Count on dopamine: influences of COMT polymorphisms on numerical cognition

Abstract

Catechol-O-methyltransferase (COMT) is an enzyme that is particularly important for the metabolism of dopamine. Functional polymorphisms of COMT have been implicated in working memory and numerical cognition. This is an exploratory study that aims at investigating associations between COMT polymorphisms, working memory, and numerical cognition. Elementary school children from 2th to 6th grades were divided into two groups according to their COMT val158met polymorphism [homozygous for valine allele (n = 61) vs. heterozygous plus methionine homozygous children or met+ group (n = 94)]. Both groups were matched for age and intelligence. Working memory was assessed through digit span and Corsi blocks. Symbolic numerical processing was assessed through transcoding and single-digit word problem tasks. Non-symbolic magnitude comparison and estimation tasks were used to assess number sense. Between-group differences were found in symbolic and non-symbolic numerical tasks, but not in working memory tasks. Children in the met+ group showed better performance in all numerical tasks while val homozygous children presented slower development of non-symbolic magnitude representations. These results suggest COMT-related dopaminergic modulation may be related not only to working memory, as found in previous studies, but also to the development of magnitude processing and magnitude representations.

Neural Mechanisms Underlying Time Perception and Reward Anticipation

“…Tasks requiring number and time magnitude estimations suggested engaging basal ganglia, prefrontal and parietal cortex activity ( Allman et al, 2011 ). COMT-related dopaminergic mechanisms were suggested to be implicated in number processing ( Julio-Costa et al, 2013 ). Findings suggest that while COMT polymorphism causing higher prefrontal dopaminergic activity affected supra-second timing performance, DRD2 polymorphism resulting in higher striatal D2 activity affected sub-second timing performance ( Wiener et al, 2011 ).…”

COMT Val158Met Polymorphism Is Associated with Verbal Working Memory in Neurofibromatosis Type 1

“…Working memory is known to be important for numerical processing ( González-Giraldo et al, 2014 ). Despite controversies regarding which allele would be advantageous to numerical abilities, the COMT Val 158 Met has been associated with arithmetical functioning ( Júlio-Costa et al, 2013 ; González-Giraldo et al, 2014 ) with dopamine playing a key role in updating new information at the neural systems level ( Tan et al, 2007 ). It is possible that the lack of association at a functional level (academic performance) with the COMT polymorphism in our study reflects a bias of sample power, but future studies are needed to investigate the existence of a more direct effect of COMT on arithmetic in NF1.…”

In How Many Ways is the Approximate Number System Associated with Exact Calculation?

“…In the non-symbolic comparison task, participants were instructed to compare two sets of black dots, which were simultaneously presented in two white circles on the left and on the right side of the screen, and they were instructed to choose the larger numerosity by pressing a key congruent to its side (left or right) (see Figure 1 ) [45] , [47] , [48] . Black dots were presented on a white circle against a black background.…”

“…In the non-symbolic estimation task, participants were asked to estimate, with a verbal response, the quantity of dots shown on the computer screen [48] (see Figure 1 ). Black dots were presented on a white circle against a black background.…”