DTI and Tractography in the Autistic Brain / Timothy P.L. ROBERTS

Public ISBD in The Neuroscience of Autism Spectrum Disorders / Joseph D. BUXBAUM Titre : DTI and Tractography in the Autistic Brain Type de document : Texte imprimé et/ou numérique Auteurs : Timothy P.L. ROBERTS, Auteur ; Jeffrey I. BERMAN, Auteur ; Ragini VERMA, Auteur Année de publication : 2013 Importance : p.267-279 Langues : Anglais (eng) Index. décimale : SCI-D SCI-D - Neurosciences Résumé : Diffusion tensor imaging (DTI) and associated fiber tractography are an emerging MRI technique for studying white matter of the brain. This chapter presents an introduction to the physical and biological bases of diffusion in white matter and the development and analysis of diffusion tensor imaging. It also includes visualization of white matter fiber tracts and quantification of physical diffusion parameters, such as the mean diffusivity (MD) and fractional anisotropy (FA) that might be used to index white matter maturation. A review of the recent findings made using DTI in ASD (autism spectrum disorder) is presented, focusing on studies with large (gt;20) sample sizes. Common themes of elevated mean diffusivity and diminished fractional anisotropy emerge, especially in structures of the frontal and temporal lobes, but also in the corpus callosum. Voxel-based as well as regional connectivity approaches to extracting quantitative information from DTI are discussed along with approaches involving machine learning of pattern classifiers to distinguish ASD from TD and also identify key features (structures, regions or connections) that contribute most to that discrimination ability. Limitations of tractography based on DTI are discussed along with the emerging advance of high angular resolution diffusion imaging (HARDI) as a means to overcome DTI limitations in regions of complex white matter organization. Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=189 in The Neuroscience of Autism Spectrum Disorders / Joseph D. BUXBAUM DTI and Tractography in the Autistic Brain [Texte imprimé et/ou numérique] / Timothy P.L. ROBERTS, Auteur ; Jeffrey I. BERMAN, Auteur ; Ragini VERMA, Auteur . - 2013 . - p.267-279. Langues : Anglais (eng) Index. décimale : SCI-D SCI-D - Neurosciences Résumé : Diffusion tensor imaging (DTI) and associated fiber tractography are an emerging MRI technique for studying white matter of the brain. This chapter presents an introduction to the physical and biological bases of diffusion in white matter and the development and analysis of diffusion tensor imaging. It also includes visualization of white matter fiber tracts and quantification of physical diffusion parameters, such as the mean diffusivity (MD) and fractional anisotropy (FA) that might be used to index white matter maturation. A review of the recent findings made using DTI in ASD (autism spectrum disorder) is presented, focusing on studies with large (gt;20) sample sizes. Common themes of elevated mean diffusivity and diminished fractional anisotropy emerge, especially in structures of the frontal and temporal lobes, but also in the corpus callosum. Voxel-based as well as regional connectivity approaches to extracting quantitative information from DTI are discussed along with approaches involving machine learning of pattern classifiers to distinguish ASD from TD and also identify key features (structures, regions or connections) that contribute most to that discrimination ability. Limitations of tractography based on DTI are discussed along with the emerging advance of high angular resolution diffusion imaging (HARDI) as a means to overcome DTI limitations in regions of complex white matter organization. Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=189

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Knockout of NMDA Receptors in Parvalbumin Interneurons Recreates Autism-Like Phenotypes / John A. SAUNDERS in Autism Research, 6-2 (April 2013)  

Public ISBD [article]  inAutism Research > 6-2 (April 2013) . - p.69-77 Titre : Knockout of NMDA Receptors in Parvalbumin Interneurons Recreates Autism-Like Phenotypes Type de document : Texte imprimé et/ou numérique Auteurs : John A. SAUNDERS, Auteur ; Valerie M. TATARD-LEITMAN, Auteur ; Jimmy SUH, Auteur ; Eddie N. BILLINGSLEA, Auteur ; Timothy P.L. ROBERTS, Auteur ; Steven J. SIEGEL, Auteur Année de publication : 2013 Article en page(s) : p.69-77 Langues : Anglais (eng) Mots-clés : autism  electrophysiology  endophenotype  animal models  NMDA receptor 1 knockout Index. décimale : PER Périodiques Résumé : Autism is a disabling neurodevelopmental disorder characterized by social deficits, language impairment, and repetitive behaviors with few effective treatments. New evidence suggests that autism has reliable electrophysiological endophenotypes and that these measures may be caused by n-methyl-d-aspartic acid receptor (NMDAR) disruption on parvalbumin (PV)-containing interneurons. These findings could be used to create new translational biomarkers. Recent developments have allowed for cell-type selective knockout of NMDARs in order to examine the perturbations caused by disrupting specific circuits. This study examines several electrophysiological and behavioral measures disrupted in autism using a PV-selective reduction in NMDA R1 subunit. Mouse electroencephalograph (EEG) was recorded in response to auditory stimuli. Event-related potential (ERP) component amplitude and latency analysis, social testing, and premating ultrasonic vocalizations (USVs) recordings were performed. Correlations were examined between the ERP latency and behavioral measures. The N1 ERP latency was delayed, sociability was reduced, and mating USVs were impaired in PV-selective NMDA Receptor 1 Knockout (NR1 KO) as compared with wild-type mice. There was a significant correlation between N1 latency and sociability but not between N1 latency and premating USV power or T-maze performance. The increases in N1 latency, impaired sociability, and reduced vocalizations in PV-selective NR1 KO mice mimic similar changes found in autism. Electrophysiological changes correlate to reduced sociability, indicating that the local circuit mechanisms controlling N1 latency may be utilized in social function. Therefore, we propose that behavioral and electrophysiological alterations in PV-selective NR1 KO mice may serve as a useful model for therapeutic development in autism. En ligne : http://dx.doi.org/10.1002/aur.1264 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=199 [article] Knockout of NMDA Receptors in Parvalbumin Interneurons Recreates Autism-Like Phenotypes [Texte imprimé et/ou numérique] / John A. SAUNDERS, Auteur ; Valerie M. TATARD-LEITMAN, Auteur ; Jimmy SUH, Auteur ; Eddie N. BILLINGSLEA, Auteur ; Timothy P.L. ROBERTS, Auteur ; Steven J. SIEGEL, Auteur . - 2013 . - p.69-77. Langues : Anglais (eng) in Autism Research > 6-2 (April 2013) . - p.69-77 Mots-clés : autism  electrophysiology  endophenotype  animal models  NMDA receptor 1 knockout Index. décimale : PER Périodiques Résumé : Autism is a disabling neurodevelopmental disorder characterized by social deficits, language impairment, and repetitive behaviors with few effective treatments. New evidence suggests that autism has reliable electrophysiological endophenotypes and that these measures may be caused by n-methyl-d-aspartic acid receptor (NMDAR) disruption on parvalbumin (PV)-containing interneurons. These findings could be used to create new translational biomarkers. Recent developments have allowed for cell-type selective knockout of NMDARs in order to examine the perturbations caused by disrupting specific circuits. This study examines several electrophysiological and behavioral measures disrupted in autism using a PV-selective reduction in NMDA R1 subunit. Mouse electroencephalograph (EEG) was recorded in response to auditory stimuli. Event-related potential (ERP) component amplitude and latency analysis, social testing, and premating ultrasonic vocalizations (USVs) recordings were performed. Correlations were examined between the ERP latency and behavioral measures. The N1 ERP latency was delayed, sociability was reduced, and mating USVs were impaired in PV-selective NMDA Receptor 1 Knockout (NR1 KO) as compared with wild-type mice. There was a significant correlation between N1 latency and sociability but not between N1 latency and premating USV power or T-maze performance. The increases in N1 latency, impaired sociability, and reduced vocalizations in PV-selective NR1 KO mice mimic similar changes found in autism. Electrophysiological changes correlate to reduced sociability, indicating that the local circuit mechanisms controlling N1 latency may be utilized in social function. Therefore, we propose that behavioral and electrophysiological alterations in PV-selective NR1 KO mice may serve as a useful model for therapeutic development in autism. En ligne : http://dx.doi.org/10.1002/aur.1264 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=199

MEG detection of delayed auditory evoked responses in autism spectrum disorders: towards an imaging biomarker for autism / Timothy P.L. ROBERTS in Autism Research, 3-1 (February 2010)  

Public ISBD [article]  inAutism Research > 3-1 (February 2010) . - p.8-18 Titre : MEG detection of delayed auditory evoked responses in autism spectrum disorders: towards an imaging biomarker for autism Type de document : Texte imprimé et/ou numérique Auteurs : Timothy P.L. ROBERTS, Auteur ; Susan E. LEVY, Auteur ; Gwenda L. SCHMIDT, Auteur ; J. Christopher EDGAR, Auteur ; Deborah M. ZARNOW, Auteur ; Mike GANDAL, Auteur ; Saba QASMIEH, Auteur ; Sarah WOLDOFF, Auteur ; Lisa BLASKEY, Auteur ; Justin F. MONROE, Auteur ; Mike REY, Auteur ; Sarah Y. KHAN, Auteur ; Katelyn M. CANNON, Auteur Année de publication : 2010 Article en page(s) : p.8-18 Langues : Anglais (eng) Mots-clés : autism-spectrum-disorders M50 M100 magnetoencephalography language-impairment auditory-evoked-response Index. décimale : PER Périodiques Résumé : Motivated by auditory and speech deficits in autism spectrum disorders (ASD), the frequency dependence of superior temporal gyrus (STG) 50 msec (M50) and 100 msec (M100) neuromagnetic auditory evoked field responses in children with ASD and typically developing controls were evaluated. Whole-cortex magnetoencephalography (MEG) was obtained from 17 typically developing children and 25 children with ASD. Subjects were presented tones with frequencies of 200, 300, 500, and 1,000 Hz, and left and right STG M50 and M100 STG activity was examined. No M50 latency or amplitude Group differences were observed. In the right hemisphere, a Group×Frequency ANOVA on M100 latency produced a main effect for Group (P=0.01), with an average M100 latency delay of 11 msec in children with ASD. In addition, only in the control group was the expected association of earlier M100 latencies in older than younger children observed. Group latency differences remained significant when hierarchical regression analyses partialed out M100 variance associated with age, IQ, and language ability (all P-values <0.05). Examining the right-hemisphere 500 Hz condition (where the largest latency differences were observed), a sensitivity of 75%, a specificity of 81%, and a positive predictive value (PPV) of 86% was obtained at a threshold of 116 msec. The M100 latency delay indicates disruption of encoding simple sensory information. Given similar findings in language impaired and nonlanguage impaired ASD subjects, a right-hemisphere M100 latency delay appears to be an electrophysiological endophenotype for autism. En ligne : http://dx.doi.org/10.1002/aur.111 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=993 [article] MEG detection of delayed auditory evoked responses in autism spectrum disorders: towards an imaging biomarker for autism [Texte imprimé et/ou numérique] / Timothy P.L. ROBERTS, Auteur ; Susan E. LEVY, Auteur ; Gwenda L. SCHMIDT, Auteur ; J. Christopher EDGAR, Auteur ; Deborah M. ZARNOW, Auteur ; Mike GANDAL, Auteur ; Saba QASMIEH, Auteur ; Sarah WOLDOFF, Auteur ; Lisa BLASKEY, Auteur ; Justin F. MONROE, Auteur ; Mike REY, Auteur ; Sarah Y. KHAN, Auteur ; Katelyn M. CANNON, Auteur . - 2010 . - p.8-18. Langues : Anglais (eng) in Autism Research > 3-1 (February 2010) . - p.8-18 Mots-clés : autism-spectrum-disorders M50 M100 magnetoencephalography language-impairment auditory-evoked-response Index. décimale : PER Périodiques Résumé : Motivated by auditory and speech deficits in autism spectrum disorders (ASD), the frequency dependence of superior temporal gyrus (STG) 50 msec (M50) and 100 msec (M100) neuromagnetic auditory evoked field responses in children with ASD and typically developing controls were evaluated. Whole-cortex magnetoencephalography (MEG) was obtained from 17 typically developing children and 25 children with ASD. Subjects were presented tones with frequencies of 200, 300, 500, and 1,000 Hz, and left and right STG M50 and M100 STG activity was examined. No M50 latency or amplitude Group differences were observed. In the right hemisphere, a Group×Frequency ANOVA on M100 latency produced a main effect for Group (P=0.01), with an average M100 latency delay of 11 msec in children with ASD. In addition, only in the control group was the expected association of earlier M100 latencies in older than younger children observed. Group latency differences remained significant when hierarchical regression analyses partialed out M100 variance associated with age, IQ, and language ability (all P-values <0.05). Examining the right-hemisphere 500 Hz condition (where the largest latency differences were observed), a sensitivity of 75%, a specificity of 81%, and a positive predictive value (PPV) of 86% was obtained at a threshold of 116 msec. The M100 latency delay indicates disruption of encoding simple sensory information. Given similar findings in language impaired and nonlanguage impaired ASD subjects, a right-hemisphere M100 latency delay appears to be an electrophysiological endophenotype for autism. En ligne : http://dx.doi.org/10.1002/aur.111 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=993

Resting-State Oscillatory Activity in Autism Spectrum Disorders / Lauren CORNEW in Journal of Autism and Developmental Disorders, 42-9 (September 2012)  

Public ISBD [article]  inJournal of Autism and Developmental Disorders > 42-9 (September 2012) . - p.1884-1894 Titre : Resting-State Oscillatory Activity in Autism Spectrum Disorders Type de document : Texte imprimé et/ou numérique Auteurs : Lauren CORNEW, Auteur ; Timothy P.L. ROBERTS, Auteur ; Lisa BLASKEY, Auteur ; J. Christopher EDGAR, Auteur Année de publication : 2012 Article en page(s) : p.1884-1894 Langues : Anglais (eng) Mots-clés : Autism  Magnetoencephalography  Resting-state  Oscillations  Alpha  Gamma Index. décimale : PER Périodiques Résumé : Neural oscillatory anomalies in autism spectrum disorders (ASD) suggest an excitatory/inhibitory imbalance; however, the nature and clinical relevance of these anomalies are unclear. Whole-cortex magnetoencephalography data were collected while 50 children (27 with ASD, 23 controls) underwent an eyes-closed resting-state exam. A Fast Fourier Transform was applied and oscillatory activity examined from 1 to 120 Hz at 15 regional sources. Associations between oscillatory anomalies and symptom severity were probed. Children with ASD exhibited regionally specific elevations in delta (1–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), and high frequency (20–120 Hz) power, supporting an imbalance of neural excitation/inhibition as a neurobiological feature of ASD. Increased temporal and parietal alpha power was associated with greater symptom severity and thus is of particular interest. En ligne : http://dx.doi.org/10.1007/s10803-011-1431-6 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=180 [article] Resting-State Oscillatory Activity in Autism Spectrum Disorders [Texte imprimé et/ou numérique] / Lauren CORNEW, Auteur ; Timothy P.L. ROBERTS, Auteur ; Lisa BLASKEY, Auteur ; J. Christopher EDGAR, Auteur . - 2012 . - p.1884-1894. Langues : Anglais (eng) in Journal of Autism and Developmental Disorders > 42-9 (September 2012) . - p.1884-1894 Mots-clés : Autism  Magnetoencephalography  Resting-state  Oscillations  Alpha  Gamma Index. décimale : PER Périodiques Résumé : Neural oscillatory anomalies in autism spectrum disorders (ASD) suggest an excitatory/inhibitory imbalance; however, the nature and clinical relevance of these anomalies are unclear. Whole-cortex magnetoencephalography data were collected while 50 children (27 with ASD, 23 controls) underwent an eyes-closed resting-state exam. A Fast Fourier Transform was applied and oscillatory activity examined from 1 to 120 Hz at 15 regional sources. Associations between oscillatory anomalies and symptom severity were probed. Children with ASD exhibited regionally specific elevations in delta (1–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), and high frequency (20–120 Hz) power, supporting an imbalance of neural excitation/inhibition as a neurobiological feature of ASD. Increased temporal and parietal alpha power was associated with greater symptom severity and thus is of particular interest. En ligne : http://dx.doi.org/10.1007/s10803-011-1431-6 Permalink : https://www.cra-rhone-alpes.org/cid/opac_css/index.php?lvl=notice_display&id=180

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