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Moser C, Spencer-Smith MM, Anderson PJ, McIlroy A, Wood AG, Leventer RJ, Anderson VA, Siffredi V. Language and communication functioning in children and adolescents with agenesis of the corpus callosum. BRAIN AND LANGUAGE 2024; 255:105448. [PMID: 39083998 DOI: 10.1016/j.bandl.2024.105448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 07/19/2024] [Accepted: 07/22/2024] [Indexed: 08/02/2024]
Abstract
The corpus callosum, the largest white matter inter-hemispheric pathway, is involved in language and communication. In a cohort of 15 children and adolescents (8-15 years) with developmental absence of the corpus callosum (AgCC), this study aimed to describe language and everyday communication functioning, and explored the role of anatomical factors, social risk, and non-verbal IQ in these outcomes. Standardised measures of language and everyday communication functioning, intellectual ability and social risk were used. AgCC classification and anterior commissure volume, a potential alternative pathway, were extracted from T1-weighted images. Participants with AgCC showed reduced receptive and expressive language compared with test norms, and high rates of language and communication impairments. Complete AgCC, higher social risk and lower non-verbal IQ were associated with communication difficulties. Anterior commissure volume was not associated with language and communication. Recognising heterogeneity in language and communication functioning enhances our understanding and suggests specific focuses for potential interventions.
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Affiliation(s)
| | - Megan M Spencer-Smith
- School of Psychological Sciences, Monash University, Melbourne, Australia; Clinical Sciences, Murdoch Children's Research Institute, Parkville, Victoria, Australia
| | - Peter J Anderson
- School of Psychological Sciences, Monash University, Melbourne, Australia
| | - Alissandra McIlroy
- Clinical Sciences, Murdoch Children's Research Institute, Parkville, Victoria, Australia; Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Australia
| | - Amanda G Wood
- Clinical Sciences, Murdoch Children's Research Institute, Parkville, Victoria, Australia; School of Psychology, Deakin University, Burwood, Victoria, Australia; Aston Institute for Health and Neurodevelopment, Aston University, Birmingham, UK
| | - Richard J Leventer
- Clinical Sciences, Murdoch Children's Research Institute, Parkville, Victoria, Australia; Department of Paediatrics, University of Melbourne, Melbourne, Australia; Department of Neurology, Royal Children's Hospital, Melbourne, Australia
| | - Vicki A Anderson
- Clinical Sciences, Murdoch Children's Research Institute, Parkville, Victoria, Australia; Department of Paediatrics, University of Melbourne, Melbourne, Australia; The Royal Children's Hospital, Melbourne, Australia
| | - Vanessa Siffredi
- Clinical Sciences, Murdoch Children's Research Institute, Parkville, Victoria, Australia; Division of Development and Growth, Department of Paediatrics, Gynaecology and Obstetrics, Geneva University Hospitals and University of Geneva, Geneva, Switzerland; Department of Radiology, Lausanne University Hospital and University of Lausanne, Switzerland.
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Ferreira Furtado LM, Bernardes HM, de Souza Félix Nunes FA, Gonçalves CA, Da Costa Val Filho JA, de Miranda AS. The Role of Neuroplasticity in Improving the Decision-Making Quality of Individuals With Agenesis of the Corpus Callosum: A Systematic Review. Cureus 2022; 14:e26082. [PMID: 35747104 PMCID: PMC9206817 DOI: 10.7759/cureus.26082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2022] [Indexed: 11/29/2022] Open
Abstract
Although individuals with agenesis of corpus callosum (ACC) possess intelligence coefficients within regular parameters, current studies have demonstrated decision-making compromise and potential negative social consequences. Furthermore, alternative pathways regarding brain connectivity in acallosal patients combined with cognitive therapy that would potentially mitigate such difficulties. Therefore, this study aimed to examine the current state of the art regarding brain foundations in the role of neuroplasticity by improving the decision-making quality in ACC. A systematic revision of literature was performed including studies conducted on non-syndromic ACC individuals and analyzing the impact of the potential role of neuroplasticity on the decision-making published to date. Studies with patients who underwent callosotomy were excluded. Experimental studies performed on animal models were included. During this period, 849 studies were identified; among them, 11 were eligible for qualitative analysis. Despite the paucity of evidence on this matter, patients with ACC present considerable decision-making difficulties mainly due to the functional connectivity impairment in the frontal lobes. Moreover, neuroplasticity was characterized by increased anterior commissure width as compared with controls. Notwithstanding, no studies were conducted on cognitive therapists managing this type of disease. Although the reorganization of inter-hemispheric bundles on anterior commissure has demonstrated the main natural neuroanatomic strategy in ACC, further evidence will be needed to clarify whether cognitive stimulus could improve the decision-making quality.
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Effect of corpus callosum agenesis on the language network in children and adolescents. Brain Struct Funct 2021; 226:701-713. [PMID: 33496825 PMCID: PMC7981296 DOI: 10.1007/s00429-020-02203-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 12/16/2020] [Indexed: 12/17/2022]
Abstract
The present study is interested in the role of the corpus callosum in the development of the language network. We, therefore, investigated language abilities and the language network using task-based fMRI in three cases of complete agenesis of the corpus callosum (ACC), three cases of partial ACC and six controls. Although the children with complete ACC revealed impaired functions in specific language domains, no child with partial ACC showed a test score below average. As a group, ACC children performed significantly worse than healthy controls in verbal fluency and naming. Furthermore, whole-brain ROI-to-ROI connectivity analyses revealed reduced intrahemispheric and right intrahemispheric functional connectivity in ACC patients as compared to controls. In addition, stronger functional connectivity between left and right temporal areas was associated with better language abilities in the ACC group. In healthy controls, no association between language abilities and connectivity was found. Our results show that ACC is associated not only with less interhemispheric, but also with less right intrahemispheric language network connectivity in line with reduced verbal abilities. The present study, thus, supports the excitatory role of the corpus callosum in functional language network connectivity and language abilities.
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Relationships of Language Lateralization with Diffusion Tensor Imaging Metrics of Corpus Callosum, Tumor Grade, and Tumors Distance to Language-Eloquent Areas in Glial Neoplasms. J Comput Assist Tomogr 2020; 44:956-968. [PMID: 33196603 DOI: 10.1097/rct.0000000000001103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE The aim of the study was to search relationships between language lateralization and corpus callosum (CC) connectivity, tumor grade, and tumors distance to language-eloquent areas in glial neoplasms. MATERIALS AND METHODS The functional magnetic resonance imaging and CC diffusion tensor imaging (DTI) metrics of 42 patients with glial neoplasm were evaluated for relationships of language lateralization (left, right, and bilateral) with CC DTI metrics (tracts number, voxel, volume, length, fractional anisotropy [FA], and apparent diffusion coefficient), tumor grade, and tumors distance to language-eloquent areas and relationships of CC DTI metrics with tumor grade. Kruskal-Wallis, Mann-Whitney U, and χ tests were used. All were repeated in 26 patients with left hemispheric masses. RESULTS In glial masses, language bilateralism was more common than normal population and more pronounced in low grade than high grade. In right lateralism and bilateralism, tumor settlement nearby language-eloquent areas was more common. In the left lateralism, highest CC tract number, higher tumor grade, and more remote tumor settlements were noted. There was no relationship between CC DTI metrics and tumor grade but increase in CC tracts number and FA with increasing tumor grade. CONCLUSIONS Increased bilateralism in glial masses than normal population and in low grade tumors than high grade and increased nearby tumor settlement in right lateralism and bilateralism support interhemispheric reorganization and plasticity. This is more pronounced in low grade because of higher life span. Highest CC tract number, higher tumor grade, and more remote tumor settlement in left lateralized group suggest intact CC integrity with limited hemispheric destruction. Increasing CC tracts number and FA with increasing tumor grade support preserved CC integrity in the shorter life span of high-grade tumors.
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Monteiro M, de Oliveira-Souza R, Andrade J, Marins T, de Carvalho Rodrigues E, Bramati I, Lent R, Moll J, Tovar-Moll F. Cortical lateralization of cheirosensory processing in callosal dysgenesis. NEUROIMAGE-CLINICAL 2019; 23:101808. [PMID: 31153001 PMCID: PMC6541908 DOI: 10.1016/j.nicl.2019.101808] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 03/17/2019] [Accepted: 03/30/2019] [Indexed: 01/27/2023]
Abstract
The paradoxical absence of a split-brain syndrome in most cases of callosal dysgenesis has originated three main hypotheses, namely, (i) bilateral cortical representation of language, (ii) bilateral thalamocortical projections of somatosensory pathways conveyed by the spinothalamic-medial lemniscus system, and (iii) a variable combination of (i) and (ii). We used functional neuroimaging to investigate the cortical representation and lateralization of somatosensory information from the palm of each hand in six cases of callosal dysgenesis (hypothesis [ii]). Cortical regions of interest were contralateral and ipsilateral S1 (areas 3a and 3b, 1 and 2 in the central sulcus and postcentral gyrus) and S2 (parts of areas 40 and 43 in the parietal operculum). The degree of cortical asymmetry was expressed by a laterality index (LI), which may assume values from −1 (fully left-lateralized) to +1 (fully right-lateralized). In callosal dysgenesis, LI values for the right and the left hands were, respectively, −1 and + 1 for both S1 and S2, indicating absence of engagement of ipsilateral S1 and S2. In controls, LI values were − 0.70 (S1) and − 0.51 (S2) for right hand stimulation, and 0.82 (S1) and 0.36 (S2) for left hand stimulation, reflecting bilateral asymmetric activations, which were significantly higher in the hemisphere contralateral to the stimulated hand. Therefore, none of the main hypotheses so far entertained to account for the callosal dysgenesis-split-brain paradox have succeeded. We conclude that the preserved interhemispheric transfer of somatosensory tactile information in callosal dysgenesis must be mediated by a fourth alternative, such as aberrant interhemispheric bundles, reorganization of subcortical commissures, or both. We studied the cortical sensory representation of the hands in callosal dysgenesis. The representation of the hands was bilateral but asymmetric in controls. The representation of the hands was strictly contralateral in callosal dysgenesis. The representation of the hands is a distinguishing feature of callosal dysgenesis.
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Affiliation(s)
- Myriam Monteiro
- The D'Or Institute for Research & Education (IDOR), Brazil; The Federal University of the State of Rio de Janeiro (Uni-Rio), Brazil
| | - Ricardo de Oliveira-Souza
- The D'Or Institute for Research & Education (IDOR), Brazil; The Federal University of Rio de Janeiro (UFRJ), Brazil
| | | | - Theo Marins
- The D'Or Institute for Research & Education (IDOR), Brazil; The Federal University of Rio de Janeiro (UFRJ), Brazil
| | | | - Ivanei Bramati
- The D'Or Institute for Research & Education (IDOR), Brazil
| | - Roberto Lent
- The D'Or Institute for Research & Education (IDOR), Brazil; The Federal University of the State of Rio de Janeiro (Uni-Rio), Brazil; The Federal University of Rio de Janeiro (UFRJ), Brazil
| | - Jorge Moll
- The D'Or Institute for Research & Education (IDOR), Brazil
| | - Fernanda Tovar-Moll
- The D'Or Institute for Research & Education (IDOR), Brazil; The Federal University of the State of Rio de Janeiro (Uni-Rio), Brazil.
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Atypical language representation is unfavorable for language abilities following childhood stroke. Eur J Paediatr Neurol 2019; 23:102-116. [PMID: 30314763 PMCID: PMC6339521 DOI: 10.1016/j.ejpn.2018.09.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 08/29/2018] [Accepted: 09/17/2018] [Indexed: 12/13/2022]
Abstract
Brain plasticity has often been quoted as a reason for the more favorable outcome in childhood stroke compared to adult stroke. We investigated the relationship between language abilities and language localization in childhood stroke. Seventeen children and adolescents with left- or right-sided ischemic stroke and 18 healthy controls were tested with a comprehensive neurolinguistic test battery, and the individual neural representation of language was measured with an fMRI language paradigm. Overall, 12 of 17 stroke patients showed language abilities below average, and five patients exhibited impaired language performance. fMRI revealed increased activity in right hemisphere areas homotopic to left hemisphere language regions. In sum, seven stroke patients revealed atypical, i.e. bilateral or right lateralized language representation. Typical left hemispheric language lateralization was associated with better performance in naming and word fluency, whereas increased involvement of right homologues was accompanied by worse language outcome. In contrast, lesion lateralization or lesion volume did not correlate with language outcome or atypical language lateralization. Thus, atypical language lateralization is unfavorable for language outcome, and right homologues do not have the same cognitive capacity, even in young children.
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Bartha‐Doering L, Kollndorfer K, Kasprian G, Novak A, Schuler A, Fischmeister FPS, Alexopoulos J, Gaillard WD, Prayer D, Seidl R, Berl MM. Weaker semantic language lateralization associated with better semantic language performance in healthy right-handed children. Brain Behav 2018; 8:e01072. [PMID: 30298640 PMCID: PMC6236252 DOI: 10.1002/brb3.1072] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 06/22/2018] [Accepted: 06/26/2018] [Indexed: 12/17/2022] Open
Abstract
INTRODUCTION The relationship between language abilities and language lateralization in the developing brain is important for our understanding of the neural architecture of language development. METHODS We investigated 35 right-handed children and adolescents aged 7-16 years with a functional magnetic resonance imaging language paradigm and a comprehensive language and verbal memory examination. RESULTS We found that less lateralized language was significantly correlated with better language performance across areas of the brain and across different language tasks. Less lateralized language in the overall brain was associated with better in-scanner task accuracy on a semantic language decision task and out-of-scanner vocabulary and verbal fluency. Specifically, less lateralized frontal lobe language dominance was associated with better in-scanner task accuracy and out-of-scanner verbal fluency. Furthermore, less lateralized parietal language was associated with better out-of-scanner verbal memory across learning, short- and long-delay trials. In contrast, we did not find any relationship between temporal lobe language laterality and verbal performance. CONCLUSIONS This study suggests that semantic language performance is better with some involvement of the nondominant hemisphere.
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Affiliation(s)
- Lisa Bartha‐Doering
- Department of Pediatrics and Adolescent MedicineMedical University of ViennaViennaAustria
| | - Kathrin Kollndorfer
- Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
| | - Gregor Kasprian
- Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
| | - Astrid Novak
- Department of Pediatrics and Adolescent MedicineMedical University of ViennaViennaAustria
| | - Anna‐Lisa Schuler
- Department of Pediatrics and Adolescent MedicineMedical University of ViennaViennaAustria
| | | | - Johanna Alexopoulos
- Department of Psychoanalysis and PsychotherapyMedical University of ViennaViennaAustria
| | - William Davis Gaillard
- Center for Neuroscience and Behavioral HealthChildren's National Health System (CNHS)WashingtonDCUSA
| | - Daniela Prayer
- Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
| | - Rainer Seidl
- Department of Pediatrics and Adolescent MedicineMedical University of ViennaViennaAustria
| | - Madison M. Berl
- Center for Neuroscience and Behavioral HealthChildren's National Health System (CNHS)WashingtonDCUSA
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Cowell P, Gurd J. Handedness and the Corpus Callosum: A Review and Further Analyses of Discordant Twins. Neuroscience 2018; 388:57-68. [DOI: 10.1016/j.neuroscience.2018.06.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 06/07/2018] [Accepted: 06/08/2018] [Indexed: 11/27/2022]
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Early asymmetric inter-hemispheric transfer in the auditory network: insights from infants with corpus callosum agenesis. Brain Struct Funct 2018; 223:2893-2905. [DOI: 10.1007/s00429-018-1667-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 04/13/2018] [Indexed: 10/17/2022]
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Siffredi V, Spencer-Smith M, Barrouillet P, Vaessen M, Leventer R, Anderson V, Vuilleumier P. Neural correlates of working memory in children and adolescents with agenesis of the corpus callosum: An fMRI study. Neuropsychologia 2017; 106:71-82. [DOI: 10.1016/j.neuropsychologia.2017.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 08/19/2017] [Accepted: 09/07/2017] [Indexed: 11/16/2022]
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The Contribution of the Corpus Callosum to Language Lateralization. J Neurosci 2016; 36:4522-33. [PMID: 27098695 DOI: 10.1523/jneurosci.3850-14.2016] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 12/03/2015] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED The development of hemispheric lateralization for language is poorly understood. In one hypothesis, early asymmetric gene expression assigns language to the left hemisphere. In an alternate view, language is represented a priori in both hemispheres and lateralization emerges via cross-hemispheric communication through the corpus callosum. To address this second hypothesis, we capitalized on the high temporal and spatial resolution of magnetoencephalographic imaging to measure cortical activity during language processing, speech preparation, and speech execution in 25 participants with agenesis of the corpus callosum (AgCC) and 21 matched neurotypical individuals. In contrast to strongly lateralized left hemisphere activations for language in neurotypical controls, participants with complete or partial AgCC exhibited bilateral hemispheric activations in both auditory or visually driven language tasks, with complete AgCC participants showing significantly more right hemisphere activations than controls or than individuals with partial AgCC. In AgCC individuals, language laterality positively correlated with verbal IQ. These findings suggest that the corpus callosum helps to drive language lateralization. SIGNIFICANCE STATEMENT The role that corpus callosum development has on the hemispheric specialization of language is poorly understood. Here, we used magnetoencephalographic imaging during linguistic tests (verb generation, picture naming) to test for hemispheric dominance in patients with agenesis of the corpus callosum (AgCC) and found reduced laterality (i.e., greater likelihood of bilaterality or right hemisphere dominance) in this cohort compared with controls, especially in patients with complete agenesis. Laterality was positively correlated with behavioral measures of verbal intelligence. These findings provide support for the hypothesis that the callosum aids in functional specialization throughout neural development and that the loss of this mechanism correlates with impairments in verbal performance.
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Pirmoradi M, Jemel B, Gallagher A, Tremblay J, D’Hondt F, Nguyen DK, Béland R, Lassonde M. Verbal memory and verbal fluency tasks used for language localization and lateralization during magnetoencephalography. Epilepsy Res 2016; 119:1-9. [DOI: 10.1016/j.eplepsyres.2015.11.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 10/02/2015] [Accepted: 11/13/2015] [Indexed: 11/27/2022]
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Alsaadi T, Shahrour TM. Language lateralization in a patient with temporal lobe epilepsy and callosal agenesis. EPILEPSY & BEHAVIOR CASE REPORTS 2015; 3:1-3. [PMID: 25737961 PMCID: PMC4338855 DOI: 10.1016/j.ebcr.2014.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 07/14/2014] [Indexed: 11/06/2022]
Abstract
The corpus callosum has been proposed as a mechanism of interhemispheric inhibition that allows language dominance to develop [1]. Callosal agenesis or dysgenesis provides a test of this hypothesis, as patients lacking a normal corpus callosum should also lack normal language lateralization [2]. We report pre- and postoperative functional magnetic resonance imaging (fMRI) and neuropsychological testing in a patient with partial callosal agenesis who underwent a right temporal lobectomy for medically refractory seizures.
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Organising white matter in a brain without corpus callosum fibres. Cortex 2015; 63:155-71. [DOI: 10.1016/j.cortex.2014.08.022] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 06/29/2014] [Accepted: 08/25/2014] [Indexed: 01/08/2023]
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Safi D, Lassonde M, Nguyen DK, Vannasing P, Tremblay J, Florea O, Morin-Moncet O, Lefrançois M, Béland R. Functional near-infrared spectroscopy for the assessment of overt reading. Brain Behav 2012; 2:825-37. [PMID: 23170245 PMCID: PMC3500469 DOI: 10.1002/brb3.100] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 09/16/2012] [Accepted: 09/24/2012] [Indexed: 12/14/2022] Open
Abstract
Functional near-infrared spectroscopy (fNIRS) has become increasingly established as a promising technique for monitoring functional brain activity. To our knowledge, no study has yet used fNIRS to investigate overt reading of irregular words and nonwords with a full coverage of the cerebral regions involved in reading processes. The aim of our study was to design and validate a protocol using fNIRS for the assessment of overt reading. Twelve healthy French-speaking adults underwent one session of fNIRS recording while performing an overt reading of 13 blocks of irregular words and nonwords. Reading blocks were separated by baseline periods during which participants were instructed to fixate a cross. Sources (n = 55) and detectors (n = 16) were placed bilaterally over frontal, temporal, parietal, and occipital regions. Two wavelengths were used: 690 nm, more sensitive to deoxyhemoglobin (HbR) concentration changes, and 830 nm, more sensitive to oxyhemoglobin (HbO) concentration changes. For all participants, total hemoglobin (HbT) concentrations (HbO + HbR) were significantly higher than baseline for both irregular word and nonword reading in the inferior frontal gyri, the middle and superior temporal gyri, and the occipital cortices bilaterally. In the temporal gyri, although the difference was not significant, [HbT] values were higher in the left hemisphere. In the bilateral inferior frontal gyri, higher [HbT] values were found in nonword than in irregular word reading. This activation could be related to the grapheme-to-phoneme conversion characterizing the phonological pathway of reading. Our findings confirm that fNIRS is an appropriate technique to assess the neural correlates of overt reading.
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Affiliation(s)
- Dima Safi
- École d'orthophonie et d'audiologie, Université de Montréal Montréal, Canada ; Centre de recherche en neuropsychologie et cognition, Université de Montréal Montréal, Canada ; Centre de recherche de l'Hôpital Sainte-Justine, Hôpital Sainte-Justine Montréal, Canada
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