title: Abnormal thalamocortical structural and functional connectivity in juvenile myoclonic epilepsy.
abstract: Juvenile myoclonic epilepsy is the most common idiopathic generalized epilepsy, characterized by frequent myoclonic jerks, generalized tonic-clonic seizures and, less commonly, absences. Neuropsychological and, less consistently, anatomical studies have indicated frontal lobe dysfunction in the disease. Given its presumed thalamo-cortical basis, we investigated thalamo-cortical structural connectivity, as measured by diffusion tensor imaging, in a cohort of 28 participants with juvenile myoclonic epilepsy and detected changes in an anterior thalamo-cortical bundle compared with healthy control subjects. We then investigated task-modulated functional connectivity from the anterior thalamic region identified using functional magnetic resonance imaging in a task consistently shown to be impaired in this group, phonemic verbal fluency. We demonstrate an alteration in task-modulated connectivity in a region of frontal cortex directly connected to the thalamus via the same anatomical bundle, and overlapping with the supplementary motor area. Further, we show that the degree of abnormal connectivity is related to disease severity in those with active seizures. By integrating methods examining structural and effective interregional connectivity, these results provide convincing evidence for abnormalities in a specific thalamo-cortical circuit, with reduced structural and task-induced functional connectivity, which may underlie the functional abnormalities in this idiopathic epilepsy.
authors.affiliation: King's College London, Institute of Psychiatry, Box P043, De Crespigny Park, London SE5 8AF, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: O'Muircheartaigh
authors.forename: Christian
authors.initials: C
authors.lastname: Vollmar
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: Barker
authors.forename: Veena
authors.initials: V
authors.lastname: Kumari
authors.forename: Mark R
authors.initials: MR
authors.lastname: Symms
authors.forename: Pam
authors.initials: P
authors.lastname: Thompson
authors.forename: John S
authors.initials: JS
authors.lastname: Duncan
authors.forename: Matthias J
authors.initials: MJ
authors.lastname: Koepp
authors.forename: Mark P
authors.initials: MP
authors.lastname: Richardson
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000098:blood supply / Q000473:pathology* / Q000503:physiopathology; D004569:Electroencephalography; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D020190:Myoclonic Epilepsy, Juvenile / Q000473:pathology* / Q000503:physiopathology*; D009434:Neural Pathways / Q000502:physiology*; D059906:Neuroimaging; D009483:Neuropsychological Tests; D011603:Psychophysiology; D013223:Statistics as Topic; D013788:Thalamus / Q000098:blood supply / Q000473:pathology* / Q000503:physiopathology; D055815:Young Adult