Abnormal Functional Network Connectivity among Resting-State Networks in Children with Frontal Lobe Epilepsy

Widjaja, Elysa; Zamyadi, Mojdeh; Raybaud, C; Snead, O. Carter; Smith, Mary Lou

doi:10.3174/ajnr.a3608

Cited by 62 publications

(70 citation statements)

References 40 publications

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“…FLE, frontal lobe epilepsy. association with impaired motor function (Widjaja et al, 2013). Our findings also extend upon previous studies of temporal lobe epilepsy patients, where reduced connectivity within memory networks was correlated with poorer memory test scores (Doucet et al, 2012), and decreased connectivity within language networks provided a possible explanation for patients' language impairments (Waites et al, 2006).…”

Section: Motor Impairments and Resting-state Connectivitysupporting

confidence: 84%

“…Functional connectivity changes in attention and auditory resting-state networks of the frontal lobe were also associated with age at seizure onset in children with FLE. Specifically, weaker connectivity was seen in auditory networks, and stronger connectivity in attention networks, in children who had seizures beginning at an earlier age (Widjaja et al, 2013). However, no associations were found between connectivity in the sensorimotor network and age at seizure onset, or duration of epilepsy (Widjaja et al, 2013).…”

Section: Introductionmentioning

confidence: 87%

“…Furthermore, the extent of this frontal lobe isolation was positively correlated with the degree of cognitive impairment. Sensorimotor network connectivity has also been studied in children with FLE, revealing disruptions compared to control participants in association with poor motor function (Widjaja et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

“…While resting-state motor networks have been examined in children with FLE (Widjaja et al, 2013), to our knowledge, no studies have examined motor network connectivity in adult patients with FLE. Brain connectivity continues to change throughout childhood and into adulthood (Casey et al, 2005;Fair et al, 2009); therefore, we believed it was important to study adult subjects.…”

Section: Introductionmentioning

confidence: 99%

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Frontal Lobe Epilepsy Alters Functional Connections Within the Brain's Motor Network: A Resting-State fMRI Study

et al. 2014

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Patients with frontal lobe epilepsy (FLE) often experience motor deficits, yet little is known of the impact of FLE on the activity of motor networks in the brain. Resting-state functional magnetic resonance imaging (rs-fMRI) has previously demonstrated an association between cognitive deficits in temporal lobe epilepsy patients and disruption of activity within pertinent brain networks. Hence, in the present study, rs-fMRI was used to determine whether FLE is associated with motor network disruption. Seven right-hemisphere FLE patients, six lefthemisphere FLE patients, and nine control subjects underwent rs-fMRI. Functional connectivity was computed between the sensorimotor cortex contralateral to the seizure focus and each voxel in the brain, and then compared voxel-by-voxel between patient groups and controls. A laterality index (LI) of connectivity between contralateral and ipsilateral sensorimotor cortices was calculated to investigate its association with epilepsy duration and seizure frequency. Positive laterality indices indicate reduced connectivity, and zero values indicate strong connectivity. Connectivity between the left and right sensorimotor cortices was significantly reduced in FLE patients compared with controls ( p < 0.05), and LI was positively correlated with the number of lifetime seizures (left FLE: r s = 0.89, right FLE: r s = 1.00). Patients with FLE exhibit decreased connectivity within the motor network, in correlation with the number of lifetime seizures, thus demonstrating a potential relationship between seizure activity and changes in motor network organization. These findings suggest that motor network disturbances may in part be responsible for the motor deficits observed in FLE patients.

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Section: Motor Impairments and Resting-state Connectivitysupporting

confidence: 84%

Section: Introductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Frontal Lobe Epilepsy Alters Functional Connections Within the Brain's Motor Network: A Resting-State fMRI Study

et al. 2014

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“…The presence of slow fluctuations at frequencies between 0.01 and 0.1 Hz in brain regions involved in sensory, motor, visual, auditory, language and attention processing. These coordinated brain signals have shown to be robust and consistent across various functional imaging techniques such as fMRI (Biswal et al, 1995), optical imaging (Arieli et al, 1996), positron emission tomography (PET) (Raichle et al, 2001), electrophysiology (Laufs et al, 2003, Leopold et al, 2003 Several studies have revealed disturbances in RSNs in different types of epilepsy, including MTLE (Widjaja et al, 2013, Cataldi et al, 2013. These RSN changes may be linked to inter-ictal cognitive impairment.…”

Section: Introductionmentioning

confidence: 96%

The epileptogenic network: the relationship between resting state and pre-spike related perturbations

Faizo¹

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Mesial Temporal Lobe Epilepsy (MTLE) is the most common symptomatic focal epilepsy, with hippocampal sclerosis (HS) representing the most commonly occurring pathology linked to MTLE.In the past HS has been understood to represent a focal neuropathological alteration linked to the generation of seizures (i.e., the epileptic focus). However, the phenomenon that not all patients become seizure-free after surgical resection of the hippocampus has given rise to the concept that seizures and interictal epileptiform spikes and sharp waves (IES) captured by electroencephalography (EEG) in MTLE result from activity in a functionally connected epileptogenic network of brain regions. Large-scale network dynamics may thus be involved in the generation of IES and the temporal synchronisation of network structures may be an important factor in spike generation. Surgical outcome may be improved by broadening the focus from the identification of a single epileptogenic region to the characterisation of temporally synchronous epileptogenic networks associated with spikes.A common way to identify functional networks is to assess functional connectivity (FC) between spatially distinct brain regions. FC measures the degree of covariance between the activity in a specific brain region and other areas across the whole brain. The simultaneous acquisition of EEG and functional magnetic resonance imaging (fMRI) enables the identification of functional networks in which haemodynamic changes are time-locked to spikes. Nevertheless, whether this reflects the propagation of neural activity from a 'focus', or conversely the activation of a network linked to spike generation remains controversial. Delineation of functional connectivity patterns related to IES may be useful in shedding light on the mechanisms underlying their generation, and potentially of seizures in MTLE. Although the exact physiologic relationship between IES and seizures is not fully understood, there is a growing evidence to suggest that the neural network involved in generating IES is a reliable estimator of the network that generates seizures.My PhD aimed to explore the changes in brain network function that predispose the generation of IES using EEG-fMRI in patients with MTLE. I collected EEG-fMRI data from two groups of subjects: patients with MTLE and healthy controls. First, I examined MTLE patients to assess the presence of altered functional network connectivity identifiable immediately prior to the appearance of interictal spikes on EEG. A fundamental finding was the significant loss of bilateral hippocampal

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Dissociated multimodal hubs and seizures in temporal lobe epilepsy

Douw

DeSalvo

Tanaka

et al. 2015

Ann Clin Transl Neurol

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ObjectiveBrain connectivity at rest is altered in temporal lobe epilepsy (TLE), particularly in “hub” areas such as the posterior default mode network (DMN). Although both functional and anatomical connectivity are disturbed in TLE, the relationships between measures as well as to seizure frequency remain unclear. We aim to clarify these associations using connectivity measures specifically sensitive to hubs.MethodsConnectivity between 1000 cortical surface parcels was determined in 49 TLE patients and 23 controls with diffusion and resting-state functional magnetic resonance imaging. Two types of hub connectivity were investigated across multiple brain modules (the DMN, motor system, etcetera): (1) within-module connectivity (a measure of local importance that assesses a parcel's communication level within its own subnetwork) and (2) between-module connectivity (a measure that assesses connections across multiple modules).ResultsIn TLE patients, there was lower overall functional integrity of the DMN as well as an increase in posterior hub connections with other modules. Anatomical between-module connectivity was globally decreased. Higher DMN disintegration (DD) coincided with higher anatomical between-module connectivity, whereas both were associated with increased seizure frequency. DD related to seizure frequency through mediating effects of anatomical connectivity, but seizure frequency also correlated with anatomical connectivity through DD, indicating a complex interaction between multimodal networks and symptoms.InterpretationWe provide evidence for dissociated anatomical and functional hub connectivity in TLE. Moreover, shifts in functional hub connections from within to outside the DMN, an overall loss of integrative anatomical communication, and the interaction between the two increase seizure frequency.

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Abnormal Functional Network Connectivity among Resting-State Networks in Children with Frontal Lobe Epilepsy

Cited by 62 publications

References 40 publications

Frontal Lobe Epilepsy Alters Functional Connections Within the Brain's Motor Network: A Resting-State fMRI Study

Frontal Lobe Epilepsy Alters Functional Connections Within the Brain's Motor Network: A Resting-State fMRI Study

The epileptogenic network: the relationship between resting state and pre-spike related perturbations

Dissociated multimodal hubs and seizures in temporal lobe epilepsy

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