Distinct and common cerebral activation changes during mental time travel in relapsing-remitting multiple sclerosis patients

Abstract

Mental time travel (MTT) entails the ability to mentally travel into autobiographical memory (AM) and episodic future thinking (EFT). While AM and EFT share common phenomenological and cerebral functional properties, distinctive characteristics have been documented in healthy and clinical populations. No report, to our knowledge, has informed on the functional underpinnings of MTT impairment in multiple sclerosis (MS) patients, hence the aim of this work. We studied 22 relapsing-remitting MS patients and 22 matched controls. Participants underwent an AM/EFT assessment using the Autobiographical Interview (Levine et al. 2002), followed by a functional MRI session. The latter consisted in AM and EFT tasks, distinguishing the construction and elaboration phases of events. The results showed impaired performance for AM and EFT in patients, accompanied by increased cerebral activations mostly located in the frontal regions, which extended to the parietal, lateral temporal and posterior regions during AM/EFT tasks, relative to healthy controls. Enhanced brain activations in MS patients were particularly evident during the EFT task and involved the hippocampus, frontal, external temporal, and cingulate regions. The construction phase required greater fronto-parieto-temporal activations in MS patients relative to both healthy controls, and the elaboration phase. Taking together, our results suggested the occurrence of cerebral activation changes in the context of MTT in MS patients, expressed by distinct and common mechanisms for AM and EFT. This study may provide new insights in terms of cerebral activation changes in brain lesion and their application to clinical settings, considering AM/EFT's central role in everyday life.

Episodic Past, Future, and counterfactual thinking in Relapsing-Remitting Multiple sclerosis

“…Additionally, these initial studies failed to distinguish subtypes of MS, including participants at various stages of disease severity. Since our sample only includes a carefully curated set of RRMS, our results help to lend further support to the claim that the semantic dimension of episodic simulations in RRMS appears to be preserved, not only for EAM and EFT ( Ernst et al, 2014 ; Ernst et al, 2015; Ernst et al, 2016 ), but also for ECT.…”

“…To add to this evidence, recent studies have shown that RRMS patients also present parallel difficulties in EAM and EFT ( Ernst et al, 2014 , Ernst et al, 2015a ). As with EAM in RRMS, this impairment in EFT, too, has been associated with bilateral prefrontal and hippocampal hyperactivation ( Ernst et al, 2015b , Ernst et al, 2016 ). Such parallel impairments align with the finding that both EAM and EFT share common neurocognitive mechanisms ( Schacter et al, 2012 ).…”

Episodic foresight in multiple sclerosis.

“…1In two other studies (Ernst et al, 2015, 2016), the RRMS participants also contributed to the Ernst et al, (2014) dataset.…”

“…This document is copyrighted by the American Psychological Association or one of its allied publishers.This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.1 In two other studies(Ernst et al, 2015(Ernst et al, , 2016, the RRMS participants also contributed to theErnst et al, (2014) dataset.EPISODIC FORESIGHT IN MULTIPLE SCLEROSIS…”