Double dissociation of dopamine genes and timing in humans.
A number of lines of evidence implicate dopamine in timing [Rammsayer, T. H. Neuropharmacological approaches to human timing. In S. Grondin (Ed.), Psychology of time (pp. 295-320). Bingley, UK: Emerald, 2008; Meck, W. H. Neuropharmacology of timing and time perception. Brain Research, Cognitive Brain Research, 3, 227-242, 1996]. Two human genetic polymorphisms are known to modulate dopaminergic activity. DRD2/ANKK1-Taq1a is a D(2) receptor polymorphism associated with decreased D(2) density in the striatum [Jönsson, E. G., Nothen, M. M., Grunhage, F., Farde, L., Nakashima, Y., Propping, P., et al. Polymorphisms in the dopamine D(2) receptor gene and their relationships to striatal dopamine receptor density of healthy volunteers. Molecular Psychiatry, 4, 290-296, 1999]; COMT Val158Met is a functional polymorphism associated with increased activity of the COMT enzyme such that catabolism of synaptic dopamine is greater in pFC [Meyer-Lindenberg, A., Kohn, P. D., Kolachana, B., Kippenhan, S., McInerney-Leo, A., Nussbaum, R., et al. Midbrain dopamine and prefrontal function in humans: Interaction and modulation by COMT genotype. Nature Neuroscience, 8, 594-596, 2005]. To investigate the role of dopamine in timing, we genotyped 65 individuals for DRD2/ANKK1-Taq1a, COMT Val158Met, and a third polymorphism, BDNF Val66Met, a functional polymorphism affecting the expression of brain-derived neurotrophic factor [Egan, M. F., Kojima, M., Callicott, J. H., Goldberg, T. E., Kolachana, B. S., Bertolino, A., et al. The BDNF val66met polymorphism affects activity-dependent secretion of BDNF and human memory and hippocampal function. Cell, 112, 257-269, 2003]. Subjects were tested on a temporal discrimination task with sub- and supra-second intervals (500- and 2000-msec standards) as well as a spontaneous motor tempo task. We found a double dissociation for temporal discrimination: the DRD2/ANKK1-Taq1a polymorphism (A1+ allele) was associated with significantly greater variability for the 500-msec duration only, whereas the COMT Val158Met polymorphism (Val/Val homozygotes) was associated with significantly greater variability for the 2000-msec duration only. No differences were detected for the BDNF Vall66Met variant. Additionally, the DRD2/ANKK1-Taq1a polymorphism was associated with a significantly slower preferred motor tempo. These data provide a potential biological basis for the distinctions between sub- and supra-second timing and suggest that BG are integral for the former whereas pFC is implicated in the latter.
University of Pennsylvania, Philadelphia, PA 19104-6241, USA. Wimartin@psych.upenn.edu
Martin
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Wiener
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Lohoff
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D000293:Adolescent; D000328:Adult; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics; D002394:Catechol O-Methyltransferase / Q000235:genetics; D004192:Discrimination, Psychological; D004298:Dopamine / Q000235:genetics*; D005260:Female; D005820:Genetic Testing; D005838:Genotype; D006801:Humans; D008297:Male; D008715:Methionine / Q000235:genetics; D009043:Motor Activity / Q000235:genetics; D009483:Neuropsychological Tests; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D017448:Receptors, Dopamine D2 / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics*; D013997:Time Factors; D013998:Time Perception / Q000502:physiology*; D014633:Valine / Q000235:genetics; D055815:Young Adult
D019208:Brain-Derived Neurotrophic Factor; D017448:Receptors, Dopamine D2; D008715:Methionine; D002394:Catechol O-Methyltransferase; C489948:ANKK1 protein, human; D017346:Protein Serine-Threonine Kinases; D014633:Valine; D004298:Dopamine