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Nakamura M, Taulu S, Tachimori H, Tomo Y, Kawashima T, Miura Y, Itatani M, Tobimatsu S. Single-trial neuromagnetic analysis reveals somatosensory dysfunction in chronic Minamata disease. Neuroimage Clin 2023; 38:103422. [PMID: 37163912 PMCID: PMC10189551 DOI: 10.1016/j.nicl.2023.103422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 04/16/2023] [Accepted: 04/24/2023] [Indexed: 05/12/2023]
Abstract
Methylmercury pollution is a global problem, and Minamata disease (MD) is a stark reminder that exposure to methylmercury can cause irreversible neurological damage. A "glove and stocking type" sensory disturbance due to injured primary sensory cortex (SI) (central somatosensory disturbance) is the most common neurologic sign in MD. As this sign is also prevalent in those with polyneuropathy, we aimed to develop an objective assessment for detecting central somatosensory disturbances in cases of chronic MD. We selected 289 healthy volunteers and 42 patients with MD. We recorded the sensory nerve action potentials (SNAPs) and somatosensory evoked magnetic fields (SEFs) to median nerve stimulation with magnetoencephalography. Single-trial epochs were classified into three categories (N20m, non-response, and P20m epochs) based on the cross-correlation between averaged sensor SEFs and individual epochs. We assessed SI responses (the appearance rate of P20m [P20m rate] and non-response epochs [non-response rate]) and early somatosensory cortical processing (N20m amplitude, reproducibility of N20m in single-trial responses [cross-correlation value], and induced gamma-band oscillations of the SI [gamma response] of single epochs excluding non-response epochs). Receiver operating characteristic curve analyses were used to examine the diagnostic accuracy of each parameter. We found that SNAPs exerted a marginal effect on the N20m. The N20m amplitude, cross-correlation value, and gamma response were significantly reduced in the MD group on either side (p < 0.0001), suggestive of altered early somatosensory cortical processing. Interestingly, the P20m rate and non-response rate were significantly increased in the MD group on either side (p < 0.0001), thereby suggesting impaired SI responses. Notably, P20m and absent N20m peaks were observed in 6 and 11 patients with MD, respectively, which may be attributed to increased numbers of P20m epochs. The cross-correlation value exhibited the highest correlation with the P20m rate or non-response rate. Thus, reduced reproducibility of N20m may play an important role in chronic MD. The cross-correlation value exhibited the highest correlation with the gamma response for both SI parameters in early somatosensory cortical processing. The area under the curve was > 0.77 (range: 0.77-0.79) for all parameters. Their confidence intervals overlapped with each other; thus, each SEF parameter likely had an approximately equivalent discrimination ability. In conclusion, chronic MD is characterized by impaired SI responses and alterations in early somatosensory cortical processing. Thus, single-trial neuromagnetic analysis of somatosensory function may be useful for detecting central somatosensory disturbance and elucidating the relevant pathophysiological mechanisms even in the context of chronic MD.
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Affiliation(s)
- Masaaki Nakamura
- Department of Clinical Medicine, National Institute for Minamata Disease, Kumamoto, Japan.
| | - Samu Taulu
- Department of Physics, University of Washington, Seattle, WA, USA; Institute for Learning and Brain Sciences, University of Washington, Seattle, WA, USA.
| | - Hisateru Tachimori
- Department of Clinical Data Science, Clinical Research & Education Promotion Division, National Center of Neurology and Psychiatry, Tokyo, Japan; Endowed Course for Health System Innovation, Keio University School of Medicine, Tokyo, Japan.
| | - Yui Tomo
- Department of Clinical Data Science, Clinical Research & Education Promotion Division, National Center of Neurology and Psychiatry, Tokyo, Japan.
| | - Takahiro Kawashima
- Department of Clinical Data Science, Clinical Research & Education Promotion Division, National Center of Neurology and Psychiatry, Tokyo, Japan.
| | - Yoko Miura
- Department of Clinical Medicine, National Institute for Minamata Disease, Kumamoto, Japan.
| | - Mina Itatani
- Department of Clinical Medicine, National Institute for Minamata Disease, Kumamoto, Japan.
| | - Shozo Tobimatsu
- Department of Orthoptics, Faculty of Medical Science, Fukuoka International University of Health and Welfare, Fukuoka, Japan.
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Hale T, Knecht A, Barbarevech K, Yue Q. Central Sulcus Misfolding: Polarity Reversal of SSEP N20 Potential in "Layered" Polymicrogyria. Neurodiagn J 2019; 59:212-218. [PMID: 31487235 DOI: 10.1080/21646821.2019.1659707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Paradoxical cortical potential polarity of the upper extremity somatosensory evoked potential (SSEP) has been reported in cases of polymicrogyria (PMG) syndrome. To date, the pathophysiological basis of this electrophysiological aberration remains under investigation. Here we present a case of mild PMG that showed "layered" microgyri in the left frontoparietal cortices affecting both hand and foot sensorimotor areas. The SSEP recordings revealed an isolated polarity reversal of N20 from the dysplastic cortex. We postulate a central sulcus misfolding theory to explain the "positive" N20 potential recorded in the PMG cortex.
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Affiliation(s)
- Tyson Hale
- Department of NeurophysiologyGeisinger Medical Center, Danville, Pennsylvania
| | - Aaron Knecht
- Department of NeurophysiologyGeisinger Medical Center, Danville, Pennsylvania
| | | | - Qing Yue
- Department of Communication Science and DisordersBloomsburg University of Pennsylvania, Bloomsburg, Pennsylvania
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Maezawa H. Cortical Mechanisms of Tongue Sensorimotor Functions in Humans: A Review of the Magnetoencephalography Approach. Front Hum Neurosci 2017; 11:134. [PMID: 28400725 PMCID: PMC5368248 DOI: 10.3389/fnhum.2017.00134] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 03/08/2017] [Indexed: 11/13/2022] Open
Abstract
The tongue plays important roles in a variety of critical human oral functions, including speech production, swallowing, mastication and respiration. These sophisticated tongue movements are in part finely regulated by cortical entrainment. Many studies have examined sensorimotor processing in the limbs using magnetoencephalography (MEG), which has high spatiotemporal resolution. Such studies have employed multiple methods of analysis, including somatosensory evoked fields (SEFs), movement-related cortical fields (MRCFs), event-related desynchronization/synchronization (ERD/ERS) associated with somatosensory stimulation or movement and cortico-muscular coherence (CMC) during sustained movement. However, the cortical mechanisms underlying the sensorimotor functions of the tongue remain unclear, as contamination artifacts induced by stimulation and/or muscle activity within the orofacial region complicates MEG analysis in the oral region. Recently, several studies have obtained MEG recordings from the tongue region using improved stimulation methods and movement tasks. In the present review, we provide a detailed overview of tongue sensorimotor processing in humans, based on the findings of recent MEG studies. In addition, we review the clinical applications of MEG for sensory disturbances of the tongue caused by damage to the lingual nerve. Increased knowledge of the physiological and pathophysiological mechanisms underlying tongue sensorimotor processing may improve our understanding of the cortical entrainment of human oral functions.
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Affiliation(s)
- Hitoshi Maezawa
- Department of Oral Physiology, Graduate School of Dental Medicine, Hokkaido University Sapporo, Japan
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Kakisaka Y, Mosher JC, Wang ZI, Jin K, Dubarry AS, Alexopoulos AV, Burgess RC. Utility of temporally-extended signal space separation algorithm for magnetic noise from vagal nerve stimulators. Clin Neurophysiol 2012; 124:1277-82. [PMID: 22727713 DOI: 10.1016/j.clinph.2012.03.082] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 02/18/2012] [Accepted: 03/10/2012] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To evaluate the utility of a temporally-extended signal space separation algorithm (tSSS) for patients with vagal nerve stimulator (VNS). METHODS We evaluated median nerve somatosensory evoked responses (SER) of magnetoencephalography (MEG) in 27 VNS patients (48 sides) with/without tSSS processing. We classified SER dipoles as 'acceptable' if: (A) the location of the dipole was in the expected location in the central sulcus, and (B) the goodness of fit value (GOF) was greater than 80%. We evaluated (1) the number of sides which produced acceptable dipoles in each dataset (i.e. with/without tSSS processing), and in cases where the both data produced reliable dipoles, (2) compared their GOFs and the 95% confidence volumes (CV) (mm(3)). Statistical differences in the GOF and CV between with/without tSSS conditions were determined by paired t test. RESULTS Only 11 (23%) responses had reliable dipoles without tSSS processing, while all 48 (100%) had acceptable dipoles under tSSS processing. Additionally, the latter group had significantly higher GOF (increased by 7% on average) and lower CV (mean decrease of 200 mm(3)) than the former (p<0.01). CONCLUSIONS Processing with tSSS quantitatively improves dipole fitting of known sources in VNS patients. SIGNIFICANCE This algorithm permits satisfactory MEG testing in the relatively commonly encountered epilepsy patient with VNS.
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Affiliation(s)
- Yosuke Kakisaka
- Epilepsy Center, Department of Neurology, The Cleveland Clinic, Cleveland, OH 44195, USA
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Shiraishi H, Ahlfors SP, Stufflebeam SM, Knake S, Larsson PG, Hämäläinen MS, Takano K, Okajima M, Hatanaka K, Saitoh S, Dale AM, Halgren E. Comparison of three methods for localizing interictal epileptiform discharges with magnetoencephalography. J Clin Neurophysiol 2011; 28:431-40. [PMID: 21946369 PMCID: PMC3190234 DOI: 10.1097/wnp.0b013e318231c86f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
PURPOSE To compare three methods of localizing the source of epileptiform activity recorded with magnetoencephalography: equivalent current dipole, minimum current estimate, and dynamic statistical parametric mapping (dSPM), and to evaluate the solutions by comparison with clinical symptoms and other electrophysiological and neuroradiological findings. METHODS Fourteen children of 3 to 15 years were studied. Magnetoencephalography was collected with a whole-head 204-channel helmet-shaped sensor array. We calculated equivalent current dipoles and made minimum current estimate and dSPM movies to estimate the cortical distribution of interictal epileptiform discharges in these patients. RESULTS The results for four patients with localization-related epilepsy and one patient with Landau-Kleffner Syndrome were consistent among all the three analysis methods. In the rest of the patients, minimum current estimate and dSPM suggested multifocal or widespread activity; in these patients, the equivalent current dipole results were so scattered that interpretation of the results was not possible. For 9 patients with localization-related epilepsy and generalized epilepsy, the epileptiform discharges were wide spread or only slow waves, but dSPM suggested a possible propagation path of the interictal epileptiform discharges. CONCLUSION Minimum current estimate and dSPM could identify the propagation of epileptiform activity with high temporal resolution. The results of dSPM were more stable because the solutions were less sensitive to background brain activity.
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Affiliation(s)
- Hideaki Shiraishi
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA.
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Barba C, Montanaro D, Cincotta M, Giovannelli F, Guerrini R. An integrated fMRI, SEPs and MEPs approach for assessing functional organization in the malformed sensorimotor cortex. Epilepsy Res 2010; 89:66-71. [PMID: 20129761 DOI: 10.1016/j.eplepsyres.2009.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2009] [Revised: 10/15/2009] [Accepted: 12/26/2009] [Indexed: 11/24/2022]
Abstract
PURPOSE Malformations of cortical development are often accompanied by an abnormal cortical pattern. Due to its propensity to involve discrete cortical areas, polymicrogyria represents an interesting model for assessing the reorganization of cortical function in relation to the disrupted anatomy. Functional MRI, TMS and SEPs can provide a highly complementary, multimodal approach to map noninvasively the functional rearrangement of sensorimotor functions in the polymicrogyric cortex, and to obtain a coherent modelling. We report here an illustrative case which is included in a patients series under study using a block design 3T fMRI, short-latency SEPs as identified on the basis of their latency, polarity, and scalp distribution and an assessment of the area and volume of the motor maps and the relative position of the center of gravity and hot spot. RESULTS A 15 years old girl, with drug-resistant epilepsy and left perisylvian polymicrogyria that was part of a large epileptogenic network including also the mesial aspect of the left frontal lobe, exhibited a normal distribution of somatomotor responses in the expected anatomic sites, with a dissociation between motor functions, which were slightly impaired in the malformed hemisphere, and bilaterally normal sensory responses. In this patient, a large resection of epileptogenic zone, sparing eloquent areas as previously identified, should be planned in order to improve seizure outcome. CONCLUSIONS An integrated fMRI, TMS and SEP mapping approach helps defining the relationship between epileptogenic zones and somatomotor areas. Studies of greater number of patients will be necessary in order to identify the general rules that determine the functional representation in the malformed cortex.
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Affiliation(s)
- C Barba
- Pediatric Neurology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Viale Pieraccini 24, 50139 Florence, Italy.
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Dumoulin SO, Jirsch JD, Bernasconi A. Functional organization of human visual cortex in occipital polymicrogyria. Hum Brain Mapp 2008; 28:1302-12. [PMID: 17437294 PMCID: PMC6871296 DOI: 10.1002/hbm.20370] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Polymicrogyrias (PMG) are cortical malformations resulting from developmental abnormalities. In animal models PMG has been associated with abnormal anatomy, function, and organization. The purpose of this study was to describe the function and organization of human polymicrogyric cortex using functional magnetic resonance imaging. Three patients with epilepsy and bilateral parasagittal occipital polymicrogyri were studied. They all had normal vision as tested by Humphrey visual field perimetry. The functional organization of the visual cortex was reconstructed using phase-encoded retinotopic mapping analysis. This method sequentially stimulates each point in the visual field along the axes of a polar-coordinate system, thereby reconstructing the representation of the visual field on the cortex. We found normal cortical responses and organization of early visual areas (V1, V2, and V3/VP). The locations of these visual areas overlapped substantially with the PMG. In five out of six hemispheres the reconstructed primary visual cortex completely fell within polymicrogyric areas. Our results suggest that human polymicrogyric cortex is not only organized in a normal fashion, but is also actively involved in processing of visual information and contributes to normal visual perception.
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Affiliation(s)
- Serge O Dumoulin
- McGill Vision Research Unit, Department of Ophthalmology, McGill University, Montréal, Canada.
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Rampp S, Stefan H. On the opposition of EEG and MEG. Clin Neurophysiol 2007; 118:1658-9. [PMID: 17574913 DOI: 10.1016/j.clinph.2007.04.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Accepted: 04/28/2007] [Indexed: 11/28/2022]
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Bast T, Wright T, Boor R, Harting I, Feneberg R, Rupp A, Hoechstetter K, Rating D, Baumgärtner U. Combined EEG and MEG analysis of early somatosensory evoked activity in children and adolescents with focal epilepsies. Clin Neurophysiol 2007; 118:1721-35. [PMID: 17572142 DOI: 10.1016/j.clinph.2007.03.037] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Revised: 03/13/2007] [Accepted: 03/15/2007] [Indexed: 11/24/2022]
Abstract
OBJECTIVE The study aimed to evaluate differences between EEG and MEG analysis of early somatosensory evoked activity in patients with focal epilepsies in localizing eloquent areas of the somatosensory cortex. METHODS Twenty-five patients (12 male, 13 female; age 4-25 years, mean 11.7 years) were included. Syndromes were classified as symptomatic in 17, idiopathic in 2 and cryptogenic in 6 cases. 10 patients presented with malformations of cortical development (MCD). 122 channel MEG and simultaneous 33-channel EEG were recorded during tactile stimulation of the thumb (sampling rate 769 Hz, band-pass 0.3-260 Hz). Forty-four hemispheres were analyzed. Hemispheres were classified as type I: normal (15), II: central structural lesion (16), III: no lesion, but central epileptic discharges (ED, 8), IV: lesion or ED outside the central region (5). Analysis of both sides including one normal and one type II or III hemisphere was possible in 15 patients. Recordings were repeated in 18 hemispheres overall. Averaged data segments were filtered (10-250 Hz) and analyzed off-line with BESA. Latencies and amplitudes of N20 and P30 were analyzed. A regional source was fitted for localizing S1 by MRI co-registration. Orientation of EEG N20 was calculated from a single dipole model. RESULTS EEG and MEG lead to comparable good results in all normal hemispheres. Only EEG detected N20/P30 in 3 hemispheres of types II/III while MEG showed no signal. N20 dipoles had a more radial orientation in these cases. MEG added information in one hemisphere, when EEG source analysis of a clear N20 was not possible because of a low signal-to-noise ratio. Overall N20 dipoles had a more radial orientation in type II when compared to type I hemispheres (p=0.01). Further N20/P30 parameters (amplitudes, latencies, localization related to central sulcus) showed no significant differences between affected and normal hemispheres. Early somatosensory evoked activity was preserved within the visible lesion in 5 of the 10 patients with MCD. CONCLUSIONS MEG should be combined with EEG when analyzing tactile evoked activities in hemispheres with a central structural lesion or ED focus. SIGNIFICANCE At time, MEG analysis is frequently applied without simultaneous EEG. Our results clearly show that EEG may be superior under specific circumstances and combination is necessary when analyzing activity from anatomically altered cortex.
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Affiliation(s)
- T Bast
- Department of Pediatric Neurology, University Children's Hospital, INF 150, 69120 Heidelberg, Germany.
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Zsombok A, Jacobs KM. Postsynaptic currents prior to onset of epileptiform activity in rat microgyria. J Neurophysiol 2007; 98:178-86. [PMID: 17475719 DOI: 10.1152/jn.00106.2007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Structural malformations of the cortex, arising as a result of genetic mutation or injury during development are associated with dyslexia, epilepsy, and other neurological deficits. We have used a rat model of a microgyral malformation to examine mechanisms of epileptogenesis. Our previous studies showed that the frequency of miniature excitatory postsynaptic currents (mEPSCs) recorded in neocortical layer V pyramidal neurons is increased in malformed cortex at a time when field potential epileptiform events can be evoked. Here we show that the increase occurs at an age before onset of cortical epileptiform activity and at a time when the frequency of mEPSCs in control layer V pyramidal neurons is stable. An increase in the frequency of spontaneous (s)EPSCs in layer V pyramidal neurons of malformed cortex occurs earlier than that for mEPSCs, suggesting that there may additionally be alterations in intrinsic properties that increase the excitability of the cortical afferents. Frequencies of EPSC bursts and late evoked activity were also increased in malformed cortex. These results suggest that a hyperinnervation of layer V pyramidal neurons by excitatory afferents occurs as an active process likely contributing to subsequent development of field epileptiform events.
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Affiliation(s)
- A Zsombok
- Dept of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA 23298, USA
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