Neural networks

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Recent MRI imaging has shown that the conscious brain works by having active networks of neural pathways and brain areas.  It isn’t like one area is active and all other parts are silent.  Multiple parts of the brain are active at once.  Three important networks have been identified in the prefrontal cortex.  These are the:

I have attempted to show them in the following simplified brain diagram:

DMN neural networks.png

Scientists are still studying these networks using neural imaging, but it appears that the following brain areas are active for each:

  • DMN – vmPFC, PCC, RSC, Hippocampus, TPJ, Superior Parietal, Inferior and Middle Temporal Gyrus.  That means the DMN extends across the Limbic, Parietal, Temporal and Frontal lobes.
  • Salience – dorsal anterior cingulate and Anterior Insular cortex.
  • CEN – executive functions in the pre-frontal cortex, and several regions of the parietal lobe.

It does vary between people and during the day, but the DMN shown by the red line in the diagram above is the default waking mode of consciousness for us.  Many parts of the brain are active, with a low level of activity.  We are thinking and interacting with others and making decisions.  The Salience network is monitoring our state and the environment, and with certain conditions the Central Executive Network can be activated.  For most of us this probably occurs briefly multiple times a minute when we are really “thinking” and solving problems, and hardly at all when we are blobbed out watching TV.

Default Mode Network (DMN)

The Default Mode Network is what the thinking brain does when it is not otherwise engaged in another problem solving task.  Imagination and day dreaming.  When something important comes up requiring a decision or a life-threatening situation, the Salience Network has the ability to quickly disengage the DMN and divert all attention into the Central Executive Network to urgently work out a solution (which could mean saving your life).  This can happen quite quickly, and for many people with dull jobs and boring lives it is likely that the CEN is active for less than 1% of the time.  Watching TV does not require the CEN to do anything.  Sitting in meetings at work may require only occasional CEN activation.  We will discuss this more in the Spiritual section where I propose that people that are more “spiritual” are in fact using their CEN more often.

The DMN is the “monkey brain“.   It can be usefully engaged for abstract thinking.  This is also the area of the brain that meditation seeks to quieten.  It is useful to be able to invoke abstract thinking and imagination at will for certain tasks, but it is important that it is under control of the higher executive functions (the CEN) rather than being a tool used by the ego that dominates and rules our lives.  When the DMN is used for problem solving, it delegates to the heuristics and cognitive biases it has available, rather than letter our powerful and rational PFC work on the problem.

As the centre for Imagination the DMN can be a very powerful tool.  We do need to be able to consciously “dream“.  Some say that imagination is the most powerful organ in the human body.  Imagination is very useful when it is properly used.  If it is allowed to run wild and out of control then the monkey brain can be a menace to your health and well-being and will hinder your spiritual progress.

einstein imagination

Salience Network (SLN)

The Salience Network is shown in tan in the diagram above, and is centred in the Anterior Insular and Anterior Cingulate.  As the name suggests, its function is about awareness of the current sensory and emotional state.  It acts like a switch, engaging the CEN when required.  Otherwise, our normal conscious state is dominated by activity in the DMN.

Central Executive Network (CEN)

The CEN is shown in blue in the diagram above, and includes the DLPFC, OFC and several areas in the Parietal lobe including the TPJ.  This is our real intelligence – what the Buddhists would call the Buddhi, which means to form and retain concepts, reason, discern, judge, comprehend, understand.  Pulling together information from all parts of the brain for the purposes of reasoning, decision making, planning, and inhibiting instinctive tendencies.  People who are good at using the CEN are called “wise“.  The mechanism by which we do this is not well understood, and we will consider this again in the Spiritual section.

The ultimate end product of the CEN is to decide on a course of action, and instruct the motor cortex accordingly.  Whether this is “Will” or “free will” is another question which we will address in the Spiritual section.  The best course of action will occur if the CEN does its job properly, and is not overly influenced by the desires of the ego in the DMN.  More on that later.  The decision process can become quite complicated (see also the discussion on heuristics later on this page).  The diagram below comes from David Snowden’s Cynefin framework based on the type of situations we may face.

The framework is to help “consciously aware beings” arrive at a course of action when considering cause and effect relationships.

  • Obvious or simple situations require little assessment – we can launch ahead immediately, eg the roof is leaking; get a bucket, move the furniture, get up on roof to plug the hole.
  • Complicated situations require us to get some expert advice and come up with a plan of attack.  This is what we normally do when faced with bigger issues and is typical of many business meetings in the work environment.  For example, a tree was blown onto the roof in the night.  There isn’t much you can do immediately, and the damage is severe.  You need to talk to various authorities to get it removed; the insurance assessor; arrange for temporary patching and more permanent repairs when the weather improves, and perhaps temporary alternative accommodation.

Most of us are pretty good dealing with both obvious and complicated situations.

  • Complex situations are where you don’t know what you don’t know.  You need to probe and experiment to gain some understanding of the situation and to start asking the right questions.  We all began life this way, but as adults the situation is less familiar as we like to be in control of our surroundings.  Imagine you wake up after a late night drinking session, and have absolutely no idea where you are – your “friends” have put you on a plane and you regain consciousness on a park bench in an unfamiliar city with people speaking a foreign tongue (or you break out of a coffin awaiting burial in a Mexican graveyard!).  Personal analysis will not help much; instead you will need to probe and experiment to find out where you are and how to get home.  Starting out on the spiritual path requires the same sort of approach.
  • You may encounter a chaotic situation during an emergency – due to fire, earthquake, bomb attack or similar potentially life-threatening situation.  This situation usually requires immediate action, and often our instincts will direct us to do the right thing.  It doesn’t matter what you do, and what you do may not be the best thing to do but there isn’t time to analyse and determine what is best – doing something or anything is likely to be the correct course of action to save your life.
  • The fifth domain is that of disorder (the brown hole in the middle of the diagram).  If you find yourself completely disoriented your priority is to move to any of the first four domains.

This framework helps to provide some structure and guidance to decision-making.  It is important not to get carried away over-analysing simple problems, or procrastinating and switching off (higher brain off, DMN on) because it all seems too hard.  We need to get good at solving problems and taking the correct course of action in all situations that we are presented with.  Sometimes the experimental approach to solving complex situations is appropriate, but sometimes this can require a degree of “bravery” and stepping outside of ones comfort zone.