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The Neurosciences of Religion: Meditation, Entheogens, Mysticism




Enviado por Felix Larocca



Partes: 1, 2

    1. Inside the
      Brain
    2. Problems and
      Issues
    3. The
      Emergence of Mind
    4. A Musical
      Interlude
    5. The
      Emergence of Transcendence
    6. Dangers
      and Opportunities

    How the Neurosciences Explain Religion or
    Not

    In the last lecture1,
    we learned how humans evolved as hunter-gatherers and how our
    genetic, mental, and behavioral nature was conditioned by and for
    this kind of life, even as we now live in a very different
    environment of our techno-cultural creation.  We considered
    how evolution had shaped our predispositions for religion and
    what functions and dysfunctions religion might have played in our
    species’ history.  We were introduced to the idea that
    the human mind was modular, that there were instinctive
    dispositions
    that then developed in conjunction with social
    and environmental factors into various inference systems
    in our brains.  Religion, we were told, could be understood
    as a potent combination of these different inference systems in
    our evolved brains – agency detection, ontological
    categories, intuitive physics, intuitive psychology,
    pollution-contagion templates, memory-recall patterns, and so
    forth, all assembled and accessed as independent mental modules
    (Boyer 2001). 

    In this lecture, we are going to examine the human brain
    directly to see how the cognitive neurosciences try to understand
    and explain religious and spiritual experiences.  And we
    note first that there has been a tremendous amount of new
    research and new insights into the working of the human brain in
    the last few decades.  Powerful new tools also allow us to
    examine the function of healthy human brains and these tools have
    recently been used to study the brain functions of Buddhist
    monks, Catholic nuns, Pentecostals speaking in tongues, and
    others.

    Inside the
    Brain

    Now if you look inside the human brain, you do not
    actually see these mental modules previously referred to. 
    There is no piece of the brain that one could label the "agency
    detection module" or the "pollution-contagion module".  In
    dissecting a human cadaver, we first see large-scale
    structures.  On the outside is the cerebral cortex, or
    neocortex, including areas labeled the Frontal Lobe, the Parietal
    Lobe, the Occipital Lobe, and the Temporal Lobe, and of course,
    these are divided into two hemispheres, right and left, with a
    broad band of nerve fibers know as the Corpus Callosum connecting
    the two halves.  If we peal away the neocortex, we discover
    the mesocortex and subcortical structures in the limbic system,
    including the Thalamus, the Amygdala, the Hippocampus, and the
    Cerebellum, all connected to the brain stem and the spinal
    cord.  This much you probably already know.  Images of
    the human brain have become iconic in our 21st century
    culture.

    A lot of what we know about the specialized functions of
    different areas of the brain comes from observing survivors of
    traumatic brain injuries or stroke victims.  In both cases
    neuroscientists correlate the destruction of certain brain
    regions due to hemorrhaging or injury with the loss of particular
    mental functions, for instance the loss of motorcontrol, speech,
    or even particular parts of speech or sets of word concepts,
    the latter known as Aphasia. 

    Curiously, memory seems to be distributed throughout the
    brain and is not located in any particular region.  I recall
    a colleague at Oxford University, who I visited in the hospital
    shortly after he had had a stroke.  He could point to Paris
    or London on a map, but he could not say the word "Paris" or
    "London".   Nor could he speak the names of any number
    of other common items and places, though he certainly knew what
    they were and could directly point to any of them.  When I
    said "wallet," he reach into his back pocket, pull out the
    wallet, he just could not himself say the word "wallet". 
    Our brains are strange, indeed, though we take them for granted
    until something goes wrong.  Fortunately, my friend was able
    to fully recover his speech, but did so by training new regions
    of the brain to compensate for the loss of the one region
    destroyed by the stroke.  This is an example of another
    curious characteristic of the brain called
    neuro-plasticity.

    When we examine brains under powerful microscopes we see
    that the brain is made up of neurons, lots and lots of
    neurons.  There are different types of neurons in the brain,
    and throughout our central nervous system in the rest of the
    body, but they all share a basic structure.  The cell body
    contains the nucleus and organelle.  Extending out from the
    cell body are lots of dendrite "trees" and axon
    "arms".   These connect to other neurons.  This
    maze of connections end in synapses, linking each neurons with
    hundreds or thousands of other neurons.  The neurons fire
    electrical charges in the form of chemical ions, which are
    mediated by a variety of neurochemicals that are produced
    endogenously by the brain.  The chemicals produced and
    present in different areas of the brain are very
    important.

    There are a lot of neurons in the human brain, estimated
    at 1011 (one hundred billion).  Now each neuron has on
    average about 7*103 (seven thousand) synaptic
    connections.  A three-year old child has about
    1016 synapses (10 quadrillion), but this happily
    decreases with age to a more manageable number between
    1015 to 5*1015 synapses (1 to 5
    quadrillion). 

    Here are a few comparisons to help you remember these
    big numbers.  The number of neurons in your brain is
    approximately the same as the number of stars in our Milky Way
    galaxy, which turns out to be conveniently also the number of
    galaxies in the observable universe, i.e., one hundred
    billion.  Or if you prefer, there are more neurons in your
    brain than the number of hamburgers served by McDonalds
    (before they stopped counting).

    And it takes a lot of hamburgers, or other food, to keep
    our neurons firing.  The 1.5 kilograms of your brain, give
    or take, represents only 2 percent of your body weight and yet it
    consumes 15 percent of your cardiac output, 20 percent of your
    body oxygen, and about 25 percent of your body’s glucose
    consumption.  Just sitting around the brain needs about 0.1
    calories per minute.  With intellectual activity this can
    increase to as high as 1.5 calories per minute.  From a
    biophysical and evolutionary point of view, the human brain is an
    expensive item.  In birth, it is difficult to pass through
    the female pelvis, too often resulting in the death of the infant
    or the mother.  In life, it requires a lot of extra food and
    care. 

    The brain is best understood as a kind of Rube Goldberg
    machine.  Rube Goldberg (1883-1970) was an American
    cartoonist who was famous for depicting complex devices that
    performed simple tasks in convoluted ways.  One such cartoon
    depicts a man eating his soup. The spoon is attached to a string
    which flips a cracker to a Parrot which then activates water
    pouring into bucket which pulls a string which activates a
    lighter which launches a rocket attached to a knife which cuts a
    string that turns on a clock with a pendulum which swings back
    and forth moving a napkin that now wipes clean the soup-eating
    man’s mustache.  The entire contraption is worn on the
    head of the mustached man as a kind of hat.  Our brains are
    like this Rube Goldberg machine, except that the complex machine
    is worn inside our heads instead of outside. 
    Neuroscientists today are developing algorithmic flow charts that
    map out neural processes.  Something simple like engaging in
    meditation sets off an impossibly complex series of actions,
    reactions, and feedback loops (Newberg 2006).  Thankfully,
    we do not need to be the least bit aware of any of these
    processes to have wonderfully functional brains allowing us to
    mindlessly perform lots of simple and complex mental activities
    everyday.  It is worth stopping a moment, however, to
    reflect that the most complicate object in the known universe is
    sitting right here between our ears.

    Partes: 1, 2

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