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Substantia nigra integrity correlates with sequential working memory in Parkinson's disease.

ABSTRACT: Maintaining and manipulating sequences online is essential for daily activities such as scheduling a day. In Parkinson's disease (PD), sequential working memory deficits have been associated with altered regional activation and functional connectivity in the basal ganglia. This study demonstrates that the substantia nigra (SN) integrity correlated with basal ganglia function and sequencing performance in 29 patients with PD (17 women) and 29 healthy controls (HC, 18 women). In neuromelanin-sensitive structural MRI, PD patients showed smaller SN than HC. In a digit ordering task with functional MRI, participants either recalled sequential digits in the original order ('pure recall') or rearranged the digits and recalled the new sequence ('reorder & recall'). PD patients performed less accurately than HC, accompanied by the caudate and pallidal hypo-activation, subthalamic hyper-activation, and weakened functional connectivity between the bilateral SN and all three basal ganglia regions. PD patients with larger SN tended to exhibit smaller ordering-related accuracy costs ('reorder & recall' versus 'pure recall'). This effect was fully mediated by the ordering-related caudate activation. Unlike HC, the ordering-related accuracy cost correlated with the ordering-related caudate activation but not subthalamic activation in PD. Moreover, the ordering-related caudate activation correlated with the SN area but not the daily dose of D2/3 receptor agonists. In PD, the daily dose of D2/3 receptor agonists correlated with the ordering-related subthalamic activation, which was not related to the accuracy cost. The findings suggest that damage to the SN may lead to sequential working memory deficits in PD, mediated by basal ganglia dysfunction.SIGNIFICANCELiu et al. demonstrate that damage to the substantia nigra (SN) correlates with basal ganglia dysfunction and poor sequencing performance in Parkinson's disease (PD). In neuromelanin-sensitive MRI, PD showed smaller SN than healthy controls. In a digit ordering task with functional MRI, PD's lower task accuracy was accompanied by the caudate and pallidal hypo-activation, subthalamic hyper-activation, and weakened functional connectivity between the SN and basal ganglia. PD with larger SN exhibited greater ordering-related caudate activation and lower ordering-related accuracy cost when sequencing digits. PD with more daily exposure to D2/3 receptor agonists exhibited greater ordering-related subthalamic activation, which did not reduce accuracy cost. It suggests that the SN may affect sequencing performance by regulating the task-dependent caudate activation in PD.

SUBMITTER: Liu W

PROVIDER: S-EPMC8287987 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundParkinson's disease (PD) is the most common neurodegenerative disorder involving the motor system. Although not being the only region involved in PD, affection of the substantia nigra and its projections is responsible for some of the most debilitating features of the disease. To further advance a comprehensive understanding of nigral pathology, we conducted a tissue based comparative proteome study of healthy and diseased human substantia nigra.ResultsThe gross number of differentially regulated proteins in PD was 221. In total, we identified 37 proteins, of which 16 were differentially expressed. Identified differential proteins comprised elements of iron metabolism (H-ferritin) and glutathione-related redox metabolism (GST M3, GST P1, GST O1), including novel redox proteins (SH3BGRL). Additionally, many glial or related proteins were found to be differentially regulated in PD (GFAP, GMFB, galectin-1, sorcin), as well as proteins belonging to metabolic pathways sparsely described in PD, such as adenosyl homocysteinase (methylation), aldehyde dehydrogenase 1 and cellular retinol-binding protein 1 (aldehyde metabolism). Further differentially regulated proteins included annexin V, beta-tubulin cofactor A, coactosin-like protein and V-type ATPase subunit 1. Proteins that were similarly expressed in healthy or diseased substantia nigra comprised housekeeping proteins such as COX5A, Rho GDI alpha, actin gamma 1, creatin-kinase B, lactate dehydrogenase B, disulfide isomerase ER-60, Rab GDI beta, methyl glyoxalase 1 (AGE metabolism) and glutamine synthetase. Interestingly, also DJ-1 and UCH-L1 were expressed similarly. Furthermore, proteins believed to serve as internal standards were found to be expressed in a constant manner, such as 14-3-3 epsilon and hCRMP-2, thus lending further validity to our results.ConclusionUsing an approach encompassing high sensitivity and high resolution, we show that alterations of SN in PD include many more proteins than previously thought. The results point towards a heterogeneous aetiopathogenesis of the disease, including alterations of GSH-related proteins as well as alterations of proteins involved in retinoid metabolism, and they indicate that proteins involved in familial PD may not be differentially regulated in idiopathic Parkinson's disease.

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Substantia nigra integrity correlates with sequential working memory in Parkinson's disease.

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