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Biomedical subjects

L Mottron

Publications and source records attributed to L Mottron.

15 recordsLinked to original sources
PubMed2000

A laboratory study of sleep in Asperger's syndrome.

Asperger's syndrome (AS) is a pervasive developmental disorder that may fall along the autistic spectrum. We compared the sleep of eight patients with AS with that of participants matched for age and gender. Patients with AS showed decreased sleep time in the first two-thirds of the night, increased number of shifts into REM sleep from a waking epoch, and all but one patient showed signs of REM sleep disruption. EEG sleep spindles were significantly decreased while K complexes and REM sleep rapid eye movements were normal. Three patients with AS, but none of the comparison participants, showed a pathological index of periodic leg movements in sleep. These observations show that sleep disorders are associated with AS and suggest that defective sleep control systems may be associated with the clinical picture of AS.

Adult↗
PubMed2000

Local and global processing of music in high-functioning persons with autism: beyond central coherence?

A multi-modal abnormality in the integration of parts and whole has been proposed to account for a bias toward local stimuli in individuals with autism (Frith, 1989; Mottron & Belleville, 1993). In the current experiment, we examined the utility of hierarchical models in characterising musical information processing in autistic individuals. Participants were 13 high-functioning individuals with autism and 13 individuals of normal intelligence matched on chronological age, nonverbal IQ, and laterality, and without musical experience. The task consisted of same-different judgements of pairs of melodies. Differential local and global processing was assessed by manipulating the level, local or global, at which modifications occurred. No deficit was found in the two measures of global processing. In contrast, the clinical group performed better than the comparison group in the detection of change in nontransposed, contour-preserved melodies that tap local processing. These findings confirm the existence of a "local bias" in music perception in individuals with autism, but challenge the notion that it is accounted for by a deficit in global music processing. The present study suggests that enhanced processing of elementary physical properties of incoming stimuli, as found previously in the visual modality, may also exist in the auditory modality.

Adolescent↗
PubMed1999

Perceptual processing among high-functioning persons with autism.

Two tasks were used to assess the processing of whole versus parts of objects in a group of high-functioning children and adolescents with autism (N = 11) and a comparison group of typically developing peers (N = 11) matched for chronological age and IQ. In the first task, only the children with autism showed a global advantage, and the two groups showed similar interference between levels. In the second task, the children with autism, despite longer RTs, showed similar performance to the comparison group with regard to the effect of goodness on visual parsing. Contrary to expectations based on the central coherence and hierarchisation deficit theories, these findings indicate intact holistic processing among persons with autism. The implications of these findings are discussed in relation to apparently discrepant evidence from other studies.

Adolescent↗
PubMed1999

Local bias in autistic subjects as evidenced by graphic tasks: perceptual hierarchization or working memory deficit?

In the present study, copying tasks were used to assess hierarchical aspects of visual perception in a group of 10 nonsavant autistic individuals with normal intelligence. In Experiment 1, the hierarchical order of graphic construction and the constancy of this order were measured for the copying of objects and nonobjects. In comparison to control participants, autistic individuals produced more local features at the start of the copying. However, they did not differ from controls with respect to graphic constancy. Experiment 2 measured the effect of geometrical impossibility on the copying of figures. Results revealed that autistic individuals were less affected by figure impossibility than were controls. Therefore, these experiments seem to support the notion of a local bias for visual information processing in individuals with autism. Two interpretations are proposed to account for this effect. According to the hierarchical deficit hypothesis, individuals with autism do not manifest the normal global bias in perceiving scenes and objects. Alternatively, the executive function hypothesis suggests that autism brings about limitations in the complexity of information that can be manipulated in short-term visual memory during graphic planning.

Adolescent↗
PubMed1998

Atypical memory performance in an autistic savant.

This study explored the mechanisms underlying the hypermnesia of an autistic savant (NM) through three experiments. The first two served to assess whether absence of interference was responsible for NM's exceptional list memory. The third investigated the type of cues used in recall. Results indicated absence of retroactive interference but presence of slight proactive interference in list recall of proper names. Normal interference effects were found, however, in list recall of common nouns. Exceptional performance was also demonstrated in a missing-name task involving spatial and verbal recall cues. The findings suggest that the outstanding episodic memory presented by some savant persons with autism might be related to an abnormally high resistance to interference.

Adolescent↗
PubMed1998

Autism and visual agnosia in a child with right occipital lobectomy.

OBJECTIVES: Autistic disorder is a developmental handicap with an unknown neurological basis. Current neuropsychological models for autism suggest an abnormal construction of visual perceptual representation or a deficit in executive functions. These models predict cerebral lesions in the temporo-occipital or frontal regions of autistic patients. The present study aimed at studying the presence of symptoms of autism and visual agnosia in a 13 year old girl who had a right temporo-occipital cortical dysplasia that was surgically removed at the age of 7. METHODS: Neuropsychological evaluation included Wechsler and Kaufman intelligence scales, a test of word fluency, digit span, Corsi block, California verbal learning, Trail making, Benton facial recognition, Snoodgrass object recognition tests, Rivermead face learning subtest, and developmental test of visual perception. The ADI-R was used to show current and retrospective diagnosis of autistic disorder. Neuroimagery included brain MRI, single photon emission computed tomography (SPECT), and PET. RESULTS: Brain MRI showed a right occipital defect and an abnormal hyperintensity of the right temporal cortex. PET and SPECT disclosed a left frontal hypometabolism together with the right occipital defect. Neuropsychological testing showed a visual apperceptive agnosia and executive function deficits. Psychiatric study confirmed the diagnosis of autistic disorder. CONCLUSIONS: Although the possibility that autism and visual agnosia were dissociable factors in this patient cannot be excluded, the finding of both deficits supports the possibility that occipito-temporal lesions can predispose to the development of autism.

Adolescent↗
PubMed1998

[Case report. Therapeutic intervention using a "particular interest" of an autistic child with visual agnosia].

Although special education under its diverse forms is consensually recognized as the privileged area of pervasive developmental delay, there is little studies on re-education intervention for autistic persons of normal intelligence. This article presents a psychoeducative intervention with a three year old autistic boy in a pedopsychiatric day care centre. The interest of this observation is double. On the one hand, this child, aside from autism, is carrier of an exceptional ailment: visual agnosia. On the other hand, his "restrictive autistic interest", namely perceptive attraction and his questioning of a particular class of objects or a particular parameter of these objects were used as lever to bring him to improve his capacities of communication and social interactions.

Agnosia↗
PubMed1998

[Diagnosis of pervasive developmental disorders without mental retardation and its impact on obtaining social and educational services in Quebec].

Pervasive developmental disorders without mental retardation is a new clinical category including high-functioning autism, Asperger syndrome and pervasive developmental disorder non otherwise specified. Its recognition is recent and still problematic in many regards. This article reviews the historical, theoretical and clinical relations between pervasive developmental disorders without mental retardation and bordering disorders. The consequences of an inadequate diagnosis on measures of assistance for these patients is also investigated. The authors conclude on the necessity in considering, independently of the diagnosis, the description of symptoms, the intellectual level and the adaptative level in order to take the most appropriate educational and psychosocial decisions regarding pervasive developmental disorders without mental retardation.

Child↗
PubMed1997

Visual agnosia with bilateral temporo-occipital brain lesions in a child with autistic disorder: a case study.

A 2-year-old boy meeting the criteria for autistic disorder was diagnosed 2 years later with a visual agnosia characterised by a combination of certain aspects of associative and apperceptive agnosia. MRI then revealed a severe encephalomalacia of the right temporal lobe and bilateral temporo-occipital areas. This association is discussed in terms of a clinical and aetiological relation between autistic disorder and visual agnosia.

Agnosia↗
PubMed1996

Proper name hypermnesia in an autistic subject.

The case study of an autistic "savant" subject with person names hypermnesia is presented. NM's performance in memorizing person names is compared to that of normal controls, IQ-matched controls, and one overtrained control. The data show a selective hypermnesia for both the free recall of person names and the recognition of faces. Recall of common names and of biographical informations linked to faces is unremarkable. NM's hypermnesia is restricted to list learning as low performance is observed in face-name learning tasks. A comparison of the data with that of the overtrained control indicates that training is not responsible for NM's pattern of results. These findings, when combined with previous results involving proper names, demonstrate a double dissociation between proper names and other types of semantic and referential information. However, aspects of NM's performance pattern are more compatible with a network model of proper names than with a sequential model. We propose that the contextual regularity of proper names in ecological situations can be responsible for their high memorization by NM.

Adult↗
PubMed1995

Perspective production in a savant autistic draughtsman.

This study examines perspective construction in an autistic patient (E.C.) with quasinormal intelligence who exhibits exceptional ability when performing three-dimensional drawings of inanimate objects. Examination of E.C.'s spontaneous graphic productions showed that although his drawings approximate the 'linear perspective' system, the subject does not use vanishing points in his productions. Nevertheless, a formal computational analysis of E.C.'s accuracy in an experimental task showed that he was able to draw objects rotated in three-dimensional space more accurately than over-trained controls. This accuracy was not modified by suppressing graphic cues that permitted the construction of a vanishing point. E.C. was also able to detect a perspective incongruency between an object and a landscape at a level superior to that of control subjects. Since E.C. does not construct vanishing points in his drawings, it is proposed that his production of a precise realistic perspective is reached without the use of explicit or implicit perspective rules. 'Special abilities' in perspective are examined in relation to existing theoretical models of the cognitive deficit in autism and are compared to other special abilities in autism.

Adult↗
PubMed1995

Right-hemisphere dysfunction in Asperger's syndrome.

Asperger's syndrome has many clinical features in common with acquired right-hemisphere dysfunction and has been postulated to result from a developmental abnormality of the right hemisphere. However, right-hemisphere abnormality has not previously been documented on neuroanatomic or functional imaging in patients with Asperger's syndrome. We report three patients with Asperger's syndrome found to have abnormal right-hemisphere function on single photon emission computed tomographic (SPECT) imaging. The subjects were two males and one female, ranging from 12 to 16 years of age. All were diagnosed on the basis of the presence of the complete constellation of clinical features previously outlined. All patients were investigated with computed tomographic (CT) scanning, magnetic resonance imaging (MRI), and SPECT scanning. In one subject, CT and MRI revealed enlargement of the right lateral ventricle, reflecting a mild degree of right hemispheric atrophy. CT and MRI studies on the other two subjects were normal. SPECT scanning demonstrated right hemispheric abnormalities in each subject: right temporal hypoperfusion with a central area of increased perfusion along with frontal polar hyperperfusion in one; diffusely decreased right hemispheric uptake in the second; and decreased frontal and occipital uptake in the third. Cerebellar abnormalities were also present: a smaller right hemisphere with increased uptake in the first; decreased uptake in the vermis and right hemisphere in the second; and decreased vermal uptake in the third. These findings support the hypothesis that the neurobiologic basis of Asperger's syndrome is a developmental abnormality of the right cerebral hemisphere.

Adolescent↗
PubMed1993

A study of perceptual analysis in a high-level autistic subject with exceptional graphic abilities.

We report here the case study of a patient (E.C.) with an Asperger syndrome, or autism with quasinormal intelligence, who shows an outstanding ability for three-dimensional drawing of inanimate objects (savant syndrome). An assessment of the subsystems proposed in recent models of object recognition evidenced intact perceptual analysis and identification. The initial (or primal sketch), viewer-centered (or 2-1/2-D), or object-centered (3-D) representations and the recognition and name levels were functional. In contrast, E.C.'s pattern of performance in three different types of tasks converge to suggest an anomaly in the hierarchical organization of the local and global parts of a figure: a local interference effect in incongruent hierarchical visual stimuli, a deficit in relating local parts to global form information in impossible figures, and an absence of feature-grouping in graphic recall. The results are discussed in relation to normal visual perception and to current accounts of the savant syndrome in autism.

Adult↗