BACKGROUND: Previous studies have suggested a relationship between
neuroanatomical and neurofunctional hippocampal alterations and episodic memory
impairments in multiple sclerosis (MS) patients
OBJECTIVE: We examined hippocampus volume and functional connectivity (FC)
changes in MS patients with different episodic memory capabilities.
METHODS: hippocampal subfield volume and FC changes were compared in two
subgroups of MS patients with and without episodic memory impairment (MSi and
MSp, respectively) and healthy controls. A discriminant function (DF) analysis was
used to identify which of these neuroanatomical and neurofunctional parameters were
the most relevant components of the mnemonic profiles of HC, MSp and MSi.
RESULTS: MSi showed reduced volume in several hippocampal subfields compared
to MSp and HC. Ordinal gradation (MSi>MSp>HC) was also observed for FC between
the posterior hippocampus and several cortical areas. DF-based analyses revealed that
reduced right fimbria volume and enhanced FC at the right posterior hippocampus were
the main neural signatures of the episodic memory impairments observed in the MSi
group.
CONCLUSIONS: Before any sign of episodic memory alterations (MSp), FC
increased on several pathways that connect the hippocampus with cortical areas. These
changes further increased when the several hippocampal volumes reduced and memory
deficits appeared (MSi).This study was sponsored by grants P1-1B2014-15 awarded by Universitat Jaume I and
PSI2015-67285-R awarded by MINECO to Dr. Cristina For
