Putative cortical dopamine levels affect cortical recruitment during planning

S.J Fallon,A Hampshire,C.H Williams-Gray,R.A Barker,A.M Owen

doi:10.1016/j.neuropsychologia.2013.07.016

S.J Fallon, A Hampshire + Show 3 more

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https://doi.org/10.1016/j.neuropsychologia.2013.07.016

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Abstract

Planning, the decomposition of an ultimate goal into a number of sub-goals is critically dependent upon fronto-striatal dopamine (DA) levels. Here, we examined the extent to which the val158met polymorphism in the catechol O-methyltransferase (COMT) gene, which is thought to primarily alter cortical DA levels, affects performance and fronto-parietal activity during a planning task (Tower of London). COMT genotype was found to modulate activity in the left superior posterior parietal cortex (SPC) during planning, relative to subtracting, trials. Specifically, left SPC blood oxygenation level-dependent (BOLD) response was reduced in groups with putatively low or high cortical DA levels (COMT homozygotes) relative to those with intermediate cortical DA levels (COMT heterozygotes). These set of results are argued to occur either due to differences in neuronal processing in planning (and perhaps subtracting) caused by the COMT genotype and/or the cognitively heterogeneous nature of the TOL, which allows different cognitive strategies to be used whilst producing indistinguishable behavioural performance in healthy adults. The implications of this result for our understanding of COMT′s effect on cognition in health and disease are discussed.

Highlights

Many of the most sought after goals in the world are not immediately attainable
There was no significant effect of catechol O-methyltransferase (COMT) genotype on performance for the PRM, SRM, PAL or out-of-scanner Tower of London (TOL) performance (p’s 40.05; see Supplementary Figs. 1 and 2)
For planning accuracy, there was a significant main effect of condition, F(1,48)1⁄455.39, po0.05, in the direction of participants being less accurate on planning trials

Summary

Introduction

We have had to evolve and develop a capacity to formulate and execute a series of sub-goals whose completion will allow us to achieve our ultimate goal. These behavioural requirements are neatly captured within the Tower of London (TOL) planning task and its cognates (Shallice, 1982). This task has been used extensively to examine the necessary neuroanatomical and neurochemical substrates of planning.

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