A Brief Introduction to the Default Mode Network

  • Published1 Jul 2011
  • Reviewed1 Jul 2011
  • Author
  • Source BrainFacts/SfN

The brain remains active while we are awake, sleeping, focused, or daydreaming. In a submission to the 2011 Brain Awareness Video Contest, Thomas Sprague, student councilor at California’s Escondido High School, and Cristina Tortarolo, research associate at NCIRE — The Veterans Health Research Institute, offer some theories about what the brain could be doing during these times.

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What’s going on inside your head when your mind wanders? While it may feel like flipping on a screensaver, our brain is still very much at work. In fact, a particular group of our brain regions actually increase in activity whenever we aren’t focused on a task. This is known as the default mode network. And the functional connections typically include the medial prefrontal cortex, medial parietal cortex, and medial temporal lobes. There is still much debate as to what these cortical associations mean—if anything at all. 

One theory implicates them in introspection and mind wandering, essentially our stream of consciousness. This includes any thoughts not directly associated with the immediate external environment. Much of our waking hours are composed of stimulus independent thought, whether it be daydreaming, planning out our future actions, revisiting memories, or just listening to yourself narrate out your day. 

Another theory deposits that the network’s activity is the brain’s baseline of processing and information maintenance. Separate from conscious thought, these activations would represent how our brains consolidate experiences and prepare to react to the environment. We’re exposed to a constant stream of information from our surroundings. So maybe the default mode network activations are somehow in charge of making sense of it all. But even though neuroscientists haven’t completely agreed on what the default mode activations mean, it’s clear that resting state research is bursting with potential and applicability. Various psychological disorders including ADHD, Schizophrenia, Autism and Alzheimer’s exhibit different types of abnormal functioning in the default mode network. 

In the end, there are many interesting directions to take resting state research. From picking apart the neural correlates of consciousness, to uncovering better ways to detect, understand and maybe even treat psychological disorders.