Dyscalculia

Johanna M Debrechtjdebrecht@nvcc.edu

The Elephant in the Developmental Math Classroom

Dyscalculia

• Can we get a definition, please?

• Causes• Comorbidity • Research study results

Dyscalculia: Definition

Math is a very complex domain with very

complex processes, complicating issue.

Severe difficulty in learning arithmetic in

the absence of any other obvious factor,

such as lower IQ or ADHD, despite

adequate schooling and environment and

with a normal range IQ.

No standard definition within one country, much less worldwide

No standard symptoms

No diagnostic standard universally accepted

Estimated 3-7% of the general population

Common Characteristics

Difficulty counting small numbers of objects

Difficulty comparing numerosity Difficulty with symbolic representation

(Hindu-Arabic)

Difficulty using number words Difficulty subitizing, even for 3 The continued use of immature

strategies (finger counting)

Need to count up to place 8 between 3 and 9

Difficulty counting sequences when not starting at 1

Longer than normal response times Either guess quickly (fast but inaccurate)

or use immature strategies (slow but accurate)

NOT slower naming letters or geometric forms

May have normal memory May do well in other subjects

Other low numeric people may have poor arithmetic too, but count small numerosities and perform magnitude comparison tests normally. Dyscalculics do NOT.

NOT linked to…› Socioeconomic status› Gender› Amount of remedial tutoring

Dyscalculia: Proposed causes

Inability to represent and/or process exact numerosities, primarily small numerosities

Inability to connect symbolic representations (Hindu-Arabic) to (presumably

intact) numerosity concepts Heredity

› X chromosome (possibly) Highest incidence between mothers and daughters,

but also father-daughter and sister-sister

Comorbidity (occurs with)

ADHD Reading disabilities

› Estimated 40% of dyslexics have math difficulty too

Poor hand-eye coordination Poor memory for nonverbal information

The genetic link – if a relative has dyscalculia, then

58% of identical co-twins, 39% of fraternal co-twins have it, too

Siblings are 5 to 10 times more at risk, between 40-64% also affected

In one study of dyscalculic children,› 77 out of 149 family members were too› Of 39 families, 31 had at least one other

member also affected› 53% of parents, 53% brothers, 52% sisters

affected too

Research study results Dyscalculics are slower and less accurate for

symbolic representation on Stroop paradigm study, but not on nonsymbolic

Symbolic

2 5 2 5 2 5 Nonsymbolic

Why Dyscalculia Matters

The cost to society

Low numeracy in general is associated with…

Lower lifetime earnings Risk factor for depression

› More than 3 ½ times more likely Less employable

› UK study shows men twice as likely to be in nonworking household

› UK study shows women 3-4 times more likely to be in nonworking household

2 ½ times less likely to own a home

The benefit

Raising the mathematical ability of the lowest 19.4% one standard deviation would raise the GDP by 0.74%.

…or roughly $116 billion

The Brain

• The Basics• How do we study

neuroscience?

Brain structure

Cerebral cortex is about 1500-2000 or

roughly the size of a newspaper page

Consists of folds (gyri) and grooves

(sulci)

Frontal lobe, parietal lobe, temporal

lobe, occipital lobe, and cerebellum

http://www.healthybrainforlife.com/images/brain/brain-lobes-color.gif/image_preview

• Hippocampal region:

• Grows 15% in first 2 years of life

• Responsible for recall

• Frontal and parietal lobes:

• Most active areas during working memory usage

• Parietal lobe largely developed by age 3

• Frontal develops into adulthood

The Basics Neurons (brain cells) – the grey matter Axons – fibers extending from the cell

body to other neurons › Synapses – connect axons› Myelin – surrounds and coats synapses

Protects synapse Increases processing speed The white matter

Brain Development

Closed time tables

1. Proliferation – way more than needed

2. Migration

3. Differentiation

4. Growth

Brain Development cont’d

Open time tables1. Synaptogenesis2. Regressive processes

Cell death Axonal pruning

3. Myelination Back to front In corpus callosum, (connects left & right hemispheres)

front to back

How we study neuroscience• Brain injuries and brain

disorders• Structural and functional

imaging• Animal studies

Brain injuries and disorders

Brain damage resulting in math dysfunction – 2/3 in left hemisphere (AG)

Right IPS damage impairs visuo-spatial skill and perhaps other numerical skills

Gerstmann’s syndrome› Finger agnosia (inability to recognize fingers)› Dysgraphia (inability to write)› Acalculia (acquired later)/dyscalculia

(congenital)› Left-right disorientation

Turner’s syndrome (affects females, one X chromosome)› Normal to high IQ in language and

reasoning› Severely disabled in arithmetic

Brain injuries and disorders

Structural and functional imaging Structural

› MRI› CAT scans

Functional› fMRI does NOT use

radiation› Assesses BOLD

signal (Blood Oxygen Level Dependence)

Figure 4. Left and Right Parietal Regions Showing a Significant Effect of Adaptation in the First 30 s of Periods A1 and A2. Plots show the amount of rebound activation in those regions at the beginning of period A2, as a function of the notation used for adaptation stimuli during periods A1 and A2 (A = Arabic digits, D = setsof dots). Error bars represent 1 SEM. (Piazza, Pinel, Le Bihan, & Dehaene, 2007, p. 296)

What we’ve learned from neuroscience so far• Location of some of the

neural dysfunction

Locations of dysfunction: The what and where

IPS (intraparietal sulcus)› HiPS (horizontal intraparietal sulcus)

magnitude processing› Using TMS disruption in healthy students,

with fMRI, showed impaired numerosity activation with disruption of right IPS.

Left TPJ (temporoparietal junction) activates for symbolic magnitude tasks and deactivates for nonsymbolic.

Locations of dysfunction: The what and where

Numerosity coding takes place in a different part of the brain from analogue processing.

Addition and multiplication eventually become quickly retrieved math facts.

Subtraction is done in a different part of the brain and requires more processing.

Division has not been studied. Algebra circuits are largely independent of

arithmetical ones, but have not been much studied.

Neurological characteristics Of Students with Dyscalculia Less grey matter (neurons) in left, right, and bilateral IPS

Different patterns of connectivity in the left, right and bilateral IPS

Activation differences in nonsymbolic numerosity comparisons in the right IPS

Abnormalities in the activation of the left IPS during symbolic numerosity comparisons

Why aren’t all the results the same?

Theories

Perhaps there is a shift from right dominance to left dominance as children develop

Perhaps the parietal lobes specialize› Left handling symbolic processing and

calculation› Right handling estimation and subitizing

Diagnosis

The REAL unknown

Diagnosis

Brian Butterworth’s Dyscalculia Screener

A variety of other intelligence test have been used, but they are not consistent, nor reliable.› Below 30-35% on Woodcock-Johnson› Below 25% on ITBS› Two grades below chronological age

Teacher recommendation

Interventions

?

Why don’t we know more?

• Cognitive Neuroscience is new.

• We don’t fund the research.

• We don’t do the research.

Why don’t we know more?

We just got started.› The first fMRI study in children was

published in 1995, and it wasn’t in dyscalculia.

It’s really expensive.› One run for an fMRI study costs roughly

$600. Maintenance alone on a machine runs over $10,000 a month.

It’s barely a field yet, and it takes years of training.

Why don’t we know more?

You get what you pay for in research funding. › Severity of disorder as measured by

mortality, years of life lost, and disability-adjusted life years all affect funding.

NIH funding 2001-2009

The United States

NIH funding of Dyscalculia (DD) Research 2001-2009

2001-2003 $0 spent on DD

2004-5 $400,000 spent on DD

2005-6 $369,000 spent on DD

2006-7 $0 spent on DD

2008-2009 $1,574,000 spent on DD

Funding comparison: Dyscalculia versus ADHD Unit incidence

Severity index of

1.56

Publication ratio .07

Total funding

$2,343,000

Incidence 5/3

greater than DD

Severity index of

1.95

Publication ratio

2.19

NIH funding

$1,845,820,000

Funding comparison: Dyscalculia versus Dyslexia

Severity index of

1.56

Total funding

$2,343,000

Incidence 2 times

more than DD

Severity index of

1.90

NIH funding

$107,198,000

Funding comparison: Dyscalculia versus Autism Spectrum Disorder

Severity index of

1.56

Publication ratio .07

Total funding

$2,343,000

Incidence > 4.6

times LESS than DD

Severity index of

2.90

Publication ratio

21.39

NIH funding

$1,834,314,000

Dyslexia

Imprecise hearing of sounds Inability to manipulate phonemes Plasticity of neural networks fMRI results of interventions Age sensitive, the earlier the better

Neuromyths

No time to lose, everything important happens by age X:

Some truth: region for language changes depending on the age at which it is acquired

Only use 10% of the brain…

NOT TRUE

uh, no.

There are critical periods when particular subjects must be taught and learned…

Some falsity: always possible to learn

Neuromyths: cont’d

Left brain versus right brain: analytical versus artistic:

Sleep on it:

Memory stabilizationRestores cortical functions

Visual • Auditory • Kinesthetic:

Gender differences: Spatial tasks – evolutionary purpose

SOME TRUTH

NOT TRUE

NOT TRUE

TRUE

So…what can we do for the average student? Hands on Handwriting versus

typing Speak it out loud Be specific & direct Ask questions…&

wait for the answer Fluid intelligence

Provide structure Model planning Balance groups age-

wise Encourage,

encourage, encourage

So…what can we do for the average student? Second most

important recommendation:

EXERCISE

Most important recommendation

SLEEP

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Iuculano, T., Tang, J., Hall, C. W., & Butterworth, B. (2008). Core information processing deficits in developmental dyscalculia and low numeracy. Developmental Science, 11(5), 669-680. doi:10.1111/j.1467-7687.2008.00716.x

Landerl, K., Bevan, A., & Butterworth, B. (2004). Developmental dyscalculia and basic numerical capacities: A study of 8-9-year-old students. Cognition, 93(2), 99-125. doi:10.1016/j.cognition.2003.11.004

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Rousselle, L., & Noël, M. (2007). Basic numerical skills in children with mathematics learning disabilities: A comparison of symbolic vs non-symbolic number magnitude processing. Cognition, 102(3), 361-395. doi:10.1016/j.cognition.2006.01.005

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