Hippocampal-related memory network in multiple sclerosis: A structural connectivity analysis

Sara Llufriu, Maria A. Rocca, Elisabetta Pagani, Gianna C. Riccitelli, Elisabeth Solana, Bruno Colombo, Mariaemma Rodegher, Andrea Falini, Giancarlo Comi, Massimo Filippi

Research output: Contribution to journalArticle

Abstract

Background: We used graph theoretical analysis to quantify structural connectivity of the hippocampal-related episodic memory network and its association with memory performance in multiple sclerosis (MS) patients. Methods: Brain diffusion and T1-weighted sequences were obtained from 71 MS patients and 50 healthy controls (HCs). A total of 30 gray matter regions (selected a priori) were used as seeds to perform probabilistic tractography and create connectivity matrices. Global, nodal, and edge graph theoretical properties were calculated. In patients, verbal and visuospatial memory was assessed. Results: MS patients showed decreased network strength, assortativity, transitivity, global efficiency, and increased average path length. Several nodes had decreased strength and communicability in patients, whereas insula and left temporo-occipital cortex increased communicability. Patients had widespread decreased streamline count (SC) and communicability of edges, although a few ones increased their connectivity. Worse memory performance was associated with reduced network efficiency, decreased right hippocampus strength, and reduced SC and communicability of edges related to medial temporal lobe, thalamus, insula, and occipital cortex. Conclusion: Impaired structural connectivity occurs in the hippocampal-related memory network, decreasing the efficiency of information transmission. Network connectivity measures correlate with episodic memory, supporting the relevance of structural integrity in preserving memory processes in MS.

Original languageEnglish
Pages (from-to)801-810
Number of pages10
JournalMultiple Sclerosis Journal
Volume25
Issue number6
DOIs
Publication statusPublished - May 1 2019

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Keywords

  • Episodic memory
  • graph theory
  • hippocampus
  • MRI
  • multiple sclerosis
  • structural connectivity

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology

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