Why do we have negative thoughts?  A recent TED presentation by Michael Merzenich, a neuroscientist, on the growing evidence of brain plasticity, shed some light on this question.  Our brain is amazing.  Did you know your brain was built for change?  Interestingly, Merzenich stated that our brain is born ‘stupid’. According to the professor emeritus of neuroscience at the University of California, there is little evidence of cognitive ability in infancy.

Brain Pruning
Does this mean though that our brain is truly born ‘stupid’?  This question relates back to the neural connections within our brain.  We are born with a whole set of neurons, and connections between these neurons form and they don’t die until the age of three.  So each and every one of us has three years of learning about what is important in our environment.  Then what connections we don’t need die, in a similar way to that of a way a tree is pruned of excess or dead branches.  Through ‘pruning connections’ our brain becomes more sophisticated.  It is simply amazing what our brain can do – it can adapt and change!  We know the brain is adaptable as it can store, record, and retrieve 1000’s of objects, actions, and their relationships in the world.  The death and removal of excess brain cells and connections truly sculpts a person’s brain.  Growth and pruning continue throughout our lives, but the relative balance of the processes changes.

The Fight-or-Flight Response
To know what is important when we are young is helped by our prefrontal lobe, which doesn’t work properly during infancy. What is working is the amygdala which controls emotion – the fight or flight response.  The brain is designed to protect us.  We are flooded with negative thoughts when young that are based on the signals sent from the amygdala.  Negative thoughts are natural consequences of fight or flight based on previous memories.  Thoughts are designed to keep us safe (i.e., “Can we protect you this way?”, “Should we do this? etc.).  For example, if we walk down the stairs it can potentially hurt us so we are flooded by negative thoughts asking and questioning as to whether we should proceed.  As we learn through natural consequences of trial and error our brain becomes well practiced at it.  That is, if we walk down stairs our memory says. “Hey, remember last time?” and then our system becomes activated and increases our focus and concentration leading to more cautious behaviour (i.e., hold rails, go slowly).

Practice and Plasticity
Through practice, our prefrontal lobe helps let go of connections no longer needed and will interpret the signals from the amygdala letting our brain know we don’t need to worry anymore. Therefore, over time we let go of connections that are no longer needed and strengthen those that are needed from continued practice.  Additionally, practice means a new better pathway is formed so the old pathway goes.  Without effective practice our brain won’t let go of unhelpful pathways and thus unhelpful thoughts, as it will interpret the signals from the amygdala as real.  However, our brain can change itself with practice.  Despite having unhelpful thoughts we can learn new ways to change these thoughts in to more helpful ones, creating new and improved pathways.

Thoughts are there to protect you but it doesn’t mean they are always true based on the information/signals they receive.  So we can rewire our brain to help reinterpret those signals in a more helpful way.