• Question: So, as we grow up our number of brain cells increases. How do scientists measure the amount of brain cells a certain person has?

    Asked by kianared13 to Damien, Rachael, Suzi, Tim on 22 Jun 2011.
    • Photo: Suzi Gage

      Suzi Gage answered on 22 Jun 2011:

      Hi @kianared13
      Actually, as we grow up our number of brain cells actually decrease! I know it sounds counter intuitive. Babies are born with almost all the neurons (brain cells) their brains will ever have, and in fact something called ‘pruning’ occurs whereby connections between the neurons and indeed the neurons themselves can disappear. This might sound like a bad idea, but actually it helps the brain to specialise different areas for different functions.

      I don’t think it’s possible for scientists to look at a living human and be able to tell how many brain cells they have. I don’t know how the estimates of the number of brain cells in the average person was originally calculated. I hope that they took a small percentage of the brain, counted the cells and then used this to estimate the total, rather than some poor research assistants having to count them all (!)
      Also, perhaps they worked out how much one neuron weighs and than weighed a whole brain to work out the number of neurons. You’d have to make sure you removed any weight from other cells like the fatty insulation glia cells before you did this calculation though.

      Maybe someone else knows how this estimate was worked out? Anyone got any ideas?

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