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Emmanuel Mellet - One of the best experts on this subject based on the ideXlab platform.
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Weak language lateralization affects both verbal and spatial skills: an fMRI study in 297 subjects.
Neuropsychologia, 2014Co-Authors: Emmanuel Mellet, Laure Zago, Gael Jobard, Marc Joliot, Fabrice Crivello, Bernard Mazoyer, Laurent Petit, Nathalie Tzourio-mazoyerAbstract:The present study reappraised the relationship between hemispheric specialization strength and cognitive skills in a sample of 297 individuals including 153 left-handers. It additionally assessed the interaction with manual laterality factors, such as handedness, asymmetry of hand motor skills, and familial sinistrality. A Hemispheric Functional Lateralization Index (HFLI) for language was derived from fMRI. Through mixture Gaussian modeling, three types of language hemispheric lateralization were defined: typical (left Hemisphere Dominance with clear positive HFLI), ambilateral (no dominant Hemisphere with HFLI values close to 0), and strongly-atypical (right-Hemisphere Dominance with clear negative HFLI values). Three cognitive scores were derived from 12 tests covering various aspects of verbal and spatial cognition. Compared to both typical and strongly-atypical participants, those ambilateral for language production had lower performances in verbal and non-verbal domains, indicating that hemispheric specialization and cognitive skills are related in adults. Furthermore, this relationship was independent from handedness and asymmetry for motor skills, as no interaction was observed between these factors. On the other hand, the relationship between familial sinistrality and cognitive skills tended to differ according to language lateralization type. In contrast to previous reports in children, in the present adult population, we found no linear correlation between HFLI and cognitive skills, regardless of lateralization type.
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gaussian mixture modeling of hemispheric lateralization for language in a large sample of healthy individuals balanced for handedness
PLOS ONE, 2014Co-Authors: Bernard Mazoyer, Laure Zago, Guy Perchey, Emmanuel Mellet, Gael Jobard, Marc Joliot, Fabrice Crivello, Laurent Petit, Nathalie TzouriomazoyerAbstract:Hemispheric lateralization for language production and its relationships with manual preference and manual preference strength were studied in a sample of 297 subjects, including 153 left-handers (LH). A hemispheric functional lateralization index (HFLI) for language was derived from fMRI acquired during a covert sentence generation task as compared with a covert word list recitation. The multimodal HFLI distribution was optimally modeled using a mixture of 3 and 4 Gaussian functions in right-handers (RH) and LH, respectively. Gaussian function parameters helped to define 3 types of language hemispheric lateralization, namely “Typical” (left Hemisphere Dominance with clear positive HFLI values, 88% of RH, 78% of LH), “Ambilateral” (no dominant Hemisphere with HFLI values close to 0, 12% of RH, 15% of LH) and “Strongly-atypical” (right-Hemisphere Dominance with clear negative HFLI values, 7% of LH). Concordance between dominant Hemispheres for hand and for language did not exceed chance level, and most of the association between handedness and language lateralization was explained by the fact that all Strongly-atypical individuals were left-handed. Similarly, most of the relationship between language lateralization and manual preference strength was explained by the fact that Strongly-atypical individuals exhibited a strong preference for their left hand. These results indicate that concordance of hemispheric Dominance for hand and for language occurs barely above the chance level, except in a group of rare individuals (less than 1% in the general population) who exhibit strong right Hemisphere Dominance for both language and their preferred hand. They call for a revisit of models hypothesizing common determinants for handedness and for language Dominance.
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left Hemisphere lateralization for language in right handers is controlled in part by familial sinistrality manual preference strength and head size
The Journal of Neuroscience, 2010Co-Authors: Nathalie Tzouriomazoyer, Laure Zago, Emmanuel Mellet, Gael Jobard, Marc Joliot, Fabrice Crivello, Laurent Petit, Annick Razafimandimby, Bernard MazoyerAbstract:We investigated the effects of familial sinistrality (FS+; presence of left-handedness in one9s close relatives), manual preference strength (MPS), and head size on the hemispheric lateralization of language in right-handers. Functional magnetic resonance imaging was used to map 49 individuals while listening to a story in their mother tongue. We found that individuals who had both the FS+ trait and weak MPS had no left Hemisphere Dominance for this lexicosyntactic task, whereas others showed a leftward functional asymmetry. In addition, the smaller the brain size, the smaller the leftward asymmetry for language, independent of FS and MPS. None of these effects were observed when the same subjects performed a spatial attention task that elicited right hemispheric functional asymmetry. These results demonstrate that the left Hemisphere Dominance for language in right-handers is a variable controlled, in part, by a number of specific factors, including FS, MPS, and head size.
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right Hemisphere Dominance for auditory attention and its modulation by eye position an event related fmri study
Restorative Neurology and Neuroscience, 2007Co-Authors: Laurent Petit, Laure Zago, Emmanuel Mellet, Marc Joliot, G Simon, Frederic Andersson, Thomas Bertin, Nathalie TzouriomazoyerAbstract:PURPOSE Previous neuroimaging studies of oddball tasks and other paradigms measuring attention processes support right Hemisphere Dominance for attentional processes. Using an auditory selective attention task, we studied the functional asymmetry of the human brain in response to attended or unattended deviant tones. Secondly, we examined whether a congruency or a discrepancy between audio-spatial and visuo-spatial cued attentional resources may influence the activity elicited by an auditory selective attention task. METHODS We used event-related functional magnetic resonance imaging (fMRI) to study healthy adults as they performed an auditory oddball task in which a spatial-cued instruction indicated the ear to attend a monaural deviant tone. We addressed the question of congruency/discrepancy between attentional resources by using three different eye positions during the performance of the auditory oddball task. RESULTS Relative to standard tones, both attended and unattended deviant tones (DTs) presented to either ear elicit the activation of a widespread bilaterally distributed cortical and subcortical network. A subset of this network, essentially frontal and temporal areas, showed not only greater right than left activity but an enhancement of this rightward asymmetry in response to attended DTs. The only cortical region that showed a leftward asymmetry in response to attended DTs overlapped Heschl gyrus and planum temporale, unmasking a left Hemisphere preference of both primary and secondary auditory cortex for processing simple attended monaural stimuli. Questioning the impact of eye position during auditory oddball task, we observed a lesser activity in right integrative crossmodal areas (superior temporal sulcus, opercular part of the inferior frontal gyrus, pre-SMA) when the eye positions were contralateral to detected DTs. These regions may be tuned to best respond when both visuo-spatial and audio-spatial attentional resources work together. CONCLUSION These results support the assumption that the right Hemisphere is preferentially engaged in processing audio-spatial attentional resources and underline the interest to study the crossmodal integration of attentional resources by the mean of the detection of DTs in different eye positions.
Laurent Petit - One of the best experts on this subject based on the ideXlab platform.
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Weak language lateralization affects both verbal and spatial skills: an fMRI study in 297 subjects.
Neuropsychologia, 2014Co-Authors: Emmanuel Mellet, Laure Zago, Gael Jobard, Marc Joliot, Fabrice Crivello, Bernard Mazoyer, Laurent Petit, Nathalie Tzourio-mazoyerAbstract:The present study reappraised the relationship between hemispheric specialization strength and cognitive skills in a sample of 297 individuals including 153 left-handers. It additionally assessed the interaction with manual laterality factors, such as handedness, asymmetry of hand motor skills, and familial sinistrality. A Hemispheric Functional Lateralization Index (HFLI) for language was derived from fMRI. Through mixture Gaussian modeling, three types of language hemispheric lateralization were defined: typical (left Hemisphere Dominance with clear positive HFLI), ambilateral (no dominant Hemisphere with HFLI values close to 0), and strongly-atypical (right-Hemisphere Dominance with clear negative HFLI values). Three cognitive scores were derived from 12 tests covering various aspects of verbal and spatial cognition. Compared to both typical and strongly-atypical participants, those ambilateral for language production had lower performances in verbal and non-verbal domains, indicating that hemispheric specialization and cognitive skills are related in adults. Furthermore, this relationship was independent from handedness and asymmetry for motor skills, as no interaction was observed between these factors. On the other hand, the relationship between familial sinistrality and cognitive skills tended to differ according to language lateralization type. In contrast to previous reports in children, in the present adult population, we found no linear correlation between HFLI and cognitive skills, regardless of lateralization type.
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gaussian mixture modeling of hemispheric lateralization for language in a large sample of healthy individuals balanced for handedness
PLOS ONE, 2014Co-Authors: Bernard Mazoyer, Laure Zago, Guy Perchey, Emmanuel Mellet, Gael Jobard, Marc Joliot, Fabrice Crivello, Laurent Petit, Nathalie TzouriomazoyerAbstract:Hemispheric lateralization for language production and its relationships with manual preference and manual preference strength were studied in a sample of 297 subjects, including 153 left-handers (LH). A hemispheric functional lateralization index (HFLI) for language was derived from fMRI acquired during a covert sentence generation task as compared with a covert word list recitation. The multimodal HFLI distribution was optimally modeled using a mixture of 3 and 4 Gaussian functions in right-handers (RH) and LH, respectively. Gaussian function parameters helped to define 3 types of language hemispheric lateralization, namely “Typical” (left Hemisphere Dominance with clear positive HFLI values, 88% of RH, 78% of LH), “Ambilateral” (no dominant Hemisphere with HFLI values close to 0, 12% of RH, 15% of LH) and “Strongly-atypical” (right-Hemisphere Dominance with clear negative HFLI values, 7% of LH). Concordance between dominant Hemispheres for hand and for language did not exceed chance level, and most of the association between handedness and language lateralization was explained by the fact that all Strongly-atypical individuals were left-handed. Similarly, most of the relationship between language lateralization and manual preference strength was explained by the fact that Strongly-atypical individuals exhibited a strong preference for their left hand. These results indicate that concordance of hemispheric Dominance for hand and for language occurs barely above the chance level, except in a group of rare individuals (less than 1% in the general population) who exhibit strong right Hemisphere Dominance for both language and their preferred hand. They call for a revisit of models hypothesizing common determinants for handedness and for language Dominance.
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left Hemisphere lateralization for language in right handers is controlled in part by familial sinistrality manual preference strength and head size
The Journal of Neuroscience, 2010Co-Authors: Nathalie Tzouriomazoyer, Laure Zago, Emmanuel Mellet, Gael Jobard, Marc Joliot, Fabrice Crivello, Laurent Petit, Annick Razafimandimby, Bernard MazoyerAbstract:We investigated the effects of familial sinistrality (FS+; presence of left-handedness in one9s close relatives), manual preference strength (MPS), and head size on the hemispheric lateralization of language in right-handers. Functional magnetic resonance imaging was used to map 49 individuals while listening to a story in their mother tongue. We found that individuals who had both the FS+ trait and weak MPS had no left Hemisphere Dominance for this lexicosyntactic task, whereas others showed a leftward functional asymmetry. In addition, the smaller the brain size, the smaller the leftward asymmetry for language, independent of FS and MPS. None of these effects were observed when the same subjects performed a spatial attention task that elicited right hemispheric functional asymmetry. These results demonstrate that the left Hemisphere Dominance for language in right-handers is a variable controlled, in part, by a number of specific factors, including FS, MPS, and head size.
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right Hemisphere Dominance for auditory attention and its modulation by eye position an event related fmri study
Restorative Neurology and Neuroscience, 2007Co-Authors: Laurent Petit, Laure Zago, Emmanuel Mellet, Marc Joliot, G Simon, Frederic Andersson, Thomas Bertin, Nathalie TzouriomazoyerAbstract:PURPOSE Previous neuroimaging studies of oddball tasks and other paradigms measuring attention processes support right Hemisphere Dominance for attentional processes. Using an auditory selective attention task, we studied the functional asymmetry of the human brain in response to attended or unattended deviant tones. Secondly, we examined whether a congruency or a discrepancy between audio-spatial and visuo-spatial cued attentional resources may influence the activity elicited by an auditory selective attention task. METHODS We used event-related functional magnetic resonance imaging (fMRI) to study healthy adults as they performed an auditory oddball task in which a spatial-cued instruction indicated the ear to attend a monaural deviant tone. We addressed the question of congruency/discrepancy between attentional resources by using three different eye positions during the performance of the auditory oddball task. RESULTS Relative to standard tones, both attended and unattended deviant tones (DTs) presented to either ear elicit the activation of a widespread bilaterally distributed cortical and subcortical network. A subset of this network, essentially frontal and temporal areas, showed not only greater right than left activity but an enhancement of this rightward asymmetry in response to attended DTs. The only cortical region that showed a leftward asymmetry in response to attended DTs overlapped Heschl gyrus and planum temporale, unmasking a left Hemisphere preference of both primary and secondary auditory cortex for processing simple attended monaural stimuli. Questioning the impact of eye position during auditory oddball task, we observed a lesser activity in right integrative crossmodal areas (superior temporal sulcus, opercular part of the inferior frontal gyrus, pre-SMA) when the eye positions were contralateral to detected DTs. These regions may be tuned to best respond when both visuo-spatial and audio-spatial attentional resources work together. CONCLUSION These results support the assumption that the right Hemisphere is preferentially engaged in processing audio-spatial attentional resources and underline the interest to study the crossmodal integration of attentional resources by the mean of the detection of DTs in different eye positions.
Nathalie Tzouriomazoyer - One of the best experts on this subject based on the ideXlab platform.
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gaussian mixture modeling of hemispheric lateralization for language in a large sample of healthy individuals balanced for handedness
PLOS ONE, 2014Co-Authors: Bernard Mazoyer, Laure Zago, Guy Perchey, Emmanuel Mellet, Gael Jobard, Marc Joliot, Fabrice Crivello, Laurent Petit, Nathalie TzouriomazoyerAbstract:Hemispheric lateralization for language production and its relationships with manual preference and manual preference strength were studied in a sample of 297 subjects, including 153 left-handers (LH). A hemispheric functional lateralization index (HFLI) for language was derived from fMRI acquired during a covert sentence generation task as compared with a covert word list recitation. The multimodal HFLI distribution was optimally modeled using a mixture of 3 and 4 Gaussian functions in right-handers (RH) and LH, respectively. Gaussian function parameters helped to define 3 types of language hemispheric lateralization, namely “Typical” (left Hemisphere Dominance with clear positive HFLI values, 88% of RH, 78% of LH), “Ambilateral” (no dominant Hemisphere with HFLI values close to 0, 12% of RH, 15% of LH) and “Strongly-atypical” (right-Hemisphere Dominance with clear negative HFLI values, 7% of LH). Concordance between dominant Hemispheres for hand and for language did not exceed chance level, and most of the association between handedness and language lateralization was explained by the fact that all Strongly-atypical individuals were left-handed. Similarly, most of the relationship between language lateralization and manual preference strength was explained by the fact that Strongly-atypical individuals exhibited a strong preference for their left hand. These results indicate that concordance of hemispheric Dominance for hand and for language occurs barely above the chance level, except in a group of rare individuals (less than 1% in the general population) who exhibit strong right Hemisphere Dominance for both language and their preferred hand. They call for a revisit of models hypothesizing common determinants for handedness and for language Dominance.
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left Hemisphere lateralization for language in right handers is controlled in part by familial sinistrality manual preference strength and head size
The Journal of Neuroscience, 2010Co-Authors: Nathalie Tzouriomazoyer, Laure Zago, Emmanuel Mellet, Gael Jobard, Marc Joliot, Fabrice Crivello, Laurent Petit, Annick Razafimandimby, Bernard MazoyerAbstract:We investigated the effects of familial sinistrality (FS+; presence of left-handedness in one9s close relatives), manual preference strength (MPS), and head size on the hemispheric lateralization of language in right-handers. Functional magnetic resonance imaging was used to map 49 individuals while listening to a story in their mother tongue. We found that individuals who had both the FS+ trait and weak MPS had no left Hemisphere Dominance for this lexicosyntactic task, whereas others showed a leftward functional asymmetry. In addition, the smaller the brain size, the smaller the leftward asymmetry for language, independent of FS and MPS. None of these effects were observed when the same subjects performed a spatial attention task that elicited right hemispheric functional asymmetry. These results demonstrate that the left Hemisphere Dominance for language in right-handers is a variable controlled, in part, by a number of specific factors, including FS, MPS, and head size.
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right Hemisphere Dominance for auditory attention and its modulation by eye position an event related fmri study
Restorative Neurology and Neuroscience, 2007Co-Authors: Laurent Petit, Laure Zago, Emmanuel Mellet, Marc Joliot, G Simon, Frederic Andersson, Thomas Bertin, Nathalie TzouriomazoyerAbstract:PURPOSE Previous neuroimaging studies of oddball tasks and other paradigms measuring attention processes support right Hemisphere Dominance for attentional processes. Using an auditory selective attention task, we studied the functional asymmetry of the human brain in response to attended or unattended deviant tones. Secondly, we examined whether a congruency or a discrepancy between audio-spatial and visuo-spatial cued attentional resources may influence the activity elicited by an auditory selective attention task. METHODS We used event-related functional magnetic resonance imaging (fMRI) to study healthy adults as they performed an auditory oddball task in which a spatial-cued instruction indicated the ear to attend a monaural deviant tone. We addressed the question of congruency/discrepancy between attentional resources by using three different eye positions during the performance of the auditory oddball task. RESULTS Relative to standard tones, both attended and unattended deviant tones (DTs) presented to either ear elicit the activation of a widespread bilaterally distributed cortical and subcortical network. A subset of this network, essentially frontal and temporal areas, showed not only greater right than left activity but an enhancement of this rightward asymmetry in response to attended DTs. The only cortical region that showed a leftward asymmetry in response to attended DTs overlapped Heschl gyrus and planum temporale, unmasking a left Hemisphere preference of both primary and secondary auditory cortex for processing simple attended monaural stimuli. Questioning the impact of eye position during auditory oddball task, we observed a lesser activity in right integrative crossmodal areas (superior temporal sulcus, opercular part of the inferior frontal gyrus, pre-SMA) when the eye positions were contralateral to detected DTs. These regions may be tuned to best respond when both visuo-spatial and audio-spatial attentional resources work together. CONCLUSION These results support the assumption that the right Hemisphere is preferentially engaged in processing audio-spatial attentional resources and underline the interest to study the crossmodal integration of attentional resources by the mean of the detection of DTs in different eye positions.
Laure Zago - One of the best experts on this subject based on the ideXlab platform.
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Weak language lateralization affects both verbal and spatial skills: an fMRI study in 297 subjects.
Neuropsychologia, 2014Co-Authors: Emmanuel Mellet, Laure Zago, Gael Jobard, Marc Joliot, Fabrice Crivello, Bernard Mazoyer, Laurent Petit, Nathalie Tzourio-mazoyerAbstract:The present study reappraised the relationship between hemispheric specialization strength and cognitive skills in a sample of 297 individuals including 153 left-handers. It additionally assessed the interaction with manual laterality factors, such as handedness, asymmetry of hand motor skills, and familial sinistrality. A Hemispheric Functional Lateralization Index (HFLI) for language was derived from fMRI. Through mixture Gaussian modeling, three types of language hemispheric lateralization were defined: typical (left Hemisphere Dominance with clear positive HFLI), ambilateral (no dominant Hemisphere with HFLI values close to 0), and strongly-atypical (right-Hemisphere Dominance with clear negative HFLI values). Three cognitive scores were derived from 12 tests covering various aspects of verbal and spatial cognition. Compared to both typical and strongly-atypical participants, those ambilateral for language production had lower performances in verbal and non-verbal domains, indicating that hemispheric specialization and cognitive skills are related in adults. Furthermore, this relationship was independent from handedness and asymmetry for motor skills, as no interaction was observed between these factors. On the other hand, the relationship between familial sinistrality and cognitive skills tended to differ according to language lateralization type. In contrast to previous reports in children, in the present adult population, we found no linear correlation between HFLI and cognitive skills, regardless of lateralization type.
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gaussian mixture modeling of hemispheric lateralization for language in a large sample of healthy individuals balanced for handedness
PLOS ONE, 2014Co-Authors: Bernard Mazoyer, Laure Zago, Guy Perchey, Emmanuel Mellet, Gael Jobard, Marc Joliot, Fabrice Crivello, Laurent Petit, Nathalie TzouriomazoyerAbstract:Hemispheric lateralization for language production and its relationships with manual preference and manual preference strength were studied in a sample of 297 subjects, including 153 left-handers (LH). A hemispheric functional lateralization index (HFLI) for language was derived from fMRI acquired during a covert sentence generation task as compared with a covert word list recitation. The multimodal HFLI distribution was optimally modeled using a mixture of 3 and 4 Gaussian functions in right-handers (RH) and LH, respectively. Gaussian function parameters helped to define 3 types of language hemispheric lateralization, namely “Typical” (left Hemisphere Dominance with clear positive HFLI values, 88% of RH, 78% of LH), “Ambilateral” (no dominant Hemisphere with HFLI values close to 0, 12% of RH, 15% of LH) and “Strongly-atypical” (right-Hemisphere Dominance with clear negative HFLI values, 7% of LH). Concordance between dominant Hemispheres for hand and for language did not exceed chance level, and most of the association between handedness and language lateralization was explained by the fact that all Strongly-atypical individuals were left-handed. Similarly, most of the relationship between language lateralization and manual preference strength was explained by the fact that Strongly-atypical individuals exhibited a strong preference for their left hand. These results indicate that concordance of hemispheric Dominance for hand and for language occurs barely above the chance level, except in a group of rare individuals (less than 1% in the general population) who exhibit strong right Hemisphere Dominance for both language and their preferred hand. They call for a revisit of models hypothesizing common determinants for handedness and for language Dominance.
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left Hemisphere lateralization for language in right handers is controlled in part by familial sinistrality manual preference strength and head size
The Journal of Neuroscience, 2010Co-Authors: Nathalie Tzouriomazoyer, Laure Zago, Emmanuel Mellet, Gael Jobard, Marc Joliot, Fabrice Crivello, Laurent Petit, Annick Razafimandimby, Bernard MazoyerAbstract:We investigated the effects of familial sinistrality (FS+; presence of left-handedness in one9s close relatives), manual preference strength (MPS), and head size on the hemispheric lateralization of language in right-handers. Functional magnetic resonance imaging was used to map 49 individuals while listening to a story in their mother tongue. We found that individuals who had both the FS+ trait and weak MPS had no left Hemisphere Dominance for this lexicosyntactic task, whereas others showed a leftward functional asymmetry. In addition, the smaller the brain size, the smaller the leftward asymmetry for language, independent of FS and MPS. None of these effects were observed when the same subjects performed a spatial attention task that elicited right hemispheric functional asymmetry. These results demonstrate that the left Hemisphere Dominance for language in right-handers is a variable controlled, in part, by a number of specific factors, including FS, MPS, and head size.
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right Hemisphere Dominance for auditory attention and its modulation by eye position an event related fmri study
Restorative Neurology and Neuroscience, 2007Co-Authors: Laurent Petit, Laure Zago, Emmanuel Mellet, Marc Joliot, G Simon, Frederic Andersson, Thomas Bertin, Nathalie TzouriomazoyerAbstract:PURPOSE Previous neuroimaging studies of oddball tasks and other paradigms measuring attention processes support right Hemisphere Dominance for attentional processes. Using an auditory selective attention task, we studied the functional asymmetry of the human brain in response to attended or unattended deviant tones. Secondly, we examined whether a congruency or a discrepancy between audio-spatial and visuo-spatial cued attentional resources may influence the activity elicited by an auditory selective attention task. METHODS We used event-related functional magnetic resonance imaging (fMRI) to study healthy adults as they performed an auditory oddball task in which a spatial-cued instruction indicated the ear to attend a monaural deviant tone. We addressed the question of congruency/discrepancy between attentional resources by using three different eye positions during the performance of the auditory oddball task. RESULTS Relative to standard tones, both attended and unattended deviant tones (DTs) presented to either ear elicit the activation of a widespread bilaterally distributed cortical and subcortical network. A subset of this network, essentially frontal and temporal areas, showed not only greater right than left activity but an enhancement of this rightward asymmetry in response to attended DTs. The only cortical region that showed a leftward asymmetry in response to attended DTs overlapped Heschl gyrus and planum temporale, unmasking a left Hemisphere preference of both primary and secondary auditory cortex for processing simple attended monaural stimuli. Questioning the impact of eye position during auditory oddball task, we observed a lesser activity in right integrative crossmodal areas (superior temporal sulcus, opercular part of the inferior frontal gyrus, pre-SMA) when the eye positions were contralateral to detected DTs. These regions may be tuned to best respond when both visuo-spatial and audio-spatial attentional resources work together. CONCLUSION These results support the assumption that the right Hemisphere is preferentially engaged in processing audio-spatial attentional resources and underline the interest to study the crossmodal integration of attentional resources by the mean of the detection of DTs in different eye positions.
Marc Joliot - One of the best experts on this subject based on the ideXlab platform.
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Weak language lateralization affects both verbal and spatial skills: an fMRI study in 297 subjects.
Neuropsychologia, 2014Co-Authors: Emmanuel Mellet, Laure Zago, Gael Jobard, Marc Joliot, Fabrice Crivello, Bernard Mazoyer, Laurent Petit, Nathalie Tzourio-mazoyerAbstract:The present study reappraised the relationship between hemispheric specialization strength and cognitive skills in a sample of 297 individuals including 153 left-handers. It additionally assessed the interaction with manual laterality factors, such as handedness, asymmetry of hand motor skills, and familial sinistrality. A Hemispheric Functional Lateralization Index (HFLI) for language was derived from fMRI. Through mixture Gaussian modeling, three types of language hemispheric lateralization were defined: typical (left Hemisphere Dominance with clear positive HFLI), ambilateral (no dominant Hemisphere with HFLI values close to 0), and strongly-atypical (right-Hemisphere Dominance with clear negative HFLI values). Three cognitive scores were derived from 12 tests covering various aspects of verbal and spatial cognition. Compared to both typical and strongly-atypical participants, those ambilateral for language production had lower performances in verbal and non-verbal domains, indicating that hemispheric specialization and cognitive skills are related in adults. Furthermore, this relationship was independent from handedness and asymmetry for motor skills, as no interaction was observed between these factors. On the other hand, the relationship between familial sinistrality and cognitive skills tended to differ according to language lateralization type. In contrast to previous reports in children, in the present adult population, we found no linear correlation between HFLI and cognitive skills, regardless of lateralization type.
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gaussian mixture modeling of hemispheric lateralization for language in a large sample of healthy individuals balanced for handedness
PLOS ONE, 2014Co-Authors: Bernard Mazoyer, Laure Zago, Guy Perchey, Emmanuel Mellet, Gael Jobard, Marc Joliot, Fabrice Crivello, Laurent Petit, Nathalie TzouriomazoyerAbstract:Hemispheric lateralization for language production and its relationships with manual preference and manual preference strength were studied in a sample of 297 subjects, including 153 left-handers (LH). A hemispheric functional lateralization index (HFLI) for language was derived from fMRI acquired during a covert sentence generation task as compared with a covert word list recitation. The multimodal HFLI distribution was optimally modeled using a mixture of 3 and 4 Gaussian functions in right-handers (RH) and LH, respectively. Gaussian function parameters helped to define 3 types of language hemispheric lateralization, namely “Typical” (left Hemisphere Dominance with clear positive HFLI values, 88% of RH, 78% of LH), “Ambilateral” (no dominant Hemisphere with HFLI values close to 0, 12% of RH, 15% of LH) and “Strongly-atypical” (right-Hemisphere Dominance with clear negative HFLI values, 7% of LH). Concordance between dominant Hemispheres for hand and for language did not exceed chance level, and most of the association between handedness and language lateralization was explained by the fact that all Strongly-atypical individuals were left-handed. Similarly, most of the relationship between language lateralization and manual preference strength was explained by the fact that Strongly-atypical individuals exhibited a strong preference for their left hand. These results indicate that concordance of hemispheric Dominance for hand and for language occurs barely above the chance level, except in a group of rare individuals (less than 1% in the general population) who exhibit strong right Hemisphere Dominance for both language and their preferred hand. They call for a revisit of models hypothesizing common determinants for handedness and for language Dominance.
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left Hemisphere lateralization for language in right handers is controlled in part by familial sinistrality manual preference strength and head size
The Journal of Neuroscience, 2010Co-Authors: Nathalie Tzouriomazoyer, Laure Zago, Emmanuel Mellet, Gael Jobard, Marc Joliot, Fabrice Crivello, Laurent Petit, Annick Razafimandimby, Bernard MazoyerAbstract:We investigated the effects of familial sinistrality (FS+; presence of left-handedness in one9s close relatives), manual preference strength (MPS), and head size on the hemispheric lateralization of language in right-handers. Functional magnetic resonance imaging was used to map 49 individuals while listening to a story in their mother tongue. We found that individuals who had both the FS+ trait and weak MPS had no left Hemisphere Dominance for this lexicosyntactic task, whereas others showed a leftward functional asymmetry. In addition, the smaller the brain size, the smaller the leftward asymmetry for language, independent of FS and MPS. None of these effects were observed when the same subjects performed a spatial attention task that elicited right hemispheric functional asymmetry. These results demonstrate that the left Hemisphere Dominance for language in right-handers is a variable controlled, in part, by a number of specific factors, including FS, MPS, and head size.
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right Hemisphere Dominance for auditory attention and its modulation by eye position an event related fmri study
Restorative Neurology and Neuroscience, 2007Co-Authors: Laurent Petit, Laure Zago, Emmanuel Mellet, Marc Joliot, G Simon, Frederic Andersson, Thomas Bertin, Nathalie TzouriomazoyerAbstract:PURPOSE Previous neuroimaging studies of oddball tasks and other paradigms measuring attention processes support right Hemisphere Dominance for attentional processes. Using an auditory selective attention task, we studied the functional asymmetry of the human brain in response to attended or unattended deviant tones. Secondly, we examined whether a congruency or a discrepancy between audio-spatial and visuo-spatial cued attentional resources may influence the activity elicited by an auditory selective attention task. METHODS We used event-related functional magnetic resonance imaging (fMRI) to study healthy adults as they performed an auditory oddball task in which a spatial-cued instruction indicated the ear to attend a monaural deviant tone. We addressed the question of congruency/discrepancy between attentional resources by using three different eye positions during the performance of the auditory oddball task. RESULTS Relative to standard tones, both attended and unattended deviant tones (DTs) presented to either ear elicit the activation of a widespread bilaterally distributed cortical and subcortical network. A subset of this network, essentially frontal and temporal areas, showed not only greater right than left activity but an enhancement of this rightward asymmetry in response to attended DTs. The only cortical region that showed a leftward asymmetry in response to attended DTs overlapped Heschl gyrus and planum temporale, unmasking a left Hemisphere preference of both primary and secondary auditory cortex for processing simple attended monaural stimuli. Questioning the impact of eye position during auditory oddball task, we observed a lesser activity in right integrative crossmodal areas (superior temporal sulcus, opercular part of the inferior frontal gyrus, pre-SMA) when the eye positions were contralateral to detected DTs. These regions may be tuned to best respond when both visuo-spatial and audio-spatial attentional resources work together. CONCLUSION These results support the assumption that the right Hemisphere is preferentially engaged in processing audio-spatial attentional resources and underline the interest to study the crossmodal integration of attentional resources by the mean of the detection of DTs in different eye positions.