A Brief Introduction to the Default Mode Network

Hans Berger, inventor of the electroencephalogram was one of the first people to theorize that the brain remains perpetually active, even across a wide variety of mental states. Whether we are awake, sleeping, focused or daydreaming our brain is always hard at work. Obviously, there are key differences between these states both physically and subjectively. But how do these differences translate into brain activity? Recent fMRI investigations have shown consistent patterns of activations in people's brains when they are awake (but resting) and this has been deemed the "Default Mode" or "Resting State" network. This animation explores some relevant theories theories its activations and potential applications of the research.

Music by Ehma (2004) available under Free Art License
http://blane-est.net/ehma/?page_id=133

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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 brain regions

actually increase in activity
whenever we are not 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 buried out your day.

Another theory posits
that the network's activity

is the brain's baseline of processing
and information maintenance.

Separate from conscious thought,

these activations 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 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.