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Slušná D, Kohli JS, Hau J, Álvarez-Linera Prado J, Linke AC, Hinzen W. Functional dysregulation of the auditory cortex in bilateral perisylvian polymicrogyria: Multiparametric case analysis of the absent speech phenotype. Cortex 2024; 171:423-434. [PMID: 38109835 DOI: 10.1016/j.cortex.2023.11.006] [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: 06/20/2023] [Revised: 10/23/2023] [Accepted: 11/02/2023] [Indexed: 12/20/2023]
Abstract
The absence of speech is a clinical phenotype seen across neurodevelopmental syndromes, offering insights for neural language models. We present a case of bilateral perisylvian polymicrogyria (BPP) and complete absence of speech with considerable language comprehension and production difficulties. We extensively characterized the auditory speech perception and production circuitry by employing a multimodal neuroimaging approach. Results showed extensive cortical thickening in motor and auditory-language regions. The auditory cortex lacked sensitivity to speech stimuli despite relatively preserved thalamic projections yet had no intrinsic functional organization. Subcortical structures implicated in early stages of processing exhibited heightened sensitivity to speech. The arcuate fasciculus, a suggested marker of language in BPP, showed similar volume and integrity to a healthy control. The frontal aslant tract, linked to oromotor function, was partially reconstructed. These findings highlight the importance of assessing the auditory cortex beyond speech production structures to understand absent speech in BPP. Despite profound cortical alterations, the intrinsic motor network and motor-speech pathways remained largely intact. This case underscores the need for comprehensive phenotyping using multiple MRI modalities to uncover causes of severe disruption in language development.
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Affiliation(s)
- Dominika Slušná
- Department of Translation and Language Sciences, Campus Poblenou, Pompeu Fabra University, Barcelona, Spain.
| | - Jiwandeep S Kohli
- Brain Development Imaging Laboratories, Department of Psychology, San Diego State University, San Diego, CA, USA
| | - Janice Hau
- Brain Development Imaging Laboratories, Department of Psychology, San Diego State University, San Diego, CA, USA
| | | | - Annika C Linke
- Brain Development Imaging Laboratories, Department of Psychology, San Diego State University, San Diego, CA, USA
| | - Wolfram Hinzen
- Department of Translation and Language Sciences, Campus Poblenou, Pompeu Fabra University, Barcelona, Spain; Institució Catalana de Recerca I Estudis Avancats, ICREA, Barcelona, Spain
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Innocenti GM. Defining neuroplasticity. HANDBOOK OF CLINICAL NEUROLOGY 2022; 184:3-18. [PMID: 35034744 DOI: 10.1016/b978-0-12-819410-2.00001-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Neuroplasticity, i.e., the modifiability of the brain, is different in development and adulthood. The first includes changes in: (i) neurogenesis and control of neuron number; (ii) neuronal migration; (iii) differentiation of the somato-dendritic and axonal phenotypes; (iv) formation of connections; (v) cytoarchitectonic differentiation. These changes are often interrelated and can lead to: (vi) system-wide modifications of brain structure as well as to (vii) acquisition of specific functions such as ocular dominance or language. Myelination appears to be plastic both in development and adulthood, at least, in rodents. Adult neuroplasticity is limited, and is mainly expressed as changes in the strength of excitatory and inhibitory synapses while the attempts to regenerate connections have met with limited success. The outcomes of neuroplasticity are not necessarily adaptive, but can also be the cause of neurological and psychiatric pathologies.
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Cortical Visual Impairment in Childhood: 'Blindsight' and the Sprague Effect Revisited. Brain Sci 2021; 11:brainsci11101279. [PMID: 34679344 PMCID: PMC8533908 DOI: 10.3390/brainsci11101279] [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: 08/09/2021] [Revised: 09/14/2021] [Accepted: 09/24/2021] [Indexed: 11/29/2022] Open
Abstract
The paper discusses and provides support for diverse processes of brain plasticity in visual function after damage in infancy and childhood in comparison with injury that occurs in the adult brain. We provide support and description of neuroplastic mechanisms in childhood that do not seemingly exist in the same way in the adult brain. Examples include the ability to foster the development of thalamocortical connectivities that can circumvent the lesion and reach their cortical destination in the occipital cortex as the developing brain is more efficient in building new connections. Supporting this claim is the fact that in those with central visual field defects we can note that the extrastriatal visual connectivities are greater when a lesion occurs earlier in life as opposed to in the neurologically mature adult. The result is a significantly more optimized system of visual and spatial exploration within the ‘blind’ field of view. The discussion is provided within the context of “blindsight” and the “Sprague Effect”.
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Kuchukhidze G, Siedentopf C, Unterberger I, Koppelstaetter F, Kronbichler M, Zamarian L, Haberlandt E, Ischebeck A, Delazer M, Felber S, Trinka E. Language Dominance in Patients With Malformations of Cortical Development and Epilepsy. Front Neurol 2019; 10:1209. [PMID: 31824399 PMCID: PMC6881376 DOI: 10.3389/fneur.2019.01209] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 10/30/2019] [Indexed: 11/13/2022] Open
Abstract
Background: Language function may be reorganized in patients with malformations of cortical development (MCD). This prospective cohort study aimed in assessing language dominance in a large group of patients with MCD and epilepsy using functional MRI (fMRI). Methods: Sixty-eight patients (40 women) aged 10–73 years (median, 28.0; interquartile range, 19) with MCD and epilepsy underwent 1.5 T MRI and fMRI (word generation task). Single-subject image analysis was performed with statistical parametric mapping (SPM12). Language lateralization indices (LIs) were defined for statistically significantly activated voxels in Broca's and Wernicke's areas using the formula: LI = (VL – VR)/(VL + VR) × 100, where VL and VR were sets of activated voxels on the left and on the right, respectively. Language laterality was considered typical if LI was between +20 and +100 or atypical if LI was between +19 and −100. Results: fMRI signal was elicited in 55 of 68 (81%) patients. In 18 of 55 (33%) patients, language dominance was typical, and in 37 of 55 (67%) patients, atypical (in 68%, right hemispheric; in 32%, bilateral). Language dominance was not influenced by handedness, electroclinical, and imaging features. Conclusions: In this prospective study on a large group of patients with MCD and epilepsy, about two-thirds had atypical language dominance. These results may contribute to assessing risks of postsurgical language deficits and could assist in planning of “cortical mapping” with intracranial electrodes in patients who undergo presurgical assessment.
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Affiliation(s)
- Giorgi Kuchukhidze
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria.,Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University of Salzburg, Salzburg, Austria
| | - Christian Siedentopf
- Department of Neuroradiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Iris Unterberger
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Florian Koppelstaetter
- Department of Neuroradiology, Medical University of Innsbruck, Innsbruck, Austria.,Department of Radiology, Sanatorium Kettenbrücke, Innsbruck, Austria
| | - Martin Kronbichler
- Neuroscience Institute, Christian Doppler Klinik, Paracelsus Medical University of Salzburg, Salzburg, Austria.,Department of Psychology, University of Salzburg, Salzburg, Austria.,Centre for Cognitive Neuroscience, University of Salzburg, Salzburg, Austria
| | - Laura Zamarian
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Edda Haberlandt
- Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria.,Department of Pediatrics, City Hospital, Dornbirn, Austria
| | - Anja Ischebeck
- Institute of Psychology, University of Graz, Graz, Austria
| | - Margarete Delazer
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Stephan Felber
- Department of Diagnostic and Interventional Radiology and Neuroradiology, Gemeinschaftsklinikum Mittelrhein, Koblenz, Germany
| | - Eugen Trinka
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria.,Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University of Salzburg, Salzburg, Austria.,Centre for Cognitive Neuroscience, University of Salzburg, Salzburg, Austria
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5
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Lenge M, Barba C, Montanaro D, Aghakhanyan G, Frijia F, Guerrini R. Relationships Between Morphologic and Functional Patterns in the Polymicrogyric Cortex. Cereb Cortex 2019; 28:1076-1086. [PMID: 28334078 DOI: 10.1093/cercor/bhx036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 02/01/2017] [Indexed: 11/13/2022] Open
Abstract
Polymicrogyria is a malformation of cortical folding and layering underlying different cognitive and neurological manifestations. The polymicrogyric cortex has heterogeneous morphofunctional patterns, qualitatively described at magnetic resonance imaging (MRI) by variable severity gradients and functional activations. We investigated the link between abnormal cortical folding and cortical function in order to improve surgical planning for patients with polymicrogyria and intractable epilepsy. We performed structural and functional MRI on 14 patients with perisylvian polymicrogyria and adopted surface-based methods to detect alterations of cortical thickness (CT) and local gyrification index (LGI) compared with normal cortex (30 age-matched subjects). We quantitatively assessed the grade of anatomic disruption of the polymicrogyric cortex and defined its relationship with decreased cortical function. We observed a good matching between visual analysis and morphometric measurements. CT maps revealed sparse clusters of thickening, while LGI maps disclosed circumscribed regions of maximal alteration with a uniformly decreasing centrifugal gradient. In polymicrogyric areas in which gyral and sulcal patterns were preserved, functional activation maintained the expected location, but was reduced in extent. Morphofunctional correlations, evaluated along cortico-cortical paths between maximum morphologic alterations and significant activations, identified an interindividual threshold for LGI (z-value = -1.09) beyond which functional activations were no longer identifiable.
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Affiliation(s)
- Matteo Lenge
- Neuroscience Department, Children's Hospital A. Meyer-University of Florence, 50139 Florence, Italy
| | - Carmen Barba
- Neuroscience Department, Children's Hospital A. Meyer-University of Florence, 50139 Florence, Italy
| | | | | | - Francesca Frijia
- Unit of Neuroradiology.,U.O.C. Bioingegneria e Ingegneria Clinica, Fondazione G. Monasterio CNR-Regione Toscana, 56124 Pisa, Italy
| | - Renzo Guerrini
- Neuroscience Department, Children's Hospital A. Meyer-University of Florence, 50139 Florence, Italy.,IRCCS Stella Maris Foundation, 56018 Calambrone, Pisa, Italy
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Failure to Identify the Left Arcuate Fasciculus at Diffusion Tractography Is a Specific Marker of Language Dysfunction in Pediatric Patients with Polymicrogyria. Behav Neurol 2015; 2015:351391. [PMID: 26180373 PMCID: PMC4477425 DOI: 10.1155/2015/351391] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 05/11/2015] [Indexed: 11/18/2022] Open
Abstract
Background. Polymicrogyric cortex demonstrates interindividual variation with regard to both extent of dyslamination and functional capacity. Given the relationship between laminar structure and white matter fibers, we sought to define the relationship between polymicrogyria (PMG), intrahemispheric association pathways, and network function. Methods. Each arcuate fasciculus (AF) was categorized as present or absent. Language was characterized by a pediatric neurologist. The presence of dysplastic cortex in the expected anatomic locations of Broca's (BA) and Wernicke's areas (WA) was evaluated by two pediatric neuroradiologists blinded to DTI and language data. Results. 16 PMG patients and 16 age/gender-matched controls were included. All normative controls had an identifiable left AF. 6/7 PMG patients with dysplastic cortex within BA and/or WA had no left AF; PMG patients without involvement of these regions had a lower frequency of absence of the left AF (p < 0.006). All patients without a left AF had some degree of language impairment. PMG patients without a left AF had a significantly greater frequency of language impairment compared to those PMG patients with a left AF (p < 0.003). Conclusion. In patients with PMG (1) the presence of dysplastic cortex within WA and/or BA is associated with absence of the left AF and (2) absence of the left AF is associated with language impairment.
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Andrade CS, Leite CDC. Malformations of cortical development: current concepts and advanced neuroimaging review. ARQUIVOS DE NEURO-PSIQUIATRIA 2011; 67:570-4. [PMID: 21359436 DOI: 10.1590/s0004-282x2009000300041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Accepted: 04/11/2009] [Indexed: 12/17/2022]
Abstract
Malformations of cortical development (MCD) result from disruptions in the complex process of the human brain cortex formation and are highly associated to severe epilepsy, neurodevelopmental delay and motor dysfunction. Nowadays, magnetic resonance imaging (MRI) is the cornerstone of the work-up of patients with epilepsy and modern advanced imaging techniques have improved not only our ability to detect and characterize cortical malformations, but also in identifying associated functional abnormalities that are far beyond the structural visualized lesions. Herein, we address the most currently used classifications of MCD and make a concise review of the embryological process of cortical development. Our main goal is to summarize recent advances and new trends in diagnostic imaging techniques concerning MCD. Thereafter, follows a brief discussion of specific disorders and their radiological features.
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Affiliation(s)
- Celi Santos Andrade
- Radiology Department, School of Medicine, University of São Paulo, Brazil, SP, Brazil
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8
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Guzzetta A, D'Acunto G, Rose S, Tinelli F, Boyd R, Cioni G. Plasticity of the visual system after early brain damage. Dev Med Child Neurol 2010; 52:891-900. [PMID: 20561008 DOI: 10.1111/j.1469-8749.2010.03710.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aim of this review is to discuss the existing evidence supporting different processes of visual brain plasticity after early damage, as opposed to damage that occurs during adulthood. There is initial evidence that some of the neuroplastic mechanisms adopted by the brain after early damage to the visual system are unavailable at a later stage. These are, for example, the ability to differentiate functional tissue within a larger dysplastic cortex during its formation, or to develop new thalamo-cortical connections able to bypass the lesion and reach their cortical destination in the occipital cortex. The young brain also uses the same mechanisms available at later stages of development but in a more efficient way. For example, in people with visual field defects of central origin, the anatomical expansion of the extrastriatal visual network is greater after an early lesion than after a later one, which results in more efficient mechanisms of visual exploration of the blind field. A similar mechanism is likely to support some of the differences found in people with blindsight, the phenomenon of unconscious visual perception in the blind field. In particular, compared with people with late lesions, those with early brain damage appear to have stronger subjective awareness of stimuli hitting the blind visual field, reported as a conscious feeling that something is present in the visual field. Expanding our knowledge of these mechanisms could help the development of early therapeutic interventions aimed at supporting and enhancing visual reorganization at a time of greatest potential brain plasticity.
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Affiliation(s)
- Andrea Guzzetta
- Department of Developmental Neuroscience, Stella Maris Scientific Institute, Pisa, Italy.
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9
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Imaging malformations of cortical development. HANDBOOK OF CLINICAL NEUROLOGY 2008. [PMID: 18809040 DOI: 10.1016/s0072-9752(07)87026-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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10
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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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11
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12
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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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13
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Innocenti GM, Price DJ. Exuberance in the development of cortical networks. Nat Rev Neurosci 2007; 6:955-65. [PMID: 16288299 DOI: 10.1038/nrn1790] [Citation(s) in RCA: 383] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The cerebral cortex is the largest and most intricately connected part of the mammalian brain. Its size and complexity has increased during the course of evolution, allowing improvements in old functions and causing the emergence of new ones, such as language. This has expanded the behavioural and cognitive repertoire of different species and has determined their competitive success. To allow the relatively rapid emergence of large evolutionary changes in a structure of such importance and complexity, the mechanisms by which cortical circuitry develops must be flexible and yet robust against changes that could disrupt the normal functions of the networks.
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Affiliation(s)
- Giorgio M Innocenti
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, S-17177 Stockholm.
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14
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Subcortical regulation of cortical development: some effects of early, selective deprivations. PROGRESS IN BRAIN RESEARCH 2007; 164:23-37. [DOI: 10.1016/s0079-6123(07)64002-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Kinoshita M, Ikeda A, Taki J, Usui K, Matsumoto R, Mikuni N, Takahashi JB, Fukuyama H, Hashimoto N, Takahashi R. Heterogeneous epileptogenicity and cortical function within malformations of cortical development: a case report. J Neurol Sci 2006; 251:129-33. [PMID: 17097681 DOI: 10.1016/j.jns.2006.09.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Revised: 07/19/2006] [Accepted: 09/11/2006] [Indexed: 10/23/2022]
Abstract
The authors report a 24-year-old patient with intractable partial epilepsy and massive malformations of cortical development (MCD). Subdural EEG recordings of habitual seizures showed heterogeneous epileptogenicity, and visual evoked potential was recorded within the MCD just adjacent to the most active epileptogenic focus. Resection of the small cortical area presumably with core epileptogenicity, while sparing the cortical functional area, improved seizure outcome without any postoperative functional deficits.
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Affiliation(s)
- Masako Kinoshita
- Department of Neurology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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16
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Munakata M, Onuma A, Takeo K, Oishi T, Haginoya K, Iinuma K. Morphofunctional organization in three patients with unilateral polymicrogyria: combined use of diffusion tensor imaging and functional magnetic resonance imaging. Brain Dev 2006; 28:405-9. [PMID: 16503392 DOI: 10.1016/j.braindev.2005.12.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2005] [Revised: 10/13/2005] [Accepted: 12/05/2005] [Indexed: 11/26/2022]
Abstract
We examined the fiber organization of the brain in three patients with unilateral polymicrogyria (PMG) using diffusion tensor imaging (DTI) in combination with functional magnetic resonance imaging (fMRI). DTI revealed altered fiber tract architecture in patients with PMG. Long projection fibers, such as the corticospinal tract, were reduced the most, whereas long association fibers were less affected. The diminution of the fiber tracts was relevant to the loss of functionality of the PMG-affected cortex. Our preliminary study suggests that the combination of DTI and fMRI reinforces the clinical assessment of functionality in PMG.
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Affiliation(s)
- Mitsutoshi Munakata
- Department of Pediatrics, Tohoku University School of Medicine, Sendai 980-8574, Japan.
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17
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Araujo D, de Araujo DB, Pontes-Neto OM, Escorsi-Rosset S, Simao GN, Wichert-Ana L, Velasco TR, Sakamoto AC, Leite JP, Santos AC. Language and Motor fMRI Activation in Polymicrogyric Cortex. Epilepsia 2006; 47:589-92. [PMID: 16529627 DOI: 10.1111/j.1528-1167.2006.00473.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE To analyze the patterns of brain activation in polymicrogyric cortex in epilepsy patients by blood oxygenation level-dependent (BOLD) functional MRI (fMRI), during language and motor activation tasks. METHODS Five patients with extratemporal epilepsy associated with polymicrogyria were scanned in a 1.5-T Siemens scanner with BOLD fMRI sequences, by following language and motor paradigms. Functional images were processed by using Brain Voyager software. RESULTS Activation of polymicrogyric cortex in the brain area that corresponds to the motor strip was present in all patients. Language studies revealed activation of polymicrogyric cortex over Broca's area in three cases. CONCLUSIONS Functionality was shown in polymicrogyric areas. Therefore if surgical resection is indicated, a careful functional planning is necessary because of functionality of the polymicrogyric cortex.
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Affiliation(s)
- David Araujo
- Department of Neurology-FMRP, University of Sao Paulo, Ribeirao Preto, Brazil
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Knyazeva MG, Fornari E, Meuli R, Innocenti G, Maeder P. Imaging of a synchronous neuronal assembly in the human visual brain. Neuroimage 2006; 29:593-604. [PMID: 16182570 DOI: 10.1016/j.neuroimage.2005.07.045] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2005] [Revised: 07/26/2005] [Accepted: 07/29/2005] [Indexed: 10/25/2022] Open
Abstract
Perception, motion, and cognition involve the formation of cooperative neuronal assemblies distributed over the cerebral cortex. It remains to explore what characterizes the assemblies, their location, and the structural substrate of assembly formation. In this EEG/fMRI study, we describe the response of the visual areas of the two hemispheres in subjects who viewed bilateral iso-oriented (IG) or orthogonally-oriented (OG) moving gratings projected in the two hemifields. The IG stimulus synchronized activity across the hemispheres, as shown by an increased EEG coherence. The increase was restricted to the occipital electrodes and to the beta band. Compared with OG, IG increased the BOLD signal in a restricted territory corresponding to area VP/V4. Within this territory, a linear relation was found between the increased interhemispheric EEG coherence and BOLD. Thus, the increased BOLD localized a trans-hemispheric, synchronous neuronal assembly probably achieved by a callosal cortico-cortical connection. This assembly might reflect an early stage of perceptual grouping since the IG stimulus conforms to Gestalt psychology principles of collinearity and common fate.
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Affiliation(s)
- Maria G Knyazeva
- Department of Radiology, Centre Hospitalier Universitaire Vaudois, CHUV, 1011 Lausanne, Switzerland.
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19
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Palmini A, Halasz P, Scheffer IE, Takahashi Y, Jimenez AP, Dubeau F, Andermann F, Paglioli-Neto E, da Costa JC, Rosenow F, Fritsch B. Reflex Seizures in Patients with Malformations of Cortical Development and Refractory Epilepsy. Epilepsia 2005; 46:1224-34. [PMID: 16060932 DOI: 10.1111/j.1528-1167.2005.52904.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE Malformations of cortical development (MCDs) are usually highly epileptogenic, and their hyperexcitability could facilitate the occurrence of reflex seizures. We sought to characterize reflex seizures in patients with MCDs and refractory epilepsy. METHODS Clinical, electrographic, and neuroimaging data were reviewed in eight patients with MCDs who had reflex seizures reproduced during presurgical evaluation. RESULTS All eight patients had both reflex and spontaneous seizures. In six, however, drop attacks or axial myoclonic seizures occurred only upon specific sensory stimulation. Reflex seizures were induced by more than one type of stimulus in most patients, but anatomofunctional correlations could usually be invoked. Six patients had significant intellectual impairment. Surgical resection controlled seizures in two patients. CONCLUSIONS Reflex seizures in patients with MCDs may be medically refractory and may often manifest as drop attacks or axial myoclonus. Surgical resection of focal lesions can bring reflex seizures under control. Putative mechanisms related to the relatively low frequency of reflex seizures in MCDs are discussed.
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Affiliation(s)
- André Palmini
- Porto Alegre Epilepsy Surgery Program, Hospital São Lucas, Pontificia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.
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Paetau R, Saraneva J, Salonen O, Valanne L, Ignatius J, Salenius S. Electromagnetic function of polymicrogyric cortex in congenital bilateral perisylvian syndrome. J Neurol Neurosurg Psychiatry 2004; 75:717-22. [PMID: 15090566 PMCID: PMC1763559 DOI: 10.1136/jnnp.2002.004754] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Congenital bilateral perisylvian syndrome (CBPS) is characterised by bilateral perisylvian polymicrogyria and suprabulbar paresis. Mild tetraparesis, cognitive impairment, and epilepsy are frequently associated. Sensory deficits are surprisingly rare, even though polymicrogyria often extends to auditory and sensorimotor cortex. OBJECTIVES To study the sensorimotor and auditory cortex function and location in CBPS patients. METHODS We mapped the sensory and motor cortex function onto brain magnetic resonance images in six CBPS patients and seven control subjects using sources of somatosensory and auditory evoked magnetic fields, and of rhythmic magnetoencephalographic (MEG) activity phase-locked to surface electromyogram (EMG) during voluntary hand muscle contraction. RESULTS MEG-EMG coherence in CBPS patients varied from normal (if normal central sulcus anatomy) to absent, and could occur at abnormally low frequency. Coherent MEG activity was generated at the central sulcus or in the polymicrogyric frontoparietal cortex. Somatosensory and auditory evoked responses were preserved and also originated within the polymicrogyric cortex, but the locations of some source components could be grossly shifted. CONCLUSION Plastic changes of sensory and motor cortex location suggest disturbed cortex organisation in CBPS patients. Because the polymicrogyric cortex of CBPS patients may embed normal functions in unexpected locations, functional mapping should be considered before brain surgery.
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Affiliation(s)
- R Paetau
- Brain Research Unit, Low Temperature Laboratory, Helsinki University of Technology, Espoo, Finland.
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21
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Chang BS, Walsh CA. Mapping form and function in the human brain: the emerging field of functional neuroimaging in cortical malformations. Epilepsy Behav 2003; 4:618-25. [PMID: 14698694 DOI: 10.1016/j.yebeh.2003.09.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Malformations of cortical development (MCDs) are increasingly being recognized as a common cause of epilepsy in cases previously felt to be cryptogenic. MCDs occur when the normal process of cerebral cortical development is disrupted, and include disorders of neuronal proliferation, migration, and organization. Many have a genetic basis and the genes responsible for some MCDs have been identified. MCDs represent a unique and valuable substrate in functional brain mapping studies, since as developmental lesions they provide complementary information to studies performed on patients with acquired brain lesions. In recent years an increasing number of functional neuroimaging methods, including positron emission tomography, single photon emission computed tomography, magnetic resonance spectroscopy, and functional magnetic resonance imaging, have been applied to patients with MCDs. In this review we highlight some of the prominent findings in this emerging field by presenting the functional neuroimaging characteristics of selected MCDs.
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Affiliation(s)
- Bernard S Chang
- Comprehensive Epilepsy Center, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
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Francione S, Vigliano P, Tassi L, Cardinale F, Mai R, Lo Russo G, Munari C. Surgery for drug resistant partial epilepsy in children with focal cortical dysplasia: anatomical-clinical correlations and neurophysiological data in 10 patients. J Neurol Neurosurg Psychiatry 2003; 74:1493-501. [PMID: 14617703 PMCID: PMC1738223 DOI: 10.1136/jnnp.74.11.1493] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To analyse a population of children with focal cortical dysplasia operated on for drug resistant partial epilepsy, with emphasis on clinical features, seizure semiology, interictal and ictal EEG and stereo EEG findings, histological and topographical characteristics of the lesions, extension and localisation of cerebral excision, and its postoperative effect on seizure frequency. METHODS 10 patients were studied, aged between 26 months and 11 years (median 6 years). Magnetic resonance imaging (MRI) abnormalities were unilobar (temporal 3, frontal 2), bilobar (2), or multilobar (1); the two patients with negative MRI suffered from frontal seizures. Presurgical diagnostic steps varied in complexity and invasiveness depending on the anatomical/electrical/clinical features of each patient. In four patients they included only scalp video EEG monitoring, and in six, also invasive recordings using stereotactically implanted intracerebral electrodes. Surgery consisted of corticectomy plus lesionectomy in all cases. RESULTS 70% of the patients were seizure-free after a minimum postoperative follow up of 25 months. These included three patients with temporal lesions and four of seven patients with other lobar or multilobar extratemporal localisation. One patient had improvement in seizure control. Outcome was poor in multilobar patients, but a class Ia outcome was obtained in one case after partial lesionectomy associated with bilobar corticectomy. All patients showed developmental improvement. CONCLUSIONS Analysis of the data in these patients allowed the production of an "anatomical-clinical concordance" list, which appeared to be correlated with the diagnostic steps performed. Carrying out a stereo EEG exploration in the most complex cases proved useful in defining the epileptogenic zone in extratemporal and multilobar epilepsies. Stereo EEG recordings facilitated a tailored resection of extralesional cortex.
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Affiliation(s)
- S Francione
- Epilepsy Surgery Centre "C Munari", Department of Neuroscience, Niguarda Hospital, Milan, Italy.
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23
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Restrepo CE, Manger PR, Spenger C, Innocenti GM. Immature cortex lesions alter retinotopic maps and interhemispheric connections. Ann Neurol 2003; 54:51-65. [PMID: 12838520 DOI: 10.1002/ana.10591] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Unilateral lesions of the occipital visual areas performed on postnatal day 5 (P5) in the ferret are not compensated by the appearance, in the lesioned hemisphere, of visual responses at ectopic locations. Instead, when parts of the visual areas are spared, they show abnormal retinotopic organizations; furthermore, callosal connections are abnormally distributed in relation to the retinotopic maps. Lesions that completely eliminate the visual areas including the posterior parietal cortex cause the appearance of abnormal callosal connections from the primary somatosensory cortex on the lesion side to the contralateral, intact, posterior parietal cortex. The occipital visual areas (17, 18, 19, and 21) of the intact hemisphere show a normal retinotopy but lose callosal connections in territories homotopic to the lesions. These findings clarify the nature and limits of structural developmental plasticity in the visual cortex. Early in life, certain regions of cortex have been irreversibly allocated to the visual areas, but two properties defining the areas, that is, retinotopy and connections, remain modifiable. The findings might be relevant for understanding the consequences of early-onset visual cortical lesions in humans.
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Affiliation(s)
- C Ernesto Restrepo
- Division of Neuroanatomy and Brain Development, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
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Janszky J, Ebner A, Kruse B, Mertens M, Jokeit H, Seitz RJ, Witte OW, Tuxhorn I, Woermann FG. Functional organization of the brain with malformations of cortical development. Ann Neurol 2003; 53:759-67. [PMID: 12783422 DOI: 10.1002/ana.10545] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We examined the localization of cerebral functions in 28 patients with focal epilepsy and malformations of cortical development (MCDs). Polymicrogyria occurred in nine, hemimegalencephaly in four, heterotopia in eight, and focal cortical dysplasia (FCD) in nine cases. We used simple (sensomotor, visual) or complex (language, memory) functional magnetic resonance imaging (fMRI) paradigms. Two thirds of MCDs were activated by simple fMRI paradigms, whereas they less frequently showed activity during complex cognitive fMRI paradigms. During simple paradigms, all disturbances of cortical organization (polymicrogyria, schizencephaly, and mild-type FCD) showed activity, whereas other MCDs (disturbances of earlier steps of cortical development: hemimegalencephaly, Taylor-type FCD, and heterotopia) showed activity in only 44% (p < 0.01). The association between the pathophysiology and morphology of MCDs confirms the recently proposed classification system. Both focal neurological signs (p < 0.05) and focal electroencephalogram slowing (p < 0.05) independently correlated with MCD inactivity, confirming that fMRI showed neuronal functions of MCDs. Conclusively, fMRI visualizes the MCD functions and their relationship to the eloquent cortex, providing useful information before epilepsy surgery. Surgery of cortical organization disturbances should be cautiously performed because these malformations may participate to some degree in brain functions.
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Affiliation(s)
- Jozsef Janszky
- Epilepsy Surgery Department, Bethel Epilepsy Center, Bielefeld, Germany
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25
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Kirschstein T, Fernández G, Grunwald T, Pezer N, Urbach H, Blümcke I, Van Roost D, Lehnertz K, Elger CE. Heterotopias, cortical dysplasias and glioneural tumors participate in cognitive processing in patients with temporal lobe epilepsy. Neurosci Lett 2003; 338:237-41. [PMID: 12581840 DOI: 10.1016/s0304-3940(02)01398-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Focal brain lesions such as cortical dysplasia and glioneural tumors generate epileptic activity and thus may be synaptically connected with normal cortex. To test this hypothesis, we compared event-related potentials recorded directly from the medial temporal lobe (MTL) and a dysplastic lesion in eight patients with intractable temporal lobe epilepsy. The P3 component, related to visual target detection, showed different peak latencies in four patients and a larger intralesional amplitude compared to established anterior-MTL-generators in two patients. Semantic processing was identified by the N400 component and showed a different latency in four patients and larger intralesional amplitudes in two patients. These results are compatible with the hypothesis that cortical lesions interact with synaptic pathways related to cognitive functions such as visual target detection, and verbal processing.
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Affiliation(s)
- Timo Kirschstein
- Department of Epileptology, University of Bonn, Sigmund-Freud-Strasse 25, D-53105, Bonn, Germany.
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Miki A, Haselgrove JC, Liu GT. Functional magnetic resonance imaging and its clinical utility in patients with visual disturbances. Surv Ophthalmol 2002; 47:562-79. [PMID: 12504740 DOI: 10.1016/s0039-6257(02)00356-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Functional magnetic resonance imaging (fMRI) is a powerful, non-invasive technique for mapping human brain function. Because of the robust signal intensity changes associated with visual stimuli, fMRI is particularly useful for studying visual cortex (including both striate and extrastriate cortex). Also, activation of the lateral geniculate nuclei has been successfully demonstrated by fMRI. Therefore, fMRI may be potentially useful in patients with visual deficits by providing a non-invasive method for assessing the afferent visual pathways and higher cortical areas. Although there have been several reviews on fMRI, few have highlighted its clinical applicability in patients with visual disturbances. Our article will review fMRI principles and methodology, then focus on the possible applications and limitations of this technique in clinical ophthalmology.
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Affiliation(s)
- Atsushi Miki
- The Functional MRI Research Unit, Children's Hospital of Philadelphia, Philadelphia, PA, USA
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Zesiger P, Kiper D, Maeder P, Deonna T, Innocenti GM. Preserved visual function in a case of occipitoparietal microgyria. Ann Neurol 2002; 52:492-8. [PMID: 12325079 DOI: 10.1002/ana.10327] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A 20-year-old man with bilateral parasagittal occipitoparietal polymicrogyria and epilepsy, from whom normal functional magnetic resonance imaging and electroencephalogram responses to visual stimuli were obtained, was found to have no visual perceptual deficits. This suggests that microgyric cortex can perform normal visual functions, despite its gross structural abnormalities.
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Affiliation(s)
- Pascal Zesiger
- Faculty of Psychology and Educational Sciences, University of Geneva, Geneva, Switzerland
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28
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Knyazeva MG, Innocenti GM. EEG coherence studies in the normal brain and after early-onset cortical pathologies. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2001; 36:119-28. [PMID: 11690608 DOI: 10.1016/s0165-0173(01)00087-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Visual corpus callosum (CC) preferentially interconnects neurons selective for similar stimulus orientation near the representations of the vertical meridian. These properties allow studying the CC functionality with EEG coherence analysis. Iso-oriented and orthogonally-oriented gratings were presented to the two hemifields, either close to the vertical meridian or far from it. In animals with intact CC, and in man, interhemispheric coherence (ICoh) increased only with iso-oriented gratings presented near or crossing the vertical meridian. The increase was localized to occipital electrodes and was specific for the beta-gamma frequency band. Visual-stimulus induced changes in ICoh were studied in patients with early pathologies of the visual areas. From a girl with abnormal vision and severe bilateral lesion of the primary visual areas at 3 weeks, after premature birth at 30 weeks, we obtained no ICoh response until 9 years. In control children visual stimulation increased occipital ICoh at 6-7 years. From a young man having suffered similar lesions when he was 9 months older than the girl, no consistent increase in ICoh could be obtained. In a 14-year-old girl with congenital visual agnosia, no visible lesions, but with a temporal-occipital epileptic focus, ICoh responses were evoked both by iso-oriented, and by orthogonally-oriented gratings. In a young man with bilateral parieto-occipital microgyria extending into the calcarine sulcus, visual stimuli increased ICoh as in normal individuals, but the response was weaker. These cases are discussed in terms of development of CC connections and point to a variety of plastic changes in the cortical connectivity of children.
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Affiliation(s)
- M G Knyazeva
- Institute of Cellular Biology and Morphology, University of Lausanne, Rue du Bugnon 9, 1005, Lausanne, Switzerland.
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