5 recherche sur le mot-clé 'visual cortex'

A Magnetic Resonance Spectroscopy Study of Superior Visual Search Abilities in Children with Autism Spectrum Disorder / David A. EDMONDSON in Autism Research, 13-4 (April 2020)  

Public ISBD [article]  inAutism Research > 13-4 (April 2020) . - p.550-562 Titre : A Magnetic Resonance Spectroscopy Study of Superior Visual Search Abilities in Children with Autism Spectrum Disorder Type de document : Texte imprimé et/ou numérique Auteurs : David A. EDMONDSON, Auteur ; Pingyu XIA, Auteur ; Rebecca MCNALLY KEEHN, Auteur ; Ulrike DYDAK, Auteur ; Brandon KEEHN, Auteur Article en page(s) : p.550-562 Langues : Anglais (eng) Mots-clés : autism spectrum disorder  frontal eye field  gamma-aminobutyric acid  magnetic resonance spectroscopy  temporal-parietal junction  visual cortex  visual search Index. décimale : PER Périodiques Résumé : Although diagnosed on the basis of deficits in social communication and interaction, autism spectrum disorder (ASD) is also characterized by superior performance on a variety of visuospatial tasks, including visual search. In neurotypical individuals, region-specific concentrations of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) are associated with individual differences in attention and perception. While it has been hypothesized that ASD may be associated with an excitatory-inhibitory imbalance, it remains unclear how this may contribute to accelerated visual search performance in individuals with ASD. To investigate this, 21 children with ASD and 20 typically developing children participated in a visual search task and a magnetic resonance spectroscopy study to detect neurochemical concentrations, including GABA. Region-specific neurochemicals were examined in the right frontal eye fields, right temporal-parietal junction (rTPJ), and bilateral visual cortex (VIS). GABA concentrations did not differ between groups; however, in children with ASD, greater GABA concentration in the VIS was related to more efficient search. Additionally, lower VIS GABA levels were also associated with increased social impairment. Finally, we found reduced N-acetyl aspartate, total creatine, glutamate and glutamine (Glx), GABA/Glx in the rTPJ, suggestive of neuronal dysfunction in a critical network hub. Our results show that GABA concentrations in the VIS are related to efficient search in ASD, thus providing further evidence of enhanced discrimination in ASD. Autism Res 2020, 13: 550-562. (c) 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Children with autism spectrum disorder (ASD) often perform better than their non-ASD peers on visual search tasks; however, it is unclear how they achieve this superior performance. Using magnetic resonance spectroscopy to measure neurochemicals in the brain, we found that the level of one, gamma-aminobutyric acid, in the visual cortex was directly related to search abilities in children with ASD. These results suggest that faster search may relate to enhanced perceptual functioning in children with ASD. En ligne : http://dx.doi.org/10.1002/aur.2258 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=421 [article] A Magnetic Resonance Spectroscopy Study of Superior Visual Search Abilities in Children with Autism Spectrum Disorder [Texte imprimé et/ou numérique] / David A. EDMONDSON, Auteur ; Pingyu XIA, Auteur ; Rebecca MCNALLY KEEHN, Auteur ; Ulrike DYDAK, Auteur ; Brandon KEEHN, Auteur . - p.550-562. Langues : Anglais (eng) in Autism Research > 13-4 (April 2020) . - p.550-562 Mots-clés : autism spectrum disorder  frontal eye field  gamma-aminobutyric acid  magnetic resonance spectroscopy  temporal-parietal junction  visual cortex  visual search Index. décimale : PER Périodiques Résumé : Although diagnosed on the basis of deficits in social communication and interaction, autism spectrum disorder (ASD) is also characterized by superior performance on a variety of visuospatial tasks, including visual search. In neurotypical individuals, region-specific concentrations of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) are associated with individual differences in attention and perception. While it has been hypothesized that ASD may be associated with an excitatory-inhibitory imbalance, it remains unclear how this may contribute to accelerated visual search performance in individuals with ASD. To investigate this, 21 children with ASD and 20 typically developing children participated in a visual search task and a magnetic resonance spectroscopy study to detect neurochemical concentrations, including GABA. Region-specific neurochemicals were examined in the right frontal eye fields, right temporal-parietal junction (rTPJ), and bilateral visual cortex (VIS). GABA concentrations did not differ between groups; however, in children with ASD, greater GABA concentration in the VIS was related to more efficient search. Additionally, lower VIS GABA levels were also associated with increased social impairment. Finally, we found reduced N-acetyl aspartate, total creatine, glutamate and glutamine (Glx), GABA/Glx in the rTPJ, suggestive of neuronal dysfunction in a critical network hub. Our results show that GABA concentrations in the VIS are related to efficient search in ASD, thus providing further evidence of enhanced discrimination in ASD. Autism Res 2020, 13: 550-562. (c) 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Children with autism spectrum disorder (ASD) often perform better than their non-ASD peers on visual search tasks; however, it is unclear how they achieve this superior performance. Using magnetic resonance spectroscopy to measure neurochemicals in the brain, we found that the level of one, gamma-aminobutyric acid, in the visual cortex was directly related to search abilities in children with ASD. These results suggest that faster search may relate to enhanced perceptual functioning in children with ASD. En ligne : http://dx.doi.org/10.1002/aur.2258 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=421

Microglia in the Cerebral Cortex in Autism / Nicole A. TETREAULT in Journal of Autism and Developmental Disorders, 42-12 (December 2012)  

Public ISBD [article]  inJournal of Autism and Developmental Disorders > 42-12 (December 2012) . - p.2569-2584 Titre : Microglia in the Cerebral Cortex in Autism Type de document : Texte imprimé et/ou numérique Auteurs : Nicole A. TETREAULT, Auteur ; Atiya Y. HAKEEM, Auteur ; Sue JIANG, Auteur ; Brian A. WILLIAMS, Auteur ; Elizabeth ALLMAN, Auteur ; Barbara J. WOLD, Auteur ; John M. ALLMAN, Auteur Article en page(s) : p.2569-2584 Langues : Anglais (eng) Mots-clés : Microglia  Autism  Fronto-insular cortex  Visual cortex Index. décimale : PER Périodiques Résumé : We immunocytochemically identified microglia in fronto-insular (FI) and visual cortex (VC) in autopsy brains of well-phenotyped subjects with autism and matched controls, and stereologically quantified the microglial densities. Densities were determined blind to phenotype using an optical fractionator probe. In FI, individuals with autism had significantly more microglia compared to controls (p = 0.02). One such subject had a microglial density in FI within the control range and was also an outlier behaviorally with respect to other subjects with autism. In VC, microglial densities were also significantly greater in individuals with autism versus controls (p = 0.0002). Since we observed increased densities of microglia in two functionally and anatomically disparate cortical areas, we suggest that these immune cells are probably denser throughout cerebral cortex in brains of people with autism. En ligne : http://dx.doi.org/10.1007/s10803-012-1513-0 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=184 [article] Microglia in the Cerebral Cortex in Autism [Texte imprimé et/ou numérique] / Nicole A. TETREAULT, Auteur ; Atiya Y. HAKEEM, Auteur ; Sue JIANG, Auteur ; Brian A. WILLIAMS, Auteur ; Elizabeth ALLMAN, Auteur ; Barbara J. WOLD, Auteur ; John M. ALLMAN, Auteur . - p.2569-2584. Langues : Anglais (eng) in Journal of Autism and Developmental Disorders > 42-12 (December 2012) . - p.2569-2584 Mots-clés : Microglia  Autism  Fronto-insular cortex  Visual cortex Index. décimale : PER Périodiques Résumé : We immunocytochemically identified microglia in fronto-insular (FI) and visual cortex (VC) in autopsy brains of well-phenotyped subjects with autism and matched controls, and stereologically quantified the microglial densities. Densities were determined blind to phenotype using an optical fractionator probe. In FI, individuals with autism had significantly more microglia compared to controls (p = 0.02). One such subject had a microglial density in FI within the control range and was also an outlier behaviorally with respect to other subjects with autism. In VC, microglial densities were also significantly greater in individuals with autism versus controls (p = 0.0002). Since we observed increased densities of microglia in two functionally and anatomically disparate cortical areas, we suggest that these immune cells are probably denser throughout cerebral cortex in brains of people with autism. En ligne : http://dx.doi.org/10.1007/s10803-012-1513-0 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=184

The language network in autism: Atypical functional connectivity with default mode and visual regions / Y. GAO in Autism Research, 12-9 (September 2019)  

Public ISBD [article]  inAutism Research > 12-9 (September 2019) . - p.1344-1355 Titre : The language network in autism: Atypical functional connectivity with default mode and visual regions Type de document : Texte imprimé et/ou numérique Auteurs : Y. GAO, Auteur ; A. LINKE, Auteur ; R. J. JAO KEEHN, Auteur ; S. PUNYAMURTHULA, Auteur ; A. JAHEDI, Auteur ; K. GATES, Auteur ; I. FISHMAN, Auteur ; R. A. MULLER, Auteur Article en page(s) : p.1344-1355 Langues : Anglais (eng) Mots-clés : autism spectrum disorders  default mode  language  resting-state functional magnetic resonance imaging  visual cortex Index. décimale : PER Périodiques Résumé : Autism spectrum disorders (ASDs) are neurodevelopmental disorders associated with atypical brain connectivity. Although language abilities vary widely, they are impaired or atypical in most children with ASDs. Underlying brain mechanisms, however, are not fully understood. The present study examined intrinsic functional connectivity (iFC) of the extended language network in a cohort of 52 children and adolescents with ASDs (ages 8-18 years), using resting-state functional magnetic resonance imaging. We found that, in comparison to typically developing peers (n = 50), children with ASDs showed increased connectivity between some language regions. In addition, seed-to-whole brain analyses revealed increased connectivity of language regions with posterior cingulate cortex (PCC) and visual regions in the ASD group. Post hoc effective connectivity analyses revealed a mediation effect of PCC on the iFC between bilateral inferior frontal and visual regions in an ASD subgroup. This finding qualifies and expands on previous reports of recruitment of visual areas in language processing in ASDs. In addition, increased iFC between PCC and visual regions was linked to lower language scores in this ASD subgroup, suggesting that increased connectivity with visual cortices, mediated by default mode regions, may be detrimental to language abilities. Autism Res 2019, 12: 1344-1355. (c) 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: We examined the functional connectivity between regions of the language network in children with autism spectrum disorders (ASDs) compared to typically developing peers. We found connectivity to be intact between core language in the ASD group, but also showed abnormally increased connectivity between regions of an extended language network. Additionally, connectivity was increased with regions associated with brain networks responsible for self-reflection and visual processing. En ligne : http://dx.doi.org/10.1002/aur.2171 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=406 [article] The language network in autism: Atypical functional connectivity with default mode and visual regions [Texte imprimé et/ou numérique] / Y. GAO, Auteur ; A. LINKE, Auteur ; R. J. JAO KEEHN, Auteur ; S. PUNYAMURTHULA, Auteur ; A. JAHEDI, Auteur ; K. GATES, Auteur ; I. FISHMAN, Auteur ; R. A. MULLER, Auteur . - p.1344-1355. Langues : Anglais (eng) in Autism Research > 12-9 (September 2019) . - p.1344-1355 Mots-clés : autism spectrum disorders  default mode  language  resting-state functional magnetic resonance imaging  visual cortex Index. décimale : PER Périodiques Résumé : Autism spectrum disorders (ASDs) are neurodevelopmental disorders associated with atypical brain connectivity. Although language abilities vary widely, they are impaired or atypical in most children with ASDs. Underlying brain mechanisms, however, are not fully understood. The present study examined intrinsic functional connectivity (iFC) of the extended language network in a cohort of 52 children and adolescents with ASDs (ages 8-18 years), using resting-state functional magnetic resonance imaging. We found that, in comparison to typically developing peers (n = 50), children with ASDs showed increased connectivity between some language regions. In addition, seed-to-whole brain analyses revealed increased connectivity of language regions with posterior cingulate cortex (PCC) and visual regions in the ASD group. Post hoc effective connectivity analyses revealed a mediation effect of PCC on the iFC between bilateral inferior frontal and visual regions in an ASD subgroup. This finding qualifies and expands on previous reports of recruitment of visual areas in language processing in ASDs. In addition, increased iFC between PCC and visual regions was linked to lower language scores in this ASD subgroup, suggesting that increased connectivity with visual cortices, mediated by default mode regions, may be detrimental to language abilities. Autism Res 2019, 12: 1344-1355. (c) 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: We examined the functional connectivity between regions of the language network in children with autism spectrum disorders (ASDs) compared to typically developing peers. We found connectivity to be intact between core language in the ASD group, but also showed abnormally increased connectivity between regions of an extended language network. Additionally, connectivity was increased with regions associated with brain networks responsible for self-reflection and visual processing. En ligne : http://dx.doi.org/10.1002/aur.2171 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=406

Deletion and duplication of 16p11.2 are associated with opposing effects on visual evoked potential amplitude / J. J. LEBLANC in Molecular Autism, 7 (2016)  

Public ISBD [article]  inMolecular Autism > 7 (2016) . - 30p. Titre : Deletion and duplication of 16p11.2 are associated with opposing effects on visual evoked potential amplitude Type de document : Texte imprimé et/ou numérique Auteurs : J. J. LEBLANC, Auteur ; C. A. NELSON, Auteur Article en page(s) : 30p. Langues : Anglais (eng) Mots-clés : Adolescent  Child  Child, Preschool  Chromosomes, Human, Pair 16/genetics  DNA Copy Number Variations  Developmental Disabilities/diagnosis/physiopathology  Electroencephalography  Evoked Potentials, Visual/physiology  Female  Gene Deletion  Gene Duplication  Humans  Male  Visual Cortex/diagnostic imaging  16p11.2 copy number variation  Visual cortex  Visual evoked potential Index. décimale : PER Périodiques Résumé : BACKGROUND: Duplication and deletion of the chromosomal region 16p11.2 cause a broad range of impairments, including intellectual disability, language disorders, and sensory symptoms. However, it is unclear how changes in 16p11.2 dosage affect cortical circuitry during development. The aim of this study was to investigate whether the visual evoked potential (VEP) could be used as a noninvasive quantitative measure of cortical processing in children with 16p11.2 copy number variation. METHODS: Pattern-reversal VEPs were successfully recorded in 19 deletion carriers, 9 duplication carriers, and 13 typically developing children between the ages of 3 and 14 years. The stimulus was a black and white checkerboard (60') that reversed contrast at 2 Hz. VEP responses were extracted from continuous EEG recorded using a high-density elasticized electrode net. RESULTS: Quantitative analysis of the VEP waveform revealed that, relative to controls, deletion carriers displayed increased amplitude and duplication carriers displayed diminished amplitude. Latencies of the VEP waveform components were unaffected by 16p11.2 status. P1 amplitude did not correlate with age, IQ, or head circumference. CONCLUSIONS: The results of this study suggest that recording VEP is a useful method to assay cortical processing in children with 16p11.2 copy number variation. There is a gene dosage-dependent effect on P1 amplitude that merits further investigation. The VEP is directly translatable to animal models, offering a promising way to probe the neurobiological mechanisms underlying cortical dysfunction in this developmental disorder. En ligne : http://dx.doi.org/10.1186/s13229-016-0095-7 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=328 [article] Deletion and duplication of 16p11.2 are associated with opposing effects on visual evoked potential amplitude [Texte imprimé et/ou numérique] / J. J. LEBLANC, Auteur ; C. A. NELSON, Auteur . - 30p. Langues : Anglais (eng) in Molecular Autism > 7 (2016) . - 30p. Mots-clés : Adolescent  Child  Child, Preschool  Chromosomes, Human, Pair 16/genetics  DNA Copy Number Variations  Developmental Disabilities/diagnosis/physiopathology  Electroencephalography  Evoked Potentials, Visual/physiology  Female  Gene Deletion  Gene Duplication  Humans  Male  Visual Cortex/diagnostic imaging  16p11.2 copy number variation  Visual cortex  Visual evoked potential Index. décimale : PER Périodiques Résumé : BACKGROUND: Duplication and deletion of the chromosomal region 16p11.2 cause a broad range of impairments, including intellectual disability, language disorders, and sensory symptoms. However, it is unclear how changes in 16p11.2 dosage affect cortical circuitry during development. The aim of this study was to investigate whether the visual evoked potential (VEP) could be used as a noninvasive quantitative measure of cortical processing in children with 16p11.2 copy number variation. METHODS: Pattern-reversal VEPs were successfully recorded in 19 deletion carriers, 9 duplication carriers, and 13 typically developing children between the ages of 3 and 14 years. The stimulus was a black and white checkerboard (60') that reversed contrast at 2 Hz. VEP responses were extracted from continuous EEG recorded using a high-density elasticized electrode net. RESULTS: Quantitative analysis of the VEP waveform revealed that, relative to controls, deletion carriers displayed increased amplitude and duplication carriers displayed diminished amplitude. Latencies of the VEP waveform components were unaffected by 16p11.2 status. P1 amplitude did not correlate with age, IQ, or head circumference. CONCLUSIONS: The results of this study suggest that recording VEP is a useful method to assay cortical processing in children with 16p11.2 copy number variation. There is a gene dosage-dependent effect on P1 amplitude that merits further investigation. The VEP is directly translatable to animal models, offering a promising way to probe the neurobiological mechanisms underlying cortical dysfunction in this developmental disorder. En ligne : http://dx.doi.org/10.1186/s13229-016-0095-7 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=328

Concentrations of Cortical GABA and Glutamate in Young Adults With Autism Spectrum Disorder / Tamar KOLODNY in Autism Research, 13-7 (July 2020)  

Public ISBD [article]  inAutism Research > 13-7 (July 2020) . - p.1111-1129 Titre : Concentrations of Cortical GABA and Glutamate in Young Adults With Autism Spectrum Disorder Type de document : Texte imprimé et/ou numérique Auteurs : Tamar KOLODNY, Auteur ; Michael-Paul SCHALLMO, Auteur ; Jennifer GERDTS, Auteur ; Richard A. E. EDDEN, Auteur ; Raphael BERNIER, Auteur ; Scott O. MURRAY, Auteur Article en page(s) : p.1111-1129 Langues : Anglais (eng) Mots-clés : auditory cortex  autism spectrum disorders  glutamate  magnetic resonance spectroscopy  sensorimotor cortex  visual cortex  ?-aminobutyric acid Index. décimale : PER Périodiques Résumé : The balance of excitation and inhibition in neural circuits is hypothesized to be increased in autism spectrum disorder, possibly mediated by altered signaling of the inhibitory neurotransmitter ?-aminobutyric acid (GABA), yet empirical evidence in humans is inconsistent. We used edited magnetic resonance spectroscopy (MRS) to quantify signals associated with both GABA and the excitatory neurotransmitter glutamate in multiple regions of the sensory and sensorimotor cortex, including primary visual, auditory, and motor areas in adult individuals with autism and in neurotypical controls. Despite the strong a priori hypothesis of reduced GABA in autism spectrum disorder, we found no group differences in neurometabolite concentrations in any of the examined regions and no correlations of MRS measure with psychophysical visual sensitivity or autism symptomatology. We demonstrate high data quality that is comparable across groups, with a relatively large sample of well-characterized participants, and use Bayesian statistics to corroborate the lack of any group differences. We conclude that levels of GABA and Glx (glutamate, glutamine, and glutathione) in the sensory and sensorimotor cortex, as measured with MRS at 3T, are comparable in adults with autism and neurotypical individuals. Autism Res 2020, 13: 1111-1129. © 2020 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: ?-Aminobutyric acid (GABA) and glutamate are the main inhibitory and excitatory neurotransmitters in the human brain, respectively, and their balanced interaction is necessary for neural function. Previous research suggests that the GABA and glutamate systems might be altered in autism. In this study, we used magnetic resonance spectroscopy to measure concentrations of these neurotransmitters in the sensory areas in the brains of young adults with autism. In contradiction to the common hypothesis of reduced GABA in autism, we demonstrate that concentrations of both GABA and glutamate, in all the brain regions examined, are comparable in individuals with autism and in neurotypical adults. © 2020 International Society for Autism Research, Wiley Periodicals, Inc. En ligne : http://dx.doi.org/10.1002/aur.2300 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=429 [article] Concentrations of Cortical GABA and Glutamate in Young Adults With Autism Spectrum Disorder [Texte imprimé et/ou numérique] / Tamar KOLODNY, Auteur ; Michael-Paul SCHALLMO, Auteur ; Jennifer GERDTS, Auteur ; Richard A. E. EDDEN, Auteur ; Raphael BERNIER, Auteur ; Scott O. MURRAY, Auteur . - p.1111-1129. Langues : Anglais (eng) in Autism Research > 13-7 (July 2020) . - p.1111-1129 Mots-clés : auditory cortex  autism spectrum disorders  glutamate  magnetic resonance spectroscopy  sensorimotor cortex  visual cortex  ?-aminobutyric acid Index. décimale : PER Périodiques Résumé : The balance of excitation and inhibition in neural circuits is hypothesized to be increased in autism spectrum disorder, possibly mediated by altered signaling of the inhibitory neurotransmitter ?-aminobutyric acid (GABA), yet empirical evidence in humans is inconsistent. We used edited magnetic resonance spectroscopy (MRS) to quantify signals associated with both GABA and the excitatory neurotransmitter glutamate in multiple regions of the sensory and sensorimotor cortex, including primary visual, auditory, and motor areas in adult individuals with autism and in neurotypical controls. Despite the strong a priori hypothesis of reduced GABA in autism spectrum disorder, we found no group differences in neurometabolite concentrations in any of the examined regions and no correlations of MRS measure with psychophysical visual sensitivity or autism symptomatology. We demonstrate high data quality that is comparable across groups, with a relatively large sample of well-characterized participants, and use Bayesian statistics to corroborate the lack of any group differences. We conclude that levels of GABA and Glx (glutamate, glutamine, and glutathione) in the sensory and sensorimotor cortex, as measured with MRS at 3T, are comparable in adults with autism and neurotypical individuals. Autism Res 2020, 13: 1111-1129. © 2020 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: ?-Aminobutyric acid (GABA) and glutamate are the main inhibitory and excitatory neurotransmitters in the human brain, respectively, and their balanced interaction is necessary for neural function. Previous research suggests that the GABA and glutamate systems might be altered in autism. In this study, we used magnetic resonance spectroscopy to measure concentrations of these neurotransmitters in the sensory areas in the brains of young adults with autism. In contradiction to the common hypothesis of reduced GABA in autism, we demonstrate that concentrations of both GABA and glutamate, in all the brain regions examined, are comparable in individuals with autism and in neurotypical adults. © 2020 International Society for Autism Research, Wiley Periodicals, Inc. En ligne : http://dx.doi.org/10.1002/aur.2300 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=429