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. 2017 Jul 12:16:52-57.
doi: 10.1016/j.nicl.2017.07.008. eCollection 2017.

Sleep onset uncovers thalamic abnormalities in patients with idiopathic generalised epilepsy

Andrew P Bagshaw  1   2 , Joanne R Hale  1   2   3 , Brunno M Campos  4 , David T Rollings  1   2   5 , Rebecca S Wilson  1   2 , Marina K M Alvim  4 , Ana Carolina Coan  4 , Fernando Cendes  4
Affiliations

Sleep onset uncovers thalamic abnormalities in patients with idiopathic generalised epilepsy

Andrew P Bagshaw et al. Neuroimage Clin. .

Abstract

The thalamus is crucial for sleep regulation and the pathophysiology of idiopathic generalised epilepsy (IGE), and may serve as the underlying basis for the links between the two. We investigated this using EEG-fMRI and a specific emphasis on the role and functional connectivity (FC) of the thalamus. We defined three types of thalamic FC: thalamocortical, inter-hemispheric thalamic, and intra-hemispheric thalamic. Patients and controls differed in all three measures, and during wakefulness and sleep, indicating disorder-dependent and state-dependent modification of thalamic FC. Inter-hemispheric thalamic FC differed between patients and controls in somatosensory regions during wakefulness, and occipital regions during sleep. Intra-hemispheric thalamic FC was significantly higher in patients than controls following sleep onset, and disorder-dependent alterations to FC were seen in several thalamic regions always involving somatomotor and occipital regions. As interactions between thalamic sub-regions are indirect and mediated by the inhibitory thalamic reticular nucleus (TRN), the results suggest abnormal TRN function in patients with IGE, with a regional distribution which could suggest a link with the thalamocortical networks involved in the generation of alpha rhythms. Intra-thalamic FC could be a more widely applicable marker beyond patients with IGE.

Keywords: Functional connectivity; Generalised epilepsy; Sleep; Thalamic reticular nucleus thalamus.

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Figures

Fig. 1
Fig. 1
Thalamocortical FC was generally higher in patients with IGE, and the SOM and PRE regions demonstrated a differential response to sleep onset. W: Wake, N1: non-REM sleep stage 1. Error bars represent standard error.
Fig. 2
Fig. 2
Inter-hemispheric thalamic FC was increased by sleep onset. Patients with IGE had generally increased FC compared to control subjects as well as specifically during sleep in OCC and SOM. W: Wake, N1: non-REM sleep stage 1. Error bars represent standard error.
Fig. 3
Fig. 3
Intra-thalamic FC was higher in patients with IGE than control subjects, due to the increased FC in patients during N1. Patients and controls differed in FC in several pairs of regions that always included either OCC, MOT or SOM (OCC-TEM, MOT-SOM, MOT-TEM). W: Wake, N1: non-REM sleep stage 1. Error bars represent standard error.
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