Aristotle said ‘the more you know, the more you know you don’t know’.  

And Dr. Seuss wrote ‘the more that you read, the more things you will know, the more that you learn, the more places you’ll go’.   And sure enough this journey started simply. 

I was watching the annual tree pruning. It always seems so ruthless and I wondered, what was it about pruning that triggered new growth?  So silly me, I posed the question to mrs. Google.   

Up came an article on tree growth hormones. Ok cool. That made sense. Cut off the leading tip of the tree, growth hormones are secreted and new shoots form. 

I was moving on from plant biology when my attention was caught by a series of articles describing the pruning of brain cells  and oh my gosh, the more I learned about this, the further down the rabbit hole I went. Yet another subject I would love to have the time to study. I have got to figure out how to clone my brain so at least one part of me would have time to dig into all the things I want to know. 

Way back in the days when I was a Neurology fellow, we were taught that babies’ brains are densely packed with neurons and that we lose lots of  these brain cells by the time we are adults. It was also understood that when brain cells died  they were not replaced, a concept we know today is not true.  

But pruning does not mean killing off neurons but thinning out the number of synapses or points at which two cells connect to transmit a signal.  

 Imagine a nerve cell,  like a starfish, with s long cord extending from it.  The cord ends in a number of branches that  make contact with similar branches from another nerve cell. That point of contact is called a synapse and a message, either electrical or chemical is sent across the synaptic junction to the other neuron. 

A nerve cell also has multiple protrusions called dendrites which can connect to those from other neurons.  The amount of these synapses present at birth increase rapidly during the first 1-2 years of life, drops off during the teen years and in adults are about half of what they were in infancy. 

Like pruning trees, the removal of less robust neural connections leaves room and resources for the remaining connections to be stronger and more efficient.  

It is speculated that aberrant pruning may account for some of the developmental neurological disorders like autism, that are still poorly understood. 

Deep in the rabbit hole I nearly got lost reading about the discoveries of the factors that control and bring about this pruning. I don’t yet see how we can prune our brains efficiently.  We can however prune away negative thoughts and poor choices that make us less effective and less happy. A good point to ponder further.

 But it was time to get back to completing my daily tasks so reluctantly I filed the references away for another day. 

It is a glorious spring day here in Vancouver. What do you think about pruning? you can email me at or leave a comment below.

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