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Narasimhan S, González HFJ, Johnson GW, Wills KE, Paulo DL, Morgan VL, Englot DJ. Functional connectivity between mesial temporal and default mode structures may help lateralize surgical temporal lobe epilepsy. J Neurosurg 2022; 137:1571-1581. [PMID: 35364587 PMCID: PMC9525455 DOI: 10.3171/2022.1.jns212031] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 01/31/2022] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The most common surgically treatable epilepsy syndrome is mesial temporal lobe epilepsy (mTLE). Preoperative noninvasive lateralization of mTLE is challenging in part due to rapid contralateral seizure spread. Abnormal connections in both the mesial temporal lobe and resting-state networks have been described in mTLE, but it is unclear if connectivity between these networks may aid in lateralization. METHODS In 52 patients with left mTLE (LmTLE) or right mTLE (RmTLE) and 52 matched control subjects, the authors acquired 20 minutes of resting-state functional MRI (fMRI) and evaluated functional connectivity of bilateral hippocampi and amygdalae with selected resting-state networks. They used Pearson correlation, network-based statistic, and dynamic causal modeling. Also, to evaluate the clinical utility of a resting-state connectivity model in lateralizing unilateral presurgical mTLE patients, they used receiver operating characteristic curve analysis. RESULTS RmTLE patients demonstrated decreased nondirected connectivity between the right hippocampus and default mode network compared with LmTLE patients and control subjects. Network-based statistic analysis revealed that the network with most decreased connectivity that distinguished LmTLE from RmTLE patients included the right hippocampus and amygdala, right lateral orbitofrontal cortices, and bilateral inferior parietal lobules, precuneus, and medial orbitofrontal cortices. Dynamic causal modeling analysis revealed that cross-hemispheric connectivity between hippocampi and amygdalae was predominantly inward toward the epileptogenic side. A regression model incorporating these connectivity patterns was used to accurately lateralize mTLE patients with an area under the receiver operating characteristic curve of 0.87. CONCLUSIONS Evaluating fMRI connectivity between mesial temporal structures and default mode network may aid in mTLE lateralization, reduce need for intracranial monitoring, and guide surgical planning.
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Affiliation(s)
- Saramati Narasimhan
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt Institute for Surgery and Engineering, Nashville, Tennessee
- Department of Biomedical, Nashville, Tennessee
| | - Hernán F. J. González
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt Institute for Surgery and Engineering, Nashville, Tennessee
- Department of Biomedical, Nashville, Tennessee
| | - Graham W. Johnson
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt Institute for Surgery and Engineering, Nashville, Tennessee
- Department of Biomedical, Nashville, Tennessee
| | - Kristin E. Wills
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt Institute for Surgery and Engineering, Nashville, Tennessee
| | - Danika L. Paulo
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Victoria L. Morgan
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt Institute for Surgery and Engineering, Nashville, Tennessee
- Department of Biomedical, Nashville, Tennessee
| | - Dario J. Englot
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt Institute for Surgery and Engineering, Nashville, Tennessee
- Department of Biomedical, Nashville, Tennessee
- Department of Electrical Engineering and Computer Science at Vanderbilt University, Nashville, Tennessee
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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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Zhao X, Kang H, Zhou Z, Hu Y, Li J, Li S, Li J, Zhu W. Interhemispheric functional connectivity asymmetry is distinctly affected in left and right mesial temporal lobe epilepsy. Brain Behav 2022; 12:e2484. [PMID: 35166072 PMCID: PMC8933759 DOI: 10.1002/brb3.2484] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 11/15/2021] [Accepted: 12/14/2021] [Indexed: 11/09/2022] Open
Abstract
INTRODUCTION The differences of functional connectivity (FC) and functional asymmetry between left and right mesial temporal lobe epilepsy with hippocampal sclerosis (LMTLE and RMTLE) have not been completely clarified yet. The purpose of the present study is to investigate the FC changes and the FC asymmetric patterns of MTLE, and to compare the differences in FC and functional asymmetry between LMTLE and RMTLE. METHODS In total, 12 LMTLE, 11 RMTLE patients, and 23 healthy controls (HC) were included. Region of interest (ROI)-based analysis was used to evaluate FC. The right functional connectivity (rFC) and left functional connectivity (lFC) of each ROI were calculated. Asymmetry index (AI) was calculated based on the following formula: AI=100×(rFC-lFC)/[(rFC+lFC)/2]${\rm{AI\ }} = {\rm{\ }}100{\rm{\ }} \times {\rm{\ }}( {{\rm{rFC}} - {\rm{lFC}}} )/[ {( {{\rm{rFC}} + {\rm{lFC}}} )/2} ]$ . Paired t-test and univariate analysis of variance were used to analyze FC asymmetry. Linear correlation analysis was performed between significant FC changes and lateralized ROIs and epilepsy onset age and duration. RESULTS LMTLE and RMTLE patients showed different patterns of alteration in FC and functional asymmetry when compared with controls. RMTLE presented more extensive FC abnormalities than LMTLE. Regions in ipsilateral temporal lobe presented as central regions of abnormalities in both patient groups. In addition, the asymmetric characteristics of FC were reduced in MTLE compared with HC, with even more pronounced reduction for RMTLE group. Meanwhile, ROIs presented FC AI differences among the three groups were mostly involving left temporal lobe (L_hippo, L_amyg, L_TP, L_aMTG, and L_pTFusC). No correlation was found between significant FC changes and lateralized ROIs and epilepsy onset age and duration. CONCLUSION The FC and asymmetric features of MTLE are altered and involve both the temporal lobe and extra-temporal lobe. Furthermore, the altered FC and asymmetric features were distinctly affected in LMTLE and RMTLE compared to controls.
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Affiliation(s)
- Xu Zhao
- Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Huicong Kang
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhiqiang Zhou
- Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ying Hu
- Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Juan Li
- Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shihui Li
- Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jia Li
- Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wenzhen Zhu
- Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Functional connectivity of hippocampus in temporal lobe epilepsy depends on hippocampal dominance: a systematic review of the literature. J Neurol 2022; 269:221-232. [PMID: 33564915 DOI: 10.1007/s00415-020-10391-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 12/27/2020] [Accepted: 12/28/2020] [Indexed: 01/03/2023]
Abstract
BACKGROUND Lateralized alterations in hippocampal function in the resting-state have been demonstrated for patients with temporal lobe epilepsy (TLE). However, resting-state fMRI of the hippocampus has yet to be substantiated as an adjunct to standard pre-operative assessments of the seizure focus. OBJECTIVE Here we report the results of a systematic review of resting-state fMRI studies investigating laterality of hippocampal network connectivity in TLE patients. METHODS A search of the PubMed, SCOPUS, Web of Science, and Embase databases for full-length articles written in English was conducted through June 2020 using the following terms: 'resting state fMRI,' 'hippocampus,' 'epilepsy,' and 'laterality.' RESULTS Our literature search yielded a total of 42 papers. After excluding studies that did not include patients with epilepsy, utilize resting-state fMRI, or explore the relationship between functional connectivity and disease lateralization, 20 publications were selected for inclusion. From these studies, a total of 528 patients, 258 with left TLE and 270 with right TLE, and 447 healthy controls were included. Of the 20 studies included, 18 found that patients with TLE demonstrated decreased hippocampal functional connectivity ipsilateral to the epileptogenic focus and 10 additionally reported increased hippocampal functional connectivity contralateral to the epileptogenic focus. Several studies demonstrated that the duration of disease was correlated with these changes in functional connectivity. This implies that a compensatory mechanism may be present in patients with treatment-refractory TLE. CONCLUSION The consistency of this hippocampal connectivity pattern across multiple studies suggests resting-state fMRI may be useful as a non-invasive diagnostic tool for preoperative evaluation of TLE patients.
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Liang X, Pang X, Liu J, Zhao J, Yu L, Zheng J. Comparison of topological properties of functional brain networks with graph theory in temporal lobe epilepsy with different duration of disease. ANNALS OF TRANSLATIONAL MEDICINE 2020; 8:1503. [PMID: 33313248 PMCID: PMC7729351 DOI: 10.21037/atm-20-6823] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Background Our study was performed to measure the alterations in topological properties of the functional brain network of temporal lobe epilepsy (TLE) at different durations, exploring the potential progression and neuropathophysiological mechanisms of TLE. Methods Fifty-eight subjects, including 17 TLE patients with a disease duration of ≤5 years (TLE-SD), 20 TLE patients with a disease duration of >5 years (TLE-LD), and 21 healthy controls firstly underwent the Attention Network Test (ANT) to assess the alertness function and received the resting-state functional magnetic resonance imaging (rs-fMRI). Next, a functional brain network was set up, and then the related graph of theoretical network analysis was conducted. Finally, the correlation between network property and the neuropsychological score was analyzed. Results The global and local efficiencies of functional brain networks in TLE-SD patients significantly decreased and tended toward random alterations. Also, the degree centrality (DC) and nodal efficiency (Ne) in right medial pre-frontal thalamus (mPFtha) and right rostral temporal thalamus (rTtha) of TLE-SD patients significantly reduced. Further analysis showed that alertness was positively associated with the characteristic path length but negatively related to the global and local efficiencies in TLE-SD patients; alertness was negatively related to the Ne of mPFtha in TLE-LD patients. Conclusions Our study showed that the functional brain network of TLE patients might undergo compensatory reorganization as the disease progresses, which provides useful insights into the progression and mechanism of TLE.
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Affiliation(s)
- Xiulin Liang
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Xiaomin Pang
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Jinping Liu
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Jingyuan Zhao
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Lu Yu
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Jinou Zheng
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning, China
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Mihály I, Orbán-Kis K, Gáll Z, Berki ÁJ, Bod RB, Szilágyi T. Amygdala Low-Frequency Stimulation Reduces Pathological Phase-Amplitude Coupling in the Pilocarpine Model of Epilepsy. Brain Sci 2020; 10:brainsci10110856. [PMID: 33202818 PMCID: PMC7696538 DOI: 10.3390/brainsci10110856] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 10/31/2020] [Accepted: 11/11/2020] [Indexed: 02/07/2023] Open
Abstract
Temporal-lobe epilepsy (TLE) is the most common type of drug-resistant epilepsy and warrants the development of new therapies, such as deep-brain stimulation (DBS). DBS was applied to different brain regions for patients with epilepsy; however, the mechanisms of action are not fully understood. Therefore, we tried to characterize the effect of amygdala DBS on hippocampal electrical activity in the lithium-pilocarpine model in male Wistar rats. After status epilepticus (SE) induction, seizure patterns were determined based on continuous video recordings. Recording electrodes were inserted in the left and right hippocampus and a stimulating electrode in the left basolateral amygdala of both Pilo and age-matched control rats 10 weeks after SE. Daily stimulation protocol consisted of 4 × 50 s stimulation trains (4-Hz, regular interpulse interval) for 10 days. The hippocampal electroencephalogram was analyzed offline: interictal epileptiform discharge (IED) frequency, spectral analysis, and phase-amplitude coupling (PAC) between delta band and higher frequencies were measured. We found that the seizure rate and duration decreased (by 23% and 26.5%) and the decrease in seizure rate correlated negatively with the IED frequency. PAC was elevated in epileptic animals and DBS reduced the pathologically increased PAC and increased the average theta power (25.9% ± 1.1 vs. 30.3% ± 1.1; p < 0.01). Increasing theta power and reducing the PAC could be two possible mechanisms by which DBS may exhibit its antiepileptic effect in TLE; moreover, they could be used to monitor effectiveness of stimulation.
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Affiliation(s)
- István Mihály
- Department of Physiology, Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania; (K.O.-K.); (Á.-J.B.); (R.-B.B.), (T.S.)
- Correspondence: ; Tel.: +40-749-768-257
| | - Károly Orbán-Kis
- Department of Physiology, Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania; (K.O.-K.); (Á.-J.B.); (R.-B.B.), (T.S.)
| | - Zsolt Gáll
- Department of Pharmacology and Clinical Pharmacy, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania;
| | - Ádám-József Berki
- Department of Physiology, Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania; (K.O.-K.); (Á.-J.B.); (R.-B.B.), (T.S.)
| | - Réka-Barbara Bod
- Department of Physiology, Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania; (K.O.-K.); (Á.-J.B.); (R.-B.B.), (T.S.)
| | - Tibor Szilágyi
- Department of Physiology, Faculty of Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Târgu Mureș, 540142 Târgu Mureș, Romania; (K.O.-K.); (Á.-J.B.); (R.-B.B.), (T.S.)
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Xu J, Guan X, Li H, Xu X, Zhang M. Integration and segregation of functional segmented anterior and posterior hippocampal networks in memory performance. Behav Brain Res 2019; 364:256-263. [PMID: 30768997 DOI: 10.1016/j.bbr.2019.02.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Revised: 01/23/2019] [Accepted: 02/12/2019] [Indexed: 01/13/2023]
Abstract
PURPOSE To determine the association between functional connectivity (FC) of functional-segmented anterior and posterior portions of the hippocampus and performance on verbal and visual memory tests in a young, healthy population. METHODS We recruited 100 healthy participants in the age of 19-29. Resting state fMRI data were acquired and voxel-wise correlation analysis was performed to functionally divide the hippocampus. We investigated the inter-hemispheric hippocampal-cortical functional connectivity after the participants took the assessment of episodic memory using verbal (California Verbal Learning Test II, CVLT-II) and visual subtests (Rey-Osterrieth Complex Figure, ROCF). The partial correlations were used to identify the association between the intra-hemispheric hippocampal-cortical mean resting correlation and memory performance. RESULTS The results showed that the anterior and posterior hippocampal networks involved differently in verbal and visual memory. Intra-hemispheric FC between left posterior hippocampus and posterior parahippocampal gyrus (PPHG) was positively correlated with CVLT-II Trail 2 Immediate Free Recall (r = 0.223, p = 0.029). Intra-hemispheric FC between left posterior hippocampus and posterior cingulate (PCC) was negatively correlated with ROCF Immediate Recall (r = -0.217 p = 0.034). Intra-hemispheric FC between left anterior hippocampus and temporal pole (TP) negatively correlated with ROCF Delayed Recall (r = -0.228, p = 0.025). Split half resampling procedure results showed some repeatability in our subjects. CONCLUSION The present results demonstrated that, the anterior hippocampus was specifically involved in the visual memory processing, whereas the posterior hippocampus contributed to both the verbal and visual memories, which may have implications for a functionally synergetic and dissociable role of the hippocampus in different kinds of memory.
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Reorganization of anterior and posterior hippocampal networks associated with memory performance in mesial temporal lobe epilepsy. Clin Neurophysiol 2017; 128:830-838. [DOI: 10.1016/j.clinph.2017.02.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 02/14/2017] [Accepted: 02/23/2017] [Indexed: 11/23/2022]
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Englot DJ, Konrad PE, Morgan VL. Regional and global connectivity disturbances in focal epilepsy, related neurocognitive sequelae, and potential mechanistic underpinnings. Epilepsia 2016; 57:1546-1557. [PMID: 27554793 DOI: 10.1111/epi.13510] [Citation(s) in RCA: 145] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2016] [Indexed: 12/19/2022]
Abstract
Epilepsy is among the most common brain network disorders, and it is associated with substantial morbidity and increased mortality. Although focal epilepsy was traditionally considered a regional brain disorder, growing evidence has demonstrated widespread network alterations in this disorder that extend beyond the epileptogenic zone from which seizures originate. The goal of this review is to summarize recent investigations examining functional and structural connectivity alterations in focal epilepsy, including neuroimaging and electrophysiologic studies utilizing model-based or data-driven analytic methods. A significant subset of studies in both mesial temporal lobe epilepsy and focal neocortical epilepsy have demonstrated patterns of increased connectivity related to the epileptogenic zone, coupled with decreased connectivity in widespread distal networks. Connectivity patterns appear to be related to the duration and severity of disease, suggesting progressive connectivity reorganization in the setting of recurrent seizures over time. Global resting-state connectivity disturbances in focal epilepsy have been linked to neurocognitive problems, including memory and language disturbances. Although it is possible that increased connectivity in a particular brain region may enhance the propensity for seizure generation, it is not clear if global reductions in connectivity represent the damaging consequences of recurrent seizures, or an adaptive mechanism to prevent seizure propagation away from the epileptogenic zone. Overall, studying the connectome in focal epilepsy is a critical endeavor that may lead to improved strategies for epileptogenic-zone localization, surgical outcome prediction, and a better understanding of the neuropsychological implications of recurrent seizures.
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Affiliation(s)
- Dario J Englot
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, U.S.A..
| | - Peter E Konrad
- Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, U.S.A
| | - Victoria L Morgan
- Department of Radiology and Radiological Sciences, Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, U.S.A
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Vanli Yavuz EN, Bilgiç B, Matur Z, Bebek N, Gürses C, Gökyiğit A, Öktem Ö, Baykan B. Comparison of Cognitive Parameters Between Bilateral and Unilateral Hippocampal Sclerosis. Noro Psikiyatr Ars 2016; 53:199-204. [PMID: 28373795 DOI: 10.5152/npa.2016.14862] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 02/03/2016] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION Recent studies showed that hippocampal sclerosis (HS) patients with unilateral involvement had more diffuse cognitive impairment than expected. Therefore, we aimed to compare the cognitive profiles of bilateral HS (BHS) patients with unilateral HS (UHS) patients. METHODS Consecutive patients, diagnosed with epilepsy, who fulfilled two major magnetic resonance imaging (MRI) criteria (T1 atrophy and T2-FLAIR hyperintensity) for HS were included. Standard neuro-psychological test (NPT) battery consisted of the Turkish version of 15-word verbal memory processes test, Wechsler memory scale visual reproduction subtest, forward and backward digit span, phonemic and semantic fluency, and Stroop test were applied; and the groups with right HS, left HS, and bilateral HS were compared statistically. RESULTS Ninety-one patients, completing the NPT (34 males, 57 females)-16 with BHS, 36 with right HS, and 39 with left HS-were included. Six out of 43 operated patients had BHS. There were no significant differences in education and handedness of the groups. Even though NPT performances of the BHS group were found to be poor compared to UHS subgroups, this was beyond statistical significance. Comparison of BHS with the right HS group showed a significant difference in the learning score of the Verbal Memory Processes Test, but recognition scores were found to be similar in all groups. Compared to the BHS group, both right and left HS groups revealed a significant difference in delayed recall score of the Verbal Memory Processes Test. Although there were no significant differences in the postoperative parameters of the BHS group, UHS subgroups had deficits in many postoperative parameters. CONCLUSION Our study revealed that bilateral involvement of the hippocampi was correlated with a poor cognitive performance. Retrieval failure, rather than a total recall problem, in the memory of the patients resembles a more diffuse involvement not only limited to limbic structures.
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Affiliation(s)
- Ebru Nur Vanli Yavuz
- Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey
| | - Başar Bilgiç
- Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey
| | - Zeliha Matur
- Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey
| | - Nerses Bebek
- Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey
| | - Candan Gürses
- Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey
| | - Ayşen Gökyiğit
- Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey
| | - Öget Öktem
- Department of Neurology, Laboratory of Neuropsychology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey
| | - Betül Baykan
- Department of Neurology, İstanbul University İstanbul School of Medicine, İstanbul, Turkey
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