title: Thalamo-Cortical Disruption Contributes to Short-Term Memory Deficits in Patients with Medial Temporal Lobe Damage.
abstract: Short-term (STM) and long-term memory (LTM) have largely been considered as separate brain systems reflecting fronto-parietal and medial temporal lobe (MTL) functions, respectively. This functional dichotomy has been called into question by evidence of deficits on aspects of working memory in patients with MTL damage, suggesting a potentially direct hippocampal contribution to STM. As the hippocampus has direct anatomical connections with the thalamus, we tested the hypothesis that damage to thalamic nuclei regulating cortico-cortical interactions may contribute to STM deficits in patients with hippocampal dysfunction. We used diffusion-weighted magnetic resonance imaging-based tractography to identify anatomical subdivisions in patients with MTL epilepsy. From these, we measured resting-state functional connectivity with detailed cortical divisions of the frontal, temporal, and parietal lobes. Whereas thalamo-temporal functional connectivity reflected LTM performance, thalamo-prefrontal functional connectivity specifically predicted STM performance. Notably, patients with hippocampal volume loss showed thalamic volume loss, most prominent in the pulvinar region, not detected in patients with normal hippocampal volumes. Aberrant thalamo-cortical connectivity in the epileptic hemisphere was mirrored in a loss of behavioral association with STM performance specifically in patients with hippocampal atrophy. These findings identify thalamo-cortical disruption as a potential mechanism contributing to STM deficits in the context of MTL damage.
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences Epilepsy Research Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK.
authors.forename: Natalie L
authors.initials: NL
authors.lastname: Voets
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences.
authors.forename: Ricarda A L
authors.initials: RA
authors.lastname: Menke
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences.
authors.forename: Saad
authors.initials: S
authors.lastname: Jbabdi
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences Epilepsy Research Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, UK.
authors.forename: Masud
authors.initials: M
authors.lastname: Husain
authors.affiliation: Department of Neurosurgery, John Radcliffe Hospital, Oxford OX3 9DU, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Stacey
authors.affiliation: Russell Cairns Unit, John Radcliffe Hospital, Oxford OX3 9DU, UK.
authors.forename: Katherine
authors.initials: K
authors.lastname: Carpenter
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences Epilepsy Research Group, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK.
authors.forename: Jane E
authors.initials: JE
authors.lastname: Adcock
mesh_terms: D000293:Adolescent; D000328:Adult; D001930:Brain Injuries / Q000150:complications* / Q000473:pathology*; D002540:Cerebral Cortex / Q000503:physiopathology*; D015331:Cohort Studies; D038524:Diffusion Magnetic Resonance Imaging; D004833:Epilepsy, Temporal Lobe / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D005260:Female; D006624:Hippocampus / Q000098:blood supply / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008569:Memory Disorders / Q000209:etiology*; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D009434:Neural Pathways / Q000098:blood supply / Q000473:pathology; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D013702:Temporal Lobe / Q000473:pathology*; D013788:Thalamus / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: epilepsy; functional connectivity; hippocampus; memory; thalamus