M-J Caron | PubMed Health

PubMed2006

Cognitive mechanisms, specificity and neural underpinnings of visuospatial peaks in autism.

In order to explain the cognitive and cerebral mechanisms responsible for the visuospatial peak in autism, and to document its specificity to this condition, a group of eight high-functioning individuals with autism and a visuospatial peak (HFA-P) performed a modified block-design task (BDT; subtest from Wechsler scales) at various levels of perceptual cohesiveness, as well as tasks tapping visuomotor speed, global perception, visual memory, visual search and speed of visual encoding. Their performance was compared with that of 8 autistics without a visuospatial peak (HFA-NP), 10 typically developing individuals (TD) and 8 gifted comparison participants with a visuospatial peak (TD-P). Both HFA-P and HFA-NP groups presented with diminished detrimental influence of increasing perceptual coherence compared with their BDT-matched comparison groups. Neither autistic group displayed a deficit in construction of global representations. The HFA-P group showed no differences in performance level or profile in comparison with the gifted BDT-matched [i.e. higher full-scale IQ (FSIQ)] group, apart from locally oriented perception. Diminished detrimental influence of perceptual coherence on BDT performance is both sensitive and specific to autism, and superior low-level processing interacts with locally oriented bias to produce outstanding BDT performance in a subgroup of autistic individuals. Locally oriented processing, enhanced performance in multiple tasks relying on detection of simple visual material and enhanced discrimination of first-order gratings converge towards an enhanced functioning and role of the primary visual cortex (V1) in autism. In contrast, superior or typical performance of autistics in tasks requiring global processing is inconsistent with the global-deficit-driven Weak Central Coherence hypothesis and its neurobiological magnocellular deficit counterpart.

Adolescent↗

PubMed2004

Do high functioning persons with autism present superior spatial abilities?

This series of experiments was aimed at assessing spatial abilities in high functioning individuals with autism (HFA), using a human-size labyrinth. In the context of recent findings that the performance of individuals with HFA was superior to typically developing individuals in several non-social cognitive operations, it was expected that the HFA group would outperform a typically developing comparison group matched on full-scale IQ. Results showed that individuals with autism performed all spatial tasks at a level at least equivalent to the typically developing comparison group. No differences between groups were found in route and survey tasks. Superior performance for individuals with HFA was found in tasks involving maps, in the form of superior accuracy in graphic cued recall of a path, and shorter learning times in a map learning task. We propose that a superior ability to detect [Human Perception and Performance 27 (3) (2001) 719], match [Journal of Child Psychology and Psychiatry 34 (1993) 1351] and reproduce [Journal of Child Psychology and Psychiatry 40 (5) (1999) 743] simple visual elements yields superior performance in tasks relying on the detection and graphic reproduction of the visual elements composing a map. Enhanced discrimination, detection, and memory for visually simple patterns in autism may account for the superior performance of persons with autism on visuo-spatial tasks that heavily involve pattern recognition, either in the form of recognizing and memorizing landmarks or in detecting the similarity between map and landscape features. At a neuro-anatomical level, these findings suggest an intact dorso-lateral pathway, and enhanced performance in non social tasks relying on the infero-temporal pathway.

Adolescent↗