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Effective connectivity in subcortical visual structures in de novo Patients with Parkinson’s Disease

Abstract : Background: Parkinson's disease (PD) manifests with the appearance of non-motor symptoms before motor symptoms onset. Among these, dysfunctioning visual structures have recently been reported to occur at early disease stages. Objective: This study addresses effective connectivity in the visual network of PD patients. Methods: Using functional MRI and dynamic causal modeling analysis, we evaluated the connectivity between the superior colliculus, the lateral geniculate nucleus and the primary visual area V1 in de novo untreated PD patients (n = 22). A subset of the PD patients (n = 8) was longitudinally assessed two times at two months and at six months after starting dopaminergic treatment. Results were compared to those of age-matched healthy controls (n = 22). Results: Our results indicate that the superior colliculus drives cerebral activity for luminance contrast processing both in healthy controls and untreated PD patients. The same effective connectivity was observed with neuromodulatory differences in terms of neuronal dynamic interactions. Our main findings were that the modulation induced by luminance contrast changes of the superior colliculus connectivity (self-connectivity and connectivity to the lateral geniculate nucleus) was inhibited in PD patients (effect of contrast: p = 0.79 and p = 0.77 respectively). The introduction of dopaminergic medication in a subset (n = 8) of the PD patients failed to restore the effective connectivity modulation observed in the healthy controls. Interpretation: The deficits in luminance contrast processing in PD was associated with a deficiency in connectivity adjustment from the superior colliculus to the lateral geniculate nucleus and to V1. No differences in cerebral blood flow were observed between controls and PD patients suggesting that the deficiency was at the neuronal level. Administration of a dopaminergic treatment over six months was not able to normalize the observed alterations in inter-regional coupling. These findings highlight the presence of early dysfunctions in primary visual areas, which might be used as early markers of the disease.
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Contributeur : Christine Cannard Connectez-vous pour contacter le contributeur
Soumis le : lundi 21 février 2022 - 14:01:37
Dernière modification le : jeudi 3 mars 2022 - 11:19:15
Archivage à long terme le : : dimanche 22 mai 2022 - 18:47:30


Bellot et al. 2022 NeuroImage_...
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Emmanuelle Bellot, Louise Kauffmann, Véronique Coizet, Sara Meoni, Elena Moro, et al.. Effective connectivity in subcortical visual structures in de novo Patients with Parkinson’s Disease. Neuroimage-Clinical, Elsevier, 2022, 33, pp.102906. ⟨10.1016/j.nicl.2021.102906⟩. ⟨hal-03582724⟩



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