processes information which enables us to function effectively and productively, even when we are daydreaming.
Source: Proceedings of the National Academy of Sciences
