Sari Karlsson

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In an fMRI study, 20 younger and 20 healthy older adults were scanned while performing a spatial working-memory task under two levels of load. On a separate occasion, the same subjects underwent PET measurements using the radioligand [(11)C] SCH23390 to determine dopamine D(1) receptor binding potential (BP) in caudate nucleus and dorsolateral prefrontal(More)
LMX1A is a transcription factor involved in the development of dopamine (DA)-producing neurons in midbrain. Previous research has shown that allelic variations in three LMX1A single nucleotide polymorphisms (SNPs) were related to risk of Parkinson's disease (PD), suggesting that these SNPs may influence the number of mesencephalic DA neurons. Prompted by(More)
Dopamine (DA) is implicated in working memory (WM) functioning. Variations in the DA transporter (DAT1) gene (SLC6A3) regulate DA availability in striatum. Compared to DAT1 9/10-repeat carriers, homozygosity of the DAT1 10-repeat allele has been related to less active dopaminergic pathways. A group of younger adults received 4 weeks of computerized adaptive(More)
Associations between genotypes and cognitive outcomes may provide clues as to which mechanisms cause individual differences in old-age cognitive performance. We investigated the effects of five polymorphisms on cognitive functioning in a population-based sample of 2,694 persons without dementia (60-102 years). A structural equation model (SEM) was fit to(More)
Age-related dopamine (DA) losses have been extensively demonstrated for the D2 receptor subtype. Comparatively little is known about adult age changes regarding D1 receptors. In this study, we demonstrate marked age-related D1 receptor losses in striatal, limbic, and cortical areas using positron emission tomography and the radioligand [(11)C]SCH23390 in(More)
BACKGROUND Previous correlational studies have indirectly linked dysfunctional dopaminergic neurotransmission to age-related cognitive deficits and associated reductions in task-induced functional brain activity. METHODS We used an experimental-pharmacological functional magnetic resonance imaging (fMRI) approach to more directly examine the role of(More)
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(More)
Finding biomarkers constitutes a crucial step for early detection of Alzheimer's disease (AD). Brain imaging techniques have revealed structural alterations in the brain that may be phenotypic in preclinical AD. The most prominent polymorphism that has been associated with AD and related neural changes is the Apolipoprotein E (APOE) ε4. The translocase of(More)
Prospective memory (ProM) involves remembering to perform actions after a delay, such as buying groceries on the way home from work. Retrospective memory (RetM) involves remembering events from the past. It is known that the memory impairment in Alzheimer's disease (AD) generalizes across (a) these two types of memory, and (b) encoding, storage, and(More)
There is strong evidence that dopamine (DA) is implicated in higher-order cognitive functioning, but it remains controversial whether D1 receptor binding can be modified by cognitive activity. We examined striatal D1 binding potential (BP) in 20 younger (22-30 years) and 20 older (65-75 years) persons who underwent two [(11)C] SCH 23390 PET measurements,(More)