The Default Mode Network

A particular topic of interest to me as of late is the Default Network, or Default Mode Network (DMN) - as I have more commonly heard it. It seemed fitting to write something about it, since it's been on my mind... haha... get it... anyway.

Here's some general information about the Default Mode Network that I have found interesting and informative.


Structure of the DMN:

Left and Right Inferior Parietal Lobes, Posterior Cingulate
Cortex, and the Medial Prefrontal Cortex.
Photo from ScienceNews. Korenblat,

For a long time, it was assumed that various parts of the brain just stopped functioning and there was essentially a great deal less brain activity when someone enters their daydreaming world. More recently, however, cognitive researchers are discovering that this previous belief is incorrect. When parts of the brain stop functioning, new areas become active. These areas are now being identified as the Default Mode Network. While the areas are under debate, there is a general acceptance that the Posterior Cingulate Cortex (seen in photo) plays a key role. The Posterior Cingulate Cortex is involved in human awareness and retrieval of episodic memory. There is also some speculation that it may help us understand what other people are thinking/what they believe and value, which would make sense considering its involvement in a daydream network. Another area involved in the DMN is the Medial Prefrontal Cortex.
This region of the brain is involved in decision making and social behavior (among other things). Additionally, there are regions in the Parietal lobes that are implicated in the DMN. The Parietal lobe deals with sensory perception and comprehension.

Interesting information, certainly, but what does this all really mean? Researchers are starting to look into the applications of the DMN in many aspects of life. I've gathered a small fraction of this research and decided to share it here.

Happiness Level and its relation to the DMN:

Most people have experienced a time where they were completely absorbed in an enjoyable task and time just flew by. For those who can recall this feeling, this seems to be a moment of ultimate happiness and fulfillment. During these times, the DMN has shut down and other regions of the brain are active. Conversely, most people have also experienced a time when they were bored and unable to focus on anything because their mind would "wander." Those times would be an example of when the Default Mode Network is very active. Generally, when the DMN is active, the daydreams aren't the most pleasant. Human beings think about concerns and replay scenarios, wondering what they could have and should have done differently. According to Westly (2011), when participants in a Harvard study reported that their thoughts were wandering, their mood was lower than when they were distracted with something that required mental processing (pp. 9).

What could this mean for mental health? Well, when it comes to depression it could mean that people who are depressed have a more active DMN than people who aren't. People who have a melancholic outlook on life may not have much to distract them in life, or at least enough to get their full attention, so their DMN is more active. It's not clear is this structure int he brain is influencing depression or if it might be the other way around, but there does seem to be a correlation that could use some further investigation. Healy (2010) explains that there might be some relation to other psychiatric disorders, such as PTSD, schizophrenia, and autism. Further research on the DMN could prove helpful to diagnoses of these disorders and potentially others as well.

Childhood Development:

I'm sure a lot of you would agree with the suggestion that there are few things more annoying than someone else's screaming child in the grocery store or a restaurant. I've always thought of it mostly s poor parenting skills, but my theory may not be entirely correct. According to Labr (2011), researchers are finding that the Default Mode Network is not developed in children, until about age 13. A study was performed by the Georgetown University Medical Center that measured arousal in the brain of participants while they were inside an fMRI. The participants (ages six to 27) were instructed to participate in a simple game while in the machine that required them to mentally search for an anomaly in a photo. What the researchers were looking for, however, was what happened in the brain while the participants were not playing the game. In the adolescents and adults, certain areas, which we now identify as the DMN, become active when they were allowing their thoughts to wander and daydream. In children, however, these areas were not active, implying that the DMN had not yet developed (pp.14).

See sources for photo credit

Since children haven't fully developed the DMN, they likely cannot understand that their behavior is socially unacceptable. They aren't able to see themselves in the scenario, and therefore are not uncomfortable acting out.

But, if I may defend my own theory of poor parenting- while the children aren't able to understand that their behavior is socially unacceptable, they should be able to comprehend that a parent would disapprove of the behavior. Regardless of their view of the world, consequences can be comprehended, and outrageous behavior seems like it could still be avoided, if not reduced (but those are just my thoughts).


So, what does all of this really mean for us? 

Daydreaming has its benefits (namely sparking creativity and providing motivation for the future), but it can also have consequences (like distractions and becoming preoccupied with a time other than the present). When you truly find something that grabs your attention, time goes by quickly and you can truly enjoy living in the moment. If you have experienced this, you know how appealing that glimpse of time was. It's possible you may even find yourself day dreaming about that activity or point in time.

Happiness is a difficult thing to define, but I believe it is when the Default Mode Network is completely shut down. For me, I find happiness in moments where I can emerge myself in research. Case in point, it's after 2:00am right now, but I'm wide awake and keep writing even though my readers are probably about ready for me to stop.

So, understanding the DMN a bit more may help us understand a bit more about happiness, which is what we all really want, right?

I'm sure I'll have more on this topic in the future.

Cheers!

Sources:

• Healy, M. (2010, August 30). Brain's Default Mode Network May Hold Key to Better Psychiatric Diagnosis. Los Angeles Times. Retrieved June 23, 2011, From: http://www.latimes.com/health/la-he-brain-side-20100830,0,5044867.story
• Jabr, F. (2011, March/April). Blissfully Unaware. Scientific American Mind, 14.
• Westly, E. (2011, March/April). Lose Focus, Lose Happiness. Scientific American Mind, 9.

Photo Credits:

• Korenblat, J. (2009, July 18). Wandering and Wondering. ScienceNews, vol. 176 #2. Retrieved June 23, 2011, From: http://www.sciencenews.org/view/access/id/45263/title/Wandering_and_wondering_
• Thedeets. (2007, April 20). Reactionary Grocery Store Signs. The Deets. Retrieved June 23, 2011. From: http://www.thedeets.com/wp-content/uploads/2007/04/466169614_3cb9c6e4b8.jpg