Default mode network

I am often ‘sitting quietly doing nothing’ other than noticing the breathing. It is then obvious that the unconscious is active because it inserts units of thought, feeling and mood (TFM) into the attention centre. The unconscious appears to have a mind and an agenda of its own although it is not always clear what these are.

When tightly focussed on a particular problem or activity I often experience an existential peacefulness due to being non-egoic and outwith time and space. There is ‘flow’ in the ‘zone’ regarding a topic. A form of non-self-consciousness is in control.

But, most often, there is the default monkey mind where the Zombie follows an autopilot programme put together in the unconscious.

For some time my image of the mindbrain has been of an iceberg - with consciousness as the small bit above the surface and with the unconscious as the huge mass beneath.

The feeling was that the conscious bit was reasonable and rational, and that it dealt well with the high level executive functions. The unconscious bit served to match up and evaluate incoming stimuli relative to memories. This set the feeling tone as positive, neutral or negative.

Note that this matches with Kahneman’s two systems of thought – fast, intuitive reactions v slow, rational responses.

From a survival point of view there would be need for fast reactions in life threatening emergencies and for slow responses in intellectually challenging situations. The fast reactions often happen before consciousness kicks in.

The above model assumes that the ongoing churn of the unconscious is foundational and that now and again it channels some stuff to consciousness for higher level processing.

HOWEVER - Recent research offers some fine tuning on the above model; this includes dividing the unconscious into networks which are made up of centres and associative areas.

The Default Mode Network (DMN) is different from other networks in that it is most active when the rest of the mindbrain is at ease, and least active when the rest is most active. The DMN consists of six areas of the cortex that are most active when no external tasks demand attention; and the DMN responds by going back to a high default activity level

Earlier thinking was that when we are not busy doing demanding things, our brain is “free”, or more passive; and we automatically think that we mainly use the brain to solve difficult tasks, or control goal-directed activities. However the new thinking is that the DMN occupies a substantial part of our cortex and spends every free moment on things other than being involved in external tasks.

There are three main DMN functions. It helps build our self perceptions; it builds a dynamic store of autobiographic episodic memories; and it integrates memories from our lives in a self-relevant way. This subjectively feels like mind wandering, daydreaming and reminiscence. These play a role in making a model of the world in which we live, and in predicting the future. They are also a source of creativity and of spontaneous thoughts about interesting problems.

The DMN includes five cooperating areas of the cortex. Two other networks in the association area are the attention and salience networks

The attention network controls how well we attend to specific tasks. Studies indicate that certain areas of the cortex have increased activity when we perform tasks with the attention focused in a specific direction or on specific aspects of the task.

These areas are active all the time, no matter what we are doing. But their activity increases, as does their impact, when we focus on distinct tasks. This feels like losing yourself in your task or work, and you just focus on what you are doing.

The salience network helps you to figure out how relevant a particular piece of information, or a thing you are looking at or thinking about, is to you.

To summarize:

• the attention network makes it possible for us to relate directly to the world around us, i.e., here and now,
• the default mode network makes it possible to relate to ourselves and our memories and previous experiences, i.e., the past and future.
• the salience network makes us switch between the two others according to our needs.

This brings us closer to the perception we have of how we integrate information from the world around us with ourselves. We must be capable of relating to the external world, as well as our bodies, with some sort of self-image. Something could be important to you because you like it, or because you don’t like it and it is potentially dangerous. Those are critical decisions for survival.

New knowledge about the default mode network and the self-reflecting thoughts that it stimulates may help us to understand how we get by in our daily lives.

Ref: http://www.themeditationblog.com/the-brains-default-mode-network-what-does-it-mean-to-us/    Marcus Raichle interviewed by Svend Davanger on March 9, 2015