title: Autistic fluid intelligence: Increased reliance on visual functional connectivity with diminished modulation of coupling by task difficulty.
abstract: Different test types lead to different intelligence estimates in autism, as illustrated by the fact that autistic individuals obtain higher scores on the Raven's Progressive Matrices (RSPM) test than they do on the Wechsler IQ, in contrast to relatively similar performance on both tests in non-autistic individuals. However, the cerebral processes underlying these differences are not well understood. This study investigated whether activity in the fluid "reasoning" network, which includes frontal, parietal, temporal and occipital regions, is differently modulated by task complexity in autistic and non-autistic individuals during the RSPM. In this purpose, we used fMRI to study autistic and non-autistic participants solving the 60 RSPM problems focussing on regions and networks involved in reasoning complexity. As complexity increased, activity in the left superior occipital gyrus and the left middle occipital gyrus increased for autistic participants, whereas non-autistic participants showed increased activity in the left middle frontal gyrus and bilateral precuneus. Using psychophysiological interaction analyses (PPI), we then verified in which regions did functional connectivity increase as a function of reasoning complexity. PPI analyses revealed greater connectivity in autistic, compared to non-autistic participants, between the left inferior occipital gyrus and areas in the left superior frontal gyrus, right superior parietal lobe, right middle occipital gyrus and right inferior temporal gyrus. We also observed generally less modulation of the reasoning network as complexity increased in autistic participants. These results suggest that autistic individuals, when confronted with increasing task complexity, rely mainly on visuospatial processes when solving more complex matrices. In addition to the now well-established enhanced activity observed in visual areas in a range of tasks, these results suggest that the enhanced reliance on visual perception has a central role in autistic cognition.
authors.affiliation: Department of Psychology, University of Montreal, Pavillon Marie-Victorin, C.P. 6128, Succursale Centre-ville, Montréal, Québec H3C 3J7, Canada ; Research Center, Institut universitaire en santé mentale de Montréal, 7401, rue Hochelaga, Montréal, Québec H1N 3M5, Canada.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Simard
authors.affiliation: Research Center, Institut universitaire en santé mentale de Montréal, 7401, rue Hochelaga, Montréal, Québec H1N 3M5, Canada ; Department of Psychiatry, University of Montreal, Pavillon Roger-Gaudry, Faculté de Medicine, C.P. 6128, Succursale Centre-ville, Montreal, Québec H3C 3J7, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Luck
authors.affiliation: Research Center, Institut universitaire en santé mentale de Montréal, 7401, rue Hochelaga, Montréal, Québec H1N 3M5, Canada ; Department of Psychiatry, University of Montreal, Pavillon Roger-Gaudry, Faculté de Medicine, C.P. 6128, Succursale Centre-ville, Montreal, Québec H3C 3J7, Canada.
authors.forename: Laurent
authors.initials: L
authors.lastname: Mottron
authors.affiliation: Neural Systems Group, Massachusetts General Hospital, 149 13th St, Psychiatry, Rm 2651, Charlestown, MA 02129, USA.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Zeffiro
authors.affiliation: Research Center, Institut universitaire en santé mentale de Montréal, 7401, rue Hochelaga, Montréal, Québec H1N 3M5, Canada ; Department of Psychology, University of Quebec in Montreal (UQAM), C.P. 8888, Succ. Centre-Ville, Montreal, Quebec H3C 3P8, Canada.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Soulières
mesh_terms: D000328:Adult; D001321:Autistic Disorder / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007360:Intelligence / Q000502:physiology*; D007361:Intelligence Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D011340:Problem Solving / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult
keywords: Autism; Connectivity; Intelligence; PPI; Reasoning; fMRI