Assessing hemispheric specialization for processing arithmetic skills in adults: A functional transcranial doppler ultrasonography (fTCD) study.
BACKGROUND
A major model of the cerebral circuits that underpin arithmetic calculation is the triple-code model of numerical processing. This model proposes that the lateralization of mathematical operations is organized across three circuits: a left-hemispheric dominant verbal code; a bilateral magnitude representation of numbers and a bilateral Arabic number code.


METHODS
This study simultaneously measured the blood flow of both middle cerebral arteries using functional transcranial Doppler ultrasonography to assess hemispheric specialization during the performance of both language and arithmetic tasks. The propositions of the triple-code model were assessed in a non-clinical adult group by measuring cerebral blood flow during the performance of multiplication and subtraction problems. Participants were 17 adults aged between 18-27 years. We obtained laterality indices for each type of mathematical operation and compared these in participants with left-hemispheric language dominance. It was hypothesized that blood flow would lateralize to the left hemisphere during the performance of multiplication operations, but would not lateralize during the performance of subtraction operations.


RESULTS
Hemispheric blood flow was significantly left lateralized during the multiplication task, but was not lateralized during the subtraction task.


METHODS
Compared to high spatial resolution neuroimaging techniques previously used to measure cerebral lateralization, functional transcranial Doppler ultrasonography is a cost-effective measure that provides a superior temporal representation of arithmetic cognition.


CONCLUSIONS
These results provide support for the triple-code model of arithmetic processing and offer complementary evidence that multiplication operations are processed differently in the adult brain compared to subtraction operations.
Neurocognitive Development Unit, School of Psychology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. Electronic address: veronica.connaughton@research.uwa.edu.au.
Veronica M
VM
Connaughton
Neurocognitive Development Unit, School of Psychology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. Electronic address: noorazhani.nooramiruddin@research.uwa.edu.au.
Azhani
A
Amiruddin
Neurocognitive Development Unit, School of Psychology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. Electronic address: Karen.clunies.ross@graduate.uwa.edu.au.
Karen L
KL
Clunies-Ross
UWA Centre for Neonatal Research & Education, Perth, Australia. Electronic address: Noel.French@health.wa.gov.au.
Noel
N
French
Neurocognitive Development Unit, School of Psychology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. Electronic address: Allison.fox@uwa.edu.au.
Allison M
AM
Fox
D000293:Adolescent; D002560:Cerebrovascular Circulation / Q000502:physiology; D054022:Cerebrum / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D004292:Dominance, Cerebral / Q000502:physiology*; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods*; D006801:Humans; D008297:Male; D055641:Mathematical Concepts; D008433:Mathematics; D009415:Nerve Net / Q000502:physiology; D018608:Ultrasonography, Doppler / Q000379:methods*; D055815:Young Adult
Arithmetic; Cerebral lateralization; Functional transcranial doppler; Multiplication; Subtraction; fTCD