Objectives: The present investigation examined functional activations of autistic patients and healthy subjects performing goal-directed actions.
Methods: Twenty right-handed male participants aged 20 to 34 years were included: ten autistic patients with normal IQ and ten healthy subjects. Subjects were scanned for anatomical and fMRI with a GE Signa 1.5 T system using a head gradient coil. Two experiments were performed using a blocked design. Experiment 1. Five conditions were proposed during 5 runs: visual perception of a real object in a box, visually-guided grasping of this object in the box, blind grasping of this object in the box, reaching this object in the box, mime of the grasping gesture without the object in the box. Experiment 2. Three video sequences were proposed: observation of a moving hand, of a moving object and of a hand manipulating the object. Data were analyzed using the freesurfer-fsfast package using a GLM and visualized on a flat representation of the cerebral cortex. Group analysis was performed using a surfacic coordinate system for coregistration and a random model effect.
Results: Both groups showed normal activations in left motor cortices in grasping experiments. Parietal (IPS) and occipital (EBA and LOC) activations were lower in the autism group than in the comparison group. During action observation tasks, inferior frontal, superior parietal and intraparietal were also less activated than in the control group. Conclusions: This suggests an impairment of the neuronal system linking action perception and execution (canonical neurons and mirror neurons systems) usually activated during the goal-directed actions in the autistic pathology.