Brain Advance Access originally published online on April 5, 2006
Brain 2006 129(7):1789-1802; doi:10.1093/brain/awl072
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Cognitive mechanisms, specificity and neural underpinnings of visuospatial peaks in autism
1 Clinique Spécialisée de l'Autisme, Hôpital Rivière-des-Prairies Montréal, Canada 2 Département de Psychologie, Université du Québec à Montréal Montréal, Canada 3 Département de Psychiatrie, Université de Montréal Montréal, Canada
Correspondance to: L. Mottron, Clinique Spécialisée des Troubles Envahissants du Développement, Hôpital Rivière-des-Prairies, 7070 Boul. Perras, Montréal (PQ), Canada H1E 1A4 E-mail: mottronl{at}istar.ca
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.
Key Words: autism; visuospatial peak; occipital cortex; parvocellular pathway; magnocellular pathway
Abbreviations: ADI, Autism Diagnosis Interview; BDT, block-design task; CT, construction time; EPF, enhanced perceptual functioning; FSIQ, full-scale IQ; HFA-NP, high-functioning individuals with autism and without a visuospatial peak; HFA-P, high-functioning individuals with autism and a visuospatial peak; ISI, interstimulus interval; PC, perceptual cohesiveness; RT, reaction times; TD-P, typically developing individuals with visuospatial peak; TU, task uncertainty; WCC, Weak Central Coherence; WISC, Wechsler Intelligence Scales
Received December 1, 2005. Revised February 28, 2006. Accepted March 1, 2006.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  E. Sheppard, D. Ropar, and P. Mitchell Perceiving the impossible: How individuals with autism copy paradoxical figures Autism, July 1, 2009; 13(4): 435 - 452. [Abstract] [PDF]
|
|
|
|
 |
|
 L. Mottron, M. Dawson, and I. Soulieres Enhanced perception in savant syndrome: patterns, structure and creativity Phil Trans R Soc B, May 27, 2009; 364(1522): 1385 - 1391. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Heaton, K. Williams, O. Cummins, and F. Happe Autism and pitch processing splinter skills: A group and subgroup analysis Autism, March 1, 2008; 12(2): 203 - 219. [Abstract] [PDF]
|
|