Objectives: To identify the neural bases of initiating and responding to joint attention in typical adults and to examine how these differ in adults with high-functioning autism and Asperger’s disorder.
Methods: For Experiment 1, functional magnetic resonance imaging (fMRI) data were collected from 22 typical adults with no known neurological impairments during a real-time face-to-face interactive game designed to elicit joint attention behaviors. During the responding to joint attention condition, the subject followed the experimenter’s gaze to find a hidden target. In the initiating joint attention condition the experimenter followed the subject’s gaze to find the hidden target. In the non-joint attention control condition, the subject searched for the target while the experimenter signaled that she was not playing the game by closing her eyes. Data from this experiment were used to identify the regions of interest (ROI) in both responding to and initiating joint attention as compared to the nonjoint attention control for Experiment 2. For Experiment 2, fMRI data were collected during the same joint attention game from 15 adults with autism spectrum disorder and 15 age- and sex- matched typical controls. Region of interest and whole-brain analyses were conducted to identify commonalities and differences in regions recruited for joint attention between the autism and typical control groups.
Results: In Experiment 1, both initiating and responding to joint attention recruited regions associated with mentalizing and attention systems [mentalizing: bilateral posterior superior temporal sulcus (pSTS), dorsal medial prefrontal cortex (dMPFC); and attention: left intraparietal cortex (LIPL), right inferior frontal gyrus (R IFG)]. In Experiment 2, percent signal change was extracted from these regions from both the autism and matched controls. Repeated measures ANOVAs revealed a significant interaction (group x condition) in the left posterior STS and dorsal medial prefrontal cortex. Furthermore, whole-brain between group analyses of responding to joint attention (RJA) revealed greater recruitment of right posterior STS and dorsal medial prefrontal cortex in controls as compared to autism.
Conclusions: Joint attention recruits both mentalizing and attention systems. Adults with high-functioning ASD show reduced activation within primarily mentalizing systems suggesting this system may underlie the pervasive impairments seen in joint attention in ASD individuals.