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Dopamine affects short-term memory corruption over time in Parkinson’s disease

Cognitive deficits are a recognised component of Parkinson’s disease (PD). However, particularly within the domain of short-term memory, it is unclear whether these impairments are masked, or caused, by patients’ dopaminergic medication. The effect of medication on pure maintenance in PD patients ha...

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Autores principales: Fallon, Sean James, Gowell, Matthew, Maio, Maria Raquel, Husain, Masud
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6683156/
https://www.ncbi.nlm.nih.gov/pubmed/31396548
http://dx.doi.org/10.1038/s41531-019-0088-2
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author Fallon, Sean James
Gowell, Matthew
Maio, Maria Raquel
Husain, Masud
author_facet Fallon, Sean James
Gowell, Matthew
Maio, Maria Raquel
Husain, Masud
author_sort Fallon, Sean James
collection PubMed
description Cognitive deficits are a recognised component of Parkinson’s disease (PD). However, particularly within the domain of short-term memory, it is unclear whether these impairments are masked, or caused, by patients’ dopaminergic medication. The effect of medication on pure maintenance in PD patients has rarely been explored, with most assessments examining maintenance intercalated between other executive tasks. Moreover, few studies have utilised methods that can measure the quality of mental representations, which can enable the decomposition of recall errors into their underlying neurocognitive components. Here, we fill this gap by examining pure maintenance in PD patients in high and low dopaminergic states. Participants had to encode the orientation of two stimuli and reproduce these orientations after a short (2 s) or long (8 s) delay. In addition, we also examined the performance of healthy, age-matched older adults to contextualise these effects and determine whether PD represents an exacerbation of the normal ageing process. Patients showed improved recall OFF compared to ON their dopaminergic medication, but only for long-duration trials. Moreover, PD patients OFF their medication actually performed at a level superior to age-matched controls, indicative of a paradoxical enhancement of memory in the low dopaminergic state. The application of a probabilistic model of response selection suggested that PD patients made fewer misbinding errors in the low, compared with high, dopaminergic state for longer-delay trials. Thus, unexpectedly, the mechanisms that prevent memoranda from being corrupted by misbinding over time appear to be enhanced in PD patients OFF dopaminergic medication. Possible explanations for this paradoxical effect are discussed.
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spelling pubmed-66831562019-08-08 Dopamine affects short-term memory corruption over time in Parkinson’s disease Fallon, Sean James Gowell, Matthew Maio, Maria Raquel Husain, Masud NPJ Parkinsons Dis Article Cognitive deficits are a recognised component of Parkinson’s disease (PD). However, particularly within the domain of short-term memory, it is unclear whether these impairments are masked, or caused, by patients’ dopaminergic medication. The effect of medication on pure maintenance in PD patients has rarely been explored, with most assessments examining maintenance intercalated between other executive tasks. Moreover, few studies have utilised methods that can measure the quality of mental representations, which can enable the decomposition of recall errors into their underlying neurocognitive components. Here, we fill this gap by examining pure maintenance in PD patients in high and low dopaminergic states. Participants had to encode the orientation of two stimuli and reproduce these orientations after a short (2 s) or long (8 s) delay. In addition, we also examined the performance of healthy, age-matched older adults to contextualise these effects and determine whether PD represents an exacerbation of the normal ageing process. Patients showed improved recall OFF compared to ON their dopaminergic medication, but only for long-duration trials. Moreover, PD patients OFF their medication actually performed at a level superior to age-matched controls, indicative of a paradoxical enhancement of memory in the low dopaminergic state. The application of a probabilistic model of response selection suggested that PD patients made fewer misbinding errors in the low, compared with high, dopaminergic state for longer-delay trials. Thus, unexpectedly, the mechanisms that prevent memoranda from being corrupted by misbinding over time appear to be enhanced in PD patients OFF dopaminergic medication. Possible explanations for this paradoxical effect are discussed. Nature Publishing Group UK 2019-08-05 /pmc/articles/PMC6683156/ /pubmed/31396548 http://dx.doi.org/10.1038/s41531-019-0088-2 Text en © The Author(s) 2019 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Fallon, Sean James
Gowell, Matthew
Maio, Maria Raquel
Husain, Masud
Dopamine affects short-term memory corruption over time in Parkinson’s disease
title Dopamine affects short-term memory corruption over time in Parkinson’s disease
title_full Dopamine affects short-term memory corruption over time in Parkinson’s disease
title_fullStr Dopamine affects short-term memory corruption over time in Parkinson’s disease
title_full_unstemmed Dopamine affects short-term memory corruption over time in Parkinson’s disease
title_short Dopamine affects short-term memory corruption over time in Parkinson’s disease
title_sort dopamine affects short-term memory corruption over time in parkinson’s disease
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6683156/
https://www.ncbi.nlm.nih.gov/pubmed/31396548
http://dx.doi.org/10.1038/s41531-019-0088-2
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