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=      Wetware: The Biological Basis of Intellectual Giftedness       =
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Why is "giftedness" such a puzzle for parents? Why is there so much 
confusion? The most common plea heard on TAGFAM is "my child is 
different; please help me understand why -- I think she's gifted."
The goal of this article is to introduce you to "wetware," the brain 
and its functions, and to help you understand, at the physical and
biological level, the puzzle of the intellectually gifted child.

OK. Stay with me folks. In order to understand what comes later, we're
going to have to wade through some tough territory for a few minutes.
If you're having trouble conceptualizing this stuff -- think in terms
of what could happen if one of these areas of the brain was damaged or
functioned suboptimally. Also, think in terms of how each of these areas
contributes to the behaviors you see in your intellectually gifted child.
Is your child hypersensitive to smells? Tags in clothing? Does she
have a terrific memory? How about physical coordination? Keep these
"differences" in mind ... maybe you'll start to see the connection between
brain structures and those little quirks of behavior that leave others
wondering what planet this child is from.

Chemicals. When you think about it, intellectual giftedness is merely
the fortunate happenstance of genetics as expressed in the chemical
relationships in the brain. A nerve impulse here, a neurotransmitter 
there. Synapse, neuron, pathways. Memory, cognition, perception,
instinct, emotion, creative thought -- these functions all start with 
chemical processes in the brain. These processes originate in the 
sequences of instructions encoded in your DNA. Intellectual giftedness
begins with the creation of new life. Sperm meets egg. Bang! Life! All
systems go! Another intellectually gifted human being is in the making.

Obviously, the functioning of the human brain is more than just a few
chemical reactions. Development of the central nervous system begins
as early as 16 days after conception and, by the sixth week, the neural
tubes which later become the cerebral hemispheres are present in the
fetus. The cerebral cortex begins to develop by the 10th week. Thus,
early in the pregnancy, chemical reactions and processes begin to
define who and what we will be -- our genetic inheritance begins the
process that gives rise to our intellectual abilities. For some, in
utero exposure to toxins, stress, and other environmental factors will
result in damage or other events which change, limit, or prevent the
development of their full intellectual potential. Even before birth, the
child's environment has a powerful influence upon the later expression of
intellectual abilities.

Our understanding of the brain and how it functions has increased 
dramatically in the past two decades due to technological advances in
diagnostic and imaging equipment. The development of Computer-Aided 
Tomography (CAT), Positron Emissions Tomography (PET), Magnetic 
Resonance Imaging (MRI) and other brain imaging techniques have made it
possible for investigators to study the intact, whole, living human
brain. Prior to the development of these techniques our understanding
of the brain was limited and derived mainly from studies of individuals
who had experienced loss or impairment of functionality due to disease,
stroke, or physical injury. These types of studies have increased our
knowledge of the anatomical structures of the brain (neuroanatomy)
and the chemical processes by which it functions (neurochemistry).
Studies of stroke victims, in particular, allowed investigators to 
identify specific areas of the brain as being associated with
certain behaviors or functions. More recent studies have shown that the
brain is able to use cooperating groups of neurons in differing regions 
to accomplish a function or produce a behavior. 

After the initial in utero growth of the human brain, there are normally
growth spurts from ages 3 to 10 months, 2 to 4 years, 6 to 8 years,
10 to 12 years, and finally from 14 to 16 years of age. In addition to
the physical growth process defined in the beginning by one's DNA, the 
brain undergoes physical changes related to exposure to environmental 
factors. The physical development of the brain benefits from some types 
of environmental factors, i.e. loving parents, good nutrition, 
interesting sensory stimuli and is harmed by others, i.e. exposure to 
lead or other toxic metals, child abuse, lack of physical contact with 
care givers. Both physical and social factors in the environment affect
the brain's growth and development. Normal, healthy growth requires a
supportive, loving, stimulating, and safe environment.

Next, we get into the really tough stuff. Stick with me, there are some
treasures to be uncovered in what comes next!

       --- Parts of The Brain and Related Systems ---

The central nervous system (CNS) is composed of the brain and the spinal 
cord. The peripheral nervous system sends sensory information to the CNS 
and sends motor commands from the CNS to the rest of the body. The 
autonomic nervous system sends nerve impulses to the body's internal 
organs. Sensory receptors in the peripheral organs (eyes, ears, skin, 
etc.) relay sensory information back to the CNS. The autonomic nervous 
system has other functions related to keeping the body's organs functioning
in a balanced manner. [Aha! Maybe the "good" side of that annoying 
hypersensitivity is an increased ability to process sensory inputs.]

The overall structure of the brain is usually defined in terms of
gray matter, the neuronal cell bodies, and white matter, primarily made
up of myelinated neuronal axons. [You've been dying to know the 
difference, right?] The brain's "gray matter" makes up the cerebral
cortex and the cerebellum (cerebellar cortex, and the subcortical cerebral
and cerebellar nuclei). The cerebellum is involved in the control of
muscles (motor movements) and posture adjustments. Because of its many
connections to the cerebral cortex, it is possible that the cerebellum
also plays a role in more complex brain functions (e.g. thinking). 

The cerebral cortex is divided into four lobes: frontal, temporal, 
parietal, and occipital. Some neuroanatomists include the limbic system
as a fifth lobe of the cerebral cortex. Within the cerebral cortex are 
regions which have been identified as the primary motor, primary sensory, 
motor association and sensory association areas. These areas of the 
brain are responsible for the planning of motor activity, the 
interpretation of primary sensory inputs, and the organization of all 
the sensory and motor information that the brain receives from the 
nervous system.

The frontal cortex is the site of motor activation, intellect, conceptual 
planning, aspects of the personality, and aspects of language production. 
Portions of the frontal cortex are involved in the movement of single 
muscles, the coordination of movement for groups of muscles, and the 
integration of primary sensory information. The temporal cortex is the seat
the brain's memory, language, and emotion functions. The parietal cortex is
the location of the association cortices for visual, tactile, and auditory
input processing. The left parietal lobe is preferential in the processing 
of verbal information. The right parietal lobe is preferential in the 
processing of visual-spatial information. The occipital cortex is the 
primary sensory cortex for visual input.

The cerebral cortex is divided from front to back into left and right 
hemispheres. These hemispheres are connected by the corpus callosum and 
other small commissural tracts. In most humans, one of the two hemispheres
is dominant and contains the area of the brain used to express language.
In 97% of the population, the left hemisphere is dominant; 99% of right
handed individuals and between 60% and 70% of left-handers are 
left-hemispheric dominant. Some individuals experience mixed dominance
for handedness and others experience mixed dominance for language. There
are tests which involve sensory inputs, either hearing or vision, that
can be used to determine which hemisphere is dominant. Persons who have
a dominant left hemisphere have a right ear advantage (hear better).
For vision the right visual field has an advantage for verbal inputs 
and the left visual field has an advantage for spatial input when
the left hemisphere is dominant. For right hemisphere dominance the
advantages are reversed, right for left, e.g. left ear, right eye for
spatial, and left eye for verbal.

Studies of individuals who have experienced brain damage have led to the
development of several theories about hemispheric function. A good book
to read on this topic is "Left-Brain/Right-Brain." The left hemisphere
is thought to be the seat of rational thought, analytic thinking, 
sequencing, abstracting, and logistical abilities. The right hemisphere
is thought to be the seat of perceptual, visual-spatial, artistic, musical,
and synthetic activity. The right hemisphere is also thought to be 
involved in both the perception and expression of affect (emotion) and 
the perception of social cues in the environment. More recent studies
have shown that while these generalizations hold in most cases, there
is increasing evidence of exceptions. [In other words, the information
about left and right hemisphericity is probably true but don't bet the
farm on it.]

The major function of the limbic system is memory. Earlier suppositions
held that the limbic system was the primary seat of one's emotions.
Two components of the limbic system, the hippocampus and the amygdalia,
play critical roles in learning and memory. The amygdalia is also thought
to play a role in the integration of memories and facial recognition and
social behavior. Two types of memory have been postulated by researches:
working memory (short-term) and consolidated memory (long-term). Short
term memory is thought to involve neurochemical changes at specific
synapses. Long term memory is thought to arise from the synthesis of
new protein molecules which create permanent changes in the brain's
synaptic architecture. [Oh! So that's why the two are different ...]

           --- Defining Intellectual Giftedness ---

Intellectual giftedness is "mental quickness and mental flexibility." 
Developmental delays or developmental precociousness affect the expression 
of one's intellectual abilities. Environmental influences can enhance or 
retard maturation. Physical development of the brain and development of 
brain functions can be significantly and irreversibly affected by physical
trauma or environmental factors. Some children are more intellectually
capable than their age-mates due to a combination of factors, both physical
and environmental. Environment can't give the child more than he started 
with physically; it can, however, adversely affect the development of the 
brain. Differences in intellectual capacity or expressions of behaviors 
seem to arise from the complex interplay between what you start with, the 
environment influences the child experiences, and the child's individual 
developmental patterns.

Hopefully, the above explanations have the set the stage for the assertion
that there is only one type of giftedness -- intellectual giftedness.

There is a clearly defined biological basis for the development of 
"superior" intellectual abilities. The label "superior," however, is 
a value judgement placed upon the expression of those abilities as 
specific behaviors. There are other more popular definitions of giftedness
in use but these appear to appear to be more a description of certain
behaviors which are held in high esteem in our culture. Definition by
description is, perhaps, a valid way of looking at the issue of giftedness.
But, does a definition based upon shifting cultural norms help us to
understand the needs and abilities of intellectually gifted children?
I think not.