Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum

Montréal, Canada

Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum

Montréal, Canada
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Ostrolenk A.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | Ostrolenk A.,University Of Montrealquebec | Forgeot d'Arc B.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | Forgeot d'Arc B.,University Of Montrealquebec | And 4 more authors.
Neuroscience and Biobehavioral Reviews | Year: 2017

Hyperlexia is defined as the co-occurrence of advanced reading skills relative to comprehension skills or general intelligence, the early acquisition of reading skills without explicit teaching, and a strong orientation toward written material, generally in the context of a neurodevelopmental disorder. In this systematic review of cases (N = 82) and group studies (including 912 participants of which 315 are hyperlexic), we address: whether the hyperlexic profile is associated with autism and why, whether models of non-autistic reading can teach us about hyperlexia, and what additional information we can get from models specific to autistic cognitive functioning. We find that hyperlexia, or a hyperlexic-like profile, characterises a substantial portion of the autistic spectrum, in which the subcomponents of the typical reading architecture are altered and dissociated. Autistic children follow a chronologically inverted path when learning to read, and make extended use of the perceptual expertise system, specifically the visual word form recognition systems. We conclude by discussing the possible use of hyperlexic skills in intervention. © 2017 The Authors


Perreault A.,Riviere des Prairies Hospital | Perreault A.,University of Montréal | Habak C.,Educational Neuroscience Research Center | Lepore F.,University of Montréal | And 4 more authors.
Neuropsychologia | Year: 2015

Background: Most investigations of visuo-perceptual abilities in the Autism Spectrum (AS) are level-specific, using tasks that selectively solicit either lower- (i.e., spatial frequency sensitivity), mid- (i.e., pattern discrimination) or higher-level processes (i.e., face identification) along the visual hierarchy. Less is known about how alterations at one level of processing (i.e., low-level) interact with that of another (i.e., mid-level). The aim of this study was to assess whether manipulating the physical properties (luminance vs texture) of local contour elements of a mid-level, visual pattern interferes with the discrimination of that pattern in a differential manner for individuals with AS. Methods: Twenty-nine AS individuals and thirty control participants (range 14-27 years) were asked to discriminate between perfect circles and Radial Frequency Patterns (RFP) of two, three, five, and 10 radial frequencies (RF), or deformations along the pattern's contour. When RFP have few deformations (


Russo N.,Syracuse University | Mottron L.,Hopital Rivieres des Prairies | Mottron L.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | Burack J.A.,McGill University | Jemel B.,Hopital Rivieres des Prairies
Neuropsychologia | Year: 2012

Individuals with autism spectrum disorders (ASD) report difficulty integrating simultaneously presented visual and auditory stimuli (Iarocci & McDonald, 2006), albeit showing enhanced perceptual processing of unisensory stimuli, as well as an enhanced role of perception in higher-order cognitive tasks (Enhanced Perceptual Functioning (EPF) model; Mottron, Dawson, Soulières, Hubert, & Burack, 2006). Individuals with an ASD also integrate auditory-visual inputs over longer periods of time than matched typically developing (TD) peers (Kwakye, Foss-Feig, Cascio, Stone & Wallace, 2011). To tease apart the dichotomy of both extended multisensory processing and enhanced perceptual processing, we used behavioral and electrophysiological measurements of audio-visual integration among persons with ASD. 13 TD and 14 autistics matched on IQ completed a forced choice multisensory semantic congruence task requiring speeded responses regarding the congruence or incongruence of animal sounds and pictures. Stimuli were presented simultaneously or sequentially at various stimulus onset asynchronies in both auditory first and visual first presentations. No group differences were noted in reaction time (RT) or accuracy. The latency at which congruent and incongruent waveforms diverged was the component of interest. In simultaneous presentations, congruent and incongruent waveforms diverged earlier (circa 150. ms) among persons with ASD than among TD individuals (around 350. ms). In sequential presentations, asymmetries in the timing of neuronal processing were noted in ASD which depended on stimulus order, but these were consistent with the nature of specific perceptual strengths in this group. These findings extend the Enhanced Perceptual Functioning Model to the multisensory domain, and provide a more nuanced context for interpreting ERP findings of impaired semantic processing in ASD. © 2012 Elsevier Ltd.


Keita L.,University of Montréal | Keita L.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | Mottron L.,University of Montréal | Mottron L.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | And 2 more authors.
Autism Research | Year: 2010

Although autism presents a unique perceptual phenotype defined in part by atypical (often enhanced) analysis of spatial information, few biologically plausible hypotheses have been advanced to explain its neural underpinnings. One plausible explanation is functional but altered lateral connectivity mediating early or local mechanisms selectively responsive to different stimulus attributes, including spatial frequency and contrast. The goal of the present study was first to assess far visual acuity in autism using Landolt-C optotypes defined by different local stimulus attributes. Second, we investigated whether acuity is differentially affected in autism when target optotypes are simultaneously presented with flanking stimuli at different distances. This typical detrimental "crowding effect" of flanking stimuli on target optotype discrimination is attributed to lateral inhibitory interaction of neurons encoding for visual properties of distracters close to the target. Results failed to demonstrate a between-group difference in acuity to Landolt-C optotypes, whether defined by luminance- or texture-contrast. However, the expected crowding effect at one gap-size opening distance was evidenced for the control group only; a small effect was observed for the autism group at two gap-size opening. These results suggest that although far visual acuity is unremarkable in autism, altered local lateral connectivity within early perceptual areas underlying spatial information processing in autism is atypical. Altered local lateral connectivity in autism might originate from an imbalance in excitatory/inhibitory neural signaling, resulting in changes regarding elementary feature extraction and subsequent downstream visual integration and visuo-spatial analysis. This notion is discussed within the context of characteristic lower- and higher-level perceptual processing in autism. © 2010, International Society for Autism Research, Wiley Periodicals, Inc.


Soulieres I.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | Soulieres I.,Harvard University | Dawson M.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | Gernsbacher M.A.,University of Wisconsin - Madison | Mottron L.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum
PLoS ONE | Year: 2011

A distinctively uneven profile of intelligence is a feature of the autistic spectrum. Within the spectrum, individuals with Asperger syndrome differ from patients with autism in their early speech development and in being less likely to be characterized by visuospatial peaks. While different specific strengths characterize different autistic spectrum subgroups, all such peaks of ability have been interpreted as deficits: isolated, aberrant, and irreconcilable with real human intelligence. This view has recently been challenged by findings of autistic strengths in performance on Raven's Progressive Matrices (RPM), an important marker of general and fluid intelligence. We investigated whether these findings extend to Asperger syndrome, an autistic spectrum subgroup characterized by verbal peaks of ability, and whether the cognitive mechanisms underlying autistic and Asperger RPM performance differ. Thirty-two adults with Asperger syndrome displayed a significant advantage on RPM over Wechsler Full-Scale and Performance scores relative to their typical controls, while in 25 children with Asperger syndrome, an RPM advantage was found over Wechsler Performance scores only. As previously found with patients with autism, children and adults with Asperger syndrome achieved RPM scores at a level reflecting their Wechsler peaks of ability. Therefore, strengths in RPM performance span the autistic spectrum and imply a common mechanism advantageously applied to different facets of cognition. Autistic spectrum intelligence is atypical, but also genuine, general, and underestimated. © 2011 Soulières et al.


Samson F.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | Mottron L.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | Soulieres I.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | Soulieres I.,Massachusetts General Hospital | Zeffiro T.A.,Massachusetts General Hospital
Human Brain Mapping | Year: 2012

Autistics often exhibit enhanced perceptual abilities when engaged in visual search, visual discrimination, and embedded figure detection. In similar fashion, while performing a range of perceptual or cognitive tasks, autistics display stronger physiological engagement of the visual system than do non-autistics. To account for these findings, the Enhanced Perceptual Functioning Model proposes that enhanced autistic performance in basic perceptual tasks results from stronger engagement of sensory processing mechanisms, a situation that may facilitate an atypically prominent role for perceptual mechanisms in supporting cognition. Using quantitative meta-analysis of published functional imaging studies from which Activation Likelihood Estimation maps were computed, we asked whether autism is associated with enhanced task-related activity for a broad range of visual tasks. To determine whether atypical engagement of visual processing is a general or domain-specific phenomenon, we examined three different visual processing domains: faces, objects, and words. Overall, we observed more activity in autistics compared to non-autistics in temporal, occipital, and parietal regions. In contrast, autistics exhibited less activity in frontal cortex. The spatial distribution of the observed differential between-group patterns varied across processing domains. Autism may be characterized by enhanced functional resource allocation in regions associated with visual processing and expertise. Atypical adult organizational patterns may reflect underlying differences in developmental neural plasticity that can result in aspects of the autistic phenotype, including enhanced visual skills, atypical face processing, and hyperlexia. ©; 2011 Wiley-Liss, Inc.


Guy J.,McGill University | Mottron L.,McGill University | Berthiaume C.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | Bertone A.,McGill University
Autism Research | Year: 2015

Autism Spectrum Disorder (ASD) is characterized by a detail-driven visual processing strategy, evidence for which has been based largely on cross-sectional studies in small participant groups of limited age ranges. It is therefore unknown when sensitivity to detailed information emerges and develops in ASD. Contrast sensitivity to sinusoidal gratings of different spatial frequencies (0.5, 1, 2, 4, and 8 cycles per degree (cpd)) was measured for 34 participants with ASD and 55 typically developing participants (aged 6-16 years). Cross-sectional, developmental trajectories were constructed to examine within and between group differences across the range of spatial frequencies tested. Developmental trajectories indicated that sensitivity across low (i.e., 0.5 and 1 cpd) and mid (2 and 4 cpd) spatial frequencies varied by chronological age within each group, with mid frequencies developing at a more significant rate than low frequencies. There was no overall difference between groups in terms of the relationship of sensitivity and age across spatial frequencies, yet the ASD group had an overall lower level of sensitivity. Closer examination revealed that the youngest participants with ASD had a reduced sensitivity for mid frequencies. Moreover, the ASD group showed a statistically significant developmental relationship at 8 cpd, which suggests that a trend for increased sensitivity to early detailed information may manifest beyond the ages tested. These findings demonstrate a differential development of contrast sensitivity for spatial frequencies in ASD and underscore the need to better identify what drives such differences in the "building blocks" of visual perception. © 2015 International Society for Autism Research, Wiley Periodicals, Inc.


Collignon O.,University of Montréal | Collignon O.,University of Trento | Charbonneau G.,University of Montréal | Peters F.,University of Montréal | And 6 more authors.
Cortex | Year: 2013

Although the literature concerning auditory and visual perceptual capabilities in the autism spectrum is growing, our understanding of multisensory integration (MSI) is rather limited. In the present study, we assessed MSI in autism by measuring whether participants benefited from an auditory cue presented in synchrony with the color change of a target during a complex visual search task. The synchronous auditory pip typically increases search efficacy (pip and pop effect), indicative of the beneficial use of sensory input from both modalities. We found that for conditions without auditory information, autistic participants were better at visual search compared to neurotypical participants. Importantly, search efficiency was increased by the presence of auditory pip for neurotypical participants only. The simultaneous occurrence of superior unimodal performance with altered audio-visual integration in autism suggests autonomous sensory processing in this population. © 2012 Elsevier Ltd.


Galle S.A.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | Galle S.A.,University of Amsterdam | Courchesne V.,University of Montréal | Mottron L.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | Frasnelli J.,University of Montréal
Perception | Year: 2013

The autism spectrum (AS) is characterized by enhanced perception in vision and audition, described by the enhanced perceptual functioning (EPF) model. This model predicts enhanced low-level (discrimination of psychophysical dimensions), and mid- and high-level (pattern detection and identification) perception. The EPF model is here tested for olfaction by investigating olfactory function in autistic and Asperger participants. Experiment 1 targeted higher-order olfactory processing by assessing olfactory identification in nine Asperger, ten autistic, and eleven typically developed individuals. Experiment 2 focused on low-level olfactory processing; we assessed odour detection thresholds and odour discrimination in five Asperger, five autistic, and five typically developed males. Olfactory identification was impaired in autistic participants relative to control and Asperger participants. Typical performance in low-level olfactory processing suggests that neural mechanisms involved in the perceptual phenotype of AS do not affect structures implicated in olfactory processing. Reduced olfactory identification is limited to autistic participants who displayed speech delay and may be due to a reduced facility to use verbal labels. The apparent absence of enhanced olfactory perception of AS participants distinguishes the olfactory system from the other sensory modalities and might be caused by the absence of an obligatory thalamic relay.


Mitchell P.,University of Nottingham | Mottron L.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | Mottron L.,University of Montréal | Soulieres I.,Center Dexcellence En Troubles Envahissants Du Developpement Of Luniversite Of Montreal Cetedum | And 2 more authors.
Autism Research | Year: 2010

Previous research [Ropar & Mitchell, 2002] has shown that autistic individuals are somewhat immune to biases induced by top-down processes, particularly the influence of previous knowledge on perception. In order to test this hypothesis within perception, 18 participants with autism who had measured intelligence in the normal range were compared against 18 matched controls in their susceptibility to the Shepard illusion. The illusion consists in misperceiving the shape of a parallelogram in the presence of depth cues. It is attributed [Mitchell, Ropar, Ackroyd, & Rajendran, 2005] to the effect of top-down constraints within perception. The task involved adjusting a stimulus to the dimensions of a template on a computer screen. Both groups were susceptible to the illusion and the illusion effect was stronger when three-dimensional perspective cues were prominent. Notably, participants with autism were less susceptible to the illusion than typically developing individuals. The findings raise the possibility that in some instances top-down influences are attenuated in individuals with autism. © 2010 International Society for Autism Research, Wiley Periodicals, Inc.

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