Lecture 7 - Dyscalculia Flashcards
definitions of dyscalculia
- Ladislav Kosc (1970, cited in 1974):
○ “Developmental dyscalculia is a structural disorder of mathematical abilities which has its origin in a genetic or congenital disorder of those parts of the brain that are the direct anatomico-physiological substrate of the maturation of the mathematical abilities adequate to age, without a simultaneous disorder of general mental functions.”- DSM-V (American Psychiatric Association, 2013)
○ “A neurodevelopmental disorder of biological origin manifested in learning difficulty and problems in acquiring academic skills markedly below age level and manifested in the early school years, lasting for at least 6 months ; not attributed to intellectual disabilities, developmental disorders, or neurological or motor disorders”.
- DSM-V (American Psychiatric Association, 2013)
specific characteristics of dyscalculia
○ Low performance only in the domain of mathematics that is ‘out of line’ with age-/IQ-related expectations
○ Usually 1.5-2SD below the mean
prevalence
○ ~5–6%
○ comparable to dyslexia
○ prevalence in boys and girls roughly the same
stability
○ Early onset, persists into adulthood
○ Often restricted progress and no catch-up with peers despite extra help
○ “Doesn’t grow out”
heritability
○ Dyscalculia runs in families suggesting that there is a genetic component
○ Familial recurrence (Shalev et al., 2001, see also Landerl & Moll, 2010): siblings have a 5-10 times greater risk compared to controls to also have dyscalculia
○ Twin studies (e.g., Alacron et al., 1997): if one twin has dyscalculia, then 58% of monozygotic co-twins and 39% of dizygotic co-twins also have dyscalculia
○ Searches for any particular genes that lead to dyscalculia have not lead to any real results – there is not one gene for dyscalculia (see e.g., Carvalho & Haase, 2019)
§ many genes that each have a small effect contribute to individual differences in maths
behavioural symptoms
- primary symptoms
○ persistent difficulties in maths (domain-specific skills)
○ & (often) certain domain-general skills
secondary symptoms
○ low motivation, increasing frustration
○ avoidance, maths anxiety
○ lack of self-confidence, low opinion of capabilities
○ psychosomatic symptoms
domain specific skills
- Mathematical competence not a simple, compact, or unitary concept
○ it is necessary to acquire many different skills and concepts
○ often content is hierarchical in nature (more complex skills build on previously acquired skills)
○ development of skills, concepts and strategies is not always discrete (children may develop several in parallel)- e.g., Haberstroh & Schulte-Körne (2019), Landerl, Vogel, & Grabner (2021)
○ Difficulties in, e.g.,
§ Counting
§ ordinality & cardinality understanding
§ rapid naming of small quantities (subitizing)
§ comparing two quantities or symbolic numbers
§ estimation (e.g., number of objects, time; plausibility of results)
§ determining the position of a number on the number line
§ understanding the place-value system, transcoding
§ arithmetic (e.g., immature strategies; relations between operations)
§ fact retrieval (e.g., small addition/subtraction facts, multiplication facts)
○ Difficulties in basic number processing and arithmetic (and further, more complex mathematical tasks)
- e.g., Haberstroh & Schulte-Körne (2019), Landerl, Vogel, & Grabner (2021)
domain general skills
- Landerl, Vogel, & Grabner, 2021
- Difficulties in various domain-general skills that are critical for numerical development have been associated with dyscalculia, for example difficulties with
○ verbal & visual-spatial working memory: temporarily holding information available for processing
○ visual-spatial skills: mentally manipulating and understanding the spatial relations between and within objects
○ executive functions (updating, shifting, and inhibition): monitoring and updating memory contents, switching between tasks, and suppressing distracting information and unwanted responses
- Difficulties in various domain-general skills that are critical for numerical development have been associated with dyscalculia, for example difficulties with
functional differences: magnitude processing
- What one might expect to find:
○ According to the core deficit hypothesis, individuals with dyscalculia have a deficit in number sense or problems accessing numerical magnitude
§ Does this results from an underactivation in the IPS in dyscalculia?- Children with dyscalculia showed significantly less activity in the IPS compared to controls during symbolic number magnitude comparison and symbolic ordering (Mussolin et al., 2010; Soltész et al., 2007; Kucian et al., 2006)
- Differences in non-symbolic number comparison are less consistent: less activity in the IPS during non-symbolic comparison (Price et al., 2007) vs. no difference (Kovas et al., 2009; Kucian et al., 2011)
- Functional specialization of the parietal cortex for the processing of number magnitude
might be delayed/disturbed in dyscalculia (two recent meta analyses by Tablante et al., 2023 & Martinez-Lincoln et al., 2023)
functional differences: arithmetic
- What one might expect to find:
○ Children with dyscalculia have problems in understanding and executing procedural strategies (cf. magnitude manipulation) and they show persistent deficits in the retrieval of arithmetic facts (e.g., Geary, 1993, 2011)
§ Hyperactivity in frontal regions and hypoactivity in parietal/ temporo-parietal regions?
§ No or reduced shifts in dyscalculia?- Findings in children with dyscalculia are mixed/inconclusive:
○ both increases and decreases in activity in the fronto-parietal network have been reported in comparison to typically developing children - Common observation regarding difficulty-related modulation of the IPS (De Smedt et al., 2011; Ashkenazi et al., 2012)
○ typically developing children: increased brain activity in the IPS during the solution of more complex arithmetic problems than during easier problems
○ children with dyscalculia: recruited the IPS to the same extent for both types of problems
§ children with dyscalculia may continue to rely on (more immature) procedural strategies for both easy and complex problems
- Findings in children with dyscalculia are mixed/inconclusive:
- persistent neural aberration:
even if performance deficits are successfully remediated, children with dyscalculia will continue to show atypical responses in the same brain areas that they did before tutoring
- neural compensation:
children with dyscalculia, after tutoring, will recruit additional and distinct (compensatory) brain systems compared with TD children
neural normalization:
atypical brain responses before tutoring becomes indistinguishable from typically developing peers after tutoring
gray and white matter volume
cf. McCaskey et al., 2020
- Reductions in gray and white matter volume have been reported across the fronto-parietal network:
○ gray: IPS, frontal regions, occipital regions, temporal regions
○ white: parts of the superior longitudinal fasciculus and inferior longitudinal fasciculus
- ! very few studies !
○ However, no studies to date have reported increased gray or white matter volumes in individuals with dyscalculia compared to peers without dyscalculia
white matter connectivity
cf. De Smedt et al., 2019
- Few studies have investigated brain connections and how these relate to dyscalculia in children, results are mixed:
- Hypo-connectivity or hyper-connectivity
