Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Filters applied. Clear all
. 2010 Jan;48(1):86-95.
doi: 10.1016/j.neuropsychologia.2009.08.013.

Neuroimaging of the Functional and Structural Networks Underlying Visuospatial vs. Linguistic Reasoning in High-Functioning Autism

Affiliations
Free PMC article

Neuroimaging of the Functional and Structural Networks Underlying Visuospatial vs. Linguistic Reasoning in High-Functioning Autism

Chérif P Sahyoun et al. Neuropsychologia. .
Free PMC article

Abstract

High-functioning individuals with autism have been found to favor visuospatial processing in the face of typically poor language abilities. We aimed to examine the neurobiological basis of this difference using functional magnetic resonance imaging and diffusion tensor imaging. We compared 12 children with high functioning autism (HFA) to 12 age- and IQ-matched typically developing controls (CTRL) on a pictorial reasoning paradigm under three conditions: V, requiring visuospatial processing; S, requiring language (i.e., semantic) processing; and V+S, a hybrid condition in which language use could facilitate visuospatial transformations. Activated areas in the brain were chosen as endpoints for probabilistic diffusion tractography to examine tract integrity (FA) within the structural network underlying the activation patterns. The two groups showed similar networks, with linguistic processing activating inferior frontal, superior and middle temporal, ventral visual, and temporo-parietal areas, whereas visuospatial processing activated occipital and inferior parietal cortices. However, HFA appeared to activate occipito-parietal and ventral temporal areas, whereas CTRL relied more on frontal and temporal language regions. The increased reliance on visuospatial abilities in HFA was supported by intact connections between the inferior parietal and the ventral temporal ROIs. In contrast, the inferior frontal region showed reduced connectivity to ventral temporal and middle temporal areas in this group, reflecting impaired activation of frontal language areas in autism. The HFA group's engagement of posterior brain regions along with its weak connections to frontal language areas suggest support for a reliance on visual mediation in autism, even in tasks of higher cognition.

Figures

Figure 1
Figure 1
A. Example Stimuli for each condition: left: VISUOSPATIAL (V); middle: VISUOSPATIAL+SEMANTIC (V+S), right: SEMANTIC (S). Subjects were asked to fill in the blank in the matrix with one of the three proposed choices. In the V+S condition, visuospatial manipulations are necessary for successful solving, but language mediation is available as a potential facilitating strategy. B. Schematic of a typical stimulus presentation sequence for the beginning of a run. The catch-up times (4 per run) represent fixation periods of varying durations, adjusted for equating the total duration of each run to 5 minutes.
Figure 2
Figure 2
A. Regions of interest obtained from omnibus activation maps, used in tractography analysis. LH: left hemisphere; RH: right hemisphere. B. Statistical z-maps of fMRI activation for each condition vs. fixation (shown here for the CTRL group). Lateral (top) and ventral (bottom) views are shown for each condition. The maps are displayed on an inflated cortical surface template, where sulci and gyri are represented in dark and light gray, respectively.
Figure 3
Figure 3
Group comparison of fMRI activation (z-map): CTRL > HFA (red/yellow) and HFA > CTRL (blue/light blue) for each condition (S, left; V+S, middle; C, right). The maps are displayed on an inflated cortical surface template, where sulci and gyri are represented in dark and light gray, respectively. The top and bottom rows represent left (LH) and right (RH) hemisphere differences between the two groups, respectively.
Figure 4
Figure 4
Within-group subtraction z-maps of fMRI activation (S vs. V+S, S vs. V, V vs. V+S) between condition pairs in CTRL (left) and HFA (right) groups. The maps are displayed on an inflated cortical surface template, where sulci and gyri are represented in dark and light gray, respectively. The direction of subtractions was chosen such that increased language demands are shown in red/yellow, vs. blue/light blue for visuospatial demands. LH: left hemisphere; RH: right hemisphere.
Figure 5
Figure 5
A. Example output of tractography, overlayed on MNI template; Blue: endpoints of tractography (left hemisphere IPS and IF), Green: CTRL group pathway, Red: HFA group pathway. As shown in this example, pathways generally overlap almost perfectly in HFA and CTRL. B. Summary schematic of FA differences: Black lines represent pathways investigated where no differences in FA were found between HFA and CTRL. Red Lines represent pathways showing significantly decreased FA in HFA compared with CTRL; thinner red lines represent pathways showing a trend for decreased FA in HFA compared with CTRL. IPS: Inferior parietal sulcus; FG: Fusiform gyrus; STS: Superior temporal sulcus; MTG: Middle temporal gyrus; IF: Inferior frontal area.

Similar articles

See all similar articles

Cited by 59 articles

See all "Cited by" articles

Publication types

MeSH terms

Feedback