title: Episodic future thinking in semantic dementia: a cognitive and FMRI study.
abstract: Semantic dementia (SD) is characterized by gradual loss of semantic memory. While episodic autobiographical memory seems relatively preserved, behavioral studies suggest that episodic future thinking is impaired. We used fMRI to measure brain activity in four SD patients (JPL, EP, LL, EG) while they envisioned future events and remembered personal past events. Twelve healthy elders served as controls. Episodic quality, emotion, mental imagery and level of consciousness (via remember/know judgements) were checked at debriefing. We analyzed the future compared to the past for each patient. All patients presented lateral temporal atrophy, but varied in terms of frontal and anterior hippocampal atrophy. Patient JPL presented atrophy in bilateral superior medial frontal gyri and left anterior hippocampus and was unable to engage in episodic future thinking, despite hyperactivations in frontal and occipital regions. Patient EP presented no atrophy in the anterior hippocampus, but atrophy in bilateral superior medial frontal gyrus and had difficulties to engage in episodic future thinking. Patient LL presented atrophy in left anterior hippocampus, but hyperactivated its right counterpart for future compared to past thinking, permitting her to project efficiently in the future in an episodic way. Patient EG presented no atrophy in the superior medial frontal gyri or anterior hippocampi and was able to engage in episodic future thinking. Altogether, patients' future projections differed depending on the severity and localization of their atrophy. The functional integrity of bilateral superior medial frontal gyri and anterior hippocampus appear crucial for episodic future thinking: atrophy of both structures strongly impairs future projection, while integrity of these structures or hyperactivation of residual tissue normalizes episodic future projection.
authors.affiliation: Inserm, U1077, Caen, France; Université de Caen Basse-Normandie, UMR-S1077, Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, Caen, France; Centre Hospitalier Universitaire, U1077, Caen, France.
authors.forename: Armelle
authors.initials: A
authors.lastname: Viard
authors.affiliation: Université Paris Descartes, Institut de Psychologie, Memory and Cognition Lab, Paris, France; Inserm UMR S894, Centre de Psychiatrie et Neurosciences, Paris, France.
authors.forename: Pascale
authors.initials: P
authors.lastname: Piolino
authors.affiliation: Inserm, U1077, Caen, France; Université de Caen Basse-Normandie, UMR-S1077, Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, Caen, France; Centre Hospitalier Universitaire, U1077, Caen, France; CHU Pontchaillou, Rennes, France.
authors.forename: Serge
authors.initials: S
authors.lastname: Belliard
authors.affiliation: Inserm, U1077, Caen, France; Université de Caen Basse-Normandie, UMR-S1077, Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, Caen, France; Centre Hospitalier Universitaire, U1077, Caen, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: de La Sayette
authors.affiliation: Inserm, U1077, Caen, France; Université de Caen Basse-Normandie, UMR-S1077, Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, Caen, France; Centre Hospitalier Universitaire, U1077, Caen, France.
authors.forename: Béatrice
authors.initials: B
authors.lastname: Desgranges
authors.affiliation: Inserm, U1077, Caen, France; Université de Caen Basse-Normandie, UMR-S1077, Caen, France; Ecole Pratique des Hautes Etudes, UMR-S1077, Caen, France; Centre Hospitalier Universitaire, U1077, Caen, France.
authors.forename: Francis
authors.initials: F
authors.lastname: Eustache
mesh_terms: D000368:Aged; D001931:Brain Mapping; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D057180:Frontotemporal Dementia / Q000503:physiopathology*; D006624:Hippocampus / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D011939:Mental Recall / Q000502:physiology; D008875:Middle Aged; D013850:Thinking / Q000502:physiology*