title: Increased brain activity to unpleasant stimuli in individuals with the 7R allele of the DRD4 gene.
abstract: The aim of the study was to examine functional brain activity in response to unpleasant images in individuals with the 7-repeat (7R) allele compared to individuals with the 4-repeat (4R) allele of the dopamine receptor D4 (DRD4) gene (VNTR in exon 3). Based on the response ready hypothesis, individuals with the DRD4-4R/7R genotype were expected to show greater functional brain activity in response to unpleasant compared to neutral stimuli in specific regions of the frontal, temporal, parietal and limbic lobes, which form the networks involved in attentional, emotional, and preparatory responses. Functional Magnetic Resonance Imaging activity was studied in 26 young adults (13 with the DRD4-4R/7R genotype and 13 with the DRD4-4R/4R genotype). Participants were asked to look at and subjectively rate unpleasant and neutral images. Results showed increased brain activity in response to unpleasant images compared to neutral images in the right temporal lobe in participants with the DRD4-4R/7R genotype versus participants with the DRD4-4R/4R genotype. The increase in right temporal lobe activity in individuals with DRD4-4R/7R suggests greater involvement in processing negative emotional stimuli. Intriguingly, no differences were found between the two genotypes in the subjective ratings of the images. The findings corroborate the response ready hypothesis, which suggests that individuals with the 7R allele are more responsive to negative emotional stimuli compared to individuals with the 4R allele of the DRD4 gene.
authors.affiliation: Department of Pediatrics, University of California, Irvine, Irvine, CA, USA; The Center for Autism & Neurodevelopmental Disorders, Santa Ana, CA 92705, USA. Electronic address: jgehrick@uci.edu.
authors.forename: Jean-G
authors.initials: JG
authors.lastname: Gehricke
authors.affiliation: Department of Pediatrics, University of California, Irvine, Irvine, CA, USA.
authors.forename: James M
authors.initials: JM
authors.lastname: Swanson
authors.affiliation: Department of Pediatrics, University of California, Irvine, Irvine, CA, USA.
authors.forename: Sophie
authors.initials: S
authors.lastname: Duong
authors.affiliation: The Center for Autism & Neurodevelopmental Disorders, Santa Ana, CA 92705, USA.
authors.forename: Jenny
authors.initials: J
authors.lastname: Nguyen
authors.affiliation: Department of Pediatrics, University of California, Irvine, Irvine, CA, USA.
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Wigal
authors.affiliation: Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, USA.
authors.forename: James
authors.initials: J
authors.lastname: Fallon
authors.affiliation: The Center for Autism & Neurodevelopmental Disorders, Santa Ana, CA 92705, USA.
authors.forename: Cyrus
authors.initials: C
authors.lastname: Caburian
authors.affiliation: Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, USA.
authors.forename: Lutfi Tugan
authors.initials: LT
authors.lastname: Muftuler
authors.affiliation: Department of Biological Chemistry, College of Medicine and Institute of Genomics and Bioinformatics, University of California, Irvine, Irvine, CA, USA.
authors.forename: Robert K
authors.initials: RK
authors.lastname: Moyzis
mesh_terms: D000328:Adult; D000483:Alleles; D001921:Brain / Q000502:physiology*; D016022:Case-Control Studies; D002880:Chromosomes, Human, Pair 11 / Q000235:genetics; D005091:Exons / Q000235:genetics*; D005260:Female; D059907:Functional Neuroimaging; D056426:Genetic Loci / Q000235:genetics; D005838:Genotype; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D018598:Minisatellite Repeats / Q000235:genetics*; D050638:Receptors, Dopamine D4 / Q000235:genetics*
chemical_list: C493599:DRD4 protein, human; D050638:Receptors, Dopamine D4
keywords: Attention-Deficit/Hyperactivity Disorder; Emotion; Magnetic Resonance Imaging; Risk taking