Objectives: The primary objective of this study is to examine the functional integrity of cortical networks, especially the dorsal and ventral visual streams, involved in visual processing in children with autism.
Methods: Four high-functioning children (age range: 10-15 years) with autism, and two typical control participants took part in this fMRI study (data collection is in progress). The fMRI data collected from the Siemens 3.0T Allegra scanner at the UAB Civitan International Research Center is analyzed using SPM2 (Wellcome Department of Cognitive Neurology, London, UK). The stimuli consist of a series of common household objects presented in blocked design format in two experimental conditions. In the object recognition condition, the participants named an object from four choices, and in the location identification condition, they identified the location of a given object with respect to a cross on the screen.
Results: The fMRI data from this study showed that the dorsal and ventral visual streams were differentially recruited in the control participants for location and object conditions respectively. While the control participants activated inferior parietal area in the location identification condition and inferior temporal gyrus in the object recognition condition, participants with autism showed activation in parietal areas in both experimental conditions. In addition, unlike control participants, the participants with autism showed no activation in left inferior frontal gyrus in the object recognition condition. Behavioral results showed that the autism group made more errors in their responses; however both groups showed no differences in latency for either condition. The results are preliminary at this point and reveal only a trend.
Conclusions: The participants with autism seem to recruit more posterior brain areas, such as intraparietal sulcus in accomplishing both tasks suggesting their increased reliance on visuospatial processing. This type of processing is also reflected in the lack of reliance on language areas (reduced activation in left inferior frontal and left posterior superior temporal areas) when recognizing and naming an object. As the data collection is progressing, functional connectivity analysis with adequate sample size will be important in determining the integrity of the dorsal and ventral visual streams in autism.