RT Journal Article SR Electronic T1 Aging-Related Increases in Behavioral Variability: Relations to Losses of Dopamine D1 Receptors JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 8186 OP 8191 DO 10.1523/JNEUROSCI.5474-11.2012 VO 32 IS 24 A1 Stuart W. S. MacDonald A1 Sari Karlsson A1 Anna Rieckmann A1 Lars Nyberg A1 Lars Bäckman YR 2012 UL http://www.jneurosci.org/content/32/24/8186.abstract AB Intraindividual variability (IIV) reflects within-person changes in performance, such as trial-by-trial fluctuations on a reaction-time (RT) task. The neural underpinnings of IIV remain largely unknown. The neurotransmitter dopamine (DA) is of particular interest here, as human populations that exhibit DA alterations, such as the elderly, attention deficit hyperactivity disorder children, persons with schizophrenia, and Parkinson patients, also show increased behavioral IIV. We examined links between DA D1 binding potential (BP) in multiple brain regions and IIV for the control and interference conditions of the Multi-Source Interference Task (MSIT), tapping the cingulo-fronto-parietal attention network. Participants were 18 young and 20 healthy old adults. PET and the radioligand [11C]SCH23390 were used to determine D1 BP. The intraindividual standard deviation (ISD) was computed across successful latency trials of the MSIT conditions, independent of mean RT differences due to age, trial, and condition. Increasing ISDs were associated with increasing age and diminished D1 binding in several brain regions (anterior cingulate gyrus, dorsolateral prefrontal cortex, and parietal cortex) for the interference, but not control, condition. Analyses of partial associations indicate that the association between age and IIV in the interference condition was linked to D1 receptor losses in task-relevant brain regions. These findings suggest that dysfunctional DA modulation may contribute to increased variability in cognitive performance among older adults.