U9: LATERALIZATION, LANGUAGE and the SPLIT BRAIN
Mar/22/12
1. Cerebral Lateralization of
The brain is actually 2 separate structures except for the cerebral
Function – Intro
commisures connecting them
Lateralization of function talks about the differences in function and is
studied through split brain patients – who had their L and R
hemispheres separated by commissurotomy
Left Hemisphere Damage to
Aphrasia is an inability to produce or understand language
Aphasia and Apraxia
o Broca found that there was a relationship between the inferior
prefrontal cortex of the left hemisphere known as Broca’s area
Apraxia (Liepmann) is always associated with left-hemisphere damage
even though the symptoms involve both sides of the body.
These patients can’t perform movements when asked to perform them but
when performing them naturally and without think about it, they could.
These examples provided evidence for cerebral dominance where one
hemisphere (usually the left) is the dominant hemisphere in the control
of all complex behavioral and cognitive processes.
Right hemisphere is the minor hemisphere
2. Anatomical Asymmetry
Even though the 2 sides of the brain seem to look the same, there are a
number of anatomical asymmetries between the two cerebral
hemispheres
1. The RH is larger and heavier than the LH but the LH is more densely packed
2. In the temporal lobe, the planum temporale (location of Wernickes area) is
larger on the left while the primary auditory cortex or Heschel’s gyrus is
larger on the right because there are 2 on the right side
o Comparing neurons in wernicke’s area with the same part of
the right hemisphere, the areas of both hemispheres are
organized into regularly spaced columns of interconnected
neurons and the columns are connected by axons
o The L side had longer axons and are farther apart.
3. In the thalamus, the lateral posterior nucleus is larger on the left, while the
medial geniculate nucleus is larger on the right
4. Tend to have more temporal-parietal area on the right side because the
Sylvian fissure extends further back
5. In Broca’s area there is more surface area on the right and more buried area on
the left
6. There is asymmetry in the distribution of some neurotransmitters
7. The RH extends further forward and the LH extends further back
Asymmetry and Handedness
8. There is also evidence that the cortical microcircuitry differs between
comparable areas of the left and right hemispheres, suggesting that cerebral
asymmetry is expressed down to the level of how neurons communicate with
one another
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While everyone shows some brain asymmetry, a higher proportion of left
handers show no asymmetry or a reversal of the direction of anatomical
asymmetry
o Ex. 60% of Dextrals (right) with L hemisphere lesions and 2%
with R hemisphere lesions were aphasic while sinestrals (Left)
were 30% and 24% respectively.
Left handers have language functions distributed across hemispheres or
in right hemisphere.
Corpus callosum is larger in left-handers, and that might also contribute
to the greater interaction between the two hemispheres
Recovery from aphasia in left handers are more rapid and complete in left
handers because language functions aren’t as lateralized and less
sensitive to damage in one particular brain area.
Relationship between Speech laterality and Handedness
1. Nearly all (about 95%) right-handed subjects are left-hemisphere dominant for
Asymmetry and Gender
2.
3.
1.
Q: What is the CC?
2.
3.
speech
Most left-handed or ambidextrous subjects (about 70%) are also lefthemisphere dominant for speech
Early left-hemisphere damage can cause the right hemisphere to become
dominant for speech and the left hand to be preferred.
There are anatomical asymmetries that differ between males and females:
Planum temporale: Left is larger than right, more often seen in males than in
females
Sylvian Fissure: Men have a longer horizontal component in the LH than
females/ no difference in RH
The posterior portion of the CC is significantly larger in females
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The brains of males are more lateralized than the brains of females
because male victims of L hemisphere strokes had more deficits on
WAIS and 3x more likely to suffer from aphasia.
Gender differences in Behavior
1. Women have greater verbal ability than men (fluency, analogy,
comprehension)
2. Men have greater visuo-spatial abilities (mental rotation, geometry, map
reading)
3. Men have greater mathematical ability (very controversial and has been linked
to advantages in music composition and chess)
4. Men show greater aggression
Explanation of Sex Differences
1. Hormonal effects on brain function
Hormones have an organizing effect during development and men and
women have different levels of hormones can lead to differences in brain
structure and functioning.
During menstrual cycle as estrogen levels rise, this was correlated with
poorer spatial ability but enhanced articulatory and motor abilities.
3. The Split Brain
Cutting the Corpus Callosum
Myers & Sperry
2.
Genetic Sex-linkage
Another theory proposes that a major factor in behavioural sex
differences in spatial ability is genetic
Recessive gene on X chromosome responsible for differences
3.
Maturation Rate
Girls speak sooner than boys so language areas of the brain are faster to
mature in females
4.
Environment
Boys are expected to be more adventurous and explore their environment,
an activity that improves spatial skills.
5.
Preferred Cognitive Mode
Men and women use different strategies when solving problems (women
tend to solve them verbally) and this may cause observed sex differences
in behaviour.
Showed 2 functions of the Corpus Callosum:
1. Transfer learned information from one hemisphere to the other
2. When cut, each hemisphere can function independently
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Trained cats to perform visual discrimination of 2 panels – one with a
circle on it and one with a square on it with the positions of these shapes
varied from trial to trial
The cats learned which symbol to press in order to get food.
M&S thought that there are 2 ways for visual information to move from
one eye to the opposite hemisphere: (1) corpus callosum (2) optic chiasm
Wanted to study one hemisphere at a time so they cut both of these and
covered one eye with a patch, restricting all incoming visual information
to the hemisphere on the same side as the uncovered eye.
Results
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Tests of Cerebral
Lateralization
Sodium Amytal Test
All cats learned the discrimination with a patch on one eye even though
cutting the optic chiasm created an area of blindness
When the patch was transferred to the other eye for intact cats and control
with either the OC or CC transected, they performed the task with close
to 100% accuracy
When transferred the patch to the experimental cats, the performance
dropped for the hemisphere that hadn’t learned the task, but these cats
learned the task as if they had never seen it before.
4.
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Dichotic Listening Test
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Functional Brain Imaging
Patients with Unilateral Damage
Administered to patients prior to neurosurgery so that the surgeon knows
the side of speech lateralization and can take care not to damage the
language areas
Sodium amytal is injected into one carotid artery and anaesthetizes the
ipsilateral hemisphere and allows the abilities of the contralateral
hemisphere to be assessed
Inject on dominant speech hemisphere (left)  muteness or speech errors
Inject on nondominant speech hemisphere (right)  no mutism and a few
speech errors.
A sequence of 3 pairs of digits is presented through earphones, the 2
digits of each pair are presented simultaneously, one digit to each ear
When the subject is asked to report the six digits, there is a slight but
consistent tendency to report more of the digits presented to the ear
contralateral (opposite side) to the dominant language hemisphere.
o Ex. Right-hemisphere specialization for language performed
better with the L ear than the R.
Although the sounds from each ear are projected to both hemispheres,
contralateral connections are stronger and take precedence when 2
different sounds are simultaneously competing for access to the same
cortical auditory centers.
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PET or fMRI techniques have revealed that there is typically more
activity in the left hemisphere than the right
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If damage is localized to only one hemisphere, any deficits seen may be a
result of lateralization of function
o
o
Split Brain Patients
Q: What does this mean:
Commissurotomized patients have 2
independent streams of
consciousness: however, unlike splitbrain laboratory animals, the two
hemispheres of communisurized
patients are not equal?
5.
Differences in the L and R
Hemispheres
Comparing Functions of L and R
Hemispheres
Evidence of 2 Independent Streams
of Consciousness
Ex. Distinction has been made in the processing of whole objects versus the
parts of those same objects .
One part of the brain is involved in determine the overall shape of a triangle,
another part processes the specific details (i.e. dots within triangle)
R hemisphere seems responsible for global visual processing
L hemisphere responsible for local visual processing
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Have a cut in their corpus collosum to reduce the severity of convulsions
2 Hemispheres are disconnected from each other
Typical experiment involves the subject seated in front of a computer
monitor and an object or word would then appear briefly in either the
right or left visual field of the monitor and the subject would report what
they saw.
All stimuli presented in the left visual field were transmitted to the right
visual cortex and vice versa.
Fine tactual and motor tasks were performed by each hand under a ledge.
o Object in right visual field, the subject says comb because the L
hemisphere is dominant for language production
o Obj in left visual field, the subject can’t report anything
because the R hemisphere is unable to speak and L hemisphere
can’t see the stimulus.
o The R hemisphere still processes the stimulus because if asked
to identify that object by touch with their left hand, they are
able to do the task.
**Think of this as Ms. R Hemisphere who understands a few simple instructions but
can’t speak, who receives sensory information from the left visual field and left hand
and who controls the fine motor responses of the L hand. Mr. L hemisphere is verbally
adept, receives sensory information from R visual field and R hand and controls motor
responses of the R hand.
Left
Right
- Better at language-related tasks
Better at understanding spoken
- Controls ipsilateral body
words and grammar
movements
Better at spatial ability
- Verbal memory
Process emotional stimuli –
- Episodic memory
facial emotion recognition and
- Acts as the Interpreter
musical tasks
:hypothetical neuronal
Greater role in nonverbal
mechanism that continuously
memory
assesses patterns of events and
tries to make sense of them.
Language, emotion, musical ability... are composed of dozens of different
individual cognitive activities and there’s no reason to assume each of
them is lateralized in a hemisphere.
Thus, complex cognitive tasks – reading, judging space – should be
broken down into their consitutent cognitive processes.
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When an object is presented to the left hemisphere either by touching
with the right hand or viewing something in the right visual field, the
split-brain patient could pick out the correct object with the right hand
When object is presented to R hemisphere by touching with L hand or
viewing something in the L visual field, the patient could pick out the
correct object with the L hand but not the R hand
o When an apple picture was flashed in the right visual field of a
split-brain patient, the L hemisphere could do one of 2 things:
1. L could say it saw a picture of an apple
2. Patient can reach under the ledge with the right hand and
feel out the apple.
If the non-speaking R hemisphere were asked to indicate the object that
had previously been presented to the left hemisphere, it can’t.
This is communication between hemispheres via a nonneural route – in
Cross Cuing
Q: How does this work? Was shaking
his head and frowning the cue to the
left?
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If a split brain patient is presented with 2 objects at the same time, one on
each visual field, they can reach into 2 different bags at the same time
and pull out the two objects.
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Occurs when the 2 hemispheres are presented with different information
about the correct choice and then asked to reach out and pick up the
correct object from a collection in full view
Right hand pick out what left hemisphere saw but the right hemisphere
seeing what it thinks is an error being made causes the left hand to grab
the right and pull it to the other object.
Learning 2 things at once
Helping Hand Phenomenon
Q: Why does the right hand act first?
one test, a red or green light was flashed in the left visual field and the
split-brain patient was then asked to name the color: red or green, most
patients only get 50% right
However one subject performed almost perfectly when he initially said
the incorrect color using his left hemisphere, his head shook and the
patient changed his guess to the correct color because the right
hemisphere heard the left’s incorrect guess of the left and was signalled
to the left hemisphere that it was wrong by shaking the person’s head.
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6.
Experimentation with Split
Brain Patients
Lateralization of Attention
Luck, Hillyard, Mangun, Gazzaniga
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Used split-brain patients and used a visual search task in which the items
were rectangles made from red and blue squares
When the blue square was placed immediately above the red square, it
was a distractor item and when the squares were reversed, the red square
was a target item.
Stimuli was presented unilaterally or bilaterally in sets of 2,4, and 8
The subjects had to decide whether the target item was in display and if
so in which visual field
Control – no significant differences between reaction time functions for
the unilateral arrays as compared to the bilateral arrays
Split brain patients – faster for bilateral arrays, each hemisphere was able
to conduct an independent serial search.
Guided Visual Task
Split brain patient searched for a target black circle among distractor
black squares, grey circles and grey squares, the reaction times presented
in R visual field were faster than for L, suggesting that L hemisphere is
specialized for processing stimuli with specific shared features.
Faces
Levy, Trevarthen, Sperry
When disconnected, the 2
hemispheres may work differently depending
on the type of orienting required.
With reflexive/ exogenous
orienting there may be independence between
the left and right hemispheres and can work in
parallel
With endogenous
(voluntary) orienting, the hemispheres may
actually compete with each other
Chimeric figures test:
Visual images are presented to the subject that
consist of faces and other patterns that have
been split down the center and then
recombined with other images
Patients did not realize any
Z Lens
Q: What relationship does using a Z
lens have to do with hearing speech
in one ear?
Information Shared between Split
Hemipsheres
Zaidel
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The Z lens limits visual input to one hemisphere of split-brain patients
It is a contact lens that is opaque on one side and permits visual input to
enter only one hemisphere irrespective of eye movement.
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When the Z lens was used to assess the behavioral reactions of the right
hemispheres of split brain patients to various emotion-charged images:
photos of relatives, pets, themselves... the patient’s behaviors were
emotionally appropriate, meaning that R hemispheres are capable of
emotional expression.
Interestingly, the emotional content was reflected in patients’ speech and
nonverbal behavior.
A patient’s left hemisphere was able to react appropriately to an image
presented on the R hemisphere.
Task difficulty also contributes to the reduced lateralization of function,
because complex tasks require both hemispheres to be used.
Damage in the angular gyrus (border b/w the left temporal and parietal
lobes, just anterior to the occipital lobe) is the cause of alexia (lose
ability to read) and agraphia (lose ability to write and spell)
Left angular gyrus is responsible for comprehending language-related
visual input causing patients to lose ability o read and write.
Has not stood up well to the challenge of testing and hasn’t been
supported
7.
Wernicke-Geschwind
Model of Language
Lateralization
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Historical Antecedents of the
Wernicke-Geschwind Model
discordance and when asked to pick out the face they had seen, they
always chose the one in their left visual field (RH)
When Archimbaldo paintings were shown, a split-brain patient’s left
brain could only see the objects that made up the face while the right
brain could see the face.
Visual completion is when people with scotomas can fill out the missing
visual field
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Broca’s Aphasia: selective lesions of Broca’s area produce a syndrome
of aphasia whose symptoms are expressive or disjointed
Wernicke’s aphasia: Receptive deficits - Poor comprehension of both
written and spoken language and speech that is meaningless but retains
superficial structure, rhythm and intonation.
Damage to the pathway connecting Broca’s and Wernicke’s areas is the
arcuate fasciculus would produce a third type of aphasia, which he
called conduction aphasia which is difficulty repeating words they just
heard.
There are 7
components of the WernickeGeschwind model
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How it works
When you are
having a conversation, the auditory
signals triggered by the speech of the
other person are received by your
primary auditory cortex and conducted
to Wernicke’s area for understanding
Wernicke’s area
generates the neural representation of
the throught underlying the reply and it
is transmitted to Broca’s area via the left arcuate fasciculus.
Once in Broca’s area, the signal activates the right neurons of primary
motor cortex and muscles of speaking
If reading aloud, the signal received by your primary visual cortex is
transmitted to your left angular gyrus, which translates the visual form of
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Effects of Cortical damage on
Language Abilities
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Effects of Electrical Stimulation of
the Cortex on Language Abilities
the word into its auditory code and transmits it to Wernicke’s area for
comprehension
Wernicke’s area then triggers the appropriate responses in arcuate
fasciculus, Broca’s area and motor cortex to elicit the motor responses.
Surgery that destroys all of Broca’s area but little surrounding tissue
typically has no lasting effects on speech.
Some speech problems were observed after the removal of Broca’s area
but their temporal course suggested that they were products of post
surgical edema/ swelling rather than the excision of the area itself.
Small lesions to Broca’s area seldom produced lasting language deficits
and lesions restricted to Wernicke didn’t always produce lasting language
deficits.
Lesions in parietal or temporal areas were just as likely to produce
articulation problems
Refuting the Wernicke- Geschwind Model
Findings using CT and MRI on aphasia are:
1. No aphasic patients have damage restricted to Broca’s area or
Wernicke’s area and damage to the surrounding W-G areas have
little lasting effect on the use of language.
2. Aphasic patietns almost always have significant damage to
subcortical white matter
3. Large anterior lesions are more likely to produce expressive
symptoms whereas large posterior lesions are more likely to produce
receptive symptoms. Aphasia always involves both expressive and
receptive symptoms.
4. Global aphasia – severe disruption of all language related abilities
is usually related to massive lesions of anterior cortex, posterior
cortex and underlying white matter.
5. Aphasic patients sometimes have brain damage that doesn’t
encroach on the W-G areas
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Electrical stimulation was done by assessing the responses of conscious
patients who were under local anesthetic to stimulation applied to various
points on the cortical surface
Electrical stimulation is more localized than a brain lesion and found that
sites at which stimulation blocked or disrupted speech in conscious
neurosurgical patients were scattered throughout a large expanse of
frontal, temporal and parietal cortex instead of being restricted to W-G
areas.
Right hemisphere stimulation almost never disrupted speech.
Findings
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Areas of cortex at which stimulation could disrupt language extended far
beyond the boundaries of the W=G language areas
Each of the language tests were disrupted by stimulation at widely
scattered sites
There were major differences among the subjects in the organization of
language abilities.
8.
Evolutionary Perspective of
Cerebral Lateralization and
Language
Analytic-Synthetic Theory
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There are 2 basic modes of thinking:
1. Analytic mode – L hemisphere operates in this logical, analytic
manner
2. Synthetic mode – R hemisphere is a synthesizer, concerned with
overall stimulus configuration.
Problem with this theory is that it’s vague, it is not possible to specify the
degree to which any task requires either analytic or synthetic processing.
Motor Theory
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Left Hemisphere isn’t specialized for control of speech specifically but
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for the control of fine movements
The problem with this theory is that it doesn’t suggest why motor
function became lateralized in the first place.
Linguistic Theory
When did cerebral Lateralization
evolve?
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Primary role of the left hemisphere is language because when a study of
deaf people who suffer unilateral brain damage, the L hemisphere
damage can disrupt the use of sign language but not pantomime gestures.
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Lateralization of function may have preceded human evolution.
Right handed may have evolved from a preference for the right side of
the body for feeding
There are 2 main advantages of lateralization:
1. May be more efficient for the neurons performing a particular
function to be concentrated in one hemisphere
o Ex. It’s better to have one highly skilled hand rather than 2
moderately skilled hands
2. Two different kinds of cognitive processes may be more readily
performed simultaneously if they’re lateralized to different
hemispheres.
o Ex. Motor theory suggests that language was lateralized to the
L hemisphere because fine motor control was already
lateralized there.
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Evolution of Human Language
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Motor Theory of Speech
Perception
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Gestural Language
Pollick and deWaal
9.
Cognitive neuroscience
Approach to Language
Premise 1
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At 10 months, human infants can distinguish the sounds of all human
languages but by 30 months, they can readily discriminate only those
sounds that compose the languages to which they’ve been exposed.
Even the most vocal nonhumans can produce a relatively few calls but
they’re able to interpret a wide variety of other sounds in their
environments – these nonhumans are limited by their inability to exert
fine motor control over their voices, a talent only humans have.
Proposes that the perception of speech depends on the words activating
the same neural circuits in the motor system that would be activated if the
listener said the words.
Support comes from the discovery that just thinking about performing a
particular action activates the same areas of the brain as performing the
action – mirror neurons are activated
Comparing the gestures and the vocalizations of chimpanzees, a highly
nuanced vocabulary of hand gestures were used in many situations and in
various combinations.
The cognitive neuroscience approach to language is guided by 3
premises:
Language can be broken down into constituent cognitive processes that
are much simpler than the cognitive activities that Geschwind (and
others) tried to localize to a single part of the brain
These constitutent processes include phonological analysis (analysis of
language sounds), grammatical analysis (analysis of language structure)
and semantic analysis (of meaning)
Premise 2
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Areas of the brain involved in language are not exclusively involved with
that function.
Areas involved with reading might also be involved with short term
memory or pattern recognition.
Premise 3
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Brain areas involved with language are small and widely distributed
The Brain during Silent Reading
Bavelier
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Brain activity were recorded during the reading of sentences with control
periods where the participants were presented with strings of consonants
interposed between periods of silent reading.
Used sensitive fMRI to study the activity of the brain and found:
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1.
2.
PET Study of Naming
Damasio
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10. Cognitive Neuroscience of
Dyslexia
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Developmental Dyslexia: Causes
and Neural Mechanisms
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Only small areas are activated at a given time in a single subject
These areas vary from subject to subject and also within a single
subject from trial to trial
3. The activity was spread over very large areas of the brain
4. The active areas were more often in the left hemisphere than the
right
5. That the activity spread far beyond those areas predicted by
Wernicke-Geschwind model.
Also found right hemisphere damage rarely disrupts language activity
PET activity was recorded from the left temporal lobes of healthy
volunteers while they named images (famous faces, animals, tools)
presented on a screen
Naming objects activated areas of the left temporal lobe outside the
classic Wernicke’s language area.
Dyslexia is a pathological difficulty in reading, and there are 2 types:
1. Developmental Dyslexias: Which become apparent when a child is
learning to read
2. Acquired dyslexias: caused by brain damage in individuals who
were already capable of reading.
There is a large genetic component to this
Dyslexia is hard to identify because there are so many changes in the
brains of individuals that no single kind of brain pathology has been
found.
Reading or absence of reading can also induce major changes in the
brain.
Researchers have tried to attribute developmental dyslexia to attentional
and other sensorimotor deficits caused by damage to neural circuits
linked to magnocellular layers of the lateral geniculate nuclei (receive
information from rods for perception of movement)
However even when visual, auditory, or motor deficits are present in
dyslexic patients, they don’t account for all aspects of the disorder.
It’s now widely agreed upon dyslexia comes from a disturbance of
phonological processing (representation and comprehension of speech
sounds) and not a disturbance of sensorimotor functioning.
Ramus Theory on Developmental dyslexia
Ramus argues that the first stage in the development of dyslexia is the
occurrence of developmental errors in auditory areas around the lateral
fissure
A gene associated with dyslexia controls neuronal migration
However, this theory doesn’t explain why dyslexia is often associated
with cerebellar damage.
Developmental Dyslexia and
Culture
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Cognitive Neuroscience of Deep
and Surface Dyslexia
1.
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Dyslexia could be a cultural disease because twice as many English
speakers as Italians are diagnosed as dyslexic
English has more phonemes spelled in 1120 different ways, whereas
Italian is less than that
Italian readers displayed more activity in the left superior temporal lobe
whereas English readers displayed more activity in the left inferior
temporal and frontal lobes.
However both language readers display the same pattern of abnormal
PET activity – less than normal reading-related activity in the posterior
regions of the temporal lobe.
Reading aloud can be accomplished in 2 different ways:
Lexical Procedure
Based on specific stored information that has been acquired about written
words
Reader looks at word and recognizes it and says it.
2.
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Phonetic Procedure
The reader looks at the word, recognizes the letters, sounds them out and
says the word
This is used for unfamiliar words.
Knowing how reading aloud has proven useful in understanding the
symptoms of 2 kinds of dyslexia resulting from brain damage:
1. Surface dyslexia
Patients have lost their ability to pronounce words based on their specific
memories of the words but can still apply rules of pronunciation in their
reading.
o Ex. Can pronounce words and nonwords with pronunciation
that is consistent with common rules (e.g. fish, river, glass,
spleemer and twipple)
o Can’t pronounce words that don’t apply to the rules (e.g. have
is pronounced like cave)
2. Deep Dyslexia
Patients have lost their ability to apply rules of pronunciation in their
reading but can pronounce familiar words based on their specific
memories of them
Completely incapable of pronouncing nonwords and have difficulty
pronouncing uncommon words
o Ex. Respond by responding to the overall look, meaning or
derivation of the word
o Quill might be said for quail based on overall look, hen for
chicken (meaning) or wise for wisdom (derivation of the word)
CH 16: CASES
1. The Split Brain
The Case of Peter, Split Brain
Patient Tormented by Conflict
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2.
Evolutionary
Perspective
The Case of W.L The Man who
Experienced Aphasia for Sign
Language
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3. Dyslexia
The case of N.I the woman who
Read with her R Hemisphere
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In most split brain patients, the L hemisphere seems to control most
everyday activities but when in a few patient cases, the R hemisphere is
more active, there can be serious conflicts
Peter received a commissurotomy and was left-hemisphere dominant for
language
He couldn’t respond with the L side of his body to verbal input because
his L side would not control the left side via ipsilateral fibers
Peter’s R hemisphere would cause his left side to do things he didn’t
want to do.
His L hemisphere would swear at the L hand and make the Right hand
force the L hand to do what it wanted.
W.L was a deaf man who got a stroke on the left frontotemporoparietal
side.
Compared to a recording of him before the stroke, W.L suffered a loss in
his ability to use and understand sign language.
He could produce and understand pantomime gestures suggested that his
sign-language aphasia wasn’t the result of motor or sensory deficits nor
was it resulting from cognitive deficits.
N.I experienced periods of aphasia at 13 and suffered from convulsions.
In an attempt to relieve these symptoms, a left hemispherectomy was
performed – her left hemisphere was totally removed and her seizures
stopped
She recognizes letters but is incapable of translating them into sounds and
she can read concrete familiar words, she can’t pronounce even simple
nonsense words and her reading errors indicate she’s reading on the basis
of the meaning and appearance of words.
Experienced the same symptoms as patients with deep dyslexics.