The
average human adult human brain normally weighs from 2 1/4 to
3 1/4 lb
(1-1.5 kg). Differences in weight and size do not correlate with
differences in mental ability. Its average maximum weight is reached
by age 15.
The brain
has approximately 100 billion nerve cells (as many as there are
stars in our galaxy!), that allow us to think, plan, talk, imagine,
as well as control breathing, heart rate, and other autonomic
process that are independent of conscious brain functions.
The brain monitors and regulates the body's actions and reactions.
It continuously receives sensory information, and rapidly analyzes
this data and then responds, controlling bodily actions and functions.
From the moment we
are born, other human beings are the most significant element
in our environment that influences our nervous systems the most.
Some of our social values, such as those from our families, we
assimilate at a very early age and carry with us for the rest
of our lives–most often, unconsciously.
At birth, almost all
the neurons that the brain will ever have are present. However,
the brain continues to grow for a few years after birth. By the
age of 2 years old, the brain is about 80% of the adult size.
When we are babies, our brains are more open to the shaping hand
of experience than at any time in our lives. In response to the
demands of the world, the baby's brain sculpts itself. Scientists
have begun to understand how that happens.
A child's brain is
a magnificent engine for learning. A child learns to crawl, then
walk, run and explore. A child learns to reason, to pay attention,
to remember, but nowhere is learning more dramatic than in the
way a child learns language. Language is the hallmark of being
human.
The teenage brain is
strongly influenced by hormones, the prefrontal cortex, the center
of reasoning and impulse control, is still a work in progress.
For the first time, scientists can offer an explanation for what
parents already know -- adolescence can be a time of turbulent
emotions, and poor judgment. Scientists suggest that if a teen
is engaged in music, sport and academics that those connections
will get hard-wired just as a teen that lies on the couch playing
video games and MTV those are the cells and connections that will
survive.
The latest discoveries
in neuroscience present a new view of how the brain ages. Overturning
decades of dogma, scientists recently discovered that even into
our seventies, our brains continue producing new neurons. Scientists
no longer hold the longstanding belief that we lose vast numbers
of brain cells as we grow older. The normal aging process leaves
most mental functions intact, and may even provide the brain with
unique advantages that form the basis for wisdom. The aging brain
is also far more resilient than was previously believed.
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