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Thread: Natural neuron death

  1. #1 Natural neuron death 
    Time Lord
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    I became interested in the apparently normal mass extinction of brain cells with my firstborn. Some facts I found counterintuitive, others painfully harsh. I'm still sketchy here though.

    By my understanding:

    - Humans gestate with a surplus of neurons.
    - A large percentage (?) of neurons die during and immediately after birth.
    - The voids left by dead neurons contribute to the texture of grey matter.
    - Initially, neurons are unconnected. They stretch out, seeking targets for their impulses (note the catch-22).
    - An unconnected (unstimulated) neuron has a 3-5 year life span.
    - This causes a second wave of mass extinction during childhood, counted from fetal development not birthdate.
    - The "terrible twos" begin then.
    - Children deprived of sensory and cognitive stimulation prior to that phase will never recover.
    - A third, less severe wave of neural deaths is associated with the teen years restructuring.


    With these probably inaccurate insights I reflected on my own baby. At birth, I observed his brain literally squeezed to clear the birth canal. One can actually see the relatively firm brain bursting forward within the "bag" of a baby's head, at the moment of birth. Plus the prolonged loss of oxygen, mass neural death seems inevitable. Though I wonder about c-section babies. Years later I met the "terrible" phase. It did seem driven by a frantic hunger for stimulation, like his life depended on it. A lot of the wailing and flailing seemed meant for his own entertainment as in feedback loop.

    Common sense says the more neurons the better. Simple. But what I've learned suggests structure demands that neurons die. Or don't exist in the first place - note the natural folds and voids of a healthy brain. So are there optimal losses for each of the three die-back events? Is there an optimal degree of ...neural neglect... for infants?


    A pong by any other name is still a pong. -williampinn
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  3. #2  
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    Have you heard of long term potentiation? This is the origin of learning where synaptic responses improve over time...it strengthens the bonds between neurons and over time neurons that fire together wire together. There is no optimal level of "neural neglect" for anyone. The simple principle "use it or lose it" applies.


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  4. #3  
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    Quote Originally Posted by gottspieler
    Have you heard of long term potentiation?
    Yup. I'm assuming everybody understands that. It's common sense really.

    Quote Originally Posted by gottspieler
    neurons that fire together wire together
    You mean neurons that already fire in sync are more likely to bond, than ones firing out of sinc?

    Quote Originally Posted by gottspieler
    There is no optimal level of "neural neglect" for anyone. The simple principle "use it or lose it" applies.
    I disagree. Say you have a chalkboard and want to pack the greatest density of meaning onto it. All white is not meaningful. The optimum is exactly 1:1 black & white. A good strategy would be to start with gray board and both add chalk and erase chalk. The brain seems to develop just so.

    As a physical organ the brain does not need all those folds and cavities. It could be smooth and solid as a liver. I think the voids are meaningful. I think developmental neuron death is meaningful.
    A pong by any other name is still a pong. -williampinn
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  5. #4  
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    You asked a simple question and got a simple answer...
    :wink:

    You mean neurons that already fire in sync are more likely to bond, than ones firing out of sinc?
    Yes, neurons must fire in sync to form connections.
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  6. #5  
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    I disagree. Say you have a chalkboard and want to pack the greatest density of meaning onto it. All white is not meaningful. The optimum is exactly 1:1 black & white. A good strategy would be to start with gray board and both add chalk and erase chalk. The brain seems to develop just so.

    As a physical organ the brain does not need all those folds and cavities. It could be smooth and solid as a liver. I think the voids are meaningful. I think developmental neuron death is meaningful.
    There is a theory that the gyri mold the cells into different shapes and the structures which may dictate function. (See this month's Sci Am) In that sense, yes, the folds would be meaningful and lack of proper fold development could potentially cause problems. I thought you were referring to a lack of early education leading to neuron death.
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  7. #6  
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    structure demands that neurons die
    I've never heard that before.
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  8. #7  
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    Quote Originally Posted by gottspieler
    You asked a simple question and got a simple answer...
    :wink:

    Yes, neurons must fire in sync to form connections.
    Thanks for your help. Food for thought.

    Quote Originally Posted by gottspieler
    structure demands that neurons die
    I've never heard that before.
    It's just another way of looking at it.


    You could just as well say structure demands that neurons live. But the postnatal development goes die die die. I can't believe that just happens for no reason.
    A pong by any other name is still a pong. -williampinn
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  9. #8 Where did you get this information about loss of neurons 
    Forum Sophomore hokie's Avatar
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    Neurons losses during our lifetime has often been based on cell counting techniques that provide inaccurate numbers. It seems to be conventional wisdom that alcohol kills brain cells, yet people that die of alcoholism show no fewer brain cells than people that die of 'natural causes'.

    The first method to count cells in an unbiased manner was developed in 1984. Methods employed before that date were all somewhat questionable. Be careful of results before the late 90s when the 1984 technique began to see more use.

    I was curious about cell death in the teens. I found an online article talking about teens being scanned with an MRI. MRIs cannot see cells. Therefore, they cannot be used to count cells. Volumes of structures are often used to infer numbers of cells. This is a mistake.
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