More on the Critical Window

I have noted for decades now that there are  critical  windows when events have  their  major impact; windows that seem to open and close at specific biologic timeframes.  I have written about love and when it must happen. There is a new study just out that speaks more to the notion of the critical window.  It is found in Scientific American (Oct 1, 2012.  "The Story of a Lonely Brain."Read the Scientific American article here).  They start out the article  noting that we are social  animals, and when we cannot be social early on, we begin to suffer.    They use brain development as key example, demonstrating the difference between the evolution of our grey matter (the  thinking brain), and our white matter which lies below and has to do with connections between cells, and is  largely subcortical.  As white matter  becomes myelinated it develops into a  functioning cell that permits rapid  response where impulses travel at optimim speed. It is the fatty material that  covers  the cell that  allows it to become functional  spreading the message over long  distances  in the brain.  For some white matter the myelinization continues on into adulthood.    And we go on learning and evolving.    The authors point out that children who grew  up in orphanages had deficient myelin sheaths and  less  white  matter, which made learning more  difficult.  If they were soon put into a loving foster home  there was no such damage.  Their conclusion was that placement in foster homes when  early enough  and during a critical period avoided serious brain damage.  In short, they could "catch  up" neurologically.

  Part of what helps produce myelin are the oligodendrocytes.  Isolated,  non-social mice had stunted oligodendrocytes (OLIGOS) which were often  malformed and had fewer branches.  And worse, the nerve  cells connecting the right and left brains were fewer and thinner.  In other words, the ability to transmit emotional information from right to left brain is  diminished.  The  point of this was that mice that were isolated very early on had the greatest damage; those who isolated later on did not have this.  The damage had to be  during the critical  window.  That is when there is the greatest impact on the system.  Rhesus monkeys raised in  isolation had smaller sized corpus callosum.  They also had great learning difficulties.  All this to say what should be clear by now: that there is a critical period when love can have its maximum and  longest  duration; any love outside that period will have much less of an impact.  This is what they found with myelin sheaths that signal the readiness of a cell to fire.  If the mice were isolated outside the critical period, there is minimal impact.

  So to sum up: mice who were deprived of social contact  during a critical window had  lifelong damage  and learning problems.  So why don't they do good at school when they are fifteen? Maybe we should  look at much earlier times.