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Edelman BJ, Johnson N, Sohrabpour A, Tong S, Thakor N, He B. Systems Neuroengineering: Understanding and Interacting with the Brain. ENGINEERING (BEIJING, CHINA) 2015; 1:292-308. [PMID: 34336364 PMCID: PMC8323844 DOI: 10.15302/j-eng-2015078] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
In this paper, we review the current state-of-the-art techniques used for understanding the inner workings of the brain at a systems level. The neural activity that governs our everyday lives involves an intricate coordination of many processes that can be attributed to a variety of brain regions. On the surface, many of these functions can appear to be controlled by specific anatomical structures; however, in reality, numerous dynamic networks within the brain contribute to its function through an interconnected web of neuronal and synaptic pathways. The brain, in its healthy or pathological state, can therefore be best understood by taking a systems-level approach. While numerous neuroengineering technologies exist, we focus here on three major thrusts in the field of systems neuroengineering: neuroimaging, neural interfacing, and neuromodulation. Neuroimaging enables us to delineate the structural and functional organization of the brain, which is key in understanding how the neural system functions in both normal and disease states. Based on such knowledge, devices can be used either to communicate with the neural system, as in neural interface systems, or to modulate brain activity, as in neuromodulation systems. The consideration of these three fields is key to the development and application of neuro-devices. Feedback-based neuro-devices require the ability to sense neural activity (via a neuroimaging modality) through a neural interface (invasive or noninvasive) and ultimately to select a set of stimulation parameters in order to alter neural function via a neuromodulation modality. Systems neuroengineering refers to the use of engineering tools and technologies to image, decode, and modulate the brain in order to comprehend its functions and to repair its dysfunction. Interactions between these fields will help to shape the future of systems neuroengineering-to develop neurotechniques for enhancing the understanding of whole-brain function and dysfunction, and the management of neurological and mental disorders.
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Affiliation(s)
- Bradley J. Edelman
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Nessa Johnson
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Abbas Sohrabpour
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Shanbao Tong
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Nitish Thakor
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
- SINAPSE Institute, National University of Singapore, Singapore
| | - Bin He
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
- Institute for Engineering in Medicine, University of Minnesota, Minneapolis, MN 55455, USA
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152
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Wu C, Wang J, Peng J, Patel N, Huang Y, Gao X, Aljarallah S, Eubanks JH, McDonald R, Zhang L. Modeling early-onset post-ischemic seizures in aging mice. Exp Neurol 2015; 271:1-12. [PMID: 25943585 PMCID: PMC4758832 DOI: 10.1016/j.expneurol.2015.04.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 04/24/2015] [Accepted: 04/28/2015] [Indexed: 12/26/2022]
Abstract
Stroke is the leading cause of seizures and epilepsy in the aged population, with post-stroke seizures being a poor prognostic factor. The pathological processes underlying post-stroke seizures are not well understood and studies of these seizures in aging/aged animals remain scarce. Therefore, our primary objective was to model post-stroke seizures in aging mice (C57 black strain, 16-20 months-old), with a focus on early-onset, convulsive seizures that occur within 24-hours of brain ischemia. We utilized a middle cerebral artery occlusion model and examined seizure activity and brain injury using combined behavioral and electroencephalographic monitoring and histological assessments. Aging mice exhibited vigorous convulsive seizures within hours of the middle cerebral artery occlusion. These seizures manifested with jumping, rapid running, barrel-rolling and/or falling all in the absence of hippocampal-cortical electrographic discharges. Seizure development was closely associated with severe brain injury and acute mortality. Anticonvulsive treatments after seizure occurrence offered temporary seizure control but failed to improve animal survival. A separate cohort of adult mice (6-8 months-old) exhibited analogous early-onset convulsive seizures following the middle cerebral artery occlusion but had better survival outcomes following anticonvulsive treatment. Collectively, our data suggest that early-onset convulsive seizures are a result of severe brain ischemia in aging animals.
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Affiliation(s)
- Chiping Wu
- Toronto Western Research Institute, University Health Network, Canada
| | - Justin Wang
- Toronto Western Research Institute, University Health Network, Canada
| | - Jessie Peng
- Toronto Western Research Institute, University Health Network, Canada
| | - Nisarg Patel
- Toronto Western Research Institute, University Health Network, Canada
| | - Yayi Huang
- Toronto Western Research Institute, University Health Network, Canada
| | - Xiaoxing Gao
- Toronto Western Research Institute, University Health Network, Canada
| | - Salman Aljarallah
- Toronto Western Research Institute, University Health Network, Canada; Neurology Unit, Department of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - James H Eubanks
- Toronto Western Research Institute, University Health Network, Canada; Department of Surgery (Neurosurgery), University of Toronto, Canada
| | - Robert McDonald
- Department of Neuroscience, University of Lethbridge, Canada
| | - Liang Zhang
- Toronto Western Research Institute, University Health Network, Canada; Department of Medicine (Neurology), University of Toronto, Canada.
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153
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Sustained Reduction of Cerebellar Activity in Experimental Epilepsy. BIOMED RESEARCH INTERNATIONAL 2015; 2015:718591. [PMID: 26417599 PMCID: PMC4568351 DOI: 10.1155/2015/718591] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 02/18/2015] [Accepted: 03/03/2015] [Indexed: 11/18/2022]
Abstract
Clinical and experimental evidence suggests a role for the cerebellum in seizure control, while no data are available on cerebellar activity between seizures. We hypothesized that interictal regional activity of the deep cerebellar nuclei is reduced in epilepsy and tested this in an animal model by using ΔFosB and cytochrome oxidase (COX) (immuno)histochemistry. The expression of these two markers of neuronal activity was analysed in the dentate nucleus (DN), interpositus nucleus (IN), and fastigial nucleus (FN) of the cerebellum of fully amygdala kindled rats that were sacrificed 48 hours after their last seizure. The DN and FN of kindled rats exhibited 25 to 29% less ΔFosB immunopositive cells than their respective counterpart in sham controls (P < 0.05). COX expression in the DN and FN of kindled animals was reduced by 32 to 33% compared to respective control values (P < 0.05). These results indicate that an epileptogenic state is characterized by decreased activity of deep cerebellar nuclei, especially the DN and FN. Possible consequences may include a decreased activation of the thalamus, contributing to further seizure spread. Restoration of FN activity by low frequency electrical stimulation is suggested as a possible treatment option in chronic epilepsy.
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154
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Thalamocortical relationship in epileptic patients with generalized spike and wave discharges--A multimodal neuroimaging study. NEUROIMAGE-CLINICAL 2015; 9:117-27. [PMID: 26448912 PMCID: PMC4552814 DOI: 10.1016/j.nicl.2015.07.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 05/30/2015] [Accepted: 07/05/2015] [Indexed: 01/01/2023]
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.
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155
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He X, Doucet GE, Sperling M, Sharan A, Tracy JI. Reduced thalamocortical functional connectivity in temporal lobe epilepsy. Epilepsia 2015; 56:1571-9. [PMID: 26193910 DOI: 10.1111/epi.13085] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/19/2015] [Indexed: 01/06/2023]
Abstract
OBJECTIVE In temporal lobe epilepsy (TLE), the thalamus is well known for its role in the propagation and spread of epileptiform activity. However, the integrity of thalamocortical functional connectivity (FC) in TLE and its relation to specific seizure patterns have not yet been determined. We address these issues with resting-state functional magnetic resonance imaging (fMRI). METHODS Resting-state fMRI was performed on two groups of unilateral TLE patients: those with focal seizures only (16 left TLE, 16 right TLE) and those with additional generalized seizures (16 left TLE, 10 right TLE), and 16 matched controls. A thalamic parcellation based on FC between five nonoverlapping cortical seeds (prefrontal, motor, somatosensory, parietal-occipital, and temporal) and the ipsilateral thalamus was carried out to parcel each thalamus into five corresponding segments. FCs between each segment and its ipsilateral cortical seed were extracted and compared across groups using analyses of variance (ANOVAs). RESULTS Compared to healthy controls, patients with TLE displayed decreased thalamocortical FC in multiple posterior and ventromedial thalamic segments of both the ictal and nonictal hemispheres. Our parcellation analysis revealed that these thalamic regions were functionally connected to the parietal/occipital and temporal lobes. In patients with TLE with focal seizures these regional thalamocortical FC decreases were limited to the ictal hemisphere. In contrast, TLE patients with both focal and generalized epileptiform activity displayed FC decreases in both the ictal and nonictal thalamus involving the dorsolateral pulvinar, a region preferentially connected to the parietal and occipital lobes. SIGNIFICANCE Our data provide the first evidence of regional specific thalamocortical FC decreases in patients with unilateral TLE. Furthermore, our results demonstrate that patients with different seizure types present different thalamoparietal/occipital FC decrease patterns. While patients with focal seizures present thalamocortical FC decreases in the ictal hemisphere only, patients with additional generalized seizure activity also show thalamocortical FC decreases involving the thalamus in the nonictal hemisphere.
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Affiliation(s)
- Xiaosong He
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, U.S.A
| | - Gaelle E Doucet
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, U.S.A
| | - Michael Sperling
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, U.S.A
| | - Ashwini Sharan
- Department of Neurosurgery, Thomas Jefferson University, Philadelphia, Pennsylvania, U.S.A
| | - Joseph I Tracy
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, U.S.A
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156
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He B, Sohrabpour A. Imaging epileptogenic brain using high density EEG source imaging and MRI. Clin Neurophysiol 2015; 127:5-7. [PMID: 26051752 DOI: 10.1016/j.clinph.2015.04.074] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 04/30/2015] [Accepted: 04/30/2015] [Indexed: 10/23/2022]
Affiliation(s)
- Bin He
- Department of Biomedical Engineering, University of Minnesota, 312 Church Street, SE, Minneapolis, MN 55455, USA.
| | - Abbas Sohrabpour
- Department of Biomedical Engineering, University of Minnesota, 312 Church Street, SE, Minneapolis, MN 55455, USA
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157
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Wei HL, An J, Zeng LL, Shen H, Qiu SJ, Hu DW. Altered functional connectivity among default, attention, and control networks in idiopathic generalized epilepsy. Epilepsy Behav 2015; 46:118-25. [PMID: 25935514 DOI: 10.1016/j.yebeh.2015.03.031] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/22/2015] [Accepted: 03/28/2015] [Indexed: 10/23/2022]
Abstract
Numerous resting-state fMRI studies have demonstrated altered functional connectivity within canonical intrinsic connectivity networks (ICNs) in patients with idiopathic generalized epilepsy (IGE). It is possible that the widespread ICN abnormalities on electroencephalography in IGE derive from abnormal functional interactions between ICNs. To test this possibility, we explored the functional connectivity between the subnetworks of the default mode network (DMN), attention network (ATN), and frontoparietal control network (FPN) using independent component analysis of resting-state fMRI data collected from 27 patients with IGE characterized by generalized tonic-clonic seizures (GTCS) and 29 matched healthy controls. It was observed that the left FPN exhibited increased connectivity with the anterior DMN and ventral ATN, while the right FPN exhibited increased connectivity with the anterior and posterior DMNs in the patients with IGE-GTCS. Furthermore, the functional connectivity between the anterior DMN and ventral ATN was negative in healthy controls but positive in the patients with IGE-GTCS. In addition, the anterior DMN exhibited increased intranetwork functional connectivity in the right frontal pole in IGE-GTCS. These findings suggest that IGE-GTCS is likely associated with a disrupted brain organization probably derived from abnormal functional interactions among ICNs. Furthermore, the alterations in the functional architecture of the ICNs may be related to deficits in mentation and attention in IGE-GTCS, providing informative evidence for the understanding of the pathophysiology of IGE-GTCS.
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Affiliation(s)
- H L Wei
- College of Mechatronics and Automation, National University of Defense Technology, Changsha, Hunan, People's Republic of China
| | - J An
- Department of Medical Imaging, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, People's Republic of China
| | - L L Zeng
- College of Mechatronics and Automation, National University of Defense Technology, Changsha, Hunan, People's Republic of China
| | - H Shen
- College of Mechatronics and Automation, National University of Defense Technology, Changsha, Hunan, People's Republic of China
| | - S J Qiu
- Department of Medical Imaging, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, People's Republic of China.
| | - D W Hu
- College of Mechatronics and Automation, National University of Defense Technology, Changsha, Hunan, People's Republic of China.
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158
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Abstract
OPINION STATEMENT Recent years have seen the development of novel neuroimaging techniques whose roles in the management of acute stroke are sometimes confusing and controversial. This may be attributable in part to a focus on establishing simplified algorithms and terminology that omit consideration of the basic pathophysiology of cerebral ischemia and, consequently, of the full potential for optimizing patients' care based upon their individual imaging findings. This review begins by discussing cerebral hemodynamic physiology and of the effects of hemodynamic disturbances upon the brain. Particular attention will be paid to the hemodynamic measurements and markers of tissue injury that are provided by common clinical imaging techniques, with the goal of enabling greater confidence and flexibility in understanding the potential uses of these techniques in various clinical roles, which will be discussed in the remainder of the review.
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Affiliation(s)
- William A Copen
- Massachusetts General Hospital, Division of Neuroradiology, GRB-273A, 55 Fruit Street, Boston, MA, 02114, USA,
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159
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Blumenfeld H, Meador K, Jackson GD. Commentary: The return of consciousness to epilepsy seizure classification. Epilepsia 2015; 56:345-7. [PMID: 25740196 PMCID: PMC4688007 DOI: 10.1111/epi.12922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/18/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Hal Blumenfeld
- Department of Neurology, Yale University School of Medicine, New
Haven, Connecticut, U.S.A
- Department of Neurobiology, Yale University School of
Medicine, New Haven, Connecticut, U.S.A
- Department of Neurosurgery, Yale University School of
Medicine, New Haven, Connecticut, U.S.A
| | - Kimford Meador
- Department of Neurology and Neurological Sciences, Stanford
School of Medicine, Stanford, California, U.S.A
| | - Graeme D. Jackson
- Department of Neurology, Austin Health, Melbourne, Victoria,
Australia
- Florey Institute of Neuroscience and Mental Health, Melbourne,
Victoria, Australia
- University of Melbourne, Melbourne, Victoria, Australia
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160
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Vinogradova LV. Comparative potency of sensory-induced brainstem activation to trigger spreading depression and seizures in the cortex of awake rats: Implications for the pathophysiology of migraine aura. Cephalalgia 2014; 35:979-86. [PMID: 25516507 DOI: 10.1177/0333102414565672] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 10/15/2014] [Indexed: 11/15/2022]
Abstract
BACKGROUND Migraine and epilepsy are highly co-morbid neurological disorders associated with episodic dysfunction of both cortical and subcortical networks. The study examined the interrelation between cortical spreading depression, the electrophysiological correlate of migraine aura and seizures triggered at cortical and brainstem levels by repeated sound stimulation in rats with acoustic hypersensitivity (reflex audiogenic epilepsy). METHOD In awake, freely moving rats with innate audiogenic epilepsy, 25 episodes of running seizure (brainstem seizures) were induced by repeated sound stimulation. Spreading depression and seizures were recorded using implanted cortical electrodes. RESULTS The first sound-induced brainstem seizures evoked neither spreading depression nor seizures in the cortex. With repetition, brainstem seizures began to be followed by a single cortical spreading depression wave and an epileptiform discharge. Spreading depression was more frequent an early cortical event than seizures: spreading depression appeared after 8.4 ± 1.0 repeated stimulations in 100% rats (n = 24) while cortical seizures were recorded after 12.9 ± 1.2 tests in 46% rats. Brainstem seizure triggered unilateral long-latency spreading depression. Bilateral short-latency cortical spreading depression was recorded only after intense cortical seizures. CONCLUSION These data show that episodic brainstem activation is a potent trigger of unilateral cortical spreading depression. Development of intense seizures in the cortex leads to initiation of spreading depression in multiple cortical sites of both hemispheres.
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Affiliation(s)
- Lyudmila V Vinogradova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Russia
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161
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Morgan VL, Conrad BN, Abou-Khalil B, Rogers BP, Kang H. Increasing structural atrophy and functional isolation of the temporal lobe with duration of disease in temporal lobe epilepsy. Epilepsy Res 2014; 110:171-8. [PMID: 25616470 DOI: 10.1016/j.eplepsyres.2014.12.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 11/21/2014] [Accepted: 12/04/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND Due to pharmacoresistant seizures and the underutilization of surgical treatments, a large number of temporal lobe epilepsy (TLE) patients experience seizures for years or decades. The goal of this study was to generate a predictive model of duration of disease with the least number of parameters possible in order to identify and quantify the significant volumetric and functional indicators of TLE progression. METHODS Two cohorts of subjects including 12 left TLE, 21 right TLE and 20 healthy controls (duration = 0) were imaged on a 3T MRI scanner using high resolution T1-weighted structural MRI and 20 min of resting functional MRI scanning. Multivariate linear regression methods were used to compute a predictive model of duration of disease using 49 predictors including functional connectivity and gray matter volumes computed from these images. RESULTS No model developed from the full set of data accurately predicted the duration of disease across the entire range from 3 to 50 years. We then performed the regression on 35 subjects with durations of disease in the range 10 to 35 years. The resulting predictive model showed that longer durations were associated with reductions in functional connectivity from the ipsilateral temporal lobe to the contralateral temporal lobe, precuneus and mid cingulate, and with decreases in volume of the ipsilateral hippocampus and pallidum. CONCLUSIONS Functional and volumetric parameters accurately predicted duration of disease in TLE. The findings suggest that TLE is associated with a gradual functional isolation and significant progressive structural atrophy of the ipsilateral temporal lobe over years of duration in the range of 10-35 years. Furthermore, these changes can also be detected in the contralateral hemisphere in these patients, but to a lesser degree.
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Affiliation(s)
- Victoria L Morgan
- Vanderbilt University Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, USA.
| | - Benjamin N Conrad
- Vanderbilt University Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, USA
| | | | - Baxter P Rogers
- Vanderbilt University Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Hakmook Kang
- Department of Biostatistics, Vanderbilt University, Nashville, TN, USA
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162
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Gummadavelli A, Motelow JE, Smith N, Zhan Q, Schiff ND, Blumenfeld H. Thalamic stimulation to improve level of consciousness after seizures: evaluation of electrophysiology and behavior. Epilepsia 2014; 56:114-24. [PMID: 25442843 DOI: 10.1111/epi.12872] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2014] [Indexed: 10/24/2022]
Abstract
OBJECTIVE Understanding the neural mechanisms that support human consciousness is an important frontier in neuroscience and medicine. We previously developed a rodent model of temporal lobe seizures that recapitulates the human electroencephalography (EEG) signature of ictal and postictal neocortical slow waves associated with behavioral impairments in level of consciousness. The mechanism of slow-wave production in epilepsy may involve suppression of the subcortical arousal systems including the brainstem and intralaminar thalamic nuclei. We hypothesized that intralaminar thalamic stimulation may lead to electrophysiologic and functional rescue from postictal slow waves and behavioral arrest. METHODS We electrically stimulated the central lateral thalamic nucleus (a member of the intralaminar nuclei) under anesthesia and after electrically induced hippocampal seizures in anesthetized and in awake-behaving animal model preparations. RESULTS We demonstrated a proof-of-principle restoration of electrophysiologic and behavioral measures of consciousness by stimulating the intralaminar thalamic nuclei after seizures. We measured decreased cortical slow waves and increased desynchronization and multiunit activity in the cortex with thalamic stimulation following seizures. Functionally, thalamic stimulation produced resumption of exploratory behaviors in the postictal state. SIGNIFICANCE Targeting of nodes in the neural circuitry of consciousness has important medical implications. Impaired consciousness with epilepsy has dangerous consequences including decreased school/work performance, social stigmatization, and impaired airway protection. These data suggest a novel therapeutic approach for restoring consciousness after seizures. If paired with responsive neurostimulation, this may allow rapid implementation to improve level of consciousness in patients with epilepsy.
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Affiliation(s)
- Abhijeet Gummadavelli
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, U.S.A
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163
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Tang Y, Chen Q, Yu X, Xia W, Luo C, Huang X, Tang H, Gong Q, Zhou D. A resting-state functional connectivity study in patients at high risk for sudden unexpected death in epilepsy. Epilepsy Behav 2014; 41:33-8. [PMID: 25277976 DOI: 10.1016/j.yebeh.2014.08.140] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 08/28/2014] [Accepted: 08/30/2014] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Seizure-related respiratory and cardiac dysfunctions were once thought to be the direct cause of sudden unexpected death in epilepsy (SUDEP), but both may be secondary to postictal cerebral inhibition. An important issue that has not been explored to date is the neural network basis of cerebral inhibition. Our aim was to investigate the features of neural networks in patients at high risk for SUDEP using a blood oxygen level-dependent (BOLD) resting-state functional connectivity (FC) approach. SUBJECTS AND METHODS Resting-state functional magnetic resonance imaging (Rs-fMRI) data were recorded from 13 patients at high risk for SUDEP and 12 patients at low risk for SUDEP. Thirteen cerebral regions that are closely related to cardiorespiratory activity were selected as regions of interest (ROIs). The ROI-wise resting-state FC analysis was compared between the two groups. RESULTS Compared with patients at low risk for SUDEP, patients at high risk exhibited significant reductions in the resting-state FC between the pons and the right thalamus, the midbrain and the right thalamus, the bilateral anterior cingulate cortex (ACC) and the right thalamus, and the left thalamus and the right thalamus. CONCLUSIONS This investigation is the first to use neuroimaging methods in research on the mechanism of SUDEP and demonstrates the abnormally decreased resting-state FC in the ACC-thalamus-brainstem circuit in patients at high risk for SUDEP. These findings highlight the need to understand the fundamental neural network dysfunction in SUDEP, which may fill the missing link between seizure-related cardiorespiratory dysfunction and SUDEP, and provide a promising neuroimaging biomarker for risk prediction of SUDEP.
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Affiliation(s)
- Yingying Tang
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Qin Chen
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Xiaofeng Yu
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Wei Xia
- Department of Gynecology and Obstetrics, West China Second Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Chunyan Luo
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - XiaoQi Huang
- Huaxi MR Research Center, Department of Radiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Hehan Tang
- Department of Radiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - QiYong Gong
- Huaxi MR Research Center, Department of Radiology, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
| | - Dong Zhou
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
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164
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Jacobs J, Menzel A, Ramantani G, Körbl K, Assländer J, Schulze-Bonhage A, Hennig J, LeVan P. Negative BOLD in default-mode structures measured with EEG-MREG is larger in temporal than extra-temporal epileptic spikes. Front Neurosci 2014; 8:335. [PMID: 25477775 PMCID: PMC4235409 DOI: 10.3389/fnins.2014.00335] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 10/05/2014] [Indexed: 11/13/2022] Open
Abstract
Introduction: EEG-fMRI detects BOLD changes associated with epileptic interictal discharges (IED) and can identify epileptogenic networks in epilepsy patients. Besides positive BOLD changes, negative BOLD changes have sometimes been observed in the default-mode network, particularly using group analysis. A new fast fMRI sequence called MREG (Magnetic Resonance Encephalography) shows increased sensitivity to detect IED-related BOLD changes compared to the conventional EPI sequence, including frequent occurrence of negative BOLD responses in the DMN. The present study quantifies the concordance between the DMN and negative BOLD related to IEDs of temporal and extra-temporal origin. Methods: Focal epilepsy patients underwent simultaneous EEG-MREG. Areas of overlap were calculated between DMN regions, defined as precuneus, posterior cingulate, bilateral inferior parietal and mesial prefrontal cortices according to a standardized atlas, and significant negative BOLD changes revealed by an event-related analysis based on the timings of IED seen on EEG. Correlation between IED number/lobe of origin and the overlap were calculated. Results: 15 patients were analyzed, some showing IED over more than one location resulting in 30 different IED types. The average overlap between negative BOLD and DMN was significantly larger in temporal (23.7 ± 19.6 cm3) than extra-temporal IEDs (7.4 ± 5.1 cm3, p = 0.008). There was no significant correlation between the number of IEDs and the overlap between DMN structures and negative BOLD areas. Discussion: MREG results in an increased sensitivity to detect negative BOLD responses related to focal IED in single patients, with responses often occurring in DMN regions. In patients with high overlap with the DMN, this suggests that epileptic IEDs may be associated with a brief decrease in attention and cognitive ability. Interestingly this observation was not dependent on the frequency of IED but more common in IED of temporal origin.
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Affiliation(s)
- Julia Jacobs
- Department of Neuropediatrics and Muscular Diseases, University Medical Center Freiburg Freiburg, Germany ; Epilepsy Center, University Medical Center Freiburg Freiburg, Germany
| | - Antonia Menzel
- Department of Neuropediatrics and Muscular Diseases, University Medical Center Freiburg Freiburg, Germany
| | - Georgia Ramantani
- Epilepsy Center, University Medical Center Freiburg Freiburg, Germany
| | - Katharina Körbl
- Department of Neuropediatrics and Muscular Diseases, University Medical Center Freiburg Freiburg, Germany
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Cerebellar Directed Optogenetic Intervention Inhibits Spontaneous Hippocampal Seizures in a Mouse Model of Temporal Lobe Epilepsy. eNeuro 2014; 1. [PMID: 25599088 PMCID: PMC4293636 DOI: 10.1523/eneuro.0005-14.2014] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Epilepsy is a condition of spontaneous recurrent seizures. Current treatment options for epilepsy can have major negative side effects and for many patients fail to control seizures. We detected seizures on-line and tested a new selective intervention using a mouse model of temporal lobe epilepsy. Krook-Magnuson et al. report a bidirectional functional connectivity between the hippocampus and the cerebellum in a mouse model of temporal lobe epilepsy, and demonstrate that cerebellar directed on-demand optogenetic intervention can stop seizures recorded from the hippocampus. ![]()
Temporal lobe epilepsy is often medically refractory and new targets for intervention are needed. We used a mouse model of temporal lobe epilepsy, on-line seizure detection, and responsive optogenetic intervention to investigate the potential for cerebellar control of spontaneous temporal lobe seizures. Cerebellar targeted intervention inhibited spontaneous temporal lobe seizures during the chronic phase of the disorder. We further report that the direction of modulation as well as the location of intervention within the cerebellum can affect the outcome of intervention. Specifically, on-demand optogenetic excitation or inhibition of parvalbumin-expressing neurons, including Purkinje cells, in the lateral or midline cerebellum results in a decrease in seizure duration. In contrast, a consistent reduction in spontaneous seizure frequency occurs uniquely with on-demand optogenetic excitation of the midline cerebellum, and was not seen with intervention directly targeting the hippocampal formation. These findings demonstrate that the cerebellum is a powerful modulator of temporal lobe epilepsy, and that intervention targeting the cerebellum as a potential therapy for epilepsy should be revisited.
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166
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Szczurowska E, Mareš P. An antagonist of calcium permeable AMPA receptors, IEM1460: Anticonvulsant action in immature rats? Epilepsy Res 2014; 109:106-13. [PMID: 25524849 DOI: 10.1016/j.eplepsyres.2014.10.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 09/12/2014] [Accepted: 10/30/2014] [Indexed: 11/30/2022]
Abstract
AMPA receptors lacking GluA2 subunit are widely distributed in developing brain. IEM1460 as a specific antagonist of these receptors might be a potential age-specific anticonvulsant. Possible anticonvulsant action was assessed in two models of epileptic seizures: pentylenetetrazol (PTZ) - induced convulsions and cortical afterdischarges elicited in 12-, 18- and 25-day-old rats. IEM1460 was administered intraperitoneally in doses of 3, 10 and 20mg/kg. Pretreatment with IEM1460 at the dose of 20mg/kg resulted in delayed onset of PTZ-induced minimal clonic seizures in all age groups. PTZ-induced generalized tonic-clonic seizures were suppressed in 18- and 25-day-old rats by 10 and 20mg/kg doses of IEM1460. Duration of cortical afterdischarges progressively increased with repeated stimulations in control 12-day-old rats. The IEM1460 dose of 10mg/kg fully blocked this prolongation and the 20-mg/kg dose partly suppressed it. Administration of IEM1460 had moderate proconvulsant effect on 18- and 25-day-old animals - afterdischarges were prolonged with repeated stimulations. The duration of cortical epileptic afterdischarges in adult (80-day-old) animals was not affected by IEM1460. Effects of IEM1460 are dependent on the model of seizures used, their ictogenic structures and developmental changes in subunit composition of AMPA receptors.
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Affiliation(s)
- Ewa Szczurowska
- Department of Developmental Epileptology, Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 14220 Prague, Czech Republic.
| | - Pavel Mareš
- Department of Developmental Epileptology, Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 14220 Prague, Czech Republic
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167
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Hemery C, Ryvlin P, Rheims S. Prevention of generalized tonic-clonic seizures in refractory focal epilepsy: a meta-analysis. Epilepsia 2014; 55:1789-99. [PMID: 25182978 DOI: 10.1111/epi.12765] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2014] [Indexed: 12/01/2022]
Abstract
OBJECTIVES Secondary generalized tonic-clonic seizures (SGTCS) are among the most severe forms of seizures, and the main risk factor for sudden unexpected death in epilepsy (SUDEP). Whether some antiepileptic drugs (AEDs) might be more efficacious than others on SGTCS in patients with drug-resistant focal epilepsy thus represents an important clinical issue for which no data are currently available. METHODS We performed a meta-analysis of randomized controlled trials of adjunctive AED in which information on efficacy outcomes (i.e., responder rate and/or frequency per 28 days relative to baseline) were available both for all seizure types and for SGTCS. The primary analysis evaluated the efficacy of AEDs on all types of seizure and on SGTCS by comparing the responder rates for AED and for placebo. RESULTS Responder rate was available both for all seizure types and for SGTCS in 13 of the 72 eligible trials, evaluating 7 AEDs. Only three AEDs--lacosamide, perampanel and topiramate--showed greater efficacy than placebo. However, confidence intervals of relative risks overlapped for all AEDs but pregabalin, which demonstrated significantly lower efficacy than lacosamide, perampanel, and topiramate. Moreover, there was a nonsignificant trend toward a lower relative risk of responder rate for SGTCS than for all seizure types, which appeared related to a greater response to placebo for this outcome. SIGNIFICANCE Indirect comparison of AEDs using randomized placebo-controlled add-on trials does not support robust differences between AEDs to prevent SGTCS. Alternative designs for evaluation of therapeutic interventions in patients at risk for SGTCS-related complications are required.
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Affiliation(s)
- Claire Hemery
- Department of Functional Neurology and Epileptology, Institute of Epilepsies (IDEE), Hospices Civils de Lyon, Lyon, France
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168
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Buchanan GF, Murray NM, Hajek MA, Richerson GB. Serotonin neurones have anti-convulsant effects and reduce seizure-induced mortality. J Physiol 2014; 592:4395-410. [PMID: 25107926 DOI: 10.1113/jphysiol.2014.277574] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in patients with refractory epilepsy. Defects in central control of breathing are important contributors to the pathophysiology of SUDEP, and serotonin (5-HT) system dysfunction may be involved. Here we examined the effect of 5-HT neurone elimination or 5-HT reduction on seizure risk and seizure-induced mortality. Adult Lmx1b(f/f/p) mice, which lack >99% of 5-HT neurones in the CNS, and littermate controls (Lmx1b(f/f)) were subjected to acute seizure induction by maximal electroshock (MES) or pilocarpine, variably including electroencephalography, electrocardiography, plethysmography, mechanical ventilation or pharmacological therapy. Lmx1b(f/f/p) mice had a lower seizure threshold and increased seizure-induced mortality. Breathing ceased during most seizures without recovery, whereas cardiac activity persisted for up to 9 min before terminal arrest. The mortality rate of mice of both genotypes was reduced by mechanical ventilation during the seizure or 5-HT2A receptor agonist pretreatment. The selective serotonin reuptake inhibitor citalopram reduced mortality of Lmx1b(f/f) but not of Lmx1b(f/f/p) mice. In C57BL/6N mice, reduction of 5-HT synthesis with para-chlorophenylalanine increased MES-induced seizure severity but not mortality. We conclude that 5-HT neurones raise seizure threshold and decrease seizure-related mortality. Death ensued from respiratory failure, followed by terminal asystole. Given that SUDEP often occurs in association with generalised seizures, some mechanisms causing death in our model might be shared with those leading to SUDEP. This model may help determine the relationship between seizures, 5-HT system dysfunction, breathing and death, which may lead to novel ways to prevent SUDEP.
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Affiliation(s)
- Gordon F Buchanan
- Department of Neurology, Yale University School of Medicine, New Haven, CT, 06520, USA Veteran's Affairs Medical Center, West Haven, CT, 06516, USA
| | - Nicholas M Murray
- Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA
| | - Michael A Hajek
- Department of Neurology, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - George B Richerson
- Department of Neurology, Yale University School of Medicine, New Haven, CT, 06520, USA Department of Neurology, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA Veteran's Affairs Medical Center, Iowa City, IA, 52242, USA
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169
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Morgan VL, Abou-Khalil B, Rogers BP. Evolution of functional connectivity of brain networks and their dynamic interaction in temporal lobe epilepsy. Brain Connect 2014; 5:35-44. [PMID: 24901036 DOI: 10.1089/brain.2014.0251] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This study presents a cross-sectional investigation of functional networks in temporal lobe epilepsy (TLE) as they evolve over years of disease. Networks of interest were identified based on a priori hypotheses: the network of seizure propagation ipsilateral to the seizure focus, the same regions contralateral to seizure focus, the cross hemisphere network of the same regions, and a cingulate midline network. Resting functional magnetic resonance imaging data were acquired for 20 min in 12 unilateral TLE patients, and 12 age- and gender-matched healthy controls. Functional changes within and between the four networks as they evolve over years of disease were quantified by standard measures of static functional connectivity and novel measures of dynamic functional connectivity. The results suggest an initial disruption of cross-hemispheric networks and an increase in static functional connectivity in the ipsilateral temporal network accompanying the onset of TLE seizures. As seizures progress over years, the static functional connectivity across the ipsilateral network diminishes, while dynamic functional connectivity measures show the functional independence of this ipsilateral network from the network of midline regions of the cingulate declines. This implies a gradual breakdown of the seizure onset and early propagation network involving the ipsilateral hippocampus and temporal lobe as it becomes more synchronous with the network of regions responsible for secondary generalization of the seizures, a process that may facilitate the spread of seizures across the brain. Ultimately, the significance of this evolution may be realized in relating it to symptoms and treatment outcomes of TLE.
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Affiliation(s)
- Victoria L Morgan
- 1 Department of Radiology, Vanderbilt University , Nashville, Tennessee
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170
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Ibrahim GM, Morgan BR, Lee W, Smith ML, Donner EJ, Wang F, Beers CA, Federico P, Taylor MJ, Doesburg SM, Rutka JT, Snead OC. Impaired development of intrinsic connectivity networks in children with medically intractable localization-related epilepsy. Hum Brain Mapp 2014; 35:5686-700. [PMID: 24976288 DOI: 10.1002/hbm.22580] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 04/28/2014] [Accepted: 06/25/2014] [Indexed: 11/11/2022] Open
Abstract
Typical childhood development is characterized by the emergence of intrinsic connectivity networks (ICNs) by way of internetwork segregation and intranetwork integration. The impact of childhood epilepsy on the maturation of ICNs is, however, poorly understood. The developmental trajectory of ICNs in 26 children (8-17 years) with localization-related epilepsy and 28 propensity-score matched controls was evaluated using graph theoretical analysis of whole brain connectomes from resting-state functional magnetic resonance imaging (fMRI) data. Children with epilepsy demonstrated impaired development of regional hubs in nodes of the salience and default mode networks (DMN). Seed-based connectivity and hierarchical clustering analysis revealed significantly decreased intranetwork connections, and greater internetwork connectivity in children with epilepsy compared to controls. Significant interactions were identified between epilepsy duration and the expected developmental trajectory of ICNs, indicating that prolonged epilepsy may cause progressive alternations in large-scale networks throughout childhood. DMN integration was also associated with better working memory, whereas internetwork segregation was associated with higher full-scale intelligence quotient scores. Furthermore, subgroup analyses revealed the thalamus, hippocampus, and caudate were weaker hubs in children with secondarily generalized seizures, relative to other patient subgroups. Our findings underscore that epilepsy interferes with the developmental trajectory of brain networks underlying cognition, providing evidence supporting the early treatment of affected children.
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Affiliation(s)
- George M Ibrahim
- Division of Neurosurgery, Hospital for Sick Children, Department of Surgery, University of Toronto, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
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171
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Blumenfeld H, Meador KJ. Consciousness as a useful concept in epilepsy classification. Epilepsia 2014; 55:1145-50. [PMID: 24981294 DOI: 10.1111/epi.12588] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2014] [Indexed: 11/30/2022]
Abstract
Impaired consciousness has important practical consequences for people living with epilepsy. Recent pathophysiologic studies show that seizures with impaired level of consciousness always affect widespread cortical networks and subcortical arousal systems. In light of these findings and their clinical significance, efforts are underway to revise the International League Against Epilepsy (ILAE) 2010 report to include impaired consciousness in the classification of seizures. Lüders and colleagues have presented one such effort, which we discuss here. We then propose an alternative classification of impaired consciousness in epilepsy based on functional neuroanatomy. Some seizures involve focal cortical regions and cause selective deficits in the content of consciousness but without impaired overall level of consciousness or awareness. These include focal aware conscious seizures (FACS) with lower order cortical deficits such as somatosensory or visual impairment as well as FACS with higher cognitive deficits including ictal aphasia or isolated epileptic amnesia. Another category applies to seizures with impaired level of consciousness leading to deficits in multiple cognitive domains. For this category, we believe the terms "dyscognitive" or "dialeptic" should be avoided because they may create confusion. Instead we propose that seizures with impaired level of consciousness be described based on underlying pathophysiology. Widespread moderately severe deficits in corticothalamic function are seen in absence seizures and in focal impaired consciousness seizures (FICS), including many temporal lobe seizures and other focal seizures with impaired consciousness. Some simple responses or automatisms may be preserved in these seizures. In contrast, generalized tonic-clonic seizures usually produce widespread severe deficits in corticothalamic function causing loss of all meaningful responses. Further work is needed to understand and prevent impaired consciousness in epilepsy, but the first step is to keep this crucial practical and physiologic aspect of seizures front-and-center in our discussions.
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Affiliation(s)
- Hal Blumenfeld
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, U.S.A; Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut, U.S.A; Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut, U.S.A
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172
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Peng SJ, Harnod T, Tsai JZ, Ker MD, Chiou JC, Chiueh H, Wu CY, Hsin YL. Evaluation of subcortical grey matter abnormalities in patients with MRI-negative cortical epilepsy determined through structural and tensor magnetic resonance imaging. BMC Neurol 2014; 14:104. [PMID: 24885823 PMCID: PMC4080585 DOI: 10.1186/1471-2377-14-104] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 04/15/2014] [Indexed: 11/19/2022] Open
Abstract
Background Although many studies have found abnormalities in subcortical grey matter (GM) in patients with temporal lobe epilepsy or generalised epilepsies, few studies have examined subcortical GM in focal neocortical seizures. Using structural and tensor magnetic resonance imaging (MRI), we evaluated subcortical GM from patients with extratemporal lobe epilepsy without visible lesion on MRI. Our aims were to determine whether there are structural abnormalities in these patients and to correlate the extent of any observed structural changes with clinical characteristics of disease in these patients. Methods Twenty-four people with epilepsy and 29 age-matched normal subjects were imaged with high-resolution structural and diffusion tensor MR scans. The patients were characterised clinically by normal brain MRI scans and seizures that originated in the neocortex and evolved to secondarily generalised convulsions. We first used whole brain voxel-based morphometry (VBM) to detect density changes in subcortical GM. Volumetric data, values of mean diffusivity (MD) and fractional anisotropy (FA) for seven subcortical GM structures (hippocampus, caudate nucleus, putamen, globus pallidus, nucleus accumbens, thalamus and amygdala) were obtained using a model-based segmentation and registration tool. Differences in the volumes and diffusion parameters between patients and controls and correlations with the early onset and progression of epilepsy were estimated. Results Reduced volumes and altered diffusion parameters of subcortical GM were universally observed in patients in the subcortical regions studied. In the patient-control group comparison of VBM, the right putamen, bilateral nucleus accumbens and right caudate nucleus of epileptic patients exhibited a significantly decreased density Segregated volumetry and diffusion assessment of subcortical GM showed apparent atrophy of the left caudate nucleus, left amygdala and right putamen; reduced FA values for the bilateral nucleus accumbens; and elevated MD values for the left thalamus, right hippocampus and right globus pallidus A decreased volume of the nucleus accumbens consistently related to an early onset of disease. The duration of disease contributed to the shrinkage of the left thalamus. Conclusions Patients with neocortical seizures and secondary generalisation had smaller volumes and microstructural anomalies in subcortical GM regions. Subcortical GM atrophy is relevant to the early onset and progression of epilepsy.
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Affiliation(s)
| | | | | | | | | | | | | | - Yue-Loong Hsin
- Epilepsy Center, Tzu Chi General Hospital, No, 707, Sec, 3, Chung Yang Rd, Hualien City 97002, Taiwan.
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173
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Zhang CH, Lu Y, Brinkmann B, Welker K, Worrell G, He B. Lateralization and localization of epilepsy related hemodynamic foci using presurgical fMRI. Clin Neurophysiol 2014; 126:27-38. [PMID: 24856460 DOI: 10.1016/j.clinph.2014.04.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 03/09/2014] [Accepted: 04/16/2014] [Indexed: 12/01/2022]
Abstract
OBJECTIVE The aim was to develop a method for the purpose of localizing epilepsy related hemodynamic foci for patients suffering intractable focal epilepsy using task-free fMRI alone. METHODS We studied three groups of subjects: patients with intractable focal epilepsy, healthy volunteers performing motor tasks, and healthy volunteers in resting state. We performed spatial independent component analysis (ICA) on the fMRI alone data and developed a set of IC selection criteria to identify epilepsy related ICs. The method was then tested in the two healthy groups. RESULTS In seven out of the nine surgery patients, identified ICs were concordant with surgical resection. Our results were also consistent with presurgical evaluation of the remaining one patient without surgery and may explain why she was not suitable for resection treatment. In the motor task study of ten healthy subjects, our method revealed components with concordant spatial and temporal features as expected from the unilateral motor tasks. In the resting state study of seven healthy subjects, the method successfully rejected all components in four out of seven subjects as non-epilepsy related components. CONCLUSION These results suggest the lateralization and localization value of fMRI alone in presurgical evaluation for patients with intractable unilateral focal epilepsy. SIGNIFICANCE The proposed method is noninvasive in nature and easy to implement. It has the potential to be incorporated in current presurgical workup for treating intractable focal epilepsy patients.
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Affiliation(s)
| | - Yunfeng Lu
- Department of Biomedical Engineering, University of Minnesota, USA
| | - Benjamin Brinkmann
- Department of Neurology, Mayo Clinic, USA; Mayo Systems Electrophysiology Laboratory, Mayo Clinic, USA
| | | | - Gregory Worrell
- Department of Neurology, Mayo Clinic, USA; Mayo Systems Electrophysiology Laboratory, Mayo Clinic, USA
| | - Bin He
- Department of Biomedical Engineering, University of Minnesota, USA; Institute for Engineering in Medicine, University of Minnesota, USA.
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174
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Çarçak N, Zheng T, Ali I, Abdullah A, French C, Powell KL, Jones NC, van Raay L, Rind G, Onat F, O'Brien TJ. The effect of amygdala kindling on neuronal firing patterns in the lateral thalamus in the GAERS model of absence epilepsy. Epilepsia 2014; 55:654-665. [DOI: 10.1111/epi.12592] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/07/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Nihan Çarçak
- Department of Pharmacology; Faculty of Pharmacy; Istanbul University; Istanbul Turkey
| | - Thomas Zheng
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
| | - Idrish Ali
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
| | - Ahmad Abdullah
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
| | - Chris French
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
- Department of Neurology; Royal Melbourne Hospital; Melbourne Vic. Australia
| | - Kim L. Powell
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
| | - Nigel C. Jones
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
| | - Leena van Raay
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
| | - Gil Rind
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
| | - Filiz Onat
- Department of Pharmacology and Clinical Pharmacology; Marmara University School of Medicine; Istanbul Turkey
| | - Terence J. O'Brien
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
- Department of Neurology; Royal Melbourne Hospital; Melbourne Vic. Australia
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175
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Kadiyala SB, Papandrea D, Herron BJ, Ferland RJ. Segregation of seizure traits in C57 black mouse substrains using the repeated-flurothyl model. PLoS One 2014; 9:e90506. [PMID: 24594686 PMCID: PMC3940897 DOI: 10.1371/journal.pone.0090506] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 02/03/2014] [Indexed: 11/18/2022] Open
Abstract
Identifying the genetic basis of epilepsy in humans is difficult due to its complexity, thereby underlying the need for preclinical models with specific aspects of seizure susceptibility that are tractable to genetic analyses. In the repeated-flurothyl model, mice are given 8 flurothyl-induced seizures, once per day (the induction phase), followed by a 28-day rest period (incubation phase) and final flurothyl challenge. This paradigm allows for the tracking of multiple phenotypes including: initial generalized seizure threshold, decreases in generalized seizure threshold with repeated flurothyl exposures, and changes in the complexity of seizures over time. Given the responses we previously reported in C57BL/6J mice, we analyzed substrains of the C57BL lineage to determine if any of these phenotypes segregated in these substrains. We found that the generalized seizure thresholds of C57BL/10SNJ and C57BL/10J mice were similar to C57BL/6J mice, whereas C57BL/6NJ and C57BLKS/J mice showed lower generalized seizure thresholds. In addition, C57BL/6J mice had the largest decreases in generalized seizure thresholds over the induction phase, while the other substrains were less pronounced. Notably, we observed only clonic seizures during the induction phase in all substrains, but when rechallenged with flurothyl after a 28-day incubation phase, ∼80% of C57BL/6J and 25% of C57BL/10SNJ and C57BL/10J mice expressed more complex seizures with tonic manifestations with none of the C57BL/6NJ and C57BLKS/J mice having complex seizures with tonic manifestations. These data indicate that while closely related, the C57BL lineage has significant diversity in aspects of epilepsy that are genetically controlled. Such differences further highlight the importance of genetic background in assessing the effects of targeted deletions of genes in preclinical epilepsy models.
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Affiliation(s)
- Sridhar B. Kadiyala
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, New York, United States of America
| | - Dominick Papandrea
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, New York, United States of America
| | - Bruce J. Herron
- Wadsworth Center, Albany, New York, United States of America
- Department of Biomedical Sciences, School of Public Health, University at Albany - State University of New York, Albany, New York, United States of America
| | - Russell J. Ferland
- Center for Neuropharmacology and Neuroscience, Albany Medical College, Albany, New York, United States of America
- Department of Neurology, Albany Medical College, Albany, New York, United States of America
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176
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Disrupting posterior cingulate connectivity disconnects consciousness from the external environment. Neuropsychologia 2014; 56:239-44. [PMID: 24508051 DOI: 10.1016/j.neuropsychologia.2014.01.020] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 01/05/2014] [Accepted: 01/27/2014] [Indexed: 01/23/2023]
Abstract
Neurophysiological and neuroimaging studies including both patients with disorders of consciousness and healthy subjects with modified states of consciousness suggest a crucial role of the medial posteroparietal cortex in conscious information processing. However no direct neuropsychological evidence supports this hypothesis and studies including patients with restricted lesions of this brain region are almost non-existent. Using direct intraoperative electrostimulations, we showed in a rare patient that disrupting the subcortical connectivity of the left posterior cingulate cortex (PCC) reliably induced a breakdown in conscious experience. This acute phenomenon was mainly characterized by a transient behavioral unresponsiveness with loss of external connectedness. In all cases, when he regained consciousness, the patient described himself as in dream, outside the operating room. This finding suggests that functional integrity of the PPC connectivity is necessary for maintaining consciousness of external environment.
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177
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Zhang T, Zhou J, Jiang R, Yang H, Carney PR, Jiang H. Pre-seizure state identified by diffuse optical tomography. Sci Rep 2014; 4:3798. [PMID: 24445927 PMCID: PMC3896905 DOI: 10.1038/srep03798] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 12/30/2013] [Indexed: 11/23/2022] Open
Abstract
In epilepsy it has been challenging to detect early changes in brain activity that occurs prior to seizure onset and to map their origin and evolution for possible intervention. Here we demonstrate using a rat model of generalized epilepsy that diffuse optical tomography (DOT) provides a unique functional neuroimaging modality for noninvasively and continuously tracking such brain activities with high spatiotemporal resolution. We detected early hemodynamic responses with heterogeneous patterns, along with intracranial electroencephalogram gamma power changes, several minutes preceding the electroencephalographic seizure onset, supporting the presence of a "pre-seizure" state. We also observed the decoupling between local hemodynamic and neural activities. We found widespread hemodynamic changes evolving from local regions of the bilateral cortex and thalamus to the entire brain, indicating that the onset of generalized seizures may originate locally rather than diffusely. Together, these findings suggest DOT represents a powerful tool for mapping early seizure onset and propagation pathways.
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Affiliation(s)
- Tao Zhang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida Gainesville, FL 32611, USA
| | - Junli Zhou
- Department of Pediatrics, University of Florida Gainesville, FL 32611, USA
| | - Ruixin Jiang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida Gainesville, FL 32611, USA
| | - Hao Yang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida Gainesville, FL 32611, USA
| | - Paul R. Carney
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida Gainesville, FL 32611, USA
- Department of Pediatrics, University of Florida Gainesville, FL 32611, USA
- Department of Neurology, University of Florida Gainesville, FL 32611, USA
- Department of Neuroscience, University of Florida Gainesville, FL 32611, USA
| | - Huabei Jiang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida Gainesville, FL 32611, USA
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Yoo JY, Farooque P, Chen WC, Youngblood MW, Zaveri HP, Gerrard JL, Spencer DD, Hirsch LJ, Blumenfeld H. Ictal spread of medial temporal lobe seizures with and without secondary generalization: an intracranial electroencephalography analysis. Epilepsia 2014; 55:289-95. [PMID: 24417694 DOI: 10.1111/epi.12505] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2013] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Secondary generalization of seizures has devastating consequences for patient safety and quality of life. The aim of this intracranial electroencephalography (icEEG) study was to investigate the differences in onset and propagation patterns of temporal lobe seizures that remained focal versus those with secondary generalization, in order to better understand the mechanism of secondary generalization. METHODS A total of 39 seizures were analyzed in nine patients who met the following criteria: (1) icEEG-video monitoring with at least one secondarily generalized tonic-clonic seizure (GTCS), (2) pathologically proven hippocampal sclerosis, and (3) no seizures for at least 1 year after anteromedial temporal lobe resection. Seizures were classified as focal or secondary generalized by behavioral analysis of video. Onset and propagation patterns were compared by analysis of icEEG. RESULTS We obtained data from 22 focal seizures without generalization (FS), and 17 GTCS. Seizure-onset patterns did not differ between FS and GTCS, but there were differences in later propagation. All seizures started with low voltage fast activity, except for seven seizures in one patient (six FS, one GTCS), which started with sharply contoured theta activity. Fifteen of 39 seizures started from the hippocampus, and 24 seizures (including six seizures in a patient without hippocampal contacts) started from other medial temporal lobe areas. We observed involvement or more prominent activation of the posterior-lateral temporal regions in GTCS prior to propagation to the other cortical regions, versus FS, which had no involvement or less prominent activation of the posterior lateral temporal cortex. Occipital contacts were not involved at the time of clinical secondary generalization. SIGNIFICANCE The posterior-lateral temporal cortex may serve as an important "gateway" controlling propagation of medial temporal lobe seizures to other cortical regions. Identifying the mechanisms of secondary generalization of focal seizures could lead to improved treatments to confine seizure spread.
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Affiliation(s)
- Ji Yeoun Yoo
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, U.S.A
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179
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Chen WC, Chen EY, Gebre RZ, Johnson MR, Li N, Vitkovskiy P, Blumenfeld H. Epilepsy and driving: potential impact of transient impaired consciousness. Epilepsy Behav 2014; 30:50-7. [PMID: 24436967 PMCID: PMC4098969 DOI: 10.1016/j.yebeh.2013.09.024] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Driving is an important part of everyday life for most adults, and restrictions on driving can place a significant burden on individuals diagnosed with epilepsy. Although sensorimotor deficits during seizures may impair driving, decreased level of consciousness often has a more global effect on patients' ability to respond appropriately to the environment. Better understanding of the mechanisms underlying alteration of consciousness in epilepsy is important for decision-making by people with epilepsy, their physicians, and regulators in regard to the question of fitness to drive. Retrospective cohort and cross-sectional studies based on surveys or crash records can provide valuable information about driving in epilepsy. However, prospective objective testing of ictal driving ability during different types of seizures is needed to more fully understand the role of impaired consciousness and other deficits in disrupting driving. Driving simulators adapted for use in the epilepsy video-EEG monitoring unit may be well suited to provide both ictal and interictal data in patients with epilepsy. Objective information about impaired driving in specific types of epilepsy and seizures can provide better informed recommendations regarding fitness to drive, potentially improving the quality of life of people living with epilepsy.
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Affiliation(s)
- William C. Chen
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA
| | - Eric Y. Chen
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA
| | - Rahiwa Z. Gebre
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA
| | - Michelle R. Johnson
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA
| | - Ningcheng Li
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA
| | - Petr Vitkovskiy
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA
| | - Hal Blumenfeld
- Department of Neurology, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA,Department of Neurobiology, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA,Department of Neurosurgery, Yale University School of Medicine, 333 Cedar Street, New Haven, Connecticut 06520, USA
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180
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Modern Techniques of Epileptic Focus Localization. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 114:245-78. [DOI: 10.1016/b978-0-12-418693-4.00010-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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181
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Aso T. [MRI in epilepsy and migraine]. Rinsho Shinkeigaku 2013; 53:1097-9. [PMID: 24291890 DOI: 10.5692/clinicalneurol.53.1097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In vivo observation of the ictal events are thought to help understanding the etiology and pathology in both epilepsy and migraine. While simultaneous recording of EEG and fMRI is actively conducted for the former, in some cases, epileptogenic activity is undetectable by EEG. Attempts to detect such abnormal brain activity by using fMRI are underway. Analysis methods for resting-state fMRI can be applicable for such purposes. For migraine, fMRI is also highly valuable in detecting series of ictal events. However, since the disease is suspected to involve abnormal neuro-vascular coupling, it is not always straightforward how to interpret the observation by vascular-dependent methods. Therefore development of non-vascular methods is critical for future advances.
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Affiliation(s)
- Toshihiko Aso
- Human Brain Research Center, Kyoto University Graduate School of Medicine
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182
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Caulder EH, Riegle MA, Godwin DW. Activation of group 2 metabotropic glutamate receptors reduces behavioral and electrographic correlates of pilocarpine induced status epilepticus. Epilepsy Res 2013; 108:171-81. [PMID: 24305700 DOI: 10.1016/j.eplepsyres.2013.10.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 09/25/2013] [Accepted: 10/18/2013] [Indexed: 12/11/2022]
Abstract
Novel treatments for epilepsy are necessary because many epilepsy patients are resistant to medication. Metabotropic glutamate receptors (mGluRs), specifically mGluR 2 and 3, may serve as antiepileptic drug targets because of their role in controlling synaptic release. In this study, we administered a Group 2 mGluR agonist, LY379268, one of two mGluR2-specific positive allosteric modulators, BINA or CBiPES, or a cocktail of both BINA and LY379268 in a series of experiments using the pilocarpine model of SE. In one study, groups received treatments 15 min prior to pilocarpine, while in a second study groups received treatments after SE had been initiated to determine whether the drugs could reduce development and progression of SE. We measured bouts of stage 5 seizures, latency to the first seizure, and the maximum Racine score to characterize the seizure severity. We analyzed mouse EEG with implanted electrodes using a power analysis. We found that pretreatment and posttreatment with LY379268 was effective at reducing both behavioral correlates and power in EEG bandwidths associated with seizure, while CBiPES was less effective and BINA was ineffective. These data generally support continued development of mGluR2 pharmacology for novel antiepileptic drugs, though further study with additional drugs and concentrations will be necessary.
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Affiliation(s)
- Erin H Caulder
- Wake Forest University Graduate School of Arts and Sciences, Department of Neurobiology and Anatomy, 1 Medical Center Boulevard, Winston Salem, NC 27157, USA.
| | - Melissa A Riegle
- Wake Forest University Graduate School of Arts and Sciences, Department of Neurobiology and Anatomy, 1 Medical Center Boulevard, Winston Salem, NC 27157, USA; Wake Forest University Graduate School of Arts and Sciences, Neuroscience Program, 1 Medical Center Boulevard, Winston Salem, NC 27157, USA.
| | - Dwayne W Godwin
- Wake Forest University Graduate School of Arts and Sciences, Department of Neurobiology and Anatomy, 1 Medical Center Boulevard, Winston Salem, NC 27157, USA; Wake Forest University Graduate School of Arts and Sciences, Neuroscience Program, 1 Medical Center Boulevard, Winston Salem, NC 27157, USA.
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183
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Weiss SA, Banks GP, McKhann GM, Goodman RR, Emerson RG, Trevelyan AJ, Schevon CA. Ictal high frequency oscillations distinguish two types of seizure territories in humans. ACTA ACUST UNITED AC 2013; 136:3796-808. [PMID: 24176977 DOI: 10.1093/brain/awt276] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
High frequency oscillations have been proposed as a clinically useful biomarker of seizure generating sites. We used a unique set of human microelectrode array recordings (four patients, 10 seizures), in which propagating seizure wavefronts could be readily identified, to investigate the basis of ictal high frequency activity at the cortical (subdural) surface. Sustained, repetitive transient increases in high gamma (80-150 Hz) amplitude, phase-locked to the low-frequency (1-25 Hz) ictal rhythm, correlated with strong multi-unit firing bursts synchronized across the core territory of the seizure. These repetitive high frequency oscillations were seen in recordings from subdural electrodes adjacent to the microelectrode array several seconds after seizure onset, following ictal wavefront passage. Conversely, microelectrode recordings demonstrating only low-level, heterogeneous neural firing correlated with a lack of high frequency oscillations in adjacent subdural recording sites, despite the presence of a strong low-frequency signature. Previously, we reported that this pattern indicates a failure of the seizure to invade the area, because of a feedforward inhibitory veto mechanism. Because multi-unit firing rate and high gamma amplitude are closely related, high frequency oscillations can be used as a surrogate marker to distinguish the core seizure territory from the surrounding penumbra. We developed an efficient measure to detect delayed-onset, sustained ictal high frequency oscillations based on cross-frequency coupling between high gamma amplitude and the low-frequency (1-25 Hz) ictal rhythm. When applied to the broader subdural recording, this measure consistently predicted the timing or failure of ictal invasion, and revealed a surprisingly small and slowly spreading seizure core surrounded by a far larger penumbral territory. Our findings thus establish an underlying neural mechanism for delayed-onset, sustained ictal high frequency oscillations, and provide a practical, efficient method for using them to identify the small ictal core regions. Our observations suggest that it may be possible to reduce substantially the extent of cortical resections in epilepsy surgery procedures without compromising seizure control.
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Affiliation(s)
- Shennan A Weiss
- 1 Department of Neurology, Columbia University, New York, NY, USA
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184
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Intusoma U, Abbott DF, Masterton RAJ, Stagnitti MR, Newton MR, Jackson GD, Freeman JL, Harvey AS, Archer JS. Tonic seizures of Lennox-Gastaut syndrome: Periictal single-photon emission computed tomography suggests a corticopontine network. Epilepsia 2013; 54:2151-7. [DOI: 10.1111/epi.12398] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/30/2013] [Indexed: 11/27/2022]
Affiliation(s)
- Utcharee Intusoma
- Pediatric Neurology Unit; Department of Paediatrics; Faculty of Medicine; Prince of Songkla University; Hat Yai Songkhla Thailand
- Department of Medicine; Austin Health; The University of Melbourne; Melbourne Victoria Australia
| | - David F. Abbott
- Department of Medicine; Austin Health; The University of Melbourne; Melbourne Victoria Australia
- Florey Institute of Neuroscience and Mental Health; Melbourne Victoria Australia
| | - Richard A. J. Masterton
- Department of Medicine; Austin Health; The University of Melbourne; Melbourne Victoria Australia
- Florey Institute of Neuroscience and Mental Health; Melbourne Victoria Australia
| | - Monique R. Stagnitti
- Department of Medicine; Austin Health; The University of Melbourne; Melbourne Victoria Australia
| | - Mark R. Newton
- Florey Institute of Neuroscience and Mental Health; Melbourne Victoria Australia
| | - Graeme D. Jackson
- Department of Medicine; Austin Health; The University of Melbourne; Melbourne Victoria Australia
- Florey Institute of Neuroscience and Mental Health; Melbourne Victoria Australia
- Department of Radiology; The University of Melbourne; Melbourne Victoria Australia
| | - Jeremy L. Freeman
- Department of Neurology; The Royal Children's Hospital; Melbourne Victoria Australia
| | - A. Simon Harvey
- Department of Neurology; The Royal Children's Hospital; Melbourne Victoria Australia
- Department of Paediatrics; The University of Melbourne; Melbourne Victoria Australia
| | - John S. Archer
- Department of Medicine; Austin Health; The University of Melbourne; Melbourne Victoria Australia
- Florey Institute of Neuroscience and Mental Health; Melbourne Victoria Australia
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185
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Hanaya R, Okamoto H, Fujimoto A, Ochi A, Go C, Snead CO, Widjaja E, Chuang SH, Kemp SM, Otsubo H. Total intravenous anesthesia affecting spike sources of magnetoencephalography in pediatric epilepsy patients: Focal seizures vs. non-focal seizures. Epilepsy Res 2013; 105:326-36. [DOI: 10.1016/j.eplepsyres.2013.02.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Revised: 12/29/2012] [Accepted: 02/27/2013] [Indexed: 01/24/2023]
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186
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Fahoum F, Zelmann R, Tyvaert L, Dubeau F, Gotman J. Epileptic discharges affect the default mode network--FMRI and intracerebral EEG evidence. PLoS One 2013; 8:e68038. [PMID: 23840805 PMCID: PMC3695970 DOI: 10.1371/journal.pone.0068038] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 05/23/2013] [Indexed: 11/18/2022] Open
Abstract
Functional neuroimaging studies of epilepsy patients often show, at the time of epileptic activity, deactivation in default mode network (DMN) regions, which is hypothesized to reflect altered consciousness. We aimed to study the metabolic and electrophysiological correlates of these changes in the DMN regions. We studied six epilepsy patients that underwent scalp EEG-fMRI and later stereotaxic intracerebral EEG (SEEG) sampling regions of DMN (posterior cingulate cortex, Pre-cuneus, inferior parietal lobule, medial prefrontal cortex and dorsolateral frontal cortex) as well as non-DMN regions. SEEG recordings were subject to frequency analyses comparing sections with interictal epileptic discharges (IED) to IED-free baselines in the IED-generating region, DMN and non-DMN regions. EEG-fMRI and SEEG were obtained at rest. During IEDs, EEG-fMRI demonstrated deactivation in various DMN nodes in 5 of 6 patients, most frequently the pre-cuneus and inferior parietal lobule, and less frequently the other DMN nodes. SEEG analyses demonstrated decrease in gamma power (50–150 Hz), and increase in the power of lower frequencies (<30 Hz) at times of IEDs, in at least one DMN node in all patients. These changes were not apparent in the non-DMN regions. We demonstrate that, at the time of IEDs, DMN regions decrease their metabolic demand and undergo an EEG change consisting of decreased gamma and increased lower frequencies. These findings, specific to DMN regions, confirm in a pathological condition a direct relationship between DMN BOLD activity and EEG activity. They indicate that epileptic activity affects the DMN, and therefore may momentarily reduce the consciousness level and cognitive reserve.
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Affiliation(s)
- Firas Fahoum
- Montreal Neurological Institute, McGill University, Montréal, Québec, Canada
- * E-mail:
| | - Rina Zelmann
- Montreal Neurological Institute, McGill University, Montréal, Québec, Canada
| | - Louise Tyvaert
- Clinical Neurophysiology Department, Roger Salengro Hospital, Lille University Medical Center, Lille, France
| | - François Dubeau
- Montreal Neurological Institute, McGill University, Montréal, Québec, Canada
| | - Jean Gotman
- Montreal Neurological Institute, McGill University, Montréal, Québec, Canada
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187
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Abstract
PURPOSE OF REVIEW Classifications of epilepsies (1989) and seizures (1981) took a central role in epilepsy care and research. Based on nearly century-old concepts, they were abandoned in 2010, and recommendations for new concepts and terminology were made in accordance with a vision of what a future classification would entail. This review outlines the major changes, the ways these changes relate to the earlier systems, the implications for the practicing health care provider, and some of the recommendations for future classification systems. RECENT FINDINGS New terminology for underlying causes (genetic, structural-metabolic, and unknown) was introduced to replace the old (idiopathic, symptomatic, and cryptogenic) in 2010. The use of generalized and focal to refer to the underlying epilepsy was largely abandoned, but the terms were retained in reference to mode of seizure initiation and presentation. The terms "complex" and "simple partial" for focal seizures were abandoned in favor of more descriptive terms. Electroclinical syndromes were highlighted as specific epilepsy diagnoses and distinguished from nonsyndromic-nonspecific diagnoses. The importance of diagnosis (a clinical goal focused on the individual patient) over classification (an intellectual system for organizing information) was emphasized. SUMMARY Accurate description and diagnosis of the seizures, causes, and specific type of epilepsy remain the goal in clinical epilepsy care. While terminology and concepts are being revised, the implications for patient care currently are minimal; however, the gains in the future of clear, accurate terminology and a multidomain classification system could potentially be considerable.
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Affiliation(s)
- Anne T Berg
- Ann & Robert H Lurie Children’s Hospital of Chicago Epilepsy Center, 225 East Chicago St, Box 29, Chicago, IL 60611, USA.
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188
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Deconstructing the neural and ionic involvement of seizure-like events in the striatal network. Neurobiol Dis 2013; 52:128-36. [DOI: 10.1016/j.nbd.2012.11.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 11/28/2012] [Indexed: 02/07/2023] Open
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189
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Does the patient's hand hold the key to preventing secondary generalization in mesial temporal lobe epilepsy? Epilepsy Res 2013; 105:125-32. [PMID: 23490657 DOI: 10.1016/j.eplepsyres.2013.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 12/17/2012] [Accepted: 02/07/2013] [Indexed: 11/23/2022]
Abstract
This study aimed to analyze the impact of ictal dystonic posturing (DP) in postoperative seizure outcome and to assess the influence of DP in generalized tonic-clonic seizure (GTCS) occurrence during video-EEG monitoring of patients with temporal lobe epilepsy with mesial temporal sclerosis. The impact of DP on surgical outcome remains controversial. Moreover, DP has been recently associated with brain networks avoiding GTCS occurrence. Five hundred twenty-seven seizures of 171 patients who were submitted to standard anterior temporal lobectomy (ATL) between 2002 and 2010, with at least one year of post-surgical follow-up, were retrospectively analyzed and classified as with or without DP and as evolving or not to GTCS. The ictal semiologic correlates of DP, timing elapsed since precedent seizure and antiepileptic drug (AED) intake before each seizure were evaluated. Seizure outcome after ATL was assessed according to Engel's scale. Fifty-eight out of 171 patients (34%) exhibited ictal DP, of which 91.5% were always unilateral and contralateral to the operated side. DP was related to shorter seizures (p=0.007) and a much lower likelihood of the seizure evolving to GTCS (p=0.001), even during AED withdrawal (p=0.002). There was no association between DP and prognosis regarding seizure control as the result of the surgical resection, either in patients with shorter or in those with longer period of follow-up. Our data support the hypothesis that DP reflects a brain network activation that helps avoid GTCS, even during AED withdrawal.
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190
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Chipaux M, Vercueil L, Kaminska A, Mahon S, Charpier S. Persistence of cortical sensory processing during absence seizures in human and an animal model: evidence from EEG and intracellular recordings. PLoS One 2013; 8:e58180. [PMID: 23483991 PMCID: PMC3587418 DOI: 10.1371/journal.pone.0058180] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 01/31/2013] [Indexed: 11/19/2022] Open
Abstract
Absence seizures are caused by brief periods of abnormal synchronized oscillations in the thalamocortical loops, resulting in widespread spike-and-wave discharges (SWDs) in the electroencephalogram (EEG). SWDs are concomitant with a complete or partial impairment of consciousness, notably expressed by an interruption of ongoing behaviour together with a lack of conscious perception of external stimuli. It is largely considered that the paroxysmal synchronizations during the epileptic episode transiently render the thalamocortical system incapable of transmitting primary sensory information to the cortex. Here, we examined in young patients and in the Genetic Absence Epilepsy Rats from Strasbourg (GAERS), a well-established genetic model of absence epilepsy, how sensory inputs are processed in the related cortical areas during SWDs. In epileptic patients, visual event-related potentials (ERPs) were still present in the occipital EEG when the stimuli were delivered during seizures, with a significant increase in amplitude compared to interictal periods and a decrease in latency compared to that measured from non-epileptic subjects. Using simultaneous in vivo EEG and intracellular recordings from the primary somatosensory cortex of GAERS and non-epileptic rats, we found that ERPs and firing responses of related pyramidal neurons to whisker deflection were not significantly modified during SWDs. However, the intracellular subthreshold synaptic responses in somatosensory cortical neurons during seizures had larger amplitude compared to quiescent situations. These convergent findings from human patients and a rodent genetic model show the persistence of cortical responses to sensory stimulations during SWDs, indicating that the brain can still process external stimuli during absence seizures. They also demonstrate that the disruption of conscious perception during absences is not due to an obliteration of information transfer in the thalamocortical system. The possible mechanisms rendering the cortical operation ineffective for conscious perception are discussed, but their definite elucidation will require further investigations.
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Affiliation(s)
- Mathilde Chipaux
- Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière, UPMC/INSERM UMR-S 975; CNRS UMR 7225, Hôpital Pitié-Salpêtrière, Paris, France
- Pediatric Neurosurgery Unit, Fondation Ophtalmologique A. de Rothschild, Paris, France
| | - Laurent Vercueil
- Grenoble Institute of Neurosciences, Centre de Recherche INSERM U 836-UJF-CEA-CHU, Equipe 9, Grenoble, France
| | - Anna Kaminska
- AP-HP, Service d'explorations fonctionnelles, laboratoire de neurophysiologie clinique, Hôpital Necker Enfants Malades, Paris, France
| | - Séverine Mahon
- Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière, UPMC/INSERM UMR-S 975; CNRS UMR 7225, Hôpital Pitié-Salpêtrière, Paris, France
| | - Stéphane Charpier
- Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière, UPMC/INSERM UMR-S 975; CNRS UMR 7225, Hôpital Pitié-Salpêtrière, Paris, France
- UPMC University Paris 06, Paris, France
- * E-mail:
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191
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Zhang X, Wu J, Liu H, Zhang X. Age- and gender-related metabonomic alterations in striatum and cerebellar cortex in rats. Brain Res 2013; 1507:28-34. [PMID: 23454230 DOI: 10.1016/j.brainres.2013.02.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 01/21/2013] [Accepted: 02/19/2013] [Indexed: 11/28/2022]
Abstract
In order to identify the neurochemical alterations in motor associated subcortical nuclei, and enhance our understanding of neurophysiology of progressive reduction in fine motor control with aging, the metabolic changes in striatum and cerebellar cortex in SD rats along with aging were investigated using a metabonomic approach based on high resolution "magic angle spinning" 1H-NMR spectroscopy and partial least squares-discriminant analysis. It was found that there were increased myo-inositol and lactate, and decreased taurine in these two brain regions of old rats. The above changes may be a marker for alterations of neuronal cells, which reduce fine motor control. Besides, some of the metabolites are gender-related and region-specific. Old female rats had decreased glutamate and increased creatine in striatum, while old male rats had increased choline in striatum, and increased GABA in cerebellar cortex, respectively. However, further analyses showed that most of the metabolites in male rats were not distinctively different with those of female ones except choline, which was in a relative lower level in striatum of male rats. All this results suggest that energy metabolism is an important indication of age-related change, which is not only in male, but also in female rats.
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Affiliation(s)
- Xianrong Zhang
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, Wuhan 430071, China.
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192
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Hosomi K, Kishima H, Oshino S, Hirata M, Tani N, Maruo T, Khoo HM, Shimosegawa E, Hatazawa J, Kato A, Yoshimine T. Altered extrafocal iomazenil activity in mesial temporal lobe epilepsy. Epilepsy Res 2013; 103:195-204. [DOI: 10.1016/j.eplepsyres.2012.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 06/06/2012] [Accepted: 07/03/2012] [Indexed: 11/28/2022]
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193
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Holmes MJ, Yang X, Landman BA, Ding Z, Kang H, Abou-Khalil B, Sonmezturk HH, Gore JC, Morgan VL. Functional networks in temporal-lobe epilepsy: a voxel-wise study of resting-state functional connectivity and gray-matter concentration. Brain Connect 2013; 3:22-30. [PMID: 23150897 DOI: 10.1089/brain.2012.0103] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Temporal-lobe epilepsy (TLE) involves seizures that typically originate in the hippocampus. There is evidence that seizures involve anatomically and functionally connected brain networks within and beyond the temporal lobe. Many studies have explored the effect of TLE on gray matter and resting-state functional connectivity in the brain. However, the relationship between structural and functional changes has not been fully explored. The goal of this study was to investigate the relationship between gray matter concentration (GMC) and functional connectivity in TLE at the voxel level. A voxel-wise linear regression analysis was performed between GMC maps and whole-brain resting-state functional connectivity maps to both the left thalamus (Lthal) and the left hippocampus (LH) in a group of 15 patients with left TLE. Twenty regions were found that exhibited GMC decreases linearly correlated with resting-state functional connectivity to either the LH or the Lthal in the patient group only. A subset of these regions had significantly reduced GMC, and one of these regions also had reduced functional connectivity to the LH in TLE compared to the controls. These results suggest a network of impairment in left TLE where more severe reductions in GMC accompany decreases (LH, Lthal, right midcingulate gyrus, left precuneus, and left postcentral gyrus) or increases (LH to right thalamus) in resting functional connectivity. However, direct relationships between these imaging parameters and disease characteristics in these regions have yet to be established.
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Affiliation(s)
- Martha J Holmes
- Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee 37232-2310, USA
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194
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Zeng H, Pizarro R, Nair VA, La C, Prabhakaran V. Alterations in regional homogeneity of resting-state brain activity in mesial temporal lobe epilepsy. Epilepsia 2013; 54:658-66. [PMID: 23294137 DOI: 10.1111/epi.12066] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2012] [Indexed: 11/30/2022]
Abstract
PURPOSE The purpose of the present study was to identify abnormal areas of regional synchronization in patients with mesial temporal lobe epilepsy and hippocampus sclerosis (mTLE-HS) compared to healthy controls, by applying a relatively novel method, the Regional Homogeneity (ReHo) method to resting state fMRI (RS-fMRI) data. METHODS Eyes closed RS-fMRI data were acquired from 10 mTLE-HS patients (four right-side, six left-side) and 15 age- and gender-matched healthy subjects, and were analyzed by using ReHo. For group analysis, four right-side MTLE-HS patients' functional images were flipped, in order to make a homogeneous left MTLE-HS group (10 cases) and increase the sample size. KEY FINDINGS Compared to the healthy control group, patients showed significantly increased ReHo in ipsilateral parahippocampal gyrus, midbrain, insula, corpus callosum, bilateral sensorimotor cortex, and frontoparietal subcortical structures, whereas decreased ReHo was observed mainly in default mode network (DMN) (including precuneus and posterior cingulate gyrus, bilateral inferior lateral parietal, and mesial prefrontal cortex) and cerebellum in patients relative to the control group. SIGNIFICANCE This study identified that ReHo pattern in mTLE-HS patients was altered compared to healthy controls. We consider decreased ReHo in DMN to be responsible for wide functional impairments in cognitive processes. We propose that the increased ReHo in specific regions may form a network that might be responsible for seizure genesis and propagation.
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Affiliation(s)
- Hongwu Zeng
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792, USA
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Duchaczek B, Ghaeni L, Matzen J, Holtkamp M. Interictal and periictal headache in patients with epilepsy. Eur J Neurol 2012; 20:1360-6. [DOI: 10.1111/ene.12049] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2012] [Accepted: 10/25/2012] [Indexed: 11/28/2022]
Affiliation(s)
- B. Duchaczek
- Department of Neurology; Charité-Universitätsmedizin Berlin; Berlin; Germany
| | - L. Ghaeni
- Department of Neurology; Charité-Universitätsmedizin Berlin; Berlin; Germany
| | - J. Matzen
- Department of Neurology; Charité-Universitätsmedizin Berlin; Berlin; Germany
| | - M. Holtkamp
- Department of Neurology; Charité-Universitätsmedizin Berlin; Berlin; Germany
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196
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197
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Huang X, McMahon J, Yang J, Shin D, Huang Y. Rapamycin down-regulates KCC2 expression and increases seizure susceptibility to convulsants in immature rats. Neuroscience 2012; 219:33-47. [PMID: 22613737 PMCID: PMC3402618 DOI: 10.1016/j.neuroscience.2012.05.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 05/02/2012] [Accepted: 05/03/2012] [Indexed: 11/30/2022]
Abstract
Seizure susceptibility to neurological insults, including chemical convulsants, is age-dependent and most likely reflective of overall differences in brain excitability. The molecular and cellular mechanisms underlying development-dependent seizure susceptibility remain to be fully understood. Because the mammalian target of rapamycin (mTOR) pathway regulates neurite outgrowth, synaptic plasticity and cell survival, thereby influencing brain development, we tested if exposure of the immature brain to the mTOR inhibitor rapamycin changes seizure susceptibility to neurological insults. We found that inhibition of mTOR by rapamycin in immature rats (3-4 weeks old) increases the severity of seizures induced by pilocarpine, including lengthening the total seizure duration and reducing the latency to the onset of seizures. Rapamycin also reduces the minimal dose of pentylenetetrazol (PTZ) necessary to induce clonic seizures. However, in mature rats, rapamycin does not significantly change the seizure sensitivity to pilocarpine and PTZ. Likewise, kainate sensitivity was not significantly affected by rapamycin treatment in either mature or immature rats. Additionally, rapamycin treatment down-regulates the expression of potassium-chloride cotransporter 2 (KCC2) in the thalamus and to a lesser degree in the hippocampus. Pharmacological inhibition of thalamic mTOR or KCC2 increases susceptibility to pilocarpine-induced seizure in immature rats. Thus, our study suggests a role for the mTOR pathway in age-dependent seizure susceptibility.
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Affiliation(s)
- Xiaoxing Huang
- Center for Neuropharmacology and Neuroscience, Albany Medical College, NY, USA
| | - John McMahon
- Center for Neuropharmacology and Neuroscience, Albany Medical College, NY, USA
| | - Jun Yang
- Center for Neuropharmacology and Neuroscience, Albany Medical College, NY, USA
| | - Damian Shin
- Center for Neuropharmacology and Neuroscience, Albany Medical College, NY, USA
| | - Yunfei Huang
- Center for Neuropharmacology and Neuroscience, Albany Medical College, NY, USA
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Abstract
Consciousness is essential to normal human life. In epileptic seizures consciousness is often transiently lost, which makes it impossible for the individual to experience or respond. These effects have huge consequences for safety, productivity, emotional health, and quality of life. To prevent impaired consciousness in epilepsy, it is necessary to understand the mechanisms that lead to brain dysfunction during seizures. Normally the consciousness system-a specialised set of cortical-subcortical structures-maintains alertness, attention, and awareness. Advances in neuroimaging, electrophysiology, and prospective behavioural testing have shed light on how epileptic seizures disrupt the consciousness system. Diverse seizure types, including absence, generalised tonic-clonic, and complex partial seizures, converge on the same set of anatomical structures through different mechanisms to disrupt consciousness. Understanding of these mechanisms could lead to improved treatment strategies to prevent impairment of consciousness and improve the quality of life of people with epilepsy.
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Affiliation(s)
- Hal Blumenfeld
- Departments of Neurology, Neurobiology, and Neurosurgery, Yale University School of Medicine, New Haven, CT 06520, USA.
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199
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McPherson A, Rojas L, Bauerschmidt A, Ezeani CC, Yang L, Motelow JE, Farooque P, Detyniecki K, Giacino JT, Blumenfeld H. Testing for minimal consciousness in complex partial and generalized tonic-clonic seizures. Epilepsia 2012; 53:e180-3. [PMID: 22931210 DOI: 10.1111/j.1528-1167.2012.03657.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Impaired consciousness in epilepsy has a major negative impact on quality of life. Prior work suggests that complex partial seizures (CPS) and generalized tonic-clonic seizures (GTCS), which both cause loss of consciousness, affect similar frontoparietal networks. Milder involvement in CPS than in GTCS may spare some simple behavioral responses, resembling the minimally conscious state. However, this difference in responses has not been rigorously tested previously. During video-electroencephalography (EEG) monitoring, we administered a standardized prospective testing battery including responses to questions and commands, as well as tests for reaching/grasping a ball and visual tracking in 27 CPS (in 14 patients) and 7 GTCS (in six patients). Behavioral results were analyzed in the ictal and postictal periods based on video review. During both CPS and GTCS, patients were unable to respond to questions or commands. However, during CPS, patients often retained minimally conscious ball grasping and visual tracking responses. Patients were able to successfully grasp a ball in 60% or to visually track in 58% of CPS, and could carry out both activities in 52% of CPS. In contrast, during GTCS, preserved ball grasp (10%), visual tracking (11%), or both (7%), were all significantly less than in CPS. Postictal ball grasping and visual tracking were also somewhat better following CPS than GTCS. These findings suggest that impaired consciousness in CPS is more similar to minimally conscious state than to coma. Further work may elucidate the specific brain networks underlying relatively spared functions in CPS, ultimately leading to improved treatments aimed at preventing impaired consciousness.
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Affiliation(s)
- Alison McPherson
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520-8018, USA
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Yang L, Worrell GA, Nelson C, Brinkmann B, He B. Spectral and spatial shifts of post-ictal slow waves in temporal lobe seizures. Brain 2012; 135:3134-43. [PMID: 22923634 DOI: 10.1093/brain/aws221] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Temporal lobe seizures have a significant chance to induce impairment of normal brain functions. Even after the termination of ictal discharges, during the post-ictal period, loss of consciousness, decreased responsiveness or other cognitive dysfunctions can persist. Previous studies have found various anatomical and functional abnormalities accompanying temporal lobe seizures, including an abnormal elevation of cortical slow waves. Intracranial electroencephalography studies have shown a prominent increase of lower frequency components during and following seizures that impair (complex partial seizures) but not those that preserve (simple partial seizures) normal consciousness and responsiveness. However, due to the limited spatial coverage of intracranial electroencephalography, the investigation of cortical slow waves cannot be easily extended to the whole brain. In this study, we used scalp electroencephalography to study the spectral features and spatial distribution of post-ictal slow waves with comprehensive spatial coverage. We studied simple partial, complex partial and secondarily generalized seizures in 28 patients with temporal lobe seizures. We used dense-array electroencephalography and source imaging to reconstruct the post-ictal slow-wave distribution. In the studied cohort, we found that a 'global' spectral power shift to lower frequencies accompanied the increased severity of seizures. The delta spectral power relative to higher frequency bands was highest for secondarily generalized seizures, followed by complex partial seizures and lastly simple partial seizures. In addition to this 'global' spectral shift, we found a 'regional' spatial shift in slow-wave activity. Secondarily generalized seizures and complex partial seizures exhibited increased slow waves distributed to frontal areas with spread to contralateral temporal and parietal regions than in simple partial seizures. These results revealed that a widespread cortical network including temporal and fronto-parietal cortex is involved in abnormal slow-wave activity following temporal lobe seizures. The differential spectral and spatial shifts of post-ictal electroencephalography activity in simple partial, complex partial and secondarily generalized seizures suggest a possible connection between cortical slow waves and behavioural and cognitive changes in a human epilepsy model.
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Affiliation(s)
- Lin Yang
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
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