Neuroimaging and Reading
Research
Presented by Mindy Keefer
EDSP 765
©2006
Dyslexia
• “a developmental disorder characterized by an
unexpected difficulty in reading in children and
adults who otherwise possess the intelligence,
motivation, and education considered necessary
for developing accurate and fluent reading.”
(p.419)
– 80% of SLD cases
– 40% of school-age students read below grade level
• Different theories
– Phonological-deficit subtype
– Naming speed-deficit subtype
– Double-deficit subtype
(Shaywitz & Shaywitz, 2004; Vukovic & Siegel, 2006)
Impact of Phonological Awareness
• “phonological awareness measures
predict later reading achievement”
• “deficits in phonological awareness
consistently separate RD and nondisabled
children”
• “phonological deficits persist into
adulthood”
• “instruction in phonological awareness
promotes the acquisition of reading skills”
(Pugh et al., 2000)
Phonologic Model of Dyslexia
• Higher-order cognitive and linguistic
functions intact (intelligence, verbal
reasoning, vocabulary, and syntax)
• BUT lower-order phonologic processing of
small units or phonemes (decoding) block
access to higher-order processes
(Shaywitz & Shaywitz, 2004)
Brain Terms
Superior (Dorsal)
Posterior (Caudal)
Anterior (Rostral)
Inferior (Ventral)
• Frontal Lobe
– Motor
– Executive Functions
– Broca’s Area
• Parietal Lobe
–
–
–
–
Somatosensory
O-P-T crossroads
Sound-symbol association
Perceptual-motor
• Temporal Lobe
– Auditory
– Wernicke’s Area
– Object Recognition
• Occipital Lobe
– Vision
Left vs. Right Hemisphere
Left
• Leading
• Verbal
• Analytic
• Routinized
• Sequential
• Local
• Microstructural
• Fine
• Successive
• Concordant/convergent
Right
• Automatic
• Nonverbal
• Holistic
• Novel
• Simultaneous
• Global
• Macrostructural
• Coarse
• Simultaneous
• Discordant/Divergent
Reading the Mind
1973 – Computed
Tomography (CT)
Phrenology
Postmortem Studies
• Brain Localization
– Wernicke’s area
– Broca’s area
– X-rays; 3-D image
Magnetic Resonance
Imaging (MRI)
**provided info on
structure but not
function
(Collins & Rourke, 2003)
Reading the Mind
1980s – functional brain
imaging
• Baseline activation
– Metabolism, signaling
• Function-specific
activation
– Functional connectivity
Magnetoencephalography
(MEG)
– Functional mapping info
– Co-registration
Positron emission
tomography (PET)
– Measured blood flow
through injected dye
Functional magnetic
resonance imaging (fMRI)
– Noninvasive
– Blood oxygen level
dependent (BOLD)
– Before/during/after images
(Papanicolaou et al., 2004)
Brain Circuit that Supports Reading
• Primary visual cortex
• Association visual cortex in the ventral
temporo-occipital areas
• Posterior portion of the superior temporal
gyrus extending posteriorly into the
supramarginal gyrus (Wernicke’s area)
• Inferior frontal gyrus (Broca’s area)
***except for primary visual cortex, all
activity stronger in left hemisphere
Major Reading
ReadingCircuits
Circuits
Major
Word Analysis
Word Form
Pathways for Reading
Beginning Reading
• Parieto-temporal
– Step-by-step
– Analyzing word,
pulling it apart, linking
letters to sounds
Skilled Reading
• Occipito-temporal
–
–
–
–
Express pathway
Hub of sensory info
Reacts to whole word
Neural model
permanently stored
(spelling,
pronunciation,
meaning)
(Pugh et al., 2000; Shaywitz, 2003)
Circuitry in Dyslexic Readers
• Underactivation of left hemisphere and posterior areas
• Overactivation in frontal/Broca’s region
• Use of right hemisphere
– Functional system (accuracy), but not automatic (fluency)
(Shaywitz, 2003)
In Summary…
Two functional-neurobiological hallmarks of
dyslexia:
– Dysfunction of the perisylvian
• Posterior superior temporal gyrus (STG)
• Parieto-temporal region (phonological processing)
– Dysfunction of the left fusiform regions
• Visual word form area (VWFA)
• Occipito-temporal region (automaticity/whole word)
• Most highly correlated with reading skill
Compensatory Shift:
– Anterior brain sites
– Right hemisphere regions
(McCandliss & Noble, 2003)
Connection?
“We propose that functional and structural
abnormalities in the perisylvian regions
that subserve phonological processing
may have a cascading effect on the
development of rapid word recognition
processes during the years when the
VWFA is becoming increasingly
specialized to respond to regularities
within the writing system.” (p.201)
(McCandliss & Noble, 2003)
Is this a global or phonological
deficit?
• Global-deficit
Results
– Disruption in functional
connectivity?
– Structural
malformation?
• Phonological deficit
– Confined to tasks that
make explicit demands
on phonological
assembly
– High phono assembly
• NI displayed functional
connectivity
• DYS displayed
correlations with the
right hemisphere
– Low phono assembly
• NI & DYS displayed
functional connectivity
(Pugh et al., 2000b)
Implications
• No structural dysfunction that would
prevent functional connectivity
• Weakness in phonological representations
– Breakdown occurs when orthographic-tophonological assembly required
– Phonological assembly required, DYS readers
use right hemisphere
• Specific training could prompt cohesive
functioning
Connecticut Longitudinal Study
• Participants followed
from age 5 – 18
– Persistently poor
readers (PP)
– Accuracy-improved
readers (AI)
– Nonimpaired readers
(NI)
• Assessments
involved pseudoword
rhyming and reading
real words
• Pseduoword rhyming
– PP & AI demonstrated
underactivation in
posterior neural
systems
• Real word reading
– AI demonstrated
underactivation of
posterior regions
– PP demonstrated
similar activation
patterns as NI
(Shaywitz & Shaywitz, 2004)
• What are the benefits of sight words?
• If students struggle to crack the code, is rote
memorization the key?
• “With time, effective instruction and the
experience of repeatedly reading the same word
correctly, the child forms the synaptic
connections that result in increasingly accurate
neural representations of that word.” (p. 428)
– Is repetition all that is needed for synaptic
connections?
• Repeated readings based on repetition
(memorization?)…
Direction
• Potential for a cohesive
system with sufficient
training
• “Strongly implies that left
hemisphere posterior
circuits, although poorly
developed, are not
fundamentally disrupted
in readers with RD.”
(Papanicolaou et al.,
2004, p. 408)
(Pugh et al., 2000b)
• Compensatory strategies
inefficient
– Never achieve fluency
when utilizing RH
– Persistently poor readers
rely on rote memorization
for recognizing real words
• Demonstrates need to
incorporate analytic
strategies for word
identification
(Shaywitz & Shaywitz, 2004)
Can Dyslexic Readers Develop the FastPaced Word Form Reading System?
• Used fMRI to study
• End of year images:
struggling readers
– Right side pathways
less prominent
before and after a
– Further development
yearlong experimental
of primary neural
reading program
systems on left side
– Observed “brain
repair”
– Necessary for fluency
Neural Effects of Remediation
(Temple et al., 2003)
• 20 DYS & 12 NI
• Fast ForWord Language
– Computerized intervention
program
– Designed to improve
auditory and language
processing
• 100 min per day/ 5 days
per week/ 27.9 days
Results
• Significant improvement
in reading ability
– Word id, pseudoword,
passage comp, rapid
naming, oral language
• Increased activity in brain
regions
– LH temporo-parietal cortex,
inferior frontal gyrus
– RH structures and
attentional structures
Neural Effects of Remediation
(Simos et al., 2002)
• 8 DYS & 8 NI
• 80 hours of 1:1 instruction
– 1-2 hr/day; 8 wks
Results
• Significant gains in
reading skills
– Basic word reading avg.
• Increased brain activation
• Phono-Graphix program
• Lindamood Phonemic
Sequencing program (2)
– Posterior portion of left
superior temporal gyrus in
all 8 children
– dev. of phonologic
processing and decoding
skills
• http://www.brookespublis
hing.com/mccardlemris/
Future Directions
•
•
•
•
•
Replication/ Large-scale studies
Follow-up studies of brain activation
Use untreated dyslexics as control
Use more experimental treatments
Direct measurement of reading ability
Nature vs. Nurture
• Are there differences in
the structure of the brain
when comparing the
genetically RD group
images and the
environmentally
influenced RD groups?
Do their brains
compensate in the same
manner if they are
different? (Carrie)
• Examined relation of
leftward planar
asymmetry (PTa) and
SES to phonological
performance
• 39 sixth graders
Results
• Individual variability in
brain asymmetry and
SES factors account for
individual differences in
phonological skill
(Eckert, Lombardino, & Leonard, 2001)
Future imaging studies
Classic Dyslexic
• Glitch in posterior
reading system
• High verbal ability
used for
compensation
• Accurate but slow
readers
Poor Readers as a
result of Experience
• Inaccurate AND slow
readers
• Posterior reading
system wired yet
never activated
• Evidence-based
reading instruction
should improve skills
Nature vs. Nurture Summary
• Not real clear
• “Children may fail to
develop adequate
reading skills because of
their environment,
abnormal brain structure,
or both…a child with
normal leftward PTa from
a low-SES family may
benefit more than would a
child with reversed PTa”
(p. 998)
• No genetic linkage to PTa
• Study did not look at
combination of SES and
abnormal PTa
• Sample size too small
• Shaywitz suggests
differences but more
research needed
Limitations to Neuroimaging
• Lack of consensus in how to define
regions of interest
• Lack of consensus in how to measure
regions
• Lack of consensus on what part to
measure
Implications
• Dyslexia has a neurological basis BUT it is
not a disease
• “Instruction seems to play a significant role
in the development of neural systems that
are specialized for reading.” (Simos et al.,
2002, p.1212)
• Test other hypotheses
• Define at-risk and intervene early on
Discussion
• This chapter presents a wide range of evidence
that children who have reading difficulties (they
call them “disabilities”) have difficulty with
phonological processing, and good readers rely
more on the left side of the brain. Given what we
can tell about a student based on their early
skills such as DIBELS and oral reading fluency,
do we really need this information? (Nicole)
• does the medical model create a self-fulfilling
prophecy, further “disabling” students and
making schools less accountable for educating
“disabled” students? (Nicole)
Discussion
• I think confirming evidence from a variety of fields is
extremely important. Neuropsych research further
confirms what we have been reading about reading!
THIS IS A GOOD THING! How can we discount what we
have learned from a variety of fields- does a behavioral
approach tell us everything-nope, does a neuropsych
approach tell us everything-no again. THe reason all of
these fields exist is because they all have something
important to offer. (Tara)
• why use indirect measures to study the brain and
cognitive functioning when direct measures are
available? (Jodi)
Discussion
• Since there is involvement in the visual
cortex and the fast-acting recognition
circuit is in the complex visual processing
of the brain, I'm wondering if the visual
training programs that are being offered
might actually have some benefit? (Sue)
Discussion
• if parts of the brain that are implicated in
fluency are impaired, how will
interventions in this area be very effective?
(Christy)
• However, is there a point at which the
brain is no longer able to form new
circuitry for phonlogical skills? I guess until
we know, we continue to intervene? What
else is there to do? (Kristi)
Discussion
• My biggest question regarding this chapter is
that if we know that real differences exist in the
brains of individuals with specific reading
disability as compared to those with no disability,
and there are major questions regarding
accurate SLD diagnoses, then why can’t we use
functional imaging to provide confirming data?
Why is data gathered through neuroimaging so
elusive to us in this profession? If it could really
help us in our diagnoses, why can’t we do more
to cooperate with the medical community to get
this type of information? (Tom)
Discussion
• Although we know that differences exist between
the neural pathways of students with disabilities
and those without (so to speak), how can
schools best utilize this information in a practical
manner without increasing budgets? (Julie)
• when one reviews a study in which a fMRI was
used, it is important for the researcher to
mention the same MRI machine was used for all
subjects. Otherwise, dfferences in machines
may impact obtained results. (Rick)
Discussion
• What does brain imaging really tell us
anyway? Does it tell us there are damaged
areas in the brain of individuals with RD or
maybe there brains developed preferred
neuropathways that can be retrained?
(Erin)
References
• Collins, D.W., & Rourke, B.P. (2003). Learning-disabled brains: A
review of literature. Journal of Clinical and Experimental
Neuropsychology, 25(7), 1011-1034.
• Demonet, J.F., Taylor, M.J., & Chaix, Y. (2004). Developmental
dyslexia. The Lancet, 363, 1451-1460.
• Eckert, M.A., Lombardino, L.J., & Leonard, C.M. (2001). Planar
asymmetry tips the phonological playground and environment raises
the bar. Child Development, 72(4), 988-1002.
• Hale, J.B., & Fiorello, C.A. (2004). School Neuropsychology: A
Practitioner’s Handbook. New York, NY: The Guilford Press.
• Krasuski, J., Horwitz, B., & Rumsey, J.M. (1996). A survey of
functional and anatomical neuroimaging techniques. In R. Lyon & J.
Ramsey (Eds)., Neuroimaging: A Window to the Neurological
Foundations of Learning and Behavior in Children (pp. 25-52).
Baltimore, MD: Paul H. Brooks Publishing Co.
References
• Lyon, G.R. (1996). Foundations of neuroanatomy and
neuropsychology. In R. Lyon & J. Ramsey (Eds)., Neuroimaging: A
Window to the Neurological Foundations of Learning and Behavior
in Children (pp. 3-23). Baltimore, MD: Paul H. Brooks Publishing
Co.
• McCandliss, B.D., & Noble, K.G. (2003). The development of
reading impairment: A cognitive neuroscience model. Mental
Retardation and Developmental Disabilities Research Reviews, 9,
196-205.
• Papanicolaou, A.C., Pugh, K.R., Simos, P.G., & Mencl, W.E.
(2004). Functional brain imaging: An introduction to concepts and
applications. In P. McCardle & V. Chhabra (Eds.), The Voice of
Evidence in Reading Research (pp. 385-416). Baltimore, MD: Paul
H. Brooks Publishing Co.
• Pugh, K.R., Mencl, W.E., Jenner, A.R., Katz, L., Frost, S.J., Lee,
J.R., Shaywitz, S.E., & Shaywitz, B.A. (2000a). Functional
neuroimaging studies of reading and reading disability
(developmental dyslexia). Mental Retardation and Developmental
Disabilities Research Reviews, 6, 207-213.
References
• Pugh, K.R., Mencl, W.E., Shaywitz, B.A., Shaywitz, S.E., Fulbright,
R.K., Constable, R.T., Skudlarksi, P., Marchione, K.E., Jenner, A.R.,
Fletcher, J.M., Liberman, A.M., Shankweiler, D.P., Katz, L., Lacadie,
C., & Gore, J.C. (2000b). The angular gyrus in developmental
dyslexia: Task-specific differences in functional connectivity within
posterior cortex. Psychological Science, 11(1), 51-56.
• Shaywitz, B.A., Shaywitz, S.E., Pugh, K.R., Mencl, W.E., Fulbright,
R.K., Skudlarski, P., Constable, R.T., Marchione, K.E., Fletcher,
J.M., Lyon, G.R., & Gore, J.C. (2002). Disruption of posterior brain
systems for reading in children with developmental dyslexia.
Biological Psychiatry, 52, 101-110.
• Shaywitz, S. (2003). Overcoming Dyslexia: A New and Complete
Science-Based Program for Reading Problems at Any Level. New
York, NY: Vintage Books.
• Shaywitz, S.E., & Shaywitz, B.A. (2004). Neurobiologic basis for
reading and reading disability. In P. McCardle & V. Chhabra (Eds.),
The Voice of Evidence in Reading Research (pp. 417-442).
Baltimore, MD: Paul H. Brooks Publishing Co.
References
• Simos, P.G., Fletcher, J.M., Bergman, E., Breier, J.I., Foorman,
B.R., Castillo, E.M., Davis, R.N., Fitzgerald, M., & Papanicolaou,
A.C. (2002). Dyslexia-specific brain activation profile becomes
normal following successful remedial training. Neurology, 58(8),
1203-1213.
• Temple, E., Deutsch, G.K., Poldrack, R.A., Miller, S.L., Tallal, P.,
Marzenich, M.M., & Gabrieli, J.D.E. (2002). Neural deficits in
children with dyslexia ameliorated by behavioral remediation:
Evidence from functional MRI. Proceedings of the National
Academy of Sciences of the United States of America, 100(5), 28602865.
• Vukovic, R.K., & Siegel, L.S. (2006). The double-deficit hypothesis:
A comprehensive analysis of the evidence. Journal of Learning
Disabilities, 39(1), 25-47.