Article

The DAT1 gene codes for the dopamine transporter, which clears dopamine from the
synaptic cleft, and a variant of this gene has previously been associated with
compromised response inhibition in both healthy and clinical populations. This
variant has also been associated with ADHD, a disorder that is characterised by
disturbed dopamine function as well as problems with response inhibition. In the
present study we used fMRI to investigate the role of dopaminergic genetic
variation on executive functioning by comparing how activation associated with
successful and unsuccessful inhibitions differs based on DAT1-genotype and
ADHD-diagnosis in adolescents performing a go/nogo task. The results identify
regional specificity concerning which functional differences can be attributed to
the possession of the high risk DAT1 genotype, the clinical condition or an
interaction between the two. During response inhibition, individuals with two
copies of the 10-repeat allele showed increased activation in frontal, medial,
and parietal regions, which may indicate that inhibition is more effortful for
this group. Conversely, this group displayed a reduced error response in the
parahippocampal gyrus, suggestive of reduced learning from errors. There were
also a number of frontal, parietal, medial and occipital regions, where the
relationship between genotype and fMRI-activation differed between the ADHD group
and the typically developing adolescents. Finally, the ADHD group displayed
decreased activation in parietal and (pre)frontal regions during response
inhibition, and in frontal and medial brain regions on error trials.
CI - Copyright (c) 2011 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS