| 1. |
- Mediavilla, Tomás, et al.
(författare)
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Learning-related contraction of gray matter in rodent sensorimotor cortex is associated with adaptive myelination.
- 2022
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Ingår i: eLife. - : eLife Sciences Publications. - 2050-084X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- From observations in rodents, it has been suggested that the cellular basis of learning-dependent changes, detected using structural MRI, may be increased dendritic spine density, alterations in astrocyte volume, and adaptations within intracortical myelin. Myelin plasticity is crucial for neurological function, and active myelination is required for learning and memory. However, the dynamics of myelin plasticity and how it relates to morphometric-based measurements of structural plasticity remains unknown. We used a motor skill learning paradigm in male mice to evaluate experience-dependent brain plasticity by voxel-based morphometry (VBM) in longitudinal MRI, combined with a cross-sectional immunohistochemical investigation. Whole-brain VBM revealed nonlinear decreases in gray matter volume (GMV) juxtaposed to nonlinear increases in white matter volume (WMV) within GM that were best modeled by an asymptotic time course. Using an atlas-based cortical mask, we found nonlinear changes with learning in primary and secondary motor areas and in somatosensory cortex. Analysis of cross-sectional myelin immunoreactivity in forelimb somatosensory cortex confirmed an increase in myelin immunoreactivity followed by a return towards baseline levels. Further investigations using quantitative confocal microscopy confirmed these changes specifically to the length density of myelinated axons. The absence of significant histological changes in cortical thickness suggests that nonlinear morphometric changes are likely due to changes in intracortical myelin for which morphometric WMV in somatosensory cortex significantly correlated with myelin immunoreactivity. Together, these observations indicate a nonlinear increase of intracortical myelin during learning and support the hypothesis that myelin is a component of structural changes observed by VBM during learning.
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| 2. |
- Nyberg, Lars, 1966-, et al.
(författare)
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Forecasting memory function in aging : pattern-completion ability and hippocampal activity relate to visuospatial functioning over 25 years
- 2020
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Ingår i: Neurobiology of Aging. - : Elsevier. - 0197-4580 .- 1558-1497. ; 94, s. 217-226
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Tidskriftsartikel (refereegranskat)abstract
- Heterogeneity in episodic memory functioning in aging was assessed with a pattern-completion functional magnetic resonance imaging task that required reactivation of well-consolidated face-name memory traces from fragmented (partial) or morphed (noisy) face cues. About half of the examined individuals (N = 101) showed impaired (chance) performance on fragmented faces despite intact performance on complete and morphed faces, and they did not show a pattern-completion response in hippocampus or the examined subfields (CA1, CA23, DGCA4). This apparent pattern-completion deficit could not be explained by differential hippocampal atrophy. Instead, the impaired group displayed lower cortical volumes, accelerated reduction in mini-mental state examination scores, and lower general cognitive function as defined by longitudinal measures of visuospatial functioning and speed-of-processing. In the full sample, inter-individual differences in visuospatial functioning predicted performance on fragmented faces and hippocampal CA23 subfield activity over 25 years. These findings suggest that visuospatial functioning in middle age can forecast pattern-completion deficits in aging.
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| 3. |
- Virel, Ana, et al.
(författare)
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N-acetylcysteine decreases dopamine transporter availability in the non-lesioned striatum of the 6-OHDA hemiparkinsonian rat
- 2022
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Ingår i: Neuroscience Letters. - : Elsevier. - 0304-3940 .- 1872-7972. ; 770
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to explore the beneficial effects of the antioxidant N-acetylcysteine (NAC) on the degenerated dopamine system. The short- and long-term regulatory mechanisms of NAC on the 6-OHDA hemiparkinsonian rat model were longitudinally investigated by performing positron emission tomography (PET) imaging using the specific dopamine transporter (DAT) radioligand [18F]FE-PE2I. The results demonstrate that after a unilateral dopamine insult NAC has a strong influence on the non-lesioned hemisphere by decreasing the levels of DAT in the striatum early after the lesion. We interpret this early and short-term decrease of DAT in the healthy striatum of NAC-treated animals as a beneficial compensatory effect induced by NAC.
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