The dopamine system in idiopathic generalized epilepsies: Identification of syndrome-related changes

Ciumas, Carolina; Wahlin, Tarja-Brita Robins; Espino, Claudia; Savić, Ivanka

doi:10.1016/j.neuroimage.2010.02.051

Cited by 46 publications

(18 citation statements)

References 75 publications

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“…Furthermore, in contrast to EEG, fMRI allows for detection of signals from small regions such as the orbitofrontal cortex that are not close to the skull surface. Of note, other neuroimaging techniques, including fluoro-2-deoxy-D-glucose PET, 34,35 magnetic resonance spectroscopy, 36 and voxel-based morphometry in MRI, 37 have also been useful in investigating interictal changes in idiopathic generalized epilepsy. Like these other methods, the resting functional connectivity could potentially serve as a useful biomarker for CAE during the interictal period, with the advantage of detecting abnormal network function.…”

Section: Discussionmentioning

confidence: 99%

Resting functional connectivity between the hemispheres in childhood absence epilepsy

Xiang¹,

Guo

Killory

et al. 2011

Neurology

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Objective:The fundamental mechanisms by which childhood absence epilepsy (CAE) changes neural networks even between seizures remain poorly understood. During seizures, cortical and subcortical networks exhibit bihemspheric synchronous activity based on prior EEG-fMRI studies. Our aim was to investigate whether this abnormal bisynchrony may extend to the interictal period, using a blood oxygen level-dependent (BOLD) resting functional connectivity approach.Methods: EEG-fMRI data were recorded from 16 patients with CAE and 16 age-and gendermatched controls. Three analyses were performed. 1) Using 16 pairs of seizure-related regions of interest (ROI), we compared the between-hemisphere interictal resting functional connectivity of patients and controls. 2) For regions showing significantly increased interhemispheric connectivity in CAE, we then calculated connectivity to the entire brain. 3) A paired-voxel approach was performed to calculate resting functional connectivity between hemispheres without the constraint of predefined ROIs. Results:We found significantly increased resting functional connectivity between hemispheres in the lateral orbitofrontal cortex of patients with CAE compared to normal controls. Enhanced between-hemisphere connectivity localized to the lateral orbitofrontal cortex was confirmed by all 3 analysis methods.Conclusions: Our results demonstrate abnormal increased connectivity between the hemispheres in patients with CAE in seizure-related regions, even when seizures were not occurring. These findings suggest that the lateral orbitofrontal cortex may play an important role in CAE pathophysiology, warranting further investigation. In addition, resting functional connectivity analysis may provide a promising biomarker to improve our understanding of altered brain function in CAE during the interictal period. Neurology Childhood absence epilepsy (CAE) is increasingly recognized as a disorder characterized by impaired function both during seizures, and in the interictal period.1-4 Notably, 3-4 Hz spikewave discharges (SWD) seen in CAE 5-7 and their associated blood oxygenation level-dependent (BOLD) fMRI changes [8][9][10][11][12][13][14][15][16] are bilateral and fairly symmetric. Evidence from animal models indicates that this bihemispheric synchrony during SWD is mediated by the corpus callosum. 17,18 We hypothesize that abnormal bihemispheric synchrony persists in the interictal period, and may participate in generating abnormal function, including enhanced bilateral excitability. The possible role of abnormal long-range bilateral synchrony during the interictal period in CAE has not been previously investigated.The recent development of the resting functional connectivity approach to fMRI has provided a window to observe intrinsic brain activity in health and disease. This method has been used to

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Section: Discussionmentioning

confidence: 99%

Resting functional connectivity between the hemispheres in childhood absence epilepsy

Xiang¹,

Guo

Killory

et al. 2011

Neurology

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“…The MRI protocol included the following scans: (1) 3D-weighted T1 SPGR images with 1 mm isotropic voxel size according to a previously described protocol (Ciumas et al, 2010); (2) 2D T2-weighted fast spin echo (FSE) images in the axial plane (effective TE = 56 ms, TR = 2500 ms, FOV = 24 cm, 23 slices of 3 mm thickness). The latter images were not used in the present report.…”

Section: Methodsmentioning

confidence: 99%

Asymmetry of cerebral gray and white matter and structural volumes in relation to sex hormones and chromosomes

Savić

2014

Front. Neurosci.

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Whilst many studies show sex differences in cerebral asymmetry, their mechanisms are still unknown. This report describes the potential impact of sex hormones and sex chromosomes by comparing MR data from 39 male and 47 female controls and 33 men with an extra X-chromosome (47,XXY).Methods: Regional asymmetry in gray and white matter volumes (GMV and WMV) was calculated using voxel based moprhometry (SPM5), by contrasting the unflipped and flipped individual GMV and WMV images. In addition, structural volumes were calculated for the thalamus, caudate, putamen, amygdala, and hippocampus, using the FreeSurfer software. Effects of plasma testosterone and estrogen on the GMV and WMV, as well on the right/left ratios of the subcortical volumes were tested by multi-regression analysis.Results: All three groups showed a leftward asymmetry in the motor cortex and the planum temporale, and a rightward asymmetry of the middle occipital cortex. Both asymmetries were more pronounced in 46,XY males than 46,XX females and 47,XXY males, and were positively correlated with testosterone levels. There was also a rightward asymmetry of the vermis and leftward GMV asymmetry in the cerebellar hemispheres in all groups. Notably, cerebellar asymmetries were larger in 46,XX females and 47,XXY males, but were not related to sex hormone levels. No asymmetry differences between 46,XX females and 47,XXY males, and no overall effects of brain size were detected.Conclusion: The asymmetry in the planum temporale area and the occipital cortex seem related to processes associated with testosterone, whereas the observed cerebellar asymmetries suggest a link with X-chromosome escapee genes. Sex differences in cerebral asymmetry are moderated by sex hormones and X-chromosome genes, in a regionally differentiated manner.

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“…Of these, the dopaminergic signalling appears of greater importance because it is necessary for normal motor skill learning and synaptic plasticity within the primary motor cortex of animal models [49]. Interestingly, a specific alteration of the dopaminergic system [50] and impaired dopamine uptake in the midbrain of JME patients [51][52][53] has been revealed with positron emission tomography (PET). Additionally, dopamine itself is neuroprotective and have inhibitory properties on seizures [54,55], particularly myoclonic seizures [56].…”

Section: Discussionmentioning

confidence: 99%

Abnormal motor cortex plasticity in juvenile myoclonic epilepsy

Strigaro

Falletta

Cerino

et al. 2015

Seizure

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The dopamine system in idiopathic generalized epilepsies: Identification of syndrome-related changes

Cited by 46 publications

References 75 publications

Resting functional connectivity between the hemispheres in childhood absence epilepsy

Resting functional connectivity between the hemispheres in childhood absence epilepsy

Asymmetry of cerebral gray and white matter and structural volumes in relation to sex hormones and chromosomes

Abnormal motor cortex plasticity in juvenile myoclonic epilepsy

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