fMRI activation during response inhibition and error process
Research Field:Life Sciences
Lead PI:Prof Hugh Garavan
Abstract:ADHD is thought to have a strong genetic component and executive function measures such as response inhibition might index susceptibility to ADHD. 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 individuals with ADHD. In the present study, we used fMRI to investigate how activation associated with successful and unsuccessful inhibitions differs based on ADHD-diagnosis and DAT1-genotype in adolescents performing a go/nogo task. The results identify regional specificity concerning which functional differences can be attributed to the clinical condition, the possession of the HR DAT1 genotype 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 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.