Seizure Frequency Can Alter Brain Connectivity: Evidence from Resting-State fMRI

Bharath, Rose Dawn; Sinha, Sanjib; Panda, Rajanikant; Kenchaiah, Raghavendra; George, Lija; Chaitanya, Ganne; Gupta, Ajay; Satishchandra, P

doi:10.3174/ajnr.a4373

Cited by 28 publications

(29 citation statements)

References 45 publications

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“…The volumes of the corpus callosum in epilepsy patients are significantly lower than those in normal controls. Among the epilepsy patients, they are significantly lower in antiepileptic drug responders than nonresponders T A B L E 2 Differences in the demographic, clinical, and radiologic characteristics between antiepileptic drug responders and nonresponders brain connectivity (Bharath et al, 2015), and AEDs can largely affect the activation of functional networks in patients with epilepsy (Wandschneider et al, 2014). Thus, it was not able to determine if there was a true causal relationship between the AED response and brain connectivity in the study with patients with chronic epilepsy.…”

Section: Discussionmentioning

confidence: 82%

Can we predict drug response by volumes of the corpus callosum in newly diagnosed focal epilepsy?

Kim

Lee

et al. 2017

Brain and Behavior

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Objective: The aim of this study was to investigate whether volumes of the corpus callosum could predict a response to antiepileptic drugs in patients with newly diagnosed focal epilepsy. Methods:Fifty-three patients with newly diagnosed focal epilepsy of unknown etiology and healthy subjects were enrolled in this study. First, we analyzed the differences in the volumes of the corpus callosum between patients with epilepsy and healthy subjects. Second, we divided patients with epilepsy into antiepileptic drug responders and drug nonresponders groups, according to their seizure controls, and evaluated the differences in the volumes of the corpus callosum between the groups. Third, we conducted correlation analyses between the volumes of the corpus callosum and mean diffusion measures in healthy subjects. Results:The volumes of the corpus callosum in patients with epilepsy were significantly lower than those in normal controls (p = .0001). Among epilepsy patients, the volumes of the corpus callosum were significantly lower in antiepileptic drug responders compared with nonresponders (p = .0481), which was the only independent variable for predicting antiepileptic drug response (OR = 10.07, p = .0434). In addition, we found that the volumes of the corpus callosum were significantly correlated with the mean diffusion measures (fractional anisotropy, r = .408, p = .0027; mean diffusivity, r = −0.403, p = .0028) in normal controls. Conclusions:We demonstrated that the volumes of the corpus callosum were different according to antiepileptic drug responses in patients with newly diagnosed focal epilepsy, which might suggest that the volumes of the corpus callosum could be a new biomarker for predicting responses to antiepileptic drugs. K E Y W O R D Santiconvulsants, corpus callosum, epilepsy

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Section: Discussionmentioning

confidence: 82%

Can we predict drug response by volumes of the corpus callosum in newly diagnosed focal epilepsy?

Kim

Lee

et al. 2017

Brain and Behavior

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“…We hypothesize that gross changes in network structure, as those observed, for example, in the epileptic brain, may lead to transitions among cellular-based and network-based dynamical mechanisms which in turn may result in transitions between cognitive and pathological brain functions (see, for example, Bharath et al 2015;Parent et al 1997).…”

Section: Discussionmentioning

confidence: 99%

Effects of Neuromodulation on Excitatory–Inhibitory Neural Network Dynamics Depend on Network Connectivity Structure

2018

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Acetylcholine (ACh), one of the brain's most potent neuromodulators, can affect intrinsic neuron properties through blockade of an M-type potassium current. The effect of ACh on excitatory and inhibitory cells with this potassium channel modulates their membrane excitability, which in turn affects their tendency to synchronize in networks. Here, we study the resulting changes in dynamics in networks with inter-connected excitatory and inhibitory populations (E-I networks), which are ubiquitous in the brain. Utilizing biophysical models of E-I networks, we analyze how the network connectivity structure in terms of synaptic connectivity alters the influence of ACh on the generation of synchronous excitatory bursting. We investigate networks containing all combinations of excitatory and inhibitory cells with high (Type I properties) or low (Type II properties) modulatory tone. To vary network connectivity structure, we focus on the effects of the strengths of inter-connections between excitatory and inhibitory cells (E-I synapses and I-E synapses), and the strengths of intra-connections among excitatory cells (E-E synapses) and among inhibitory cells (I-I synapses). We show that the presence of ACh may or may not affect the generation of network synchrony depending on the network connectivity. Specifically, strong network inter-connectivity induces synchronous excitatory bursting regardless of the cellular propensity for synchronization, which aligns with predictions of 123J Nonlinear Sci the PING model. However, when a network's intra-connectivity dominates its interconnectivity, the propensity for synchrony of either inhibitory or excitatory cells can determine the generation of network-wide bursting.

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“…[51][52][53] Poor thermoregulatory control is thought to be genetically determined in most patients, though developmental stage is most probable in infants. 33 Overall, kindling is likely to stimulate the limbic system with greatest involvement in the hypothalamus and amygdala, which has been demonstrated by ictal SPECT recordings, 38,54 functional imaging, 44,45 and postmortem histologic investigations. 55 Simultaneously, there may be compensatory functional activation in the medial prefrontal cortex (mPFC) and the dorsal anterior cingulate (dACC), 45 which are involved in threat detection 56 and introceptive awareness of autonomic functioning.…”

Section: Pathogenesismentioning

confidence: 98%

“…33 Overall, kindling is likely to stimulate the limbic system with greatest involvement in the hypothalamus and amygdala, which has been demonstrated by ictal SPECT recordings, 38,54 functional imaging, 44,45 and postmortem histologic investigations. 55 Simultaneously, there may be compensatory functional activation in the medial prefrontal cortex (mPFC) and the dorsal anterior cingulate (dACC), 45 which are involved in threat detection 56 and introceptive awareness of autonomic functioning. 57 Frontal regions send excitatory signals to the limbic system, with the majority of connections to the amygdala.…”

Section: Pathogenesismentioning

confidence: 98%

“…28,43 Following hot water hand immersion, simultaneous EEG-functional magnetic resonance imaging (fMRI) measured activation patterns in left frontoparietal and mesial temporal regions. 44 A recent resting-state fMRI investigation by Bharath et al 45 showed widespread decreased connectivity in anterior cingulate, dorsal cingulate, and medial prefrontal cortices and increased connectivity in bilateral mesial temporal cortices in HWE patients with frequent seizures (> 2 per month) versus infrequent seizures (< 2 per month) and age-matched controls. Surprisingly, the opposite pattern was observed in patients with infrequent HWE episodes.…”

Section: Clinical Manifestationsmentioning

confidence: 99%

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Exploring Pre- and Postoperative Profiles of Hot Water Epilepsy: Revisiting Pathogenic Mechanisms

Schraegle

Nussbaum

2017

J Pediatr Epilepsy

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Hot water epilepsy (HWE) refers to a rare form of reflex epilepsy precipitated by the stimulus of pouring hot water over the head or by bathing. Despite being most commonly seen in southern India, isolated HWE cases have surfaced in western countries. HWE classically manifests as simple or complex partial with temporal lobe semiology. About a quarter of patients show interictal EEG abnormalities, which mostly occur over the temporal lobes. HWE has two established variants that are typically benign. We present two cases where HWE preceded spontaneous seizures, which later progressed to pharmacoresistant epilepsy. These cases garner further evidence for a symptomatic variant of HWE. Additionally, clinical features of HWE are discussed and an updated model of pathogenesis incorporating self-inducement phenomenon is proposed.

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Seizure Frequency Can Alter Brain Connectivity: Evidence from Resting-State fMRI

Cited by 28 publications

References 45 publications

Can we predict drug response by volumes of the corpus callosum in newly diagnosed focal epilepsy?

Can we predict drug response by volumes of the corpus callosum in newly diagnosed focal epilepsy?

Effects of Neuromodulation on Excitatory–Inhibitory Neural Network Dynamics Depend on Network Connectivity Structure

Exploring Pre- and Postoperative Profiles of Hot Water Epilepsy: Revisiting Pathogenic Mechanisms

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