| 1. |
- Sayalı, Ceyda, et al.
(författare)
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Methylphenidate undermines or enhances divergent creativity depending on baseline dopamine synthesis capacity
- 2023
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Ingår i: Neuropsychopharmacology. - : Springer Nature. - 0893-133X .- 1740-634X. ; 48:13, s. 1849-1858
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Tidskriftsartikel (refereegranskat)abstract
- Catecholamine-enhancing psychostimulants, such as methylphenidate have long been argued to undermine creative thinking. However, prior evidence for this is weak or contradictory, stemming from studies with small sample sizes that do not consider the well-established large variability in psychostimulant effects across different individuals and task demands. We aimed to definitively establish the link between psychostimulants and creative thinking by measuring effects of methylphenidate in 90 healthy participants on distinct creative tasks that measure convergent and divergent thinking, as a function of individuals’ baseline dopamine synthesis capacity, indexed with 18F-FDOPA PET imaging. In a double-blind, within-subject design, participants were administered methylphenidate, placebo or selective D2 receptor antagonist sulpiride. The results showed that striatal dopamine synthesis capacity and/or methylphenidate administration did not affect divergent and convergent thinking. However, exploratory analysis demonstrated a baseline dopamine-dependent effect of methylphenidate on a measure of response divergence, a creativity measure that measures response variability. Response divergence was reduced by methylphenidate in participants with low dopamine synthesis capacity but enhanced in those with high dopamine synthesis capacity. No evidence of any effect of sulpiride was found. These results show that methylphenidate can undermine certain forms of divergent creativity but only in individuals with low baseline dopamine levels.
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| 2. |
- van den Bosch, Ruben, et al.
(författare)
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Evidence for absence of links between striatal dopamine synthesis capacity and working memory capacity, spontaneous eye-blink rate, and trait impulsivity
- 2023
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Ingår i: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Individual differences in striatal dopamine synthesis capacity have been associated with working memory capacity, trait impulsivity, and spontaneous eye-blink rate (sEBR), as measured with readily available and easily administered, ‘off-the-shelf’ tests. Such findings have raised the suggestion that individual variation in dopamine synthesis capacity, estimated with expensive and invasive brain positron emission tomography (PET) scans, can be approximated with simple, more pragmatic tests. However, direct evidence for the relationship between these simple trait measures and striatal dopamine synthesis capacity has been limited and inconclusive. We measured striatal dopamine synthesis capacity using [18F]-FDOPA PET in a large sample of healthy volunteers (N = 94) and assessed the correlation with simple, short tests of working memory capacity, trait impulsivity, and sEBR. We additionally explored the relationship with an index of subjective reward sensitivity. None of these trait measures correlated significantly with striatal dopamine synthesis capacity, nor did they have out-of-sample predictive power. Bayes factor analyses indicated the evidence was in favour of absence of correlations for all but subjective reward sensitivity. These results warrant caution for using these off-the-shelf trait measures as proxies of striatal dopamine synthesis capacity.
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| 3. |
- van Wingen, Guido, et al.
(författare)
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How progesterone impairs memory for biologically salient stimuli in healthy young women
- 2007
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Ingår i: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 27:42, s. 11416-11423
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Tidskriftsartikel (refereegranskat)abstract
- Progesterone, or rather its neuroactive metabolite allopregnanolone, modulates amygdala activity and thereby influences anxiety. Cognition and, in particular, memory are also altered by allopregnanolone. In the present study, we investigated whether allopregnanolone modulates memory for biologically salient stimuli by influencing amygdala activity, which in turn may affect neural processes in other brain regions. A single progesterone dose was administered orally to healthy young women in a double-blind, placebo-controlled, crossover design, and participants were asked to memorize and recognize faces while undergoing functional magnetic resonance imaging. Progesterone decreased recognition accuracy without affecting reaction times. The imaging results show that the amygdala, hippocampus, and fusiform gyrus supported memory formation. Importantly, progesterone decreased responses to faces in the amygdala and fusiform gyrus during memory encoding, whereas it increased hippocampal responses. The progesterone-induced decrease in neural activity in the amygdala and fusiform gyrus predicted the decrease in memory performance across subjects. However, progesterone did not modulate the differential activation between subsequently remembered and subsequently forgotten faces in these areas. A similar pattern of results was observed in the fusiform gyrus and prefrontal cortex during memory retrieval. These results suggest that allopregnanolone impairs memory by reducing the recruitment of those brain regions that support memory formation and retrieval. Given the important role of the amygdala in the modulation of memory, these results suggest that allopregnanolone alters memory by influencing amygdala activity, which in turn may affect memory processes in other brain regions.
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