| 1. |
- Karlsson, Sari, et al.
(författare)
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Modulation of striatal dopamine D1 binding by cognitive processing
- 2009
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Ingår i: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 48:2, s. 398-404
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Tidskriftsartikel (refereegranskat)abstract
- 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, one while resting and one while performing a cognitive task taxing inhibitory functioning. The younger persons showed significant task-related BP reductions in sensorimotor, limbic, and associative striatum during cognitive activity compared to rest. Older persons showed no reliable BP reductions in any striatal subregion. These findings demonstrate that D1 receptor binding can be modified by cognitive activity in younger persons, but also provide novel evidence for the notion that human aging is associated not only with lower DA receptor density but also with altered modifiability of the DA system.
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| 2. |
- Rieckmann, Anna, et al.
(författare)
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Implicit learning in aging : extant patterns and new directions.
- 2009
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Ingår i: Neuropsychology Review. - : Springer Science and Business Media LLC. - 1040-7308 .- 1573-6660. ; 19:4, s. 490-503
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Tidskriftsartikel (refereegranskat)abstract
- Research suggests that the striatum plays an important role in implicit learning (IL). The striatum exhibits marked age-related morphological and neurochemical losses. Yet, behavioral studies suggest that IL is generally well preserved in old age, and that age-related differences emerge only when highly complex IL tasks are used. In this review, we integrate behavioral and neuroimaging evidence on IL in aging. We suggest that relative stability of IL in old age may reflect neural reorganization that compensates for age-related losses in striatal functions. Specifically, there may be an age-related increase in reliance on extrastriatal regions (e.g., medial-temporal, frontal) during IL. This reorganization of function may be beneficial under less taxing performance conditions, but not when task demands become more challenging.
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