Chapter 16:
In the Steps of the
‘Diagram Makers’
Amy Menendez
Definitions
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Aphasia is the loss of a previously held ability to speak
or understand spoken or written language, due to
disease or injury of the brain.
Alexia is a neurological disorder marked by loss of the
ability to understand written or printed language,
usually resulting from a brain lesion or a congenital
defect.
Agraphia is a cerebral disorder characterized by total
or partial inability to write.
Anomia is the inability to name objects or to recognize
the written or spoken names of objects.
Broca’s Aphasia
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Broca’s aphasia is a type
of aphasia caused by a
lesion in Broca's area of
the brain. The
predominant feature is
difficulty in finding and
speaking words, yet
patients have normal
comprehension.
Broca’s Area
Wernicke’s Aphasia
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Wernicke’s aphasia is a
type of aphasia caused
by a lesion in Wernicke's
area of the brain and
characterized by
grammatical but more or
less meaningless speech
and an apparent inability
to comprehend speech.
Wernicke’s Area
Conduction Aphasia
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Conduction aphasia is a
type of aphasia in which
the lesion is assumed to
be in the association
tracts connecting the
various language centers
of the brain.
Monsieur S.
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Woke up one morning and could not
read his newspaper.
Could, however, recognize his own
name, and could read figures.
Unable to write spontaneously or
with dictation.
Comprehension of spoken language
was normal, but when he spoke he
used wrong or malformed words.
No difficulty recognizing people or
objects.
Angular Gyrus
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The angular gyrus is a
region of the inferior
parietal lobe of the brain
that is involved in the
processing of auditory and
visual input and in the
comprehension of
language.
Jules Dejerine
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From studying Monsieur S.
Dejerine concluded damage to
this area prevents the conversion
of representations of the
appearance of words and letters
into representations of their
sounds (alexia), and also the
conversion of representations of
their sounds into representations
of their appearance (agraphia).
Monsieur C.
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Had alexia without
agraphia.
Although he could write,
he was unable to read what
he had written, unless he
could trace the letters with
his fingers.
Unable to reproduce print
as cursive or cursive as
print.
Recognized patterns
without difficulty.
Dejerine’s Explanation of Alexia
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Because the left visual cortex
had been destroyed the letters
and words could only have been
seen through signals reaching
the right visual cortex.
For these letters and words to
be understood the right visual
cortex would have to be
transferred to areas of speech
in the left hemisphere, but
damage to the white matter in
the hindermost part of the
corpus callosum made this
impossible.
Dejerine’s Explanation of Agraphia
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In the final attack on
Monsieur C. The new
lesions destroyed the
angular gyrus and
adjoining parts of both
the temporal and parietal
lobes which explained
the agraphia and
incomprehensible speech
of Monsieur C.
Criticisms of the Diagram-making
Approach
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The localization of different functions were questioned.
Broca’s aphasia was simply the loss of ‘motor images’
and Wernicke’s aphasia was a result of the loss of
‘auditory images’ failed to account for the characteristic
features of each.
Although divided speech disorders into categories, and
explained through models. The actual cases did not fit
into the categories.
Preoccupation with pinpointing damaged centres or
pathways and deducing the consequences of the
damage. (localization approach)
Cognitive Neuropsychologists
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Cognitive Neuropsychology is a branch of
neuropsychology that aims to understand how the
structure and function of the brain relates to specific
psychological processes. It places a particular emphasis
on studying the cognitive effects of brain injury or
neurological illness with a view to inferring models of
normal cognitive functioning.
“The most striking contribution of the cognitive
neuropsychologists has been to show that the
machinery handling language often behaves as if it
consists of interacting modules”.
Phonological and Lexical Routes to
Reading
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The phonological route
to reading is when we
learn the phonetics of
reading as well as the
rules of pronunciation.
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The lexical route to reading is
when we can read at a glace
without sounding out letters
or guidance from rules. The
spelling and pronunciation is
already stored in our brains.
Hyena
Yacht
Colonel
Deep Alexia and Surface Alexia
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When there is a block in the phonological route,
the patient is said to be suffering from
phonological alexia or deep alexia.
When there is a block in the lexical route the
patient is said to be suffering from lexical alexia
or surface alexia.
Learning to Use Words
Sound
Patterns of
Words
Pathway A
Meanings
of Words
Pathway B
Pathway C
Appearances
of Written
Words
Language Disorders
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She was able to read
pronounceable non-words so
her phonological reading was
intact. However, that couldn’t
account for her being able to
read words like leopard,
tortoise, and liquor.
Therefore, the lexical route
Progressive Presenile Dementia
must include a pathway from
the printed word to the word
sound that does not depend
on comprehension
This means pathway B, from sound patterns of words to
appearances of written words, must exist!
Language Disorders
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Had the ability to repeat and write
down spoken sentences that she
could not understand, but could
understand what she had written.
Inability to understand a sentence
after hearing it implies that
pathway A, from the sound of
word to the meaning of the word,
was impaired.
Word-Meaning Deafness
The fact that she could understand a sentence after writing it
down implies there is a route from the appearance of written
words to the meaning of written words, so pathway C must exist!
Language Disorders
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When reading aloud, patients with Deep Alexia, tend
to make semantic, word meaning, mistakes.
These mistakes are significant because it not only
shows a direct connection between appearance of
written words and sound, pathway B, it also shows a
direct connection between appearance of written
words and the meaning of written words, pathway C.
Right Brain vs. Left Brain
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There is evidence to
support the right side of
the brain has to do with
object recognition, spatial
analysis, recognition of
musical pitch, timbre, and
harmony.
Emotional aspects of
speech are controlled here.
The right half of the brain
is responsible for
controlling the left hand,
and the left visual field.
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Gestures used to convey
meaning are controlled in
the left hemisphere.
Spoken language is on the
left side of the brain.
The left side of the brain is
also responsible for
controlling the right hand,
and processing the right
visual field.
Right Brain vs. Left Brain
Look at the chart:
Say the color not the word.
Black
Blue
Green
White
Green
Red
Green
Aqua
Yellow
YellowPink
Tan
Red
Yellow
White
The Split Brain
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Roger Sperry published a
series of papers in which
he described what
happened when he
disconnected the two
hemispheres of the brain
in monkeys and cats.
Optic Chiasma
Epilepsy and the Split Brain
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This procedure went from
research in monkeys and cats
to research with humans who
had epilepsy.
The procedure was
performed, except the optic
chiasma was not cut.
Not only did this prevent
seizures from spreading from
one hemisphere to another it
actually mad the seizures
occur less frequently.
Brain Scans
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PET scans allow us to
measure changes in local
blood flow, glucose
consumption and
neurotransmitter uptake.
MRI scans allow us to
measure changes in local
blood flow and oxygen
content.
What Do These Scans Do For Us?
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These brain scans,
specifically the PET
scan, have shown us the
parts of the brain
associated with auditory
and visual stimuli.
What Do These Scans Do For Us?
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They have shown us that our
brains tend to store
information in a
phonological rather than
visual form.
Findings indicate conditions
that use the phonological
store lead to an increase of
blood flow to the left
supramarginal gyrus.
Also indicate the sub-vocal
rehearsal system is associated
with Broca’s area.
The supramarginal
gyrus is involved with
spatial orientation and
semantic
representation.
What Do These Scans Do For Us?
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These scans also provide
us with insight to
disorders such as
dyslexia.
Once we have a full
understanding of how
these disorders work, we
can work to help people
who have them cope
with them better.