title: Thalamocortical relationship in epileptic patients with generalized spike and wave discharges--A multimodal neuroimaging study.
abstract: Unlike focal or partial epilepsy, which has a confined range of influence, idiopathic generalized epilepsy (IGE) often affects the whole or a larger portion of the brain without obvious, known cause. It is important to understand the underlying network which generates epileptic activity and through which epileptic activity propagates. The aim of the present study was to investigate the thalamocortical relationship using non-invasive imaging modalities in a group of IGE patients. We specifically investigated the roles of the mediodorsal nuclei in the thalami and the medial frontal cortex in generating and spreading IGE activities. We hypothesized that the connectivity between these two structures is key in understanding the generation and propagation of epileptic activity in brains affected by IGE. Using three imaging techniques of EEG, fMRI and EEG-informed fMRI, we identified important players in generation and propagation of generalized spike-and-wave discharges (GSWDs). EEG-informed fMRI suggested multiple regions including the medial frontal area near to the anterior cingulate cortex, mediodorsal nuclei of the thalamus, caudate nucleus among others that related to the GSWDs. The subsequent seed-based fMRI analysis revealed a reciprocal cortical and bi-thalamic functional connection. Through EEG-based Granger Causality analysis using (DTF) and adaptive DTF, within the reciprocal thalamocortical circuitry, thalamus seems to serve as a stronger source in driving cortical activity from initiation to the propagation of a GSWD. Such connectivity change starts before the GSWDs and continues till the end of the slow wave discharge. Thalamus, especially the mediodorsal nuclei, may serve as potential targets for deep brain stimulation to provide more effective treatment options for patients with drug-resistant generalized epilepsy.
authors.affiliation: Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Clara Huishi
authors.initials: CH
authors.lastname: Zhang
authors.affiliation: Department of Neurology, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Zhiyi
authors.initials: Z
authors.lastname: Sha
authors.affiliation: Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: John
authors.initials: J
authors.lastname: Mundahl
authors.affiliation: Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA ; School of Biomedical Engineering, Shanghai Jiao Tong University, China.
authors.forename: Sa
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Department of Neurology, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Henry
authors.affiliation: Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA ; Institute for Engineering in Medicine, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: He
mesh_terms: D000328:Adult; D001931:Brain Mapping; D004569:Electroencephalography; D004829:Epilepsy, Generalized / Q000503:physiopathology*; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D020645:Mediodorsal Thalamic Nucleus / Q000503:physiopathology*; D008875:Middle Aged; D064847:Multimodal Imaging; D009434:Neural Pathways / Q000503:physiopathology; D055815:Young Adult
keywords: Adaptive directed transfer function (ADTF); Directed transfer function (DTF); EEG; Functional connectivity; Generalized spike-wave discharge; Granger Causality; Idiopathic generalized epilepsy; Independent component analysis; fMRI