The modulatory influence of the functional COMT Val158Met polymorphism on lexical decisions and semantic priming

Martin Reuter

doi:10.3389/neuro.09.020.2009

Abstract

The role of the prefrontal Cortex (PFC) in higher cognitive functions – including working memory, conflict resolution, set shifting and semantic processing – has been demonstrated unequivocally. Despite the great heterogeneity among tasks measuring these phenotypes, due in part to the different cognitive sub-processes implied and the specificity of the stimulus material used, there is agreement that all of these tasks recruit an executive control system located in the PFC. On a biochemical level it is known that the dopaminergic system plays an important role in executive control functions. Evidence comes from molecular genetics relating the functional COMT Val158Met polymorphism to working memory and set shifting. In order determine whether this pattern of findings generalises to linguistic and semantic processing, we investigated the effects of the COMT Val158Met polymorphism in lexical decision making using masked and unmasked versions of the semantic priming paradigm on N = 104 healthy subjects. Although we observed strong priming effects in all conditions (masked priming, unmasked priming with short/long stimulus asynchronies (SOAs), direct and indirect priming), COMT was not significantly related to priming, suggesting no reliable influence on semantic processing. However, COMT Val158Met was strongly associated with lexical decision latencies in all priming conditions if considered separately, explaining between 9 and 14.5% of the variance. Therefore, the findings indicate that COMT mainly influences more general executive control functions in the PFC supporting the speed of lexical decisions.

Highlights

Numerous neurophysiological and imaging studies have demonstrated the prominent role of the prefrontal cortex (PFC) for a variety of cognitive functions (e.g. D’Esposito et al, 2000; Duncan and Owen, 2000; Liu et al, 2008; Reuter et al, 2008; Volle et al, 2008)
These cognitive functions show a large diversity with respect to the cognitive sub-processes involved there is agreement that the common denominator is an executive control system assumed to be located in the PFC (Kiefer et al, 1998; Posner and DiGirolamo, 1998; Faw, 2003)
We investigated the effect of the COMT Val 158Met polymorphism on lexical decision-making within a semantic priming paradigm

Summary

Introduction

Numerous neurophysiological and imaging studies have demonstrated the prominent role of the prefrontal cortex (PFC) for a variety of cognitive functions (e.g. D’Esposito et al, 2000; Duncan and Owen, 2000; Liu et al, 2008; Reuter et al, 2008; Volle et al, 2008) These cognitive functions show a large diversity with respect to the cognitive sub-processes involved there is agreement that the common denominator is an executive control system assumed to be located in the PFC (Kiefer et al, 1998; Posner and DiGirolamo, 1998; Faw, 2003). The dorsolateral prefrontal cortex (DLPFC) seems to be crucial for non-semantic executive control tasks like the WCST (e.g. Monchi et al, 2001)

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Results

Conclusion