Functional Connectivity of Ventral and Dorsal Visual Streams in Posterior Cortical Atrophy

Article type: Research Article

Authors: Migliaccio, Raffaella^{a; b; *} | Gallea, Cécile^{a; c; j} | Kas, Aurélie^{d; e} | Perlbarg, Vincent^{a; e; i} | Samri, Dalila^b | Trotta, Laura^{a; b} | Michon, Agnès^b | Lacomblez, Lucette^{e; g; h} | Dubois, Bruno^{a; b} | Lehericy, Stéphane^{a; c} | Bartolomeo, Paolo^{a; f}

Affiliations: [a] INSERM U 1127, CNRS UMR 7225, Sorbonne Universités, and Université Pierre et Marie Curie-Paris 6, UMR S 1127, Institut du Cerveau et de la Moelle épinière (ICM), F-75013 Paris, France | [b] Department of Neurology, Institut de la mémoire et de la maladie d’Alzheimer, Hôpital de la Pitié-Salpêtrière, AP-HP, Paris, France | [c] Centre de Neuro-imagerie de Recherche (CENIR) de l’Institut du Cerveau et de la Moelle Epiniere (ICM), Hôpital de la Pitié-Salpêtrière, Paris, France | [d] Service de médecine nucléaire, Hôpital Pitié-Salpêtrière, APHP, Paris, France | [e] INSERM U1146, CNRS UMR7371, laboratoire d’imagerie biomédicale, Sorbonne université, UPMC université, Paris 60 UMCR2, Hôpital de la Pitié-Salpêtrière, Paris, France | [f] Department of Psychology, Catholic University, Milan, Italy | [g] Department des maladies du système nerveux, CIC-CET, Hôpital de la Pitié-Salpêtrière, AP-HP, Paris, France | [h] Service de pharmacologie, Hôpital de la Pitié-Salpêtrière, AP-HP, Paris, France | [i] IHU-A-ICM, Bioinformatics/Biostatistis Plateform, Paris, France | [j] Equipe “Mouvements Anormaux et Ganglions de la Base”, Institut du Cerveau et de la Moëlle Epinière, Hôpital de la Pitié-Salpêtrière, Paris, France

Correspondence: [*] Correspondence to: Raffaella Migliaccio, ICM Brain and Spine Institute, Groupe Hospitalier Pitié-Salpêtrière, 47, boulevard de l’Hôpital, Paris, France. Tel.: +33 1 57 27 41 46; E-mail: lara.migliaccio@gmail.com.

Abstract: Background:Posterior cortical atrophy (PCA) induces progressive dysfunction of ventral and dorsal visual networks. Little is known, however, about corresponding changes in functional connectivity (FC). Objectives:To investigate FC changes in the visual networks, their relationship with cortical atrophy, and the association with Alzheimer’s disease (AD) pathology. Methods:Ten PCA patients and 28 age-matched controls participated in the study. Using resting state fMRI, we measured FC in ventral and dorsal cortical visual networks, defined on the basis of a priori knowledge of long-range white matter connections. To assess the relationships with AD, we determined AD biomarkers in cerebrospinal fluid and FC in the default mode network (DMN), which is vulnerable to AD pathology. Voxel-based morphometry analysis assessed the pattern of grey matter (GM) atrophy. Results:PCA patients showed GM atrophy in bilateral occipital and inferior parietal regions. PCA patients had lower FC levels in a ventral network than controls, but higher FC in inferior components of the dorsal network. In particular, the increased connectivity correlated with greater GM atrophy in occipital regions. All PCA patients had positive cerebrospinal fluid biomarkers for AD; however, FC in global DMN did not differ from controls. Conclusions:FC in PCA reflects brain structure in a non-univocal way. Hyperconnectivity of dorsal networks may indicate aberrant communication in response to posterior brain atrophy or processes of neural resilience during the initial stage of brain dysfunction. The lack of difference from controls in global DMN FC highlights the atypical nature of PCA with respect to typical AD.

Keywords: Brain resilience, dorsal stream, functional connectivity, posterior cortical atrophy, ventral stream

DOI: 10.3233/JAD-150934

Journal: Journal of Alzheimer's Disease, vol. 51, no. 4, pp. 1119-1130, 2016