Brain Must-Knows: The Default Mode Network
Is This Our Source Of Overthinking?
Learning more about brain anatomy was a game-changer when it came to improving my mental health and navigating life.
Moment-to-moment, day to day, and year to year, the machine with which we navigate life with is our brain. It’s the thing that allows us to think; it supports our bad habits and simultaneously helps us overcome them. As much as it can help us, it can also lead us astray. Which is why understanding it’s different parts and their functions can help us.
And yet, many of us are undereducated on how it works. Walking in the dark, wondering why we do what we do or how we can overcome a particular problem, not realising that the answer can be found within.
This isn’t to say we must know everything about our brains, mind you. That is an impossible task and something neuroscience is still trying to achieve. The brain houses approximately 100 billion neurons that communicate with one another via an array of pathways and chemical messengers (neurotransmitters) with extremely complex interactions. It’s no easy feet to understand it.
That being said, neuroscience has come a long way and behavioural scientists are now beginning to understand with increased depth the relationship between our brain and us.
For example, we can say with good confidence that our amygdala, a pair of almond shaped nuclei, serve a key role in fear generation. One study I found took an individual with amygdala damage around a haunted house. They showed them evocative films and exposed them to spiders/snakes without any success of generating a fear response.
When we know our brain’s work we understand ourselves more. As our brain’s are highly adaptive, we can strengthen brain areas with targeted-daily practices (more on this later) which in turn can positively impact how we function in every-day life.
But that’s enough of an intro. I imagine you can see the significance in understanding our brain more. Which is why I wanted to mention a brain area which I find gets little spotlight in comparison to other brain regions (amygdala, pre-frontal cortex).
I wanted to talk about the default-mode-network today: what it is, how it’s function imapcts us, and how we can work with it’s supposed function to improve our lives.
The Default-Mode-Network: An Overview
Whilst the amygdala is one area of the brain, the default-mode-network, or the DMN as I’ll call it from here, is a series of brain structures that are believed to be highly-interconnected and show distinct patterns of activity between resting and engaging states.
For example, when focused on a task — like I am right now, in a state of flow as I write — , our brain’s default-mode-network tends to display little activity. However, when we are resting and supposedly not doing anything at all, the brain areas corresponding to the proposed DMN light up.
This was often seen in scientist’s studies on brain-states, as control participents would be told to rest in a scanner as a means to compare healthy control brain’s with those suffering from PTSD, depression, or other mental ailments. We know any brain area displaying activity corresponds to a particular use; like our amygdala lighting up when we become anxious, so there must be some significance to the DMNs activity suddenly coming online when asked to rest.
As it turns out, there’s a whole lot we are doing when supposedly at “rest”. Thinking about the past, worrying about the future, thinking about what we’ll make for tea tonight or how awful we were for doing that thing we regretted last weekend when we were drunk… when our focus is taken away from the task at hand it seems out brain’s “default” instinct is to begin thinking.
This tendency to start thinking when we aren’t doing anything coupled with an increased activity in the DMN is a strong indication that the two may be connected. Our default-mode-network, as it turns out, may be responsible for what scientists call “mind wandering”, our almost insticive behaviour to start thinking about stuff when our minds aren’t thinking about anything else.
The Wondering Mind As A Source of Pain
In summary of the above, the brain’s default-mode-network (DMN) may be responsible for our ability to think passively about our life. Psychology today describes it’s functions as “self-focus and mental time-travel”.
This reflective thinking also appears to be our standard way of operating — our “default” as it is aptly named. When at rest, our brain instinctively moves into self-directed thinking mode, subsequently activating key brain areas.
But why is this important? What can we learn from knowing of a brain area that is associated with passive thinking?
Knowing about the DMN is important to know as many of our mental health ailments stem from, and are perpetuated by, our tendancy to think negatively about ourselves, and our life.
In this, we may not want to think so negatively about our lives and yet our brain churns out thoughts like a hamster on a wheel. Initial thoughts turn into ruminations which turn into anxiety spirals and depressive episodes. So painful can these internal dialogues be that many people would rather dissociate through the consumption of toxic substances and unhealthy behaviours. Anything to stop us from giving ourselves the space to sit and reflect.
To back this up, dysfunction and higher activity in the default-mode network has been associated with a number of mental ailments including…
Generalised Anxiety Disorder: Dysfunctional connectivity in the DMN has been theorised to reason why individuals with GAD “get stuck” on particular thought patterns. If their DMN is constantly churning out pervasive and anxiety-inducing thoughts, these become harder to distract from.
Dissatisfaction and Unhappiness: Individuals with greater DMN activity at rest have been shown to have lower levels of happiness. More internal chatter = more reason to find problems and be unhappy?
Obsessive-Compulsive Disorders: Studies have shown that individuals diagnosed with OCD have continued activation of the DMN in the face of pleasant tasks compared to controls. This is to say, their brain’s keep running in the face of distractions. Our DMN should deactivate when we are focused on something to enable us to focus solely on the task. For OCD individuals their thoughts keep running, bothering them.
Attention-Deficit-Hyperactive-Disorders: Attention deficits have been linked to connectivity problems between key DMN areas.
Whilst not everyone is going to have a mental health diagnosis, what the above does show is that there is a clear link between our DMN and our ability to function in everyday life. Further, it seems that excessive and invasive thinking is a major part of such dysfunction.
Which begs the question, if DMN activation leads to more self-reflective thoughts, can those of us with a tendency to think negatively decrease it’s activation? Can we give ourselves a rest-bite from the harm our thoughts can cause us through altering the functionality of the DMN?
The answer is yes.
Neuroplasticity: Changing Our Thoughts
Just as we can decrease our fear-responses through practices targeted at decreasing the activation of our amygdala, we can alter the function of our default-mode network through specific practices, also.
This is because our brain’s are plastic. They can change. Donald Hebb the famous neuroscientist — renowned for his work on habit formation famously said that “Neurons that fire together, wire together”. The more we do a specific thing, the more we strengthen the neuronal networks that are fired to make that thing happen, and the stronger such networks become.
Take learning to play piano, for example. Experts become experts through continuously firing the pathways in their brain that are activated when they play the instrument. The more they fire them, the stronger the neuronal networks are, and the more skilled they become.
I see overthinking and rumination as a learned skill, also. As someone who previously struggled with invasive thoughts that sent me into spirals, the more I engaged with such thoughts the harder is was for me to ignore them. I was mentally strengthening my own habit of chewing on my problem until they became bigger problems.
Overcoming my habits of overthinking and rumination meant untangling those mental wires I’d strengthened over years and years.
Here are some of the known practices that can alter functioning of our DMN and relieve us from mental anguish…
Meditation: Studies on differences between DMN activity between non-meditator and meditators show marked decreases in DMN activity in the latter group.
Flow States: Having daily practices that engage our mind will temporarily decrease DMN activation. You’ll notice it’s difficult to think about yourself when you’re doing something productive, this is because your DMN is temporarily deactivated. Flow states are known to be extremely benefitial to health, when part of healthy practices/hobbies — like meditation, reading, working on a project, or socialising.
Exercise: Exercise has also been shown to decrease DMN activity, I’d hypothesise this is again related to a continued practice of being in flow — something you’ll notice when you are 30 minutes into the work out and “in the zone”, as they say.
There is much still be learnt about the DMN and it’s functioning impacts us. What we do know is that it has significant implications in the way we perceive life through the stories we tell ourselves.
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