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Zhang X, Feng Y, Chen Z, Long J. Altered functional connectivity in the hippocampal and striatal systems after motor sequence learning consolidation in medial temporal lobe epilepsy individuals. J Neurophysiol 2024; 131:294-303. [PMID: 38230870 DOI: 10.1152/jn.00376.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 12/20/2023] [Accepted: 01/10/2024] [Indexed: 01/18/2024] Open
Abstract
Both the hippocampal and striatal systems participate in motor sequence learning (MSL) in healthy subjects, and the prominent role of the hippocampal system in sleep-related consolidation has been demonstrated. However, some pathological states may change the functional dominance between these two systems in MSL consolidation. To better understand the functional performance within these two systems under the pathological condition of hippocampal impairment, we compared the functional differences after consolidation between patients with left medial temporal lobe epilepsy (LmTLE) and healthy control subjects (HCs). We assessed participants' performance on the finger-tapping task (FTT) during acquisition (on day 1) and after consolidation during sleep (on day 2). All participants underwent an MRI scan (T1 and resting state) before each FTT. We found that the LmTLE group showed performance deficits in offline consolidation compared to the HC group. The LmTLE group exhibited structural changes, such as decreased gray matter volume (GMV) in the left hippocampus and increased GMV in the right putamen (striatum). Our results also revealed that whereas the main effect of consolidation was observed in the hippocampus-related functional connection in the HC group, it was only evident in the striatum-related functional loop in the LmTLE group. Our findings indicated that LmTLE patients may rely more on the striatal system for offline consolidation because of structural impairments in the hippocampus. Additionally, this compensatory mechanism may not fully substitute for the role of the impaired hippocampus itself.NEW & NOTEWORTHY Motor sequence learning (MSL) relies on both the hippocampal and striatal systems, but whether functional performance is altered after MSL consolidation when the hippocampus is impaired remains unknown. Our results indicated that whereas the main effect of consolidation was observed in the hippocampus-related functional connection in the healthy control (HC) group, it was only evident in the striatum-related functional loop in the left medial temporal lobe epilepsy (LmTLE) group.
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Affiliation(s)
- Xiaotong Zhang
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, China
| | - Yanyun Feng
- Department of Radiology, The First People's Hospital of Foshan, Foshan, Guangdong, China
| | - Zhuoming Chen
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, China
| | - Jinyi Long
- College of Information Science and Technology, Jinan University, Guangzhou, Guangdong, China
- Pazhou Lab, Guangzhou, Guangdong, China
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Fallahi A, Hoseini-Tabatabaei N, Eivazi F, Mohammadi Mobarakeh N, Dehghani-Siahaki H, Alibiglou L, Rostami R, Mehvari Habibabadi J, Hashemi-Fesharaki SS, Joghataei MT, Nazem-Zadeh MR. Dynamic causal modeling of reorganization of memory and language networks in temporal lobe epilepsy. Ann Clin Transl Neurol 2023; 10:2238-2254. [PMID: 37776067 PMCID: PMC10723230 DOI: 10.1002/acn3.51908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 08/22/2023] [Accepted: 09/10/2023] [Indexed: 10/01/2023] Open
Abstract
OBJECTIVE To evaluate the alterations of language and memory functions using dynamic causal modeling, in order to identify the epileptogenic hemisphere in temporal lobe epilepsy (TLE). METHODS Twenty-two patients with left TLE and 13 patients with right TLE underwent functional magnetic resonance imaging (fMRI) during four memory and four language mapping tasks. Dynamic causal modeling (DCM) was employed on fMRI data to examine effective directional connectivity in memory and language networks and the alterations in people with TLE compared to healthy individuals. RESULTS DCM analysis suggested that TLE can influence the memory network more widely compared to the language network. For memory mapping, it demonstrated overall hyperconnectivity from the left hemisphere to the other cranial regions in the picture encoding, and from the right hemisphere to the other cranial regions in the word encoding tasks. On the contrary, overall hypoconnectivity was seen from the brain hemisphere contralateral to the seizure onset in the retrieval tasks. DCM analysis further manifested hypoconnectivity between the brain's hemispheres in the language network in patients with TLE compared to controls. The CANTAB® neuropsychological test revealed a negative correlation for the left TLE and a positive correlation for the right TLE cohorts for the connections extracted by DCM that were significantly different between the left and right TLE cohorts. INTERPRETATION In this study, dynamic causal modeling evidenced the reorganization of language and memory networks in TLE that can be used for a better understanding of the effects of TLE on the brain's cognitive functions.
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Affiliation(s)
- Alireza Fallahi
- Control and Intelligent Processing Center of Excellence (CIPCE), School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, Iran
- Biomedical Engineering Department, Hamedan University of Technology, Hamedan, Iran
| | | | - Fatemeh Eivazi
- Research Center for Molecular and Cellular Imaging, Advanced Medical Technologies and Equipment Institute (AMTEI), Tehran University of Medical Sciences, Tehran, Iran
- Institute for Cognitive and Brain Sciences, Shahid Beheshti University, Tehran, Iran
- Medical Physics and Biomedical Engineering Department, Tehran University of Medical Sciences, Tehran, Iran
| | - Neda Mohammadi Mobarakeh
- Research Center for Molecular and Cellular Imaging, Advanced Medical Technologies and Equipment Institute (AMTEI), Tehran University of Medical Sciences, Tehran, Iran
- Medical Physics and Biomedical Engineering Department, Tehran University of Medical Sciences, Tehran, Iran
| | - Hamed Dehghani-Siahaki
- Research Center for Molecular and Cellular Imaging, Advanced Medical Technologies and Equipment Institute (AMTEI), Tehran University of Medical Sciences, Tehran, Iran
- Medical Physics and Biomedical Engineering Department, Tehran University of Medical Sciences, Tehran, Iran
| | - Laila Alibiglou
- Department of Neuroscience, Iran University of Medical Sciences, Tehran, Iran
| | - Reza Rostami
- Department of Psychology, University of Tehran, Tehran, Iran
| | | | | | | | - Mohammad-Reza Nazem-Zadeh
- Research Center for Molecular and Cellular Imaging, Advanced Medical Technologies and Equipment Institute (AMTEI), Tehran University of Medical Sciences, Tehran, Iran
- Medical Physics and Biomedical Engineering Department, Tehran University of Medical Sciences, Tehran, Iran
- Department of Neuroscience, Monash University, Melbourne, VIC, Australia
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Vilà-Balló A, De la Cruz-Puebla M, López-Barroso D, Miró J, Sala-Padró J, Cucurell D, Falip M, Rodríguez-Fornells A. Reward-based decision-making in mesial temporal lobe epilepsy patients with unilateral hippocampal sclerosis pre- and post-surgery. Neuroimage Clin 2022; 36:103251. [PMID: 36510413 PMCID: PMC9668642 DOI: 10.1016/j.nicl.2022.103251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 10/26/2022] [Accepted: 10/28/2022] [Indexed: 11/06/2022]
Abstract
BACKGROUND Correct functioning of the reward processing system is critical for optimizing decision-making as well as preventing the development of addictions and/or neuropsychiatric symptoms such as depression, apathy, and anhedonia. Consequently, patients with mesial temporal lobe epilepsy due to unilateral hippocampal sclerosis (mTLE-UHS) represent an excellent opportunity to study the brain networks involved in this system. OBJECTIVE The aim of the current study was to evaluate decision-making and the electrophysiological correlates of feedback processing in a sample of mTLE-UHS patients, compared to healthy controls. In addition, we assessed the impact of mesial temporal lobe surgical resection on these processes, as well as general, neuropsychological functioning. METHOD 17 mTLE-UHS patients and 17 matched healthy controls completed: [1] a computerized version of the Game of Dice Task, [2] a Standard Iowa Gambling Task, and [3] a modified ERP version of a probabilistic gambling task coupled with multichannel electroencephalography. Neuropsychological scores were also obtained both pre- and post-surgery. RESULTS Behavioral analyses showed a pattern of increased risk for the mTLE-UHS group in decision-making under ambiguity compared to the control group. A decrease in the amplitude of the Feedback Related Negativity (FRN), a weaker effect of valence on delta power, and a general reduction of delta and theta power in the mTLE-UHS group, as compared to the control group, were also found. The beta-gamma activity associated with the delivery of positive reward was similar in both groups. Behavioral performance and electrophysiological measures did not worsen post-surgery. CONCLUSIONS Patients with mTLE-UHS showed impairments in decision-making under ambiguity, particularly when they had to make decisions based on the outcomes of their choices, but not in decision-making under risk. No group differences were observed in decision-making when feedbacks were random. These results might be explained by the abnormal feedback processing seen in the EEG activity of patients with mTLE-UHS, and by concomitant impairments in working memory, and memory. These impairments may be linked to the disruption of mesial temporal lobe networks. Finally, feedback processing and decision-making under ambiguity were already affected in mTLE-UHS patients pre-surgery and did not show evidence of clear worsening post-surgery.
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Affiliation(s)
- Adrià Vilà-Balló
- Department of Cognition, Development and Educational Psychology, University of Barcelona, Barcelona, Spain,Cognition and Brain Plasticity Group, Bellvitge Biomedical Research Institute (IDIBELL), L’Hospitalet de Llobregat, Barcelona, Spain,Institute of Neurosciences, University of Barcelona, Barcelona, Spain.,Headache and Neurological Pain Research Group, Vall d’Hebron Research Institute, Autonomous University of Barcelona, Barcelona, Spain,Department of Psychology, Faculty of Education and Psychology, University of Girona, Girona, Spain,Corresponding authors.
| | - Myriam De la Cruz-Puebla
- Cognition and Brain Plasticity Group, Bellvitge Biomedical Research Institute (IDIBELL), L’Hospitalet de Llobregat, Barcelona, Spain,Institute of Neurosciences, University of Barcelona, Barcelona, Spain.,Department of Cellular Biology, Physiology, and Immunology, Neurosciences Institute, Autonomous University of Barcelona, Barcelona, Spain,Department of Equity in Brain Health, Global Brain Health Institute (GBHI), University of California, San Francisco (UCSF), CA, USA,Department of Internal Medicine, Health Sciences Faculty, Technical University of Ambato, Tungurahua, Ecuador,Dept. of Psychobiology and Methodology of Behavioural Sciences, Faculty of Psychology, University of Málaga, Málaga, Spain
| | - Diana López-Barroso
- Cognitive Neurology and Aphasia Unit, Centro de Investigaciones Médico-Sanitarias, University of Málaga, Málaga, Spain,Instituto de Investigación Biomédica de Málaga-IBIMA, Málaga, Spain,Dept. of Psychobiology and Methodology of Behavioural Sciences, Faculty of Psychology, University of Málaga, Málaga, Spain
| | - Júlia Miró
- Cognition and Brain Plasticity Group, Bellvitge Biomedical Research Institute (IDIBELL), L’Hospitalet de Llobregat, Barcelona, Spain,Institute of Neurosciences, University of Barcelona, Barcelona, Spain.,Epilepsy Unit, Neurological Service, Neurology and Genetics Group, Neuroscience Program, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), Hospital Universitari de Bellvitge, L’Hospitalet de Llobregat, Barcelona, Spain
| | - Jacint Sala-Padró
- Cognition and Brain Plasticity Group, Bellvitge Biomedical Research Institute (IDIBELL), L’Hospitalet de Llobregat, Barcelona, Spain,Institute of Neurosciences, University of Barcelona, Barcelona, Spain.,Dept. of Psychobiology and Methodology of Behavioural Sciences, Faculty of Psychology, University of Málaga, Málaga, Spain
| | - David Cucurell
- Department of Cognition, Development and Educational Psychology, University of Barcelona, Barcelona, Spain,Cognition and Brain Plasticity Group, Bellvitge Biomedical Research Institute (IDIBELL), L’Hospitalet de Llobregat, Barcelona, Spain,Institute of Neurosciences, University of Barcelona, Barcelona, Spain
| | - Mercè Falip
- Epilepsy Unit, Neurological Service, Neurology and Genetics Group, Neuroscience Program, Institut d’Investigació Biomèdica de Bellvitge (IDIBELL), Hospital Universitari de Bellvitge, L’Hospitalet de Llobregat, Barcelona, Spain
| | - Antoni Rodríguez-Fornells
- Department of Cognition, Development and Educational Psychology, University of Barcelona, Barcelona, Spain,Cognition and Brain Plasticity Group, Bellvitge Biomedical Research Institute (IDIBELL), L’Hospitalet de Llobregat, Barcelona, Spain,Institute of Neurosciences, University of Barcelona, Barcelona, Spain.,Catalan Institution for Research and Advanced Studies, ICREA, Barcelona, Spain
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Pan L, Wu Y, Bao J, Guo D, Zhang X, Wang J, Deng M, Yu P, Wei G, Zhang L, Qin X, Song Y. Alterations in Neural Networks During Working Memory Encoding Related to Cognitive Impairment in Temporal Lobe Epilepsy. Front Hum Neurosci 2022; 15:770678. [PMID: 35069151 PMCID: PMC8766724 DOI: 10.3389/fnhum.2021.770678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 12/13/2021] [Indexed: 11/13/2022] Open
Abstract
Objective: The aim of the current study was to investigate the alterations in the neural networks of patients with temporal lobe epilepsy (TLE) during working memory (WM) encoding. Methods: Patients with TLE (n = 52) and healthy volunteers (n = 35) completed a WM task, during which 34-channel electroencephalogram signals were recorded. The neural networks during WM encoding were calculated in TLE patients with (TLE-WM) and without (TLE-N) WM deficits. Results: Functional connectivity strength decreased, and the theta network was altered in the TLE-WM group, although no significant differences in clinical features were observed between the TLE-N and TLE-WM groups. Conclusions: Not all patients with TLE present with cognitive impairments and alterations in the theta network were identified in TLE patients with functional cognitive deficits. Significance: The theta network may represent a sensitive measure of cognitive impairment and could predict cognitive outcomes among patients with TLE.
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Affiliation(s)
- Liping Pan
- General Medicine Department, Tianjin Medical University General Hospital, Tianjin, China
| | - Yakun Wu
- Department of Neurology, Tianjin Medical University General Hospital, Tianjin, China
- Department of Neurology, Tangshan Gongren Hospital, Tangshan, China
| | - Jie Bao
- Department of Rehabilitation Medicine, Tianjin Medical University General Hospital, Tianjin, China
| | - Dandan Guo
- Department of Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Xin Zhang
- Department of Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Jiajing Wang
- Department of Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Meili Deng
- Department of Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Peiran Yu
- School of Basic Medical Science, Tianjin Medical University, Tianjin, China
| | - Gaoxu Wei
- Department of Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Lulin Zhang
- Department of Neurology, Tianjin Medical University General Hospital, Tianjin, China
- Department of Neurology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Xiao Qin
- Department of Neurology, Tianjin Medical University General Hospital, Tianjin, China
| | - Yijun Song
- General Medicine Department, Tianjin Medical University General Hospital, Tianjin, China
- Key Laboratory of Central Nerve Injury Repair and Regeneration, Ministry of Education, Tianjin Neurological Institute, Tianjin, China
- *Correspondence: Yijun Song
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Li D, Liu R, Meng L, Xiong P, Ren H, Zhang L, Gao Y. Abnormal Ventral Somatomotor Network Homogeneity in Patients With Temporal Lobe Epilepsy. Front Psychiatry 2022; 13:877956. [PMID: 35782421 PMCID: PMC9247252 DOI: 10.3389/fpsyt.2022.877956] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Abnormalities of functional connectivity in the somatomotor network have been thought to play an essential role in the pathophysiology of epilepsy. However, there has been no network homogeneity (NH) study about the ventral somatomotor network (VSN) in patients with temporal lobe epilepsy (TLE). Therefore, we explored the NH of the VSN in TLE patients in this study. METHODS The sample included 52 patients with left temporal lobe epilepsy, 83 patients with right temporal lobe epilepsy, and 68 healthy controls. The NH method was utilized to analyze the resting-state functional magnetic resonance imaging data. RESULTS Compared to the controls, rTLE patients had significantly higher NH in the bilateral postcentral gyrus, and significantly lower NH in the bilateral Rolandic operculum and the right superior temporal gyrus (STG). The NH values of the left postcentral gyrus were significantly higher in lTLE patients than in the healthy controls, and lTLE patients had lower NH in the right Rolandic operculum. The altered NH in the postcentral gyrus was negatively correlated with the illness duration, and the decreased NH in the left Rolandic operculum was negatively correlated with the executive control reaction time (ECRT). CONCLUSION Our findings suggest that altered NH of the postcentral gyrus, Rolandic operculum and STG might be associated with the pathophysiology of TLE, and thus, highlight the contribution of the VSN to the pathophysiology of TLE.
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Affiliation(s)
- Dongbin Li
- Department of Neurology, The First Affiliated Hospital of Harbin Medical University, Harbin, China.,First Department of Neurology and Neuroscience Center, Heilongjiang Provincial Hospital, Harbin, China
| | - Ruoshi Liu
- Department of Neurology, The Fourth Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Lili Meng
- Department of Psychiatry, Wuhan Mental Health Center, Wuhan, China.,Department of Sleep, Wuhan Hospital for Psychotherapy, Wuhan, China
| | - Pingan Xiong
- Department of Taihe Hospital Reproductive Medicine Center Affiliated To Hubei University of Medicine, Shiyan, China
| | - Hongwei Ren
- Department of Medical Imaging, Tianyou Hospital Affiliated To Wuhan University of Science and Technology, Wuhan, China
| | - Liming Zhang
- Department of Neurology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Yujun Gao
- Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan, China
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Pan L, Guo D, Wang J, Hao Y, Zhang L, Qin X, Song Y. Alterations in neural oscillations related to working memory deficit in temporal lobe epilepsy. Epilepsy Behav 2021; 121:108063. [PMID: 34052633 DOI: 10.1016/j.yebeh.2021.108063] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/21/2021] [Accepted: 05/10/2021] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Working memory (WM) is critical for higher level cognition, but the underlying neural mechanisms are not fully understood. Impaired WM affects routine daily activities and is observed in patients with temporal lobe epilepsy (TLE). This study investigated neural oscillations associated with different WM phases, to determine the specific neural activity linked with the phases of WM impairment. METHODS Patients with TLE (n = 52) and healthy volunteers (n = 35) completed a WM task, during which 34-channel electroencephalogram signals were recorded. Characteristic neural oscillation patterns during each WM phase were compared between the 2 groups. RESULTS Patients with TLE showed decreased theta power during the encoding phase of WM, which was associated with reduced accuracy in the WM task. Altered theta power in the frontal region of the brain during the encoding phase was associated with a longer reaction time. CONCLUSIONS Alterations in theta oscillation are related to WM impairment in patients with TLE and may serve as an early marker for evaluating WM deficits. SIGNIFICANCE This study provides an early marker for evaluating WM deficits in TLE.
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Affiliation(s)
- Liping Pan
- General Medicine Department, Tianjin Medical University General Hospital, Tianjin 300052, China; Tianjin Neurological Institute, Tianjin 300052, China
| | - Dandan Guo
- Department of Neurology, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Jiajing Wang
- Department of Neurology, Tianjin Medical University General Hospital, Tianjin 300052, China; Second Clinical Medical College of Tianjin Medical University, Tianjin 300211, China
| | - Yuhan Hao
- Department of Neurology, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Lulin Zhang
- Department of Neurology, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Xiao Qin
- Department of Neurology, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Yijun Song
- General Medicine Department, Tianjin Medical University General Hospital, Tianjin 300052, China; Tianjin Neurological Institute, Tianjin 300052, China.
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Poch C, Toledano R, García-Morales I, Alemán-Gómez Y, Gil-Nagel A, Campo P. Contributions of left and right anterior temporal lobes to semantic cognition: Evidence from patients with small temporopolar lesions. Neuropsychologia 2020; 152:107738. [PMID: 33383038 DOI: 10.1016/j.neuropsychologia.2020.107738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 12/04/2020] [Accepted: 12/24/2020] [Indexed: 11/18/2022]
Abstract
Decades of research have increased the understanding of the contribution of the anterior temporal lobes (ATLs) to semantic cognition. Nonetheless, whether semantic processing of different types of information show a selective relationship with left and right ATLs, or whether semantic processing in the ATLs is independent of the modality of the input is currently unknown. There exists evidence supporting each of these alternatives. A fundamental objection to these findings is that they were obtained from studies with patients with brain damage affecting extensive regions, sometimes bilaterally. In the current study, we assessed a group of 38 temporal lobe epilepsy (TLE) patients with either left or right small epileptogenic lesions with a battery of commonly used semantic tasks that tested verbal and non-verbal semantic processing. We found that left TLE patients exhibited worse performance than controls on the verbal semantic tasks, as expected, but also on the non-verbal semantic task. On the other hand, performance of the right TLE group did not differ from controls on the non-verbal task, but was worse on a semantic fluency task. When performance between patient groups was compared, we found that left TLE not only did worse than right TLE on the naming task, but also on the non-verbal associative memory task. When considered together, current data do not support a strong view of input modality differences between left and right ATLs. Additionally, they provide evidence indicating that the left and right ATLs do not make similar contributions to a singular functional system for semantic representation.
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Affiliation(s)
- Claudia Poch
- Facultad de Lenguas y Educación, Universidad Nebrija, Spain
| | - Rafael Toledano
- Hospital Ruber Internacional, Epilepsy Unit, Neurology Department, Madrid, Spain; University Hospital of Ramón y Cajal, Epilepsy Unit, Neurology Department, Madrid, Spain
| | - Irene García-Morales
- Hospital Ruber Internacional, Epilepsy Unit, Neurology Department, Madrid, Spain; University Hospital of San Carlos, Epilepsy Unit, Neurology Department, Madrid, Spain
| | - Yasser Alemán-Gómez
- Center for Psychiatric Neuroscience, Department of Psychiatry, Centre Hospitalier Universitaire Vaudois (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland; Department of Radiology, Centre Hospitalier Universitaire Vaudois (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland; Medical Image Analysis Laboratory (MIAL), Centre D'Imagerie BioMédicale (CIBM), Lausanne, Switzerland
| | - Antonio Gil-Nagel
- Hospital Ruber Internacional, Epilepsy Unit, Neurology Department, Madrid, Spain
| | - Pablo Campo
- Department of Basic Psychology, Autonoma University of Madrid, Madrid, Spain.
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P2Y1 receptor inhibition rescues impaired synaptic plasticity and astroglial Ca 2+-dependent activity in the epileptic hippocampus. Neurobiol Dis 2020; 146:105132. [PMID: 33049315 DOI: 10.1016/j.nbd.2020.105132] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 09/15/2020] [Accepted: 10/06/2020] [Indexed: 02/06/2023] Open
Abstract
Epilepsy is characterized by a progressive predisposition to suffer seizures due to neuronal hyperexcitability, and one of its most common co-morbidities is cognitive decline. In animal models of chronic epilepsy, such as kindling, electrically induced seizures impair long-term potentiation (LTP), deteriorating learning and memory performance. Astrocytes are known to actively modulate synaptic plasticity and neuronal excitability through Ca2+-dependent gliotransmitter release. It is unclear, however, if astroglial Ca2+ signaling could contribute to the development of synaptic plasticity alterations in the epileptic hippocampus. By employing electrophysiological tools and Ca2+ imaging, we found that glutamatergic CA3-CA1 synapses from kindled rats exhibit an impairment in theta burst (TBS) and high frequency stimulation (HFS)-induced LTP, which is accompanied by an increased probability of neurotransmitter release (Pr) and an abnormal pattern of astroglial Ca2+-dependent transients. Both the impairment in LTP and the Pr were reversed by inhibiting purinergic P2Y1 receptors (P2Y1R) with the specific antagonist MRS2179, which also restored the spontaneous and TBS-induced pattern of astroglial Ca2+-dependent signals. Two consecutive, spaced TBS protocols also failed to induce LTP in the kindled group, however, this impairment was reversed and a strong LTP was induced when the second TBS was applied in the presence of MRS2179, suggesting that the mechanisms underlying the alterations in TBS-induced LTP are likely associated with an aberrant modulation of the induction threshold for LTP. Altogether, these results indicate that P2Y1R inhibition rescues both the pattern of astroglial Ca2+-activity and the plastic properties of CA3-CA1 synapses in the epileptic hippocampus, suggesting that astrocytes might take part in the mechanisms that deteriorate synaptic plasticity and thus cause cognitive decline in epileptic patients.
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Chauvière L. Potential causes of cognitive alterations in temporal lobe epilepsy. Behav Brain Res 2020; 378:112310. [DOI: 10.1016/j.bbr.2019.112310] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 10/15/2019] [Accepted: 10/15/2019] [Indexed: 12/11/2022]
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10
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Jiang Y, Liu DF, Zhang X, Liu HG, Zhang JG. Microstructure and functional connectivity-based evidence for memory-related regional impairments in the brains of pilocarpine-treated rats. Brain Res Bull 2019; 154:127-134. [PMID: 31756422 DOI: 10.1016/j.brainresbull.2019.11.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/09/2019] [Accepted: 11/17/2019] [Indexed: 12/21/2022]
Abstract
Patients with temporal lobe epilepsy (TLE) frequently suffer from memory disorders, and the pathological changes show widespread regional impairments in the brain. In lithium-pilocarpine (LIP)-treated rats with TLE, an abnormal hippocampal microstructure and functional connectivity have been observed. However, changes in other brain regions are still unclear. In the present study, diffusion tensor imaging and functional magnetic resonance imaging (MRI) signals were collected in LIP-TLE rats and controls using a 7.0 T MRI. Microstructural parameters and functional connectivity were calculated among regions of interest (ROIs), including the bilateral prefrontal cortex, amygdala, hippocampus and entorhinal cortex. A correlation analysis was further performed between the neuroimaging results and the behavioral performance in the novel object and novel location memory tests. In our results, TLE rats showed increased fractional anisotropy (FA) values in the hippocampus and decreased FA values in the amygdala and entorhinal cortex. In addition, decreased functional connectivity between the amygdala and the CA3, and increased connectivity between the prefrontal cortex and the CA1 were observed in the TLE rats compared to control rats. Moreover, FA values in the amygdala, the hippocampus and the entorhinal cortex, as well as the amygdala-CA3 and the prefrontal-CA1 connectivity correlated with the memory performance. Based on our results, both the microstructure and functional connections were impaired in memory-related brain regions of LIP-TLE rats. Furthermore, the abnormal changes in the microstructure and functional connectivity were related to behavioral deficits in object and location memory.
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Affiliation(s)
- Yin Jiang
- Department of Functional Neurosurgery, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China; Beijing Key Laboratory of Neurostimulation, Beijing, China.
| | - De-Feng Liu
- Department of Functional Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Xin Zhang
- Department of Functional Neurosurgery, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China; Beijing Key Laboratory of Neurostimulation, Beijing, China
| | - Huan-Guang Liu
- Department of Functional Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China
| | - Jian-Guo Zhang
- Department of Functional Neurosurgery, Beijing Neurosurgical Institute, Capital Medical University, Beijing, China; Beijing Key Laboratory of Neurostimulation, Beijing, China; Department of Functional Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
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Jo HJ, Kenny-Jung DL, Balzekas I, Benarroch EE, Jones DT, Brinkmann BH, Matt Stead S, Van Gompel JJ, Welker KM, Worrell GA. Nuclei-specific thalamic connectivity predicts seizure frequency in drug-resistant medial temporal lobe epilepsy. NEUROIMAGE-CLINICAL 2019; 21:101671. [PMID: 30642762 PMCID: PMC6412104 DOI: 10.1016/j.nicl.2019.101671] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 12/31/2018] [Accepted: 01/07/2019] [Indexed: 12/18/2022]
Abstract
Background and objectives We assessed correlations between the resting state functional connectivity (RSFC) of different thalamic nuclei and seizure frequency in patients with drug-resistant medial temporal lobe epilepsy (mTLE). Methods Seventeen patients with mTLE and 17 sex-/age-/handedness-matched controls participated. A seed-based correlation method for the resting-state FMRI data was implemented to get RSFC maps of 70 thalamic nuclei seed masks. Group statistics for individual RSFC for subjects and seed masks were performed to obtain within-group characteristics and between-group differences with age covariates. A linear regression was applied to test whether seizure frequency correlated with thalamic nuclear RSFC with the whole brain in mTLE patients. Results RSFC of thalamic nuclei showed spatially distinguishable connectivity patterns that reflected principal inputs and outputs that were derived from priori anatomical knowledge. We found group differences between normal control and mTLE groups in RSFC for nuclei seeds located in various subdivisions of thalamus. The RSFCs in some of those nuclei were strongly correlated with seizure frequency. Conclusions Mediodorsal thalamic nuclei may play important roles in seizure activity or in the regulation of neuronal activity in the limbic system. The RSFC of motor- and sensory-relay nuclei may help elucidate sensory-motor deficits associated with chronic seizure activity. RSFC of the pulvinar nuclei of the thalamus could also be a key reflection of symptom-related functional deficits in mTLE. We assessed the functional connectivity for 70 thalamic nuclei of temporal lobe epilepsy subjects. Each nucleus showed distinguishable connectivity along its known pathological preference. Especially, the mediodorsal thalamic nuclei may play important roles in seizure frequency.
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Affiliation(s)
- Hang Joon Jo
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA; Department of Neurologic Surgery, Mayo Clinic, Rochester, MN 55905, USA; Department of Radiology, Mayo Clinic, Rochester, MN 55905, USA.
| | | | - Irena Balzekas
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | | | - David T Jones
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA; Department of Radiology, Mayo Clinic, Rochester, MN 55905, USA
| | - Benjamin H Brinkmann
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA; Department of Biomedical Engineering and Physiology, Mayo Clinic, Rochester, MN 55905, USA
| | - S Matt Stead
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | | | - Kirk M Welker
- Department of Radiology, Mayo Clinic, Rochester, MN 55905, USA
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12
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Alagapan S, Lustenberger C, Hadar E, Shin HW, Frӧhlich F. Low-frequency direct cortical stimulation of left superior frontal gyrus enhances working memory performance. Neuroimage 2019; 184:697-706. [PMID: 30268847 PMCID: PMC6240347 DOI: 10.1016/j.neuroimage.2018.09.064] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 08/02/2018] [Accepted: 09/21/2018] [Indexed: 02/02/2023] Open
Abstract
The neural substrates of working memory are spread across prefrontal, parietal and cingulate cortices and are thought to be coordinated through low frequency cortical oscillations in the theta (3-8 Hz) and alpha (8-12 Hz) frequency bands. While the functional role of many subregions have been elucidated using neuroimaging studies, the role of superior frontal gyrus (SFG) is not yet clear. Here, we combined electrocorticography and direct cortical stimulation in three patients implanted with subdural electrodes to assess if superior frontal gyrus is indeed involved in working memory. We found left SFG exhibited task-related modulation of oscillations in the theta and alpha frequency bands specifically during the encoding epoch. Stimulation at the frequency matched to the endogenous oscillations resulted in reduced reaction times in all three participants. Our results provide evidence for SFG playing a functional role in working memory and suggest that SFG may coordinate working memory through low-frequency oscillations thus bolstering the feasibility of using intracranial electric stimulation for restoring cognitive function.
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Affiliation(s)
- Sankaraleengam Alagapan
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Caroline Lustenberger
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Eldad Hadar
- Department of Neurosurgery, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Hae Won Shin
- Department of Neurosurgery, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Flavio Frӧhlich
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA; Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
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13
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Gao Y, Zheng J, Li Y, Guo D, Wang M, Cui X, Ye W. Abnormal default-mode network homogeneity in patients with temporal lobe epilepsy. Medicine (Baltimore) 2018; 97:e11239. [PMID: 29952987 PMCID: PMC6039636 DOI: 10.1097/md.0000000000011239] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Default-mode network (DMN) plays a key role in a broad-scale cognitive problem, which occurs in temporal lobe epilepsy (TLE). However, little is known about the alterations of the network homogeneity (NH) of DMN in TLE. In the present study, we employed NH method to investigate the NH of DMN in TLE at rest.A total of 47 patients with TLE (right TLE [rTLE] 29, and left TLE [lTLE] 18) and 35 healthy controls who underwent resting-state functional magnetic resonance imaging were enrolled. NH approach was used to analyze the data.rTLE exhibited decreased NH in the right middle temporal pole gyrus and increased NH in the bilateral posterior cingulate cortex compared to the control group. In lTLE, decreased NH was observed in left inferior temporal gyrus and left hippocampus. Meanwhile, we found that lTLE had a longer performance reaction time. No significant correlation was found between abnormal NH values and clinical variables in the patients.These findings suggested that abnormal NH of the DMN exists in rTLE and lTLE, and highlighted the significance of DMN in the pathophysiology of cognitive problems occurring in TLE and also found the existence of abnormality of executive function in lTLE.
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Affiliation(s)
| | | | | | | | | | | | - Wei Ye
- Department of Radiology, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China
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14
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Tailby C, Kowalczyk MA, Jackson GD. Cognitive impairment in epilepsy: the role of reduced network flexibility. Ann Clin Transl Neurol 2017; 5:29-40. [PMID: 29376090 PMCID: PMC5771327 DOI: 10.1002/acn3.503] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Accepted: 10/18/2017] [Indexed: 01/10/2023] Open
Abstract
Objective The dominant model of cognitive impairment in focal epilepsy has emphasised structural bases for cognitive deficits. Current theories of cognition in the healthy brain emphasise the importance of the reweighting of brain network interactions in support of task performance. Here, we explore the hypothesis that cognitive deficits in epilepsy arise through abnormalities of dynamic functional network interactions. Method We studied 19 healthy controls and 37 temporal lobe epilepsy (TLE) patients, using a behavioural measure of verbal fluency (the Controlled Oral Word Association Test) and an fMRI verbal fluency paradigm (Orthographic Lexical Retrieval). Results Behaviourally, verbal fluency was significantly impaired in TLE. Psychophysiological interaction analyses of the fMRI data, which capture state-dependent changes in network connectivity, revealed reduced task-dependent modulations of connectivity from left superior medial frontal cortex to left middle frontal gyrus in TLE patients. Individual differences in verbal fluency among TLE cases was correlated with task-dependent changes in connectivity from left posterior cingulate to left superior medial frontal cortex, and from left superior medial frontal cortex to a range of right predominant brain areas. Interpretation These data reveal that the typical pattern of task-driven shifts in network connectivity is not observed in TLE. Our observations go beyond simple structure-function associations and suggest that failure of network flexibility can be an important contributor to cognitive impairment in epilepsy.
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Affiliation(s)
- Chris Tailby
- Florey Institute of Neuroscience and Mental Health Heidelberg Victoria Australia.,Institute for Social Neuroscience Heidelberg Victoria Australia.,Austin Health Heidelberg Victoria Australia
| | | | - Graeme D Jackson
- Florey Institute of Neuroscience and Mental Health Heidelberg Victoria Australia.,Austin Health Heidelberg Victoria Australia.,The University of Melbourne Parkville Victoria Australia
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15
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Englot DJ, D'Haese PF, Konrad PE, Jacobs ML, Gore JC, Abou-Khalil BW, Morgan VL. Functional connectivity disturbances of the ascending reticular activating system in temporal lobe epilepsy. J Neurol Neurosurg Psychiatry 2017. [PMID: 28630376 PMCID: PMC5634927 DOI: 10.1136/jnnp-2017-315732] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVE Seizures in temporal lobe epilepsy (TLE) disturb brain networks and lead to connectivity disturbances. We previously hypothesised that recurrent seizures in TLE may lead to abnormal connections involving subcortical activating structures including the ascending reticular activating system (ARAS), contributing to neocortical dysfunction and neurocognitive impairments. However, no studies of ARAS connectivity have been previously reported in patients with epilepsy. METHODS We used resting-state functional MRI recordings in 27 patients with TLE (67% right sided) and 27 matched controls to examine functional connectivity (partial correlation) between eight brainstem ARAS structures and 105 cortical/subcortical regions. ARAS nuclei included: cuneiform/subcuneiform, dorsal raphe, locus coeruleus, median raphe, parabrachial complex, pontine oralis, pedunculopontine and ventral tegmental area. Connectivity patterns were related to disease and neuropsychological parameters. RESULTS In control subjects, regions showing highest connectivity to ARAS structures included limbic structures, thalamus and certain neocortical areas, which is consistent with prior studies of ARAS projections. Overall, ARAS connectivity was significantly lower in patients with TLE than controls (p<0.05, paired t-test), particularly to neocortical regions including insular, lateral frontal, posterior temporal and opercular cortex. Diminished ARAS connectivity to these regions was related to increased frequency of consciousness-impairing seizures (p<0.01, Pearson's correlation) and was associated with impairments in verbal IQ, attention, executive function, language and visuospatial memory on neuropsychological evaluation (p<0.05, Spearman's rho or Kendell's tau-b). CONCLUSIONS Recurrent seizures in TLE are associated with disturbances in ARAS connectivity, which are part of the widespread network dysfunction that may be related to neurocognitive problems in this devastating disorder.
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Affiliation(s)
- Dario J Englot
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Pierre-Francois D'Haese
- Department of Electrical Engineering, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Peter E Konrad
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Monica L Jacobs
- Department of Psychiatry and Behavioral Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - John C Gore
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Bassel W Abou-Khalil
- Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Victoria L Morgan
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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16
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Farrell JS, Wolff MD, Teskey GC. Neurodegeneration and Pathology in Epilepsy: Clinical and Basic Perspectives. ADVANCES IN NEUROBIOLOGY 2017; 15:317-334. [PMID: 28674987 DOI: 10.1007/978-3-319-57193-5_12] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Epilepsy is commonly associated with a number of neurodegenerative and pathological alterations in those areas of the brain that are involved in repeated electrographic seizures. These most prominently include neuron loss and an increase in astrocyte number and size but may also include enhanced blood-brain barrier permeability, the formation of new capillaries, axonal sprouting, and central inflammation. In animal models in which seizures are either repeatedly elicited or are self-generated, a similar set of neurodegenerative and pathological alterations in brain anatomy are observed. The primary causal agent responsible for these alterations may be the cascade of events that follow a seizure and lead to an hypoperfusion/hypoxic episode. While epilepsy has long and correctly been considered an electrical disorder, the vascular system likely plays an important causal role in the neurodegeneration and pathology that occur as a consequence of repeated seizures.
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Affiliation(s)
- Jordan S Farrell
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Marshal D Wolff
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - G Campbell Teskey
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, T2N 4N1, Canada.
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17
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Mapping the neuropsychological profile of temporal lobe epilepsy using cognitive network topology and graph theory. Epilepsy Behav 2016; 63:9-16. [PMID: 27532489 PMCID: PMC5048539 DOI: 10.1016/j.yebeh.2016.07.030] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 07/01/2016] [Accepted: 07/24/2016] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Normal cognitive function is defined by harmonious interaction among multiple neuropsychological domains. Epilepsy has a disruptive effect on cognition, but how diverse cognitive abilities differentially interact with one another compared with healthy controls (HC) is unclear. This study used graph theory to analyze the community structure of cognitive networks in adults with temporal lobe epilepsy (TLE) compared with that in HC. METHODS Neuropsychological assessment was performed in 100 patients with TLE and 82 HC. For each group, an adjacency matrix was constructed representing pair-wise correlation coefficients between raw scores obtained in each possible test combination. For each cognitive network, each node corresponded to a cognitive test; each link corresponded to the correlation coefficient between tests. Global network structure, community structure, and node-wise graph theory properties were qualitatively assessed. RESULTS The community structure in patients with TLE was composed of fewer, larger, more mixed modules, characterizing three main modules representing close relationships between the following: 1) aspects of executive function (EF), verbal and visual memory, 2) speed and fluency, and 3) speed, EF, perception, language, intelligence, and nonverbal memory. Conversely, controls exhibited a relative division between cognitive functions, segregating into more numerous, smaller modules consisting of the following: 1) verbal memory, 2) language, perception, and intelligence, 3) speed and fluency, and 4) visual memory and EF. Overall node-wise clustering coefficient and efficiency were increased in TLE. SIGNIFICANCE Adults with TLE demonstrate a less clear and poorly structured segregation between multiple cognitive domains. This panorama suggests a higher degree of interdependency across multiple cognitive domains in TLE, possibly indicating compensatory mechanisms to overcome functional impairments.
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18
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Esfahani-Bayerl N, Finke C, Braun M, Düzel E, Heekeren HR, Holtkamp M, Hasper D, Storm C, Ploner CJ. Visuo-spatial memory deficits following medial temporal lobe damage: A comparison of three patient groups. Neuropsychologia 2016; 81:168-179. [PMID: 26765639 DOI: 10.1016/j.neuropsychologia.2015.12.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 12/01/2015] [Accepted: 12/22/2015] [Indexed: 10/22/2022]
Abstract
The contributions of the hippocampal formation and adjacent regions of the medial temporal lobe (MTL) to memory are still a matter of debate. It is currently unclear, to what extent discrepancies between previous human lesion studies may have been caused by the choice of distinct patient models of MTL dysfunction, as disorders affecting this region differ in selectivity, laterality and mechanisms of post-lesional compensation. Here, we investigated the performance of three distinct patient groups with lesions to the MTL with a battery of visuo-spatial short-term memory tasks. Thirty-one subjects with either unilateral damage to the MTL (postsurgical lesions following resection of a benign brain tumor, 6 right-sided lesions, 5 left) or bilateral damage (10 post-encephalitic lesions, 10 post-anoxic lesions) performed a series of tasks requiring short-term memory of colors, locations or color-location associations. We have shown previously that performance in the association task critically depends on hippocampal integrity. Patients with postsurgical damage of the MTL showed deficient performance in the association task, but performed normally in color and location tasks. Patients with left-sided lesions were almost as impaired as patients with right-sided lesions. Patients with bilateral post-encephalitic lesions showed comparable damage to MTL sub-regions and performed similarly to patients with postsurgical lesions in the association task. However, post-encephalitic patients showed additional impairments in the non-associative color and location tasks. A strikingly similar pattern of deficits was observed in post-anoxic patients. These results suggest a distinct cerebral organization of associative and non-associative short-term memory that was differentially affected in the three patient groups. Thus, while all patient groups may provide appropriate models of medial temporal lobe dysfunction in associative visuo-spatial short-term memory, additional deficits in non-associative memory tasks likely reflect damage of regions outside the MTL. Importantly, the choice of a patient model in human lesion studies of the MTL significantly influences overall performance patterns in visuo-spatial memory tasks.
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Affiliation(s)
| | - Carsten Finke
- Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany; Berlin School of Mind and Brain, Humboldt-Universität, Berlin, Germany
| | - Mischa Braun
- Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Emrah Düzel
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University Magdeburg, Magdeburg, Germany; German Center for Neurodegenerative Diseases (DZNE) Site, Magdeburg, Germany; Institute of Cognitive Neuroscience, University College London, London, United Kingdom
| | - Hauke R Heekeren
- Department of Education and Psychology, Freie Universität Berlin, Berlin, Germany; Cluster of Excellence "Languages of Emotion", Freie Universität Berlin, Berlin, Germany
| | - Martin Holtkamp
- Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany; Epilepsy-Center Berlin-Brandenburg, Evangelisches Krankenhaus Königin Elisabeth Herzberge, Berlin, Germany
| | - Dietrich Hasper
- Department of Nephrology and Medical Intensive Care Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Christian Storm
- Department of Nephrology and Medical Intensive Care Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Christoph J Ploner
- Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
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Li H, Fan W, Yang J, Song S, Liu Y, Lei P, Shrestha L, Mella G, Chen W, Xu H. Asymmetry in cross-hippocampal connectivity in unilateral mesial temporal lobe epilepsy. Epilepsy Res 2015; 118:14-21. [PMID: 26561924 DOI: 10.1016/j.eplepsyres.2015.10.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 09/15/2015] [Accepted: 10/25/2015] [Indexed: 01/06/2023]
Abstract
Mesial temporal lobe epilepsy (mTLE) is mostly characterized by hippocampal sclerosis (HS) changes. Although considerable progress has been made in understanding the altered functional network of mTLE patients, whether one side of the abnormal hippocampal (HP) structure will affect the other healthy side of the hippocampal network is still unclear. Here, we used a seed-based method to explore the commonly alterative hippocampal network in mTLE patients by comparing the bilateral hippocampal network of unilateral mTLE patients with healthy control participants. We observed that both sides of the hippocampal network in unilateral mTLE patients were changed independent of the affected or "healthy" side, which may suggest a common plasticity network for both sides of hippocampal sclerosis mesial temporal lobe epilepsy patients. Furthermore, using the HP as the ROI, we found that the functional connectivity of the intra-HP in the left mTLE-HS group was moderately positively correlated with the duration of the disease, while a strong negative correlation between functional connectivity of the intra-HP and duration were detected in the right mTLE-HS group, which suggested that it was easier for the right HP than the left HP to communicate with the contralateral HP according to the progression of mTLE disease because the hippocampus plays different roles in the communication and compensatory mechanism associated with the contralateral side of the hemisphere. We hope that this potential relevance may help us to better characterize mTLE with hippocampal sclerosis and ultimately assist in providing a better diagnosis and more accurate invasive treatments of mTLE.
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Affiliation(s)
- Hong Li
- Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Wenliang Fan
- Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Jie Yang
- Department of Communication Sciences and Disorders, Massachusetts General Hospital Institute of Health Professions, Boston, MA, USA.
| | - Shuyan Song
- School of Life Science and Technology, Key Laboratory of Image Processing and Intelligent Control of Education Ministry of China, Huazhong University of Science and Technology, Wuhan 430074, China.
| | - Yuan Liu
- Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Ping Lei
- Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Lochan Shrestha
- Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Grace Mella
- Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Wei Chen
- Department of Radiology, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, China; Radiology and Medical Imaging Center, The First People's Hospital of Yibin, Sichuan 644000, China.
| | - Haibo Xu
- Department of Radiology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; Department of Radiology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China.
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20
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Hu Y, Mi X, Xu X, Fang W, Zeng K, Yang M, Li C, Wang S, Li M, Wang X. The Brain Activity in Brodmann Area 17: A Potential Bio-Marker to Predict Patient Responses to Antiepileptic Drugs. PLoS One 2015; 10:e0139819. [PMID: 26439500 PMCID: PMC4595505 DOI: 10.1371/journal.pone.0139819] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 07/28/2015] [Indexed: 12/29/2022] Open
Abstract
In this study, we aimed to predict newly diagnosed patient responses to antiepileptic drugs (AEDs) using resting-state functional magnetic resonance imaging tools to explore changes in spontaneous brain activity. We recruited 21 newly diagnosed epileptic patients, 8 drug-resistant (DR) patients, 11 well-healed (WH) patients, and 13 healthy controls. After a 12-month follow-up, 11 newly diagnosed epileptic patients who showed a poor response to AEDs were placed into the seizures uncontrolled (SUC) group, while 10 patients were enrolled in the seizure-controlled (SC) group. By calculating the amplitude of fractional low-frequency fluctuations (fALFF) of blood oxygen level-dependent signals to measure brain activity during rest, we found that the SUC patients showed increased activity in the bilateral occipital lobe, particularly in the cuneus and lingual gyrus compared with the SC group and healthy controls. Interestingly, DR patients also showed increased activity in the identical cuneus and lingual gyrus regions, which comprise Brodmann's area 17 (BA17), compared with the SUC patients; however, these abnormalities were not observed in SC and WH patients. The receiver operating characteristic (ROC) curves indicated that the fALFF value of BA17 could differentiate SUC patients from SC patients and healthy controls with sufficient sensitivity and specificity prior to the administration of medication. Functional connectivity analysis was subsequently performed to evaluate the difference in connectivity between BA17 and other brain regions in the SUC, SC and control groups. Regions nearby the cuneus and lingual gyrus were found positive connectivity increased changes or positive connectivity changes with BA17 in the SUC patients, while remarkably negative connectivity increased changes or positive connectivity decreased changes were found in the SC patients. Additionally, default mode network (DMN) regions showed negative connectivity increased changes or negative changes with BA17 in the SUC patients. The abnormal increased in BA17 activity may be a key point that plays a substantial role in facilitating seizure onset.
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Affiliation(s)
- Yida Hu
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China
| | - Xiujuan Mi
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China
| | - Xin Xu
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China
| | - Weidong Fang
- Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China
| | - Kebin Zeng
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China
| | - Mingming Yang
- Department of Pediatrics, Chongqing City Hospital of Traditional Chinese Medicine, Chongqing, People’s Republic of China
| | - Chenyu Li
- Department of Neurology, Chongqing City Hospital of Traditional Chinese Medicine, Chongqing, People’s Republic of China
| | - Shasha Wang
- The Nursing Department, Chongqing Three Gorges Central Hospital, Chongqing, People’s Republic of China
| | - Minghui Li
- The Nursing Department, First Hospital of Shanxi Medical University, Taiyuan, People’s Republic of China
| | - Xuefeng Wang
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China
- * E-mail:
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Jin SH, Chung CK. Functional substrate for memory function differences between patients with left and right mesial temporal lobe epilepsy associated with hippocampal sclerosis. Epilepsy Behav 2015; 51:251-8. [PMID: 26300534 DOI: 10.1016/j.yebeh.2015.07.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 07/24/2015] [Accepted: 07/24/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVE Little is known about the functional substrate for memory function differences in patients with left or right mesial temporal lobe epilepsy (mTLE) associated with hippocampal sclerosis (HS) from an electrophysiological perspective. To characterize these differences, we hypothesized that hippocampal theta connectivity in the resting-state might be different between patients with left and right mTLE with HS and be correlated with memory performance. METHODS Resting-state hippocampal theta connectivity, identified via whole-brain magnetoencephalography, was evaluated. Connectivity and memory function in 41 patients with mTLE with HS (left mTLE=22; right mTLE=19) were compared with those in 46 age-matched healthy controls and 28 patients with focal cortical dysplasia (FCD) but without HS. RESULTS Connectivity between the right hippocampus and the left middle frontal gyrus was significantly stronger in patients with right mTLE than in patients with left mTLE. Moreover, this connectivity was positively correlated with delayed verbal recall and recognition scores in patients with mTLE. Patients with left mTLE had greater delayed recall impairment than patients with right mTLE and FCD. Similarly, delayed recognition performance was worse in patients with left mTLE than in patients with right mTLE and FCD. No significant differences in memory function between patients with right mTLE and FCD were detected. Patients with right mTLE showed significantly stronger hippocampal theta connectivity between the right hippocampus and left middle frontal gyrus than patients with FCD and left mTLE. CONCLUSION Our results suggest that right hippocampal-left middle frontal theta connectivity could be a functional substrate that can account for differences in memory function between patients with left and right mTLE. This functional substrate might be related to different compensatory mechanisms against the structural hippocampal lesions in left and right mTLE groups. Given the positive correlation between connectivity and delayed verbal memory function, hemispheric-specific hippocampal-frontal theta connectivity assessment could be useful as an electrophysiological indicator of delayed verbal memory function in patients with mTLE with HS.
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Affiliation(s)
- Seung-Hyun Jin
- Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Chun Kee Chung
- Neuroscience Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Neurosurgery, Seoul National University Hospital, Seoul, Republic of Korea; Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, Republic of Korea.
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22
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Zheng JO, Yu L, Huang DH, Cao XL, Chen ZR, Ye W. Reduced self-regulation of cerebrum contributes to executive impairment in patients with temporal lobe epilepsy. Int J Clin Exp Med 2015; 8:9610-9619. [PMID: 26309635 PMCID: PMC4538127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 04/28/2015] [Indexed: 06/04/2023]
Abstract
The aim of this study was to investigate the role of self-regulation of cerebrum in the executive impairment. 22 subjects were enrolled were assessed by a neuropsychological test of executive function using attentional networks test and the cerebral activity was evaluated by functional magnetic resonance imaging. The patients with TLE had a longer reaction time than controls (P < 0.05). Moreover, the healthy controls showed more right hemisphere lateralized activation in incongruent tasks. Finally, both positively and negatively correlated cerebral areas were found in the healthy controls but only negatively correlated cerebral areas were found in the TLE patients. Reduced cerebral lead to areas and lack of activation of right midline positively self-regulatory cerebral areas may executive impairment in TLE patients.
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Affiliation(s)
- Jin-Ou Zheng
- Department of Neurology, The First Affiliated Hospital of Guangxi Medical UniversityNanning, Guangxi 530021, China
| | - Lu Yu
- Department of Neurology, The First Affiliated Hospital of Guangxi Medical UniversityNanning, Guangxi 530021, China
| | - Dong-Hong Huang
- Department of Neurology, The First Affiliated Hospital of Guangxi Medical UniversityNanning, Guangxi 530021, China
| | - Xiao-Li Cao
- Department of Neurology, The First Affiliated Hospital of Guangxi Medical UniversityNanning, Guangxi 530021, China
| | - Zi-Rong Chen
- Department of Neurology, The First Affiliated Hospital of Guangxi Medical UniversityNanning, Guangxi 530021, China
| | - Wei Ye
- Department of Radiology, The First Affiliated Hospital of Guangxi Medical UniversityNanning, Guangxi 530021, China
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23
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van Graan LA, Lemieux L, Chaudhary UJ. Methods and utility of EEG-fMRI in epilepsy. Quant Imaging Med Surg 2015; 5:300-12. [PMID: 25853087 DOI: 10.3978/j.issn.2223-4292.2015.02.04] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 01/22/2015] [Indexed: 12/13/2022]
Abstract
Brain activity data in general and more specifically in epilepsy can be represented as a matrix that includes measures of electrophysiology, anatomy and behaviour. Each of these sub-matrices has a complex interaction depending upon the brain state i.e., rest, cognition, seizures and interictal periods. This interaction presents significant challenges for interpretation but also potential for developing further insights into individual event types. Successful treatments in epilepsy hinge on unravelling these complexities, and also on the sensitivity and specificity of methods that characterize the nature and localization of underlying physiological and pathological networks. Limitations of pharmacological and surgical treatments call for refinement and elaboration of methods to improve our capability to localise the generators of seizure activity and our understanding of the neurobiology of epilepsy. Simultaneous electroencephalography and functional magnetic resonance imaging (EEG-fMRI), by potentially circumventing some of the limitations of EEG in terms of sensitivity, can allow the mapping of haemodynamic networks over the entire brain related to specific spontaneous and triggered epileptic events in humans, and thereby provide new localising information. In this work we review the published literature, and discuss the methods and utility of EEG-fMRI in localising the generators of epileptic activity. We draw on our experience and that of other groups, to summarise the spectrum of information provided by an increasing number of EEG-fMRI case-series, case studies and group studies in patients with epilepsy, for its potential role to elucidate epileptic generators and networks. We conclude that EEG-fMRI provides a multidimensional view that contributes valuable clinical information to localize the epileptic focus with potential important implications for the surgical treatment of some patients with drug-resistant epilepsy, and insights into the resting state and cognitive network dynamics.
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Affiliation(s)
- Louis André van Graan
- 1 Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK ; 2 MRI Unit, Epilepsy Society, Chalfont St. Peter SL9 0RJ, UK
| | - Louis Lemieux
- 1 Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK ; 2 MRI Unit, Epilepsy Society, Chalfont St. Peter SL9 0RJ, UK
| | - Umair Javaid Chaudhary
- 1 Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK ; 2 MRI Unit, Epilepsy Society, Chalfont St. Peter SL9 0RJ, UK
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24
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Schmidt CSM, Lassonde M, Gagnon L, Sauerwein CH, Carmant L, Major P, Paquette N, Lepore F, Gallagher A. Neuropsychological functioning in children with temporal lobe epilepsy and hippocampal atrophy without mesial temporal sclerosis: a distinct clinical entity? Epilepsy Behav 2015; 44:17-22. [PMID: 25597528 DOI: 10.1016/j.yebeh.2014.12.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 12/17/2014] [Accepted: 12/18/2014] [Indexed: 12/26/2022]
Abstract
Unilateral hippocampal atrophy (HA) is considered as a precursor of mesial temporal sclerosis (MTS) in some patients with temporal lobe epilepsy. However, in other cases, it has been suggested that HA without MTS may constitute a distinct epileptic entity. Hippocampal atrophy without MTS was defined as HA without T2-weighted hyperintensity, loss of internal architecture, or associated lesion seen on the MRI data. To date, no study has focused on the cognitive pattern of children with epilepsy with HA without MTS. The objectives of the present study were to characterize the cognitive profile of these children and to investigate the presence (or the absence) of material-specific memory deficits in these young patients, as found in patients with MTS. Toward this end, 16 young patients with epilepsy with either left or right HA without MTS completed a set of neuropsychological tests, assessing overall intelligence, verbal memory and nonverbal memory, and some aspects of attention and executive functions. Results showed normal intellectual functioning without specific memory deficits in these patients. Furthermore, comparison between patients with left HA and patients with right HA failed to reveal a material-specific lateralized memory pattern. Instead, attention and executive functions were found to be impaired in most patients. These results suggest that HA may constitute a distinct epileptic entity, and this information may help health-care providers initiate appropriate and timely interventions.
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Affiliation(s)
- Charlotte S M Schmidt
- Centre de Recherche du CHU Sainte-Justine, 3175 Chemin de la Côte-Sainte-Catherine, Montréal, QC H3T 1C5, Canada; Centre de Recherche en Neuropsychologie et Cognition (CERNEC), Département de Psychologie, Université de Montréal, 90 Avenue Vincent-d'Indy, Montréal, QC H2V 2S9, Canada; Department of Neuropsychology, Maastricht University, Universiteitssingel 40, 6229 Maastricht, The Netherlands
| | - Maryse Lassonde
- Centre de Recherche du CHU Sainte-Justine, 3175 Chemin de la Côte-Sainte-Catherine, Montréal, QC H3T 1C5, Canada; Centre de Recherche en Neuropsychologie et Cognition (CERNEC), Département de Psychologie, Université de Montréal, 90 Avenue Vincent-d'Indy, Montréal, QC H2V 2S9, Canada
| | - Louise Gagnon
- Centre de Recherche du CHU Sainte-Justine, 3175 Chemin de la Côte-Sainte-Catherine, Montréal, QC H3T 1C5, Canada
| | - Catherine H Sauerwein
- Centre de Recherche du CHU Sainte-Justine, 3175 Chemin de la Côte-Sainte-Catherine, Montréal, QC H3T 1C5, Canada; Centre de Recherche en Neuropsychologie et Cognition (CERNEC), Département de Psychologie, Université de Montréal, 90 Avenue Vincent-d'Indy, Montréal, QC H2V 2S9, Canada
| | - Lionel Carmant
- Centre de Recherche du CHU Sainte-Justine, 3175 Chemin de la Côte-Sainte-Catherine, Montréal, QC H3T 1C5, Canada
| | - Philippe Major
- Centre de Recherche du CHU Sainte-Justine, 3175 Chemin de la Côte-Sainte-Catherine, Montréal, QC H3T 1C5, Canada
| | - Natacha Paquette
- Centre de Recherche du CHU Sainte-Justine, 3175 Chemin de la Côte-Sainte-Catherine, Montréal, QC H3T 1C5, Canada; Centre de Recherche en Neuropsychologie et Cognition (CERNEC), Département de Psychologie, Université de Montréal, 90 Avenue Vincent-d'Indy, Montréal, QC H2V 2S9, Canada
| | - Franco Lepore
- Centre de Recherche du CHU Sainte-Justine, 3175 Chemin de la Côte-Sainte-Catherine, Montréal, QC H3T 1C5, Canada; Centre de Recherche en Neuropsychologie et Cognition (CERNEC), Département de Psychologie, Université de Montréal, 90 Avenue Vincent-d'Indy, Montréal, QC H2V 2S9, Canada
| | - Anne Gallagher
- Centre de Recherche du CHU Sainte-Justine, 3175 Chemin de la Côte-Sainte-Catherine, Montréal, QC H3T 1C5, Canada; Centre de Recherche en Neuropsychologie et Cognition (CERNEC), Département de Psychologie, Université de Montréal, 90 Avenue Vincent-d'Indy, Montréal, QC H2V 2S9, Canada.
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25
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Cuellar-Herrera M, Velasco AL, Velasco F, Trejo D, Alonso-Vanegas M, Nuche-Bricaire A, Vázquez-Barrón D, Guevara-Guzmán R, Rocha L. Alterations of 5-HT1A receptor-induced G-protein functional activation and relationship to memory deficits in patients with pharmacoresistant temporal lobe epilepsy. Epilepsy Res 2014; 108:1853-63. [PMID: 25304920 DOI: 10.1016/j.eplepsyres.2014.09.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 08/29/2014] [Accepted: 09/13/2014] [Indexed: 10/24/2022]
Abstract
The 5-hydroxytryptamine-1A (5-HT1A) receptors are known to be involved in the inhibition of seizures in epilepsy. Moreover, studies propose a role for the 5-HT1A receptor in memory function; it is believed that the higher density of this receptor in the hippocampus plays an important role in its regulation. Positron emission tomography (PET) studies in patients with mesial temporal lobe epilepsy (mTLE) have demonstrated that a decrease in 5-HT1A receptor binding in temporal regions may play a role in memory impairment. The evidences lead us to speculate whether this decrease in receptor binding is associated with a reduced receptor number or if the functionality of the 5-HT1A receptor-induced G-protein activation and/or the second messenger cascade is modified. The purpose of the present study is to determine 5-HT1A receptor-induced G-protein functional activation by 8-OH-DPAT-stimulated [(35)S]GTPγS binding assay in hippocampal tissue of surgical patients with mTLE. We correlate functional activity with epilepsy history and neuropsychological assessment of memory. We found that maximum functional activation stimulation values (Emax) of [(35)S]GTPγS binding were significantly increased in mTLE group when compared to autopsy samples. Furthermore, significant correlations were found: (1) positive coefficients between the Emax with the age of patient and frequency of seizures; (2) negative coefficients between the Emax and working memory, immediate recall and delayed recall memory tasks. Our data suggest that the epileptic hippocampus of patients with mTLE presents an increase in 5-HT1A receptor-induced G-protein functional activation, and that this altered activity is related to age and seizure frequency, as well as to memory consolidation deficit.
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Affiliation(s)
| | - Ana Luisa Velasco
- Epilepsy Clinic, Hospital General de México Dr. Eduardo Liceaga, Mexico City, Mexico.
| | - Francisco Velasco
- Epilepsy Clinic, Hospital General de México Dr. Eduardo Liceaga, Mexico City, Mexico.
| | - David Trejo
- Epilepsy Clinic, Hospital General de México Dr. Eduardo Liceaga, Mexico City, Mexico.
| | - Mario Alonso-Vanegas
- National Institute of Neurology and Neurosurgery "Manuel Velasco Suarez", Mexico City, Mexico.
| | - Avril Nuche-Bricaire
- Epilepsy Clinic, Hospital General de México Dr. Eduardo Liceaga, Mexico City, Mexico.
| | - Daruni Vázquez-Barrón
- Epilepsy Clinic, Hospital General de México Dr. Eduardo Liceaga, Mexico City, Mexico.
| | - Rosalinda Guevara-Guzmán
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico.
| | - Luisa Rocha
- Department of Pharmacobiology. Center of Research and Advanced Studies, Mexico City, Mexico.
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26
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Eddin AS, Wang J, Wu W, Sargolzaei S, Bjornson B, Jones RA, Gaillard WD, Adjouadi M. The effects of pediatric epilepsy on a language connectome. Hum Brain Mapp 2014; 35:5996-6010. [PMID: 25082062 DOI: 10.1002/hbm.22600] [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: 12/01/2013] [Revised: 06/23/2014] [Accepted: 07/22/2014] [Indexed: 01/03/2023] Open
Abstract
This study introduces a new approach for assessing the effects of pediatric epilepsy on a language connectome. Two novel data-driven network construction approaches are presented. These methods rely on connecting different brain regions using either extent or intensity of language related activations as identified by independent component analysis of fMRI. An auditory word definition decision task paradigm was used to activate the language network for 29 patients and 30 controls. Evaluations illustrated that pediatric epilepsy is associated with a network efficiency reduction. Patients showed a propensity to inefficiently use the whole brain network to perform the language task; whereas, controls seemed to efficiently use smaller segregated network components to achieve the same task. To explain the causes of the decreased efficiency, graph theoretical analysis was performed. The analysis revealed substantial global network feature differences between the patients and controls for the extent of activation network. It also showed that for both subject groups the language network exhibited small-world characteristics; however, the patient's extent of activation network showed a tendency toward randomness. It was also shown that the intensity of activation network displayed ipsilateral hub reorganization on the local level. We finally showed that a clustering scheme was able to fairly separate the subjects into their respective patient or control groups. The clustering was initiated using local and global nodal measurements. Compared to the intensity of activation network, the extent of activation network clustering demonstrated better precision. This ascertained that the network differences presented by the networks were associated with pediatric epilepsy.
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Affiliation(s)
- Anas Salah Eddin
- Department of Computer Science and Information Technology, Florida Polytechnic University, Lakeland, Florida; Department of Electrical and Computer Engineering, Florida International University, Miami, Florida
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27
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Ozelo HFB, Alessio A, Sercheli MS, Bilevicius E, Pedro T, Pereira FRS, Rondina JM, Damasceno BP, Cendes F, Covolan RJM. Pattern changes of EEG oscillations and BOLD signals associated with temporal lobe epilepsy as revealed by a working memory task. BMC Neurosci 2014; 15:52. [PMID: 24766708 PMCID: PMC4021216 DOI: 10.1186/1471-2202-15-52] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 04/14/2014] [Indexed: 11/13/2022] Open
Abstract
Background It is known that the abnormal neural activity in epilepsy may be associated to the reorganization of neural circuits and brain plasticity in various ways. On that basis, we hypothesized that changes in neuronal circuitry due to epilepsy could lead to measurable variations in patterns of both EEG and BOLD signals in patients performing some cognitive task as compared to what would be obtained in normal condition. Thus, the aim of this study was to compare the cerebral areas involved in EEG oscillations versus fMRI signal patterns during a working memory (WM) task in normal controls and patients with refractory mesial temporal lobe epilepsy (MTLE) associated with hippocampal sclerosis (HS). The study included six patients with left MTLE-HS (left-HS group) and seven normal controls (control group) matched to the patients by age and educational level, both groups undergoing a blocked design paradigm based on Sternberg test during separated EEG and fMRI sessions. This test consisted of encoding and maintenance of a variable number of consonant letters on WM. Results EEG analysis for the encoding period revealed the presence of theta and alpha oscillations in the frontal and parietal areas, respectively. Likewise, fMRI showed the co-occurrence of positive and negative BOLD signals in both brain regions. As for the maintenance period, whereas EEG analysis revealed disappearance of theta oscillation, fMRI showed decrease of positive BOLD in frontal area and increase of negative BOLD in the posterior part of the brain. Conclusions Generally speaking, these patterns of electrophysiological and hemodynamic signals were observed for both control and left-HS groups. However, the data also revealed remarkable differences between these groups that are consistent with the hypothesis of reorganization of brain circuitry associated with epilepsy.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Roberto J M Covolan
- Neurophysics Group, Gleb Wataghin Physics Institute, University of Campinas, Unicamp, Campinas, Brazil.
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28
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Stretton J, Sidhu MK, Winston GP, Bartlett P, McEvoy AW, Symms MR, Koepp MJ, Thompson PJ, Duncan JS. Working memory network plasticity after anterior temporal lobe resection: a longitudinal functional magnetic resonance imaging study. ACTA ACUST UNITED AC 2014; 137:1439-53. [PMID: 24691395 PMCID: PMC3999723 DOI: 10.1093/brain/awu061] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Temporal lobe surgery can control seizures in drug-resistant epilepsy, but its impact on working memory is poorly understood. Using functional MRI, Stretton et al. reveal improvements in working memory post-surgery, which depend upon the functional capacity of the hippocampal remnant and the functional reserve of the contralateral hippocampus. Working memory is a crucial cognitive function that is disrupted in temporal lobe epilepsy. It is unclear whether this impairment is a consequence of temporal lobe involvement in working memory processes or due to seizure spread to extratemporal eloquent cortex. Anterior temporal lobe resection controls seizures in 50–80% of patients with drug-resistant temporal lobe epilepsy and the effect of surgery on working memory are poorly understood both at a behavioural and neural level. We investigated the impact of temporal lobe resection on the efficiency and functional anatomy of working memory networks. We studied 33 patients with unilateral medial temporal lobe epilepsy (16 left) before, 3 and 12 months after anterior temporal lobe resection. Fifteen healthy control subjects were also assessed in parallel. All subjects had neuropsychological testing and performed a visuospatial working memory functional magnetic resonance imaging paradigm on these three separate occasions. Changes in activation and deactivation patterns were modelled individually and compared between groups. Changes in task performance were included as regressors of interest to assess the efficiency of changes in the networks. Left and right temporal lobe epilepsy patients were impaired on preoperative measures of working memory compared to controls. Working memory performance did not decline following left or right temporal lobe resection, but improved at 3 and 12 months following left and, to a lesser extent, following right anterior temporal lobe resection. After left anterior temporal lobe resection, improved performance correlated with greater deactivation of the left hippocampal remnant and the contralateral right hippocampus. There was a failure of increased deactivation of the left hippocampal remnant at 3 months after left temporal lobe resection compared to control subjects, which had normalized 12 months after surgery. Following right anterior temporal lobe resection there was a progressive increase of activation in the right superior parietal lobe at 3 and 12 months after surgery. There was greater deactivation of the right hippocampal remnant compared to controls between 3 and 12 months after right anterior temporal lobe resection that was associated with lesser improvement in task performance. Working memory improved after anterior temporal lobe resection, particularly following left-sided resections. Postoperative working memory was reliant on the functional capacity of the hippocampal remnant and, following left resections, the functional reserve of the right hippocampus. These data suggest that working memory following temporal lobe resection is dependent on the engagement of the posterior medial temporal lobes and eloquent cortex.
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Affiliation(s)
- Jason Stretton
- 1 Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
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Abstract
Limbic epilepsy refers to a condition that consists of epileptic seizures that originate in or preferentially involve the limbic system. The majority of cases are medically refractory, necessitating surgical resection when possible. However, even resection of structures thought to be responsible for seizure generation may not leave a patient seizure free. While mesial temporal lobe limbic structures are centrally involved, there is growing evidence that the epileptogenic network consists of a broader area, involving structures outside of the temporal lobe and the limbic system. Information on structural, functional, and metabolic connectivity in patients with limbic epilepsy is available from a large body of studies employing methods such as MRI, EEG, MEG, fMRI, PET, and SPECT scanning, implicating the involvement of various brain regions in the epileptogenic network. To date, there are no consistent and conclusive findings to define the exact boundaries of this network, but it is possible that in the future studies of network connectivity in the individual patient may allow more tailored treatment and prognosis in terms of surgical resection.
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30
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López-Frutos JM, Poch C, García-Morales I, Ruiz-Vargas JM, Campo P. Working memory retrieval differences between medial temporal lobe epilepsy patients and controls: a three memory layer approach. Brain Cogn 2013; 84:90-6. [PMID: 24333830 DOI: 10.1016/j.bandc.2013.11.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 09/18/2013] [Accepted: 11/11/2013] [Indexed: 10/25/2022]
Abstract
Multi-store models of working memory (WM) have given way to more dynamic approaches that conceive WM as an activated subset of long-term memory (LTM). The resulting framework considers that memory representations are governed by a hierarchy of accessibility. The activated part of LTM holds representations in a heightened state of activation, some of which can reach a state of immediate accessibility according to task demands. Recent neuroimaging studies have studied the neural basis of retrieval information with different states of accessibility. It was found that the medial temporal lobe (MTL) was involved in retrieving information within immediate access store and outside this privileged zone. In the current study we further explored the contribution of MTL to WM retrieval by analyzing the consequences of MTL damage to this process considering the state of accessibility of memory representations. The performance of a group of epilepsy patients with left hippocampal sclerosis in a 12-item recognition task was compared with that of a healthy control group. We adopted an embedded model of WM that distinguishes three components: the activated LTM, the region of direct access, and a single-item focus of attention. Groups did not differ when retrieving information from single-item focus, but patients were less accurate retrieving information outside focal attention, either items from LTM or items expected to be in the WM range. Analyses focused on items held in the direct access buffer showed that consequences of MTL damage were modulated by the level of accessibility of memory representations, producing a reduced capacity.
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Affiliation(s)
| | - Claudia Poch
- Department of Biological and Health Psychology, Autonoma University of Madrid, Madrid, Spain
| | - Irene García-Morales
- University Hospital of San Carlos, Epilepsy Unit, Neurology Department, Madrid, Spain; Hospital Ruber Internacional, Epilepsy Unit, Neurology Department, Madrid, Spain
| | | | - Pablo Campo
- Department of Basic Psychology, Autonoma University of Madrid, Madrid, Spain.
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Haneef Z, Lenartowicz A, Yeh HJ, Levin HS, Engel J, Stern JM. Functional connectivity of hippocampal networks in temporal lobe epilepsy. Epilepsia 2013; 55:137-45. [PMID: 24313597 DOI: 10.1111/epi.12476] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/2013] [Indexed: 12/24/2022]
Abstract
OBJECTIVE Temporal lobe epilepsy (TLE) affects brain areas beyond the temporal lobes due to connections of the hippocampi and other temporal lobe structures. Using functional connectivity magnetic resonance imaging (MRI), we determined the changes of hippocampal networks in TLE to assess for a more complete distribution of abnormality. METHODS Regions of interest (ROIs) were defined in the right and left hippocampi in three groups of participants: left TLE (n = 13), right TLE (n = 11), and healthy controls (n = 16). Brain regions functionally connected to these ROIs were identified by correlating resting-state low-frequency functional MRI (fMRI) blood oxygenation level-dependent (BOLD) signal fluctuations. The grouped results were compared using independent sample t-test. RESULTS TLE was associated with increased hippocampal connectivity involving several key areas of the limbic network (temporal lobe, insula, thalamus), frontal lobes, angular gyrus, basal ganglia, brainstem, and cerebellum, along with reduced connectivity involving areas of the sensorimotor cortex (visual, somatosensory, auditory, primary motor) and the default mode network (precuneus). Left TLE had more marked connectivity changes than right TLE. SIGNIFICANCE The observed connectivity changes in TLE indicate dysfunctional networks that underlie widespread brain involvement in TLE. There are identifiable differences in the connectivity of the hippocampi between left and right TLE.
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Affiliation(s)
- Zulfi Haneef
- Department of Neurology, Baylor College of Medicine, Houston, Texas, U.S.A; Department of Neurology, Michael E DeBakey VA Medical Center, Houston, Texas, U.S.A
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32
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Guida A, Gobet F, Nicolas S. Functional cerebral reorganization: a signature of expertise? Reexamining Guida, Gobet, Tardieu, and Nicolas' (2012) two-stage framework. Front Hum Neurosci 2013; 7:590. [PMID: 24065910 PMCID: PMC3778237 DOI: 10.3389/fnhum.2013.00590] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 09/02/2013] [Indexed: 12/27/2022] Open
Affiliation(s)
- Alessandro Guida
- Département de Psychologie, Centre de Recherche en Psychologie, Cognition et Communication, Université Rennes 2 Rennes, France
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