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In broad terms, the phrase learning disability covers any of a range of
conditions that affect a person's ability to learn new information. These
conditions all affect the brain in some fashion. The most common causes are:
* defects or errors in brain structure
* lack of communication between various parts of the brain
* incorrect quantities of various neurotransmitters, or problems in the
brain's use of these transmitters
o common neurotransmitter problems include insufficient dopamine,
improper serotonin regulation, and excessive dopamine reuptake
where emitting neurons reabsorb too much dopamine after releasing
them to communicate with other neurons (also implicated in
Major afflictions that impair learning
Down syndrome, or Trisomy 21
Ultimately caused by an extra chromosome in the genetic makeup of the
sufferer. One of the primary consequences of the extra chromosome is
mild to severe mental retardation. Other genetic conditions with
similar consequences include Trisomy 13 and Fragile X Syndrome.
This condition has several forms in varying degrees of severity. The
three primary forms are
o difficulty in phonetic mapping, where sufferers have difficulty
with matching various orthographic representations to specific
o difficulty with spatial orientation, which is stereotyped in
the confusion of the letters and , as well as other pairs.
In its severest form, and
, all distinguished
primarily by orientation in handwriting, look identical to the
o difficulty with sequential ordering, such that a person can
see a combination of letters and recognize what word it
corresponds to with the help of phonetic mapping, but cannot
properly sequence the letters when spelling words.
Dyslexia has obvious effects on the ability to learn to read and/or
write, as well as more subtle effects on processing visual information
Language processing disorders
These are poorly-studied, but have clear effects on learning. Effects
can be semantic, syntactic or analytical, or can resemble aphasias.
Some people have difficulty with planning, sequencing, using inductive
logic, or with verbal expression. All can interfere with learning, at
both the input and output phases of the process.
Attention Deficit Hyperactivity Disorder (ADD and ADHD)
AD(H)D sufferers have difficulty in intiating and maintaining
concentration. The underlying neurological causes are not always clear.
It also appears that many persons labeled as ADD/ADHD either suffer
from other problems, or have not had the thorough neruological analysis
needed to help manage their condition.
A condition of the elderly, in which the ability to retain new
information is lost. As the condition progresses, the patient begins
losing lifelong memories, with the most recent to go first. Eventually,
they often regress to childhood, and have such poor memory that they
cannot perform simple tasks such as walking from one room to another
because they forget where they are going en route.
This has multiple causes, and consequently, multiple effects. A few
common ones are:
Stroke - can lead to aphasia
Damage to the brain tissue - effect depends on what area of the
brain is injured
Lesions and Tumors - effect depends on what area is injured.
Dysgraphia - inability to write, regardless of ability to read
While not a true learning disability, it affects the ability to
perceive visual information. When such information is presented in a
way that is confusing to the color-blind, learning is compromised.
Physical handicaps can also impede learning when proper accommodations are
Blindness interferes with the ability to process visual information, so
information must be presented in tactile or auditory form to be learnt.
Deafness and hearing impairment interfere with the ability to process
auditory information. Information presented in auditory format is
meaningless to the deaf, and not properly perceived by the hearing
impaired. Learning occurs best when accommodation is made by providing
visual and tactile means for acquiring information, as well as
providing Sign Language interpreters where needed.